MOPL
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Monday Poster Session: MOPL
08 May 2023, 16:30 -
18:30
MOPL001
Status of the beam-based measurement of the skew-sextupolar component of the radio frequency field of a HL-LHC-type crab-cavity
504
Two High Luminosity Large Hadron Collider (LHC) type crab-cavities have been installed in the CERN SPS for testing purposes. A first partially successful attempt to characterize the skew-sextupolar component of the radio frequency field of the crab-cavity by means of beam-based techniques has been carried out in 2018. The large orbit distortion produced by the crab cavity dipolar field combined with the multipolar errors in the SPS optics resulted in some systematic errors that cannot be easily accounted for. After a major overhaul of the SPS turn-by-turn BPM system a second attempt was carried out in 2022. In the attempt to keep under control systematic errors, orbit correctors have been used to compensate the large orbit excursion produced otherwise by the crab cavity. The results of the new measurement are here discussed.
Paper: MOPL001
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL001
About: Received: 31 Mar 2023 — Revised: 01 Jun 2023 — Accepted: 01 Jun 2023 — Issue date: 26 Sep 2023
MOPL002
AC excitation studies for full coupling operation
508
Betatron coupling resonance has been considered by many low emittance upgrade light sources as a candidate to produce round beams. Due to the limited literature on the topic, last year an experimental campaign was undertaken on the ALBA storage ring to establish limits and requirements to operate a light source in full coupling. The work highlighted how coupling can indeed produce a round beam with certain easiness but not free from shortcomings: the fractional betatron tunes must be set equal, resulting in a substantial constraint to the optics and requiring a sophisticated control of the optics itself in order to keep the resonance condition despite the movement of insertion devices and drifts. To work around these limitations, this year a different approach, based on the excitation of the coupling resonance with an A.C. skew quadrupole was tested. A first experiment was attempted by converting the existing tune excitation stripline into a skew quadrupole, but the limited available power allowed to produce only a barely perceptible coupling. The stripline was then turned into an electric deflector by removing the resistive terminations and allowing to drive the electrodes to higher voltage. Here the newly obtained results with the A.C excitation are presented.
Paper: MOPL002
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL002
About: Received: 02 May 2023 — Revised: 06 Jun 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL003
Polarized proton operation at RHIC with partial snakes
512
A series of power outages during setup for RHIC Run 23 damaged two of the four helical dipole modules that comprised one of the full Siberian Snakes in RHIC’s Blue ring. The remaining two helical dipoles were reconfigured as a “partial” snake, one which rotates the spin by an angle less than 180 degrees. This partial snake configuration has a rotation angle and axis which both deviate from the ideal. We describe the compensatory measures taken to address the effects of these deviations. These include reconfiguring the other Blue snake to rematch the stable spin direction at injection and a change of the nominal store energy from 255 GeV to 254.2 GeV to improve the stable spin direction condition at store. Polarization transmission through RHIC acceleration was as good as with full snakes and we present some analytical and tracking results that corroborate the observed robustness with respect to deviations from ideal snakes.
Paper: MOPL003
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL003
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPL004
Stable spin direction measurements at RHIC with polarized proton beams
515
We describe methods for measuring the three-dimensional stable spin vector for RHIC stores at two locations in the ring, namely the proton-Carbon (pC) polarimeters and the interaction point at the STAR detector. Both the pC and STAR local polarimetry can only measure the two transverse components of the stable spin direction. Measuring the full spin vector requires making a local spin rotation at the measurement point. This is accomplished using the helical dipole spin rotators for STAR and a local horizontal orbit angle for the pC polarimeters, respectively. The stable spin direction at a third point, the hydrogen jet polarimeter is determined via spin tracking from the nearby pC polarimeter. We describe the measurement and analysis methods used and present results of the measurements made during RHIC Run 22.
Paper: MOPL004
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL004
About: Received: 02 May 2023 — Revised: 22 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPL008
Lattice optimization for Electron Ion Collider Hadron storage ring injection
519
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) will utilize the Relativistic Heavy Ion Collider (RHIC) arcs and modified straight sections. Due to these modifications in the straight section of the on project electron Proton Ion Collider (ePIC) experiment, a new injection system needed to be built one arc downstream of the existing RHIC injection system. The new injection system will have capability of injecting 290 bunches with a maximum rigidity of ~81 Tm. In addition to the new injection system, the hydrogen jet (HJET) and proton-carbon (pC) polarimeters will be located in the straight section downstream of injection. This paper will report the modifications required to the lattice, optics, and magnets.
Paper: MOPL008
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL008
About: Received: 18 Apr 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL011
Strategy for proton polarization in the Electron Ion Collider
523
The Electron Ion Collier (EIC) will utilize highly polarized electron and ion beams. To preserve polarization through numerous depolarizing resonances over the whole EIC hadron accelerator chain, harmonic orbit correction, partial snakes,horizontal tune jump system and full snakes have been used. A new scheme using skew quadrupoles to compensate horizontal intrinsic resonances is under development. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8E11 bunch intensity. For the EIC era, the beam brightness has to be maintained to reach the desired luminosity.This will be achieved by electron cooling at injection of EIC hadron storage ring. Since we only have one hadron ring in the EIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. The number of snakes can be increased. With properly arranged snakes in EIC and reduction of emittance, the polarization can reach 70% at 275 GeV. The general strategy of polarization preservation scheme in the injectors and hadron ring of the EIC is described in this paper.
Paper: MOPL011
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL011
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL012
Non-destructive spin tune measurement of polarized protons in a storage ring
527
To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a polarized collider such as RHIC and EIC.
Paper: MOPL012
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL012
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL014
Challenges of K-modulation measurements in the LHC Run 3
531
The future upgrade to the High-Luminosity Large Hadron Collider (HL-LHC) will impose tight tolerances on IP optics measurements. k-modulation is currently the preferred method in the LHC for IP optics measurements and will play a critical role in the HL-LHC. As such, Run 3 of the LHC provides an ideal test-bench for addressing challenges in k-modulation. In the first commissioning year of Run 3, this method was used to measure and validate optics with beta ranging from 30cm to 24m. However unsatisfactory reproducibility was observed for low beta measurements. This paper presents the k-modulation results for the start of Run 3 with in depth analyses and it highlights the sensitivity of this method in view of the challenging HL-LHC runs.
Paper: MOPL014
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL014
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL015
LHC Run 3 optics corrections
535
The first year of Run 3 of the Large Hadron Collider (LHC) revealed significant changes in both linear and nonlinear optics errors with respect to Run 2. Several iterations of optics corrections were required to successfully bring the linear optics within operational tolerances. This paper presents the current status of optics corrections in the LHC and the challenges experienced in commissioning the optics to a beta* of 30cm in a single commissioning year after the Long Shutdown.
Paper: MOPL015
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL015
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL016
Advancements in injection efficiency modelling for the Low Energy Ion Ring (LEIR) at CERN
539
The performance of the Low Energy Ion Ring (LEIR) at CERN is mainly determined by the number of charges extracted from the machine and transferred to the downstream chain of accelerators. While the required target of 9e10 charges has now been surpassed, a series of studies have been undertaken to further push the intensity reach of LEIR. In this work, we quantify the effect of the stray fields generated by the adjoining Proton Synchrotron (PS), which were recently partially shielded, and the effect of the stripper foil in the Linac supplying LEIR with its ions, Linac 3. The impact of the stray field was measured by observing the variation in injection trajectory, while that of the stripper foil was determined from the evolution of the Schottky energy profile in LEIR. Models have been developed to extrapolate the impact of these effects to the injection efficiency of LEIR, and consequently to the extracted beam intensity.
Paper: MOPL016
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL016
About: Received: 24 Apr 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL018
Radiation field characterization for present LHC and future HL-LHC forward physics experiments
543
In recent years, there has been an increasing interest for experiments in the LHC complex that aim to push the frontiers of Physics, in locations that do not interfere with the normal operation of the machine while guaranteeing an acceptable signal-to-background ratio. This is the case with the Forward Search Experiment (FASER), which was approved in 2018, followed by the approval of the Scattering Neutrino Detector (SND) of the SHiP experiment in 2021. During the High Luminosity era, FASER and SND will continue to record data, for which a re-evaluation of the signal and background levels is required to prepare for the installation of the new detectors. Furthermore, there is a proposal for the construction of a Forward Physics Facility (FPF) at more than 600 m from the ATLAS interaction point to house far-forward physics experiments. These would benefit from a very low background due to the distance from the LHC tunnel and the more than 100 m of rock and concrete that serve as shielding, allowing the study of rare and exotic processes. Extensive calculations of physics signals, radiation levels and background conditions were performed by FLUKA Monte Carlo simulations and are summarized in this paper.
Paper: MOPL018
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL018
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL019
Mitigation of losses at injection protection devices in the CERN LHC
547
During loss maps performed with beam at injection energy in the LHC with the high octupole and chromaticity settings used for multi-train operation, large beam losses were observed at an injection protection device (TDIS). Although these losses did not present a threat to machine operation or protection, reducing them is of high importance to improve machine performance. Various strategies were developed to mitigate these losses, such as octupole setting optimization at constant Landau damping and vertical tune reduction. Further optimization of collimator settings is also considered. Results of experimental tests and first simulations are reported here together with considerations for the future.
Paper: MOPL019
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL019
About: Received: 03 May 2023 — Revised: 20 Jun 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL020
The LHC run 2022
551
Following a 3-year long shutdown for upgrade and consolidation work, the LHC was re-commissioned in spring 2022, achieving a new record of 6.8 TeV per beam. This paper will describe the beam commissioning phase, the electron cloud conditioning, and the intensity ramp-up bringing the machine to a steady production state. The main issues and achievements will be presented, including the fully automated luminosity levelling via β* adjustment. The limitations for beam intensity and peak luminosity will also be discussed.
Paper: MOPL020
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL020
About: Received: 22 Apr 2023 — Revised: 11 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL021
First results of running the LHC with lead ions at a beam energy of 6.8 Z TeV
555
A two-day test of operation with Pb ion beams was carried out in the CERN Large Hadron Collider (LHC) in 2022, with the aim of gaining experience in view of the future high luminosity heavy-ion physics runs from 2023 onwards. The LHC experiments received the first Pb-Pb collisions at a record energy of 5.36 TeV centre-of-mass energy per colliding nucleon pair (beam energy 6.8 Z TeV). Bunch trains created with a new production scheme in the injectors, including slip-stacking, were injected into the LHC, with the collimation of nuclear beams with bent crystals tested along with a new collimation scheme for collision products. This paper describes the conditions and outcomes of these tests, which are critical steps in the upgrade to higher luminosity.
Paper: MOPL021
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL021
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL022
Operational handling of Crystal collimation at the LHC
559
A non-negligible risk of magnet quenches occurring due to the reduced cleaning performance of the original LHC collimation system with lead ion beams was expected at an energy of 6.8 Z TeV beams. Crystal collimation has therefore been integrated into the HL-LHC upgrade baseline to overcome present limitations. The upgrade scope involves the installation of 4 new crystal primary collimators. Upgraded devices were installed based on the experience and experimental evidence gathered with a previously-installed test stand. In preparation to the new operational challenges, the controls of the new devices were integrated in the high-level LHC collimation control system, which is used to orchestrate the operation of these devices in harmony with all the other components of the machine. A dedicated application was also developed to address three main tasks: to find the main planar channeling of newly installed crystals using Machine Learning models developed at CERN; to optimise the angular orientation to maximise the channeling efficiency; to monitor that the optimal channeling orientation is kept throughout the fill. This paper will present and discuss all of these aspects.
Paper: MOPL022
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL022
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL023
Crystal collimation performance at the LHC with a 6.8 TeV proton beam
563
Crystal collimation is studied to improve the collimation efficiency with ion beams at the High-Luminosity Large Hadron Collider (HL-LHC). Bent crystals are used instead of conventional primary collimators to deflect high-energy halo particles at angles orders of magnitude larger than what can be achieved with scattering by conventional materials. Following the promising results obtained during Run 2 (2015-2018) and the first year of Run 3 (2022), this collimation technique is planned to be used operationally already for LHC Run 3 heavy-ion operation, starting in 2023, to mitigate the risk of magnet quenches from beams of higher energy and intensity. Tests with low-intensity proton beams are extremely important to characterize the crystal collimator hardware, assess the performance and investigate other operational aspects in preparation for the ion run. This paper presents the results of tests carried out in 2022 with proton beams at the record energy of 6.8 TeV.
Paper: MOPL023
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL023
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL024
Measurement and modelling of decapole errors in the LHC from beam-based studies
567
Studies of third-order chromaticity in the LHC during its initial two runs have consistently demonstrated a substantial discrepancy between the expected Q''' at injection and that observed in beam-based measurements. In 2022 during Run 3, for the first time, studies of Q''' have been complemented by measurements of chromatic detuning, being the momentum-dependence of amplitude detuning, and the decapole resonance driving term 𝑓1004. In this paper, these beam-based measurements are presented and compared to the magnetic model. Potential sources of the previously identified Q”’ discrepancy are discussed.
Paper: MOPL024
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL024
About: Received: 24 Apr 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL026
60° phase advance optics measurements in the Large Hadron Collider at CERN
571
The Large Hadron Collider (LHC) arcs have been designed for a FODO optics with roughly 90° betatron phase advance per arc cell, but not necessarily with exactly the same optics in the eight sectors of the ring. Measuring an optics with a significantly different arc cell phase advance, e.g. 60° which is at the limit for aperture at LHC injection, offers the possibility of understanding the LHC in an unprecedented depth. Furthermore, this optics would allow focusing higher energy beams, since the required quadrupole settings are lower than for the standard 90° optics for the same beam energy. Such an optics has therefore been designed, respecting all constraints for one low intensity pilot bunch per beam, and tested during commissioning of LHC Run 3 in 2022. First measurements, performed only for one beam at injection, are presented and compared to results obtained for the nominal 90° optics.
Paper: MOPL026
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL026
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL027
First measurement of fourth and fifth order chromaticity in the LHC
575
Chromaticity up to the third order in the LHC has been well observed in the LHC’s first and second operational runs, with regular beam-based measurements performed during commissioning and machine development. In previous runs however, no higher-order chromaticity could be observed. In 2022, dedicated collimators setups meant optics measurements could benefit from an improved range of momentum-offset for the chromaticity studies. This allowed the observation of fourth and fifth order chromaticity in the LHC at 450GeV for the first time. Measurements were performed for several machine configurations. In this paper, results of the higher order non-linear chromaticity are presented and compared to predictions of the LHC magnetic model.
Paper: MOPL027
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL027
About: Received: 25 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL028
Configuration management of the CERN accelerators complex on the road to long shutdown 3
579
The Configuration Management of the LHC and its injectors ensures a clear and coherent representation of the CERN accelerators at a given point in time. It has been evolving steadily. The methodology has been continuously improved, incorporating best practices and was also extended to the injectors to face the Long Shutdown 2 (LS2) with a set of rigorous and homogenised processes for the entire accelerator complex. Lessons learnt from the LS2 provide a strong basis to further improve the effectiveness of the change management process. This paper describes the action plan, concerning the processes and engineering tools, to further improve configuration management efficiency to face the numerous changes foreseen during the Long Shutdown 3 (LS3), with principally the equipment installation foreseen by the HL-LHC project. In addition, it reports on the smooth transition between the LHC and HL-LHC configuration teams to ensure the long-term operation and maintenance of the LHC.
Paper: MOPL028
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL028
About: Received: 28 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL029
Simulations and measurements of collisional losses with Pb beams at the LHC
582
During about one month in every operational year, the Large Hadron Collider (LHC) works as a heavy-ion collider. Four one-month Pb-Pb runs have been executed so far, as well as two p-Pb runs. The LHC heavy-ion programme is scheduled to continue in the future, featuring increased luminosity and beam energy. Beam losses caused by ions fragmenting in the collision process risk introducing performance limitations. Losses occur immediately downstream of the collision points as well as at other locations in the ring, through multi-turn beam dynamics processes and interactions with ring collimators. This paper presents simulations of collisional loss patterns using a new simulation approach that relies on the SixTrack-FLUKA coupling. Simulations of the 2018 Pb-Pb and 2016 p-Pb runs are benchmarked against experimental data and the prediction of collisional losses for future Pb-Pb and p-Pb runs is shown.
Paper: MOPL029
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL029
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL030
Optimizing Pb beam losses at the LHCb for maximum luminosity
586
In addition to the physics program with proton beams, the Large Hadron Collider (LHC) also provides collisions of fully-stripped Pb beams for about one month per year. When colliding Pb-Pb nuclei, electromagnetic interactions are the dominating processes because of the intense Coulomb field produced by the ions. These 'ultra-peripheral' interactions give rise to special losses in the machine that can impose limits on the luminosity. Among them, the bound-free pair production (BFPP) causes a localized power deposition downstream of each collision point, which could induce superconducting magnet quenches if not well controlled. These losses were studied and successfully mitigated for most LHC experiments, however the recent request by LHCb to increase the Pb-Pb luminosity requires a revision of BFPP collisional loss limitations. In this paper, the simulation of BFPP losses from Pb-Pb collisions around LHCb is presented. The loss patterns are discussed for different beam parameters. Finally, a mitigation strategy by means of an orbit bump is studied.
Paper: MOPL030
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL030
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL031
Commissioning strategies of hollow electron lens residual kick compensation
590
Hollow electron lenses (HELs) could be used in the HL-LHC to selectively remove halo particles from the circulating beams. While the ideal design should leave particles in the beam core unaffected, in reality, the core particles will be exposed to a small residual kick that could induce transverse emittance blowup if not properly compensated while the HEL is operated in pulsed mode. One possible solution would be to couple the HEL pulse with the adjacent HL-LHC transverse damper (ADT). The principle consists of exerting an oppositely directed kick with the ADT at each turn the HEL is switched on, thus compensating the HEL residual kick on the beam core. In this contribution, we simulate the performance of this compensation scheme and possible commissioning scenarios, aiming at reliably setting up the compensation scheme when the direction and amplitude of the residual kick are, a priori, unknown.
Paper: MOPL031
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL031
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL032
Combined-function optics for the lattice of the CERN hadron-hadron Future Circular Collider ring
594
Magnetic fields in the 12-16 T range are needed to bend the beams in future hadron colliders, such as the CERN FCC-hh. For these magnets, made with Nb3Sn superconducting cable, a small reduction of the field brings a non-negligible reduction of cost and complexity. Increasing the dipole filling factor is hence a priority to provide higher energies for the same magnetic fields - or the same energies for lower magnetic fields. To this aim, the use of combined-function magnets is proposed to design the ring lattice in place of the standard separate-function solution. The properties of the combined-function solution and of the magnets that would be needed for the FCC-hh are presented and discussed in detail in this paper.
Paper: MOPL032
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL032
About: Received: 19 Apr 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL033
Recent updates of the layout of the lattice of the CERN hadron-hadron Future Circular Collider
598
The Future Circular Collider (FCC) study comprises two accelerators, namely a high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh). Both rings share the same tunnel infrastructure, analogous to LEP and LHC. We present the current design status of FCC-hh, updated from the Conceptual Design Report (CDR) and with recent developments including the new designs of the combined injection and dump insertion, combined injection and RF insertion, new collimation insertions, as well as the optimization of the arc cells and dispersion suppressors to increase the dipole filling factor.
Paper: MOPL033
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL033
About: Received: 19 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL034
High Luminosity LHC optics scenarios for Run 4
602
Run 4 will be the first operational run of the LHC with full deployment of the upgrades from the High Luminosity (HL-LHC) project planned for 2026-2028 (Long Shutdown 3). The commissioning goals for the first run were defined to approach steadily the design beam current, while already fulfilling significant luminosity goals. Despite extensive operational experience already gained, intensity limitations due to electron cloud and/or impedance might require to further reduce beta* values from the very early stages. The paper presents various optics configurations considered under different Run4 scenarios together with their expected dynamic aperture.
Paper: MOPL034
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL034
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL035
Harmonics of 50 Hz on the beam spectrum of the Large Hadron Collider
606
Studies of the beam spectrum of the Large Hadron Collider (LHC) have revealed the existence of harmonics of the mains frequency (50~Hz), ranging from 50~Hz to 8~kHz, in the form of transverse dipolar excitations. The restart of the LHC operation in Run 3 was accompanied by substantial improvements in the beam instrumentation. In particular, the upgrade of the transverse damper’s observation system (ADTObsBox), currently providing bunch-by-bunch and continuous position measurements, allows for the first time a systematic follow-up of the harmonics’ evolution during the run. In this paper, we present parasitic observations collected during the LHC physics operation, as well as results from dedicated experiments with the aim of providing further insights into the source of the perturbation, especially concerning the 50~Hz harmonics around 8~kHz. These tests include modifications in the operation mode of systems such as some of the Uninterruptible Power Supplies, while observing potential changes in the spectrum of the beam position data.
Paper: MOPL035
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL035
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL036
Power deposition studies for betatron halo losses in HL-LHC
610
The Large Hadron Collider (LHC) is equipped with a betatron halo collimation system designed to prevent magnet quenches during periods of reduced beam lifetime. Protons subject to single diffractive scattering in collimators can nevertheless leak into the adjacent dispersion suppressors (DS). In view of the future high-luminosity (HL) upgrade of the LHC, a better understanding of the quench margin in these DS magnets is needed, considering the increased beam current and the resulting higher beam losses of up to 1 MW of power within a few seconds, which the collimation system is designed to withstand. In this contribution, we present FLUKA power deposition simulations for a controlled beam loss experiment at 6.8 TeV, probing the quench level of the superconducting magnets most exposed to collimation losses. The results are compared with the expected power deposition in HL-LHC operation, considering different collimator settings. In particular, we studied the power deposition for relaxed collimator gaps, which are considered as the baseline configuration for initial operation in Run 4.
Paper: MOPL036
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL036
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL038
Automated evaluation of LHC proton losses during high-energy beam dumps for the Post-Mortem System
614
All high-energy beam dump events at the Large Hadron Collider (LHC) are analysed to verify correct functioning of the Machine Protection System and to allow early identification of potential issues. This includes the evaluation of particle losses before and during the beam dump event. The paper describes a newly developed tool for the automated evaluation of beam losses during high energy proton dumps. It presents the approach to derive individual thresholds for more than 3600 Beam Loss Monitors based on historic data from Run 2 of the LHC (2015–2018) and reviews the performance of the tool.
Paper: MOPL038
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL038
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL039
Machine protection perspective on the restart of the large hadron collider after long shutdown 2
618
In 2022, the Large Hadron Collider started its third operational run. Following the three-year Long Shutdown 2, a careful re-commissioning of the machine protection system (MPS) took place. The initial hardware and beam commissioning period was followed by a 30-day-long intensity ramp-up, during which the number of circulating bunches was successively increased to 2460 bunches per beam. After each pre-defined intensity step, a detailed analysis of the functionality of the MPS was performed before advancing to the next step. It paved the way to reach a record stored energy of 400 MJ per beam in 2022. This was achieved without observing any beam-induced damage, confirming the excellent performance of the MPS. The paper reviews the strategy for the LHC re-commissioning and intensity ramp-up from a machine-protection perspective.
Paper: MOPL039
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL039
About: Received: 03 May 2023 — Revised: 16 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL040
Experience from the US contribution to HL-LHC: Nb3Sn focusing quadrupoles and SRF crab cavities
622
The Interaction Regions (IR) of many colliders benefit from the application of leading-edge technologies to ensure the highest possible luminosity delivered to the experiments. Leading-edge low-beta focusing magnets and crab cavities to handle individual bunches are critically important to increase the instantaneous and integrated luminosity in future Colliders. The High-Luminosity LHC Upgrade, HL-LHC, with Nb3Sn Magnets (called MQXF) and Superconducting Radio Frequency (SRF) crab cavities (of two types, called DQW and RFD) is a world-wide collaborative project under construction in this decade to utilize the solutions mentioned above as key ingredients to increase tenfold the integrated luminosity delivered to the CMS and ATLAS experiments in the next decade. The HL-LHC AUP is the US effort to contribute approximately 50% of the low-beta focusing magnets and crab cavities for the HL-LHC. In this contribution we present the valuable lessons learned by the US efforts in the procurement, construction, and testing phases of the Nb3Sn focusing magnets and SRF crab cavities. We will report on the experience gathered by HL-LHC AUP in the production of the first half of deliverables (magnets MQXFA03 to MQXFA13). We will also report on the test of the first cryoassemblies and the status of the cavities’ development, production and testing. Both the technical and project management lessons-learned will inform applications of these technologies to future colliders and projects.
Paper: MOPL040
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL040
About: Received: 01 May 2023 — Revised: 23 Jun 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL041
EIC crab cavity multipole effects on dynamic aperture
626
The Electron Ion Collider is adopting a crabbing scheme of 25 mrad crossing angle. The local crab cavity system designed to kick the bunches in the first interaction region (IR) also introduces higher order multipoles com-ponents in electric field which affect the dynamic aperture. We have studied the strength of each multipole up to n = 4, or octupole, with respect to the main dipole field in different operating scenarios. Dynamic aperture study has continued with a fundamental crabbing system at 197 MHz and its second harmonic system at 394 MHz. A comparison of multipole effect for different phase ad-vance between the two crab cavity systems across the IP is shown in this paper. Method of decreasing the sextupole component is investigated as a result of the dynamic aper-ture requirement.
Paper: MOPL041
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL041
About: Received: 03 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
MOPL042
Nonlinearity optimization for the 125 TeV SPPC collider ring lattice
630
As an energy frontier machine, the proposed Super Proton-Proton Collider (SPPC) will have the capability to explore a much larger region of new physics models with center of energy around 125 TeV and circumference 100 km. The nonlinearity optimization of the SPPC collider ring lattice is essential to get a high peak luminosity and lifetime of the beams. In this paper, a collider ring lattice based on the CDR one will be presented. Then, the nonlinearity of the bare lattice was optimized using Lie map analysis and frequency map analysis. With the optimization, the lattice aberration at the interaction points and dynamic aperture of whole ring were improved. Finally, the alignment tolerances and field error tolerances for the SPPC are evaluated. The correction scheme of the lattice with errors will be presented.
Paper: MOPL042
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL042
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL043
NICA ion collider and its acceleration complex
634
The Nuclotron-based Ion Collider fAcility (NICA) is under construction at JINR. The NICA project goal is to provide colliding beams for studies of hot and dense strongly interacting baryonic matter and spin physics. The NICA Collider includes two rings with 503 m circumference each and the injection complex. For the heavy ion mode, the injection complex consists of following accelerators: 3.2 MeV/u linac (HILAC), 600 MeV/u (A/Z=6) superconducting booster synchrotron (Booster) and main superconducting synchrotron (Nuclotron) with kinetic energy up to 3.9 GeV/u (A/Z=2.5). The injection complex has been under commissioning for more than 2 years. The latest half-year Run ended in February of 2023. It was devoted to preparations for the collider operation and also delivered slowly extracted 3.9 GeV/u xenon beam to the BM&N experiment. Now the injection complex is shut down for its further development and an assembly of the collider. Cryogenic tests of the collider magnetic structure are expected at the end of 2023. The next run of the injection complex is aimed at an increase of ion flux by more than an order of magnitude and will be started at 2024.
Paper: MOPL043
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL043
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL044
Prospect of operating with limited skew quadrupole corrector availability in the LHC interaction regions
638
In the Large Hadron Collider (LHC), corrections of local Interaction Region (IR) linear coupling are of importance to control beam sizes at Interaction Points (IPs) and hence the luminosity performance, as well as to prevent a significant impact on the beam dynamics. During the LHC Run 3, the skew quadrupole corrector magnets used on either side of IPs are expected to exceed their radiation dose limit. In this contribution, studies on the impact of operating with limited availability of these magnets are presented, should one or more become inoperable. Mitigation strategies for different scenarios are discussed.
Paper: MOPL044
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL044
About: Received: 25 Apr 2023 — Revised: 06 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL045
Operational beta* levelling at the LHC in 2022 and beyond
642
During the third run period of the CERN Large Hadron Collider (LHC), as well as for the future High-Luminosity LHC era, luminosity levelling by beta* is a key technique to control the pile-up in the high-luminosity experiments ATLAS and CMS while maintaining Landau damping through the head-on beam-beam interaction. This implies changing the machine optics in the interaction regions while keeping high-intensity beams in collision and the experimental detectors in their data taking configuration. This contribution summarizes the implementation and operational experiences obtained during the first year of operation with beta* levelling at the LHC and provides an outlook for the following years, when the beta* levelling range will be further extended.
Paper: MOPL045
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL045
About: Received: 21 Apr 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL046
Thermionic sources for electron cooling at IOTA
646
A new electron cooling experiment is being planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab for cooling ~2.5 MeV protons in the presence of intense space-charge. Electron cooling is integral to the study of beam dynamics and has valuable applications for producing high-intensity hadron beams in particle accelerators. For such goals, an electron lens to be placed in the IOTA ring will be used for electron cooling, space-charge compensation, and non-linear dynamics. Here we present the simulations and designs of two thermionic electron sources for the cooling at IOTA. One cooler is a basic electron source and will be used for cooling the proton beam and as a tool for other experiments at IOTA. The other cooler is a strong electron source, which will be used for studying effects of electron cooling in ion beams with intense space-charge. We particularly discuss parameters of the thermionic sources’ electrodes, as well as the simulation results. We also present a new electron source test-stand at the University of Chicago, which will be used to test the thermionic electron sources. We also discuss the results from analyzing the test stand operations with a currently existing electron source. Furthermore, we present future steps for production and commissioning of these thermionic sources at IOTA.
Paper: MOPL046
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL046
About: Received: 06 May 2023 — Revised: 16 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL048
Performance of a double-crystal setup for LHC fixed-target experiments
650
The Physics Beyond Colliders (PBC) studies at CERN address the possibility to utilise protons in the Large Hadron Collider (LHC) for a fixed-target program beyond the colliding-beam physics. As part of PBC, a double-crystal test stand is considered for installation in the LHC off-momentum collimation Insertion Region (IR) 3. In this PBC experiment, a first silicon crystal deflects beam-halo protons from the main beam onto a fixed-target. A second crystal, providing bending angles in the mrad range, is located immediately downstream of the target to deflect target-produced secondary particles onto a detector that will measure the electric and magnetic dipole moments of short-lived baryons. The LHC test stand will serve as a proof-of-principle machine experiment to assess the performance of new crystals at LHC energies and to address a number of critical machine aspects related to this complex setup. In this paper, simulations in MAD-X and SixTrack are used to predict the performance of the proposed double-crystal layout for the LHC Run 3 test stand and the LHC Run 4 final experiment.
Paper: MOPL048
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL048
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL051
CEPC damping ring design in TDR stage
654
A damping ring system which includes a small 1.1 GeV ring and two transport lines is introduced in CEPC linac in order to reduce the transverse emittance of positron beam at the end of linac and hence reduce the beam loss in the booster. The repetition rate of Linac is 100 Hz and one-bunch-per-pulse is considered. The double-bunch scheme of Linac is only considered for the high luminosity mode at Z pole. The positron beam is generated by 4 GeV electron beam hitting tungsten target and then is captured by an AMD flux concentrator. Each positron bunch is injected into damping ring every 10 ms and two bunches are stored in the ring so that the storage time for each bunch is 20 ms. The bunch number in the damping ring can be increased to 4 with an upgrade and hence the storage time for each bunch can be increased to 40 ms. The reversed bending magnet scheme is adopted for TDR in order to reduce the emittance significantly. The normalized emittance of positron beam is expected to be reduced from 2500 mm.mrad to 166 mm.mrad (or 97 mm.mrad) in the damping ring.
Paper: MOPL051
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL051
About: Received: 28 Apr 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL052
CEPC circumference optimization
658
The CEPC is a proposed high luminosity Higgs/Z factory, with the potential to be upgraded to top factory at center-of-mass energy of 360GeV. We perform an optimization study on the circumference of CEPC. We calculate the instant luminosity, the construction and operation cost for different circumferences. With respect to the total cost and average cost per particle, we conclude that the optimal circumference for the CEPC Higgs operation is 80 km. Taking into account of the Z pole operation, the potential high-energy upgrade of CEPC (top factory), the optimal circumference increased to 100 km. The long future proton-proton upgrade of CEPC (SPPC) also favors a larger circumference, and we conclude that 100 km is the global optimized circumference for this facility.
Paper: MOPL052
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL052
About: Received: 28 Apr 2023 — Revised: 08 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL053
A booster free from spin resonances for future 100 km-scale circular e+e- colliders
662
Acceleration of polarized electron and positron beams to ultra-high beam energies is of interests for polarized beam applications in future 100km-scale e+e- circular colliders. However, it was widely envisaged that crossing hundreds of spin depolarization resonances would lead to severe depolarization during the energy ramp in the booster synchrotron. In this work, we have studied the spin resonance structure of a booster lattice for the Circular Electron Positron Collider (CEPC). The 100 km-scale booster lattice has a periodicity of 8 and each arc region contains hundreds of FODO cells. We show that the first super strong depolarization resonances only occur beyond 120 GeV, and other resonances are much weaker, due to the effectively very high periodicity of the lattice structure in terms of spin resonances. This finding is similar to the concept of ``Spin resonance free injector’’ for the Electron Ion Collider [V. Ranjbar, Phys. Rev. Accel. Beams, 20, 111003, 2018]. Spin tracking simulations verify that beam polarization can be mostly maintained in the fast ramping to 45.6 GeV and 80 GeV beam energies, without using special hardware like Siberian snakes. We also discuss possible measures to maintain beam polarization up to 120 GeV. This study opens the way for injection of highly polarized beams generated from the source into the collider rings, to enable resonant depolarization measurements as well as longitudinally polarized colliding beam experiments.
Paper: MOPL053
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL053
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL054
Definition of tolerances and corrector strengths for the orbit control of the High-Energy Booster ring of the future electron-positron collider
666
After the discovery of the Higgs boson at the LHC, particle physics community is exploring and proposing next accelerators, to address the remaining open questions on the underlying mechanisms and constituents of the present universe. One of the studied possibilities is FCC (Future Circular Collider), a 100-km-long collider at CERN. The feasibility study of this future proposed accelerator implies the definition of tolerances on magnets imperfections and of the strategies of correction in order to guarantee the target performances of the High Energy Booster ring. The efficiency of the correction scheme, used to control the orbit, directly bounds the corrector needs and magnet tolerances. Analytic formulae give a first estimation of the average rms value of the required linear correctors’ strengths and of the allowed magnets misalignments and field quality along the entire ring. The distribution of the correctors along the ring is simulated in order to verify the quality of the residual orbit after the proposed correction strategy and compared with the analytical predictions. First specifications of the orbit correctors strength and tolerances for the alignment of the main elements of the ring are presented. The limits of the studied correction scheme and method are also discussed.
Paper: MOPL054
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL054
About: Received: 31 Mar 2023 — Revised: 12 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL055
Spin-polarization simulations for the Future Circular Collider e+e- using Bmad
670
The high precision measurement of the centre-of-mass energy in the Future Circular Collider e+e- (FCC-ee) at Z and W energies can be realized through resonant spin depolarization utilizing transversely polarized beams. This requires a guaranteed sufficiently-high spin polarization in the presence of lattice imperfections. Investigations of the impact of misalignments on the equilibrium polarization are conducted using analytical and Monte-Carlo spin simulations with Bmad. Potential optimization schemes to ensure high polarization using orbit bumps have been explored.
Paper: MOPL055
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL055
About: Received: 02 May 2023 — Revised: 06 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL059
The status of the energy calibration, polarization and monochromatization of the FCC-ee
674
The Future Circular electron-positron Collider, FCC- ee, is designed for unprecedented precision for particle physics experiments from the Z-pole up to above the top-pair-threshold, corresponding to a beam energy range from 45.6 to 182.5 GeV. Performing collisions at various particle-physics resonances requires precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points. Measurement of the ECM by resonant depolarization of transversely polarized pilot bunches in combination with a 3D polarimeter, aims to achieve a systematic uncertainty of 4 and 100 keV for the Z-pole and W-pair-threshold energies respectively. The ECM itself depends on the RF-cavity locations, beamstrahlung, longitudinal impedance, the Earth’s tides, opposite sign dispersion and possible collision offsets. Application of monochromatization schemes are envisaged at certain beam energies to reduce the energy spread. The latest results of studies of the energy calibration, polarization and monochromatization are reported here.
Paper: MOPL059
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL059
About: Received: 02 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL061
FCC-ee arc half-cell: preliminary design & integration studies, with ideas for a mock-up
678
During 2022, a dedicated study was undertaken at CERN, together with FCC Feasibility Study collaborators, aimed at proposing a robust configuration for the FCC-ee arc half cell. The proposed configuration takes into account integration aspects of the elements in the arc cross section, both for the booster and the collider, as well as aspects related to powering, cooling and ventilation, supporting and alignment, optics, instrumentation, handling and installation. The interfaces between the arc elements and the straight sections have also been analyzed. This paper summarizes the main conclusions of the assessment, and reports the preliminary engineering analyses performed to design the supporting system of the booster and of the collider. A proposal for a possible mock-up of the arc half-cell, to be built at CERN in the next years, is also presented.
Paper: MOPL061
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL061
About: Received: 10 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL062
Bhabha scattering model for multi-turn tracking simulations at the FCC-ee
682
The measurement of Bhabha scattered leptons enables a direct estimate of luminosity in lepton colliders. Currently existing Monte Carlo event generators for this process are optimized for high precision detector background simulations. From a beam dynamics point of view, emitted photons will modify the bunch distribution and lead to beam losses due to the limited momentum acceptance of the machine. Hence the interest in building an event generator which is optimized for beam dynamics studies requiring efficient multi-turn tracking simulations. We discuss the implementation of such a model in the newly developed Xsuite simulation framework as well as its benchmarking and performance.
Paper: MOPL062
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL062
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPL063
Benchmark and performance of beam-beam interaction models for XSUITE
686
The understanding of beam-beam effects, which influence the choice of the FCC-ee design parameters for several aspects, require sophisticated and high-performance numerical simulations. The self-consistent study of the interplay of nonlinear dynamical phenomena resulting from collisions in the machine is key to accurately assess its potential performance. Although current simulation frameworks can address specific aspects of the dynamics separately, they are difficult to interface with each other for more complex studies. To address this challenge, Xsuite, a new general purpose software framework for beam dynamics simulations, is currently under development. We discuss the implementation of the beam-beam interaction in this new toolkit and the evaluation of its performance on multiple platforms.
Paper: MOPL063
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL063
About: Received: 02 May 2023 — Revised: 08 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL064
First design of a 10 TeV centre of mass energy muon collider
690
The design of a muon collider complex requires to overcome challenges associated with muons short lifetime. To reach the expected luminosity for a multi TeV muon collider ring an interaction region with beta values of the order of a few millimetres is required. Resulting challenges are the development of a chromatic compensation section that is not degrading the physical and dynamical aperture, while allowing the control of the momentum compaction factor, as well as the control of the radiation due to muons reaching the earth surface. A preliminary version of a 10 TeV centre-of-mass energy muon collider ring fulfilling these requirements and taking limitations from the detector and magnet design into account is presented.
Paper: MOPL064
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL064
About: Received: 25 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL065
Impact of dipole quadrupolar errors in FCC-ee
694
FCC-ee performance is challenged by magnetic errors and imperfections. Magnetic design simulations predict a systematic quadrupolar component in the arc dipoles significantly impacting the machine optics. This paper studies the impact of this component in the beta-beating and explores potential mitigations.
Paper: MOPL065
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL065
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL066
Exploring FCC-ee optics designs with combined function magnets
698
The FCC-ee project takes a step forward towards the discovery of new physical phenomena beyond the frontier of the standard model, by aiming at unprecedented center of mass energies and luminosities in a double-ring lepton collider. In order to explore potential improvements to the current lattice design, this paper looks at the use of combined function magnets within the short straight sections of the arc cells. The use of High Temperature Superconductors (HTS) with an operating temperature of 12 K and maximum field of 18.2 T for the combined function magnets allows increasing the bending radius and decreasing the synchrotron radiation. A first design is presented with comparisons to the current baseline.
Paper: MOPL066
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL066
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL068
Dark sector searches based on dielectric laser acceleration
702
We discuss the beam requirements for indirect searches of dark matter and feebly coupled particles using advanced accelerator concepts. A parameter comparison reveals dielectric laser acceleration as a promising candidate for delivering the needed single-electron beams in the 5-100 GeV energy range or beyond. We suggest a parameter set for a baseline DLA-based dark sector accelerator. Enhancements through combining dielectric laser deflectors with a segmented detector or by making the dielectric structure be part of the laser oscillator could offer a performance significantly exceeding the ``Extended LDMX'' proposal based on LCLS-II.
Paper: MOPL068
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL068
About: Received: 26 Apr 2023 — Revised: 05 Jun 2023 — Accepted: 22 Jun 2023 — Issue date: 26 Sep 2023
MOPL069
Analytic derivative of orbit response matrix and dispersion with thick error sources and thick steerers implemented in python
705
While large circular colliders rely upon analysis of turn-by-turn beam trajectory data to infer and correct magnetic lattice imperfection and beam optics parameters, historically storage-ring based light sources have been exploiting orbit distortion, via the orbit response matrix. However, even large collider usually benefit of the orbit analysis during the design phase, in order to evaluate and define tolerances, correction layouts and expected performances. The proposed FCC-ee is no different, though its length (about 100 km) and amount of magnets (about ???) make the standard closed-orbit analysis time consuming. We applied new analytic tools to cope with this issue, showing a significant gain in computational time with practically no loss of accuracy. Examples of applications to the ESRF EBS storage ring and to the CERN FCC-ee are reported with an outlook to an additional challenge provided by the FCC-ee.
Paper: MOPL069
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL069
About: Received: 03 May 2023 — Revised: 18 May 2023 — Accepted: 18 May 2023 — Issue date: 26 Sep 2023
MOPL070
Status and plans for the high energy booster of the future electron-positron collider FCC-ee
708
In the context of the FCC IS European study, which investigates the feasibility of a 100 km circular $e^{+}e^{-}$ collider for the future high energy physics research, we present the status of the High Energy Booster (HEB) ring. The HEB will be located in the same tunnel as the collider and should have the same circumference. The main difference is to have a bypass near the experiments to avoid perturbing the detectors. In order to perform precision measurements of the Z, W and H bosons, as well as of the top quark, unprecedented luminosities are required. To reach this goal and to fill the collider, it is mandatory to continuously top up inject some beams with a comparable emittance and bunch length to the collider ones. One challenge of the HEB is in the fast cycling time allowing to reach the collider equilibrium emittance, especially for the Z mode. We present the status of the layout and optics design of the HEB taking into account these challenges. A special focus will be made on the cycling considerations.
Paper: MOPL070
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL070
About: Received: 27 Apr 2023 — Revised: 09 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL071
Bunch lifetime analysis based on the injection interval at SuperKEKB
712
We carried out the study of the beam lifetime at SuperKEKB to investigate beam instabilities. We analyzed the injection interval for individual bunches to evaluate their beam lifetime ratio. SuperKEKB performed the top-up operation with the equalized bunches currents. This particular condition enables us to evaluate the lifetime ratio among all operation bunches. This report introduces the analysis results for the 2020 and 2021 data. We observed the beam lifetime has dependent on the bunch spacing and the relative position in the bunch train. Besides, in the December 2021 data, we determined the magnitude of the forward/backward asymmetry of the lifetime in the bunch train depends on the bunch current. They become good hints to understand the beam instabilities such as the electron cloud, the ion cloud, the beam-beam effect in the collision, and so on.
Paper: MOPL071
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL071
About: Received: 11 May 2023 — Revised: 24 May 2023 — Accepted: 24 May 2023 — Issue date: 26 Sep 2023
MOPL072
Observation of sudden beam loss in SuperKEKB
716
SuperKEKB suffers from sudden beam loss(SBL) during operation. It causes collimator damage, QCS quench and large beam background to the Bell-II detector. Beam aborts triggered by SBL hinder us from storing large beam current. Since cause of SLB is unclear, we launched an effort to investigate it and consider measures to be taken. In this paper, we discuss phenomena of SBL and various hypotheses to explain SBL.
Paper: MOPL072
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL072
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL073
Toward a new era of spin-polarized electron beams at SuperKEKB
720
The SuperKEKB accelerator is currently in operation in Tsukuba, Japan, with a planned long shutdown in 2026. Among the possible upgrades being considered during this period is the change to a polarized electron beam in the High Energy Ring. Such a change would require modifications in the source generation and transport, geometrical and lattice variations to provide spin rotation, and polarimetry. A Polarized SuperKEKB Working Group has been formed from members of the Belle II experiment and the SuperKEKB accelerator team to investigate the possibilities and challenges of these modifications. This talk lays out the goals of the proposed upgrade, considers the necessary changes to the existing accelerator and their feasibility and lays out the physics motivation behind such an effort.
Paper: MOPL073
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL073
About: Received: 11 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL074
Modeling SuperKEKB backgrounds with the Belle II electromagnetic calorimeter
724
The largest current obstacle to SuperKEKB's luminosity goals is currently beam-related backgrounds occurring during accelerator operation. Thus, understanding the level of these backgrounds is of crucial importance for the future of the facility. In this work, we take advantage of the Belle II Electromagnetic Calorimeter's near-total coverage of the interaction region to create a spatial model of beam-induced backgrounds with the aim of providing fast feedback to improve accelerator conditions.
Paper: MOPL074
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL074
About: Received: 11 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL075
Beam backgrounds at the CEPC
728
The machine-detector interface (MDI) issues are one of the most complicated and challenging topics at the Circular Electron Positron Collider(CEPC). Comprehensive understandings of the MDI issues are decisive for achieving the optimal overall performance of the accelerator and detector. The CEPC machine will operate at different beam energies, from 45.5 GeV up to 180 GeV. A flexible interaction region design will be plausible to allow for the large beam energy range. However, the design has to provide high luminosity that is desirable for physics studies but keep the radiation backgrounds tolerable to the detectors. In this paper, the latest design of the CEPC MDI based on the TDR draft will be presented, covering the following topics: 1. The design of the beam pipe, which would foresee several constraints: In the central region (z = ±12 cm), it should be placed as close as possible to the interaction point and with a minimal material budget. But it should still stay far away enough not to interfere with the beam backgrounds. 2. The estimation of beam-induced backgrounds. A detailed simulation covering the main contributions from synchrotron radiation, pair production, and off-momentum beam particles has been performed. 3. The suppering/mitigating schemes. A preliminary design of the collimation scheme has been studied, including the position, material, shape of the collimators, and also the effectiveness of them.
Paper: MOPL075
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL075
About: Received: 11 May 2023 — Revised: 12 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL077
First studies of final focus quadrupoles vibrations of the z lattice of FCC-ee
731
The proposed FCC-ee machine is a high-energy, high-intensity and high-precision lepton collider which will require to reduce as much as possible the differential motions of its two beams at the interaction points. In this prospect, the vibration impacts of the quadrupoles in the region close to the interaction point are investigated. Considering the z-pole optics design and its dedicated optics simulation under MAD-X, the present paper describes the integration of the dynamics aspects (vibrations mitigation) to render the modelling more realistic towards operation. This simulation is based on the "particle tracking" mode. In this prospect, dynamic characteristics of the designed mechanical assembly are estimated according to an analysis in finite element models. Required transfer functions and realistic temporal sequences along the assembly are thus created and they can be implemented as inputs to the optical simulations to verify that this assembly allows the expected beam parameters. The obtained results on a dedicated cantilever mock-up are presented and the last optics simulations are discussed.
Paper: MOPL077
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL077
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL078
Beam polarization studies at the CEPC
734
In the future 100 km-scale Circular Electron Positron Collider (CEPC), beam polarization is an important design aspect. Transverse beam polarization for resonant depolarization is essential for precision measurements of the beam energies at Z-pol and WW threshold. Longitudinally polarized colliding beams are also beneficial for expanding the capability of the physics program. This paper reports the progress in the design studies of polarized beams for the CEPC. We focus on the approach of injection of polarized beams generated from the source into the collider rings for both applications. Our investigation into key issues in this approach is summarized, including polarized positron beam generation, beam polarization maintenance in the booster, and spin rotator design in the collider rings. Implications to resonant depolarization measurements are also discussed.
Paper: MOPL078
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL078
About: Received: 01 May 2023 — Revised: 10 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL079
Monochromatization Interaction Region Optics Design for Direct s-channel production at FCC-ee
738
One of the most fundamental measurements since the Higgs boson discovery, is its Yukawa couplings. Such a measurement is only feasible, if the centre-of-mass (CM) energy spread of the e+e- collisions can be reduced from ~50 MeV to a level comparable to the Higgs boson’s natural width of ~4 MeV. To reach such desired collision energy spread and improve the CM energy resolution in colliding-beam experiments, the concept of a monochromatic colliding mode has been proposed as a new mode of operation in FCC-ee. This monochromatization mode could be achieved by generating a nonzero dispersion function of opposite signs for the two beams, at the Interaction Point (IP). Several methods to implement a monochromatization colliding scheme are possible, in this paper we report the implementation of such a scheme by means of dipoles. More in detail a new Interaction Region (IR) optics design for FCC-ee at 125 GeV (direct Higgs s-channel production) has been designed and the first beam dynamics simulations are in progress.
Paper: MOPL079
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL079
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPL080
Design of a S band high power klystron for BEPCII
742
A S band high power klystron for BEPCII operating at frequency of 2856 MHz has been designed and simulated at Institute of High Energy Physics, Chinese Academy of Sciences. A thermionic electron gun have been designed. A beam current of 379 A is obtained at operating voltage of 325 kV with cathode current density of 6.6 A/cm2. Then, the full 3-dimensional particle-in-cell simulation of the whole klystron in CST verified that the klystron efficiency was achieved about 40% with output power of 50 MW. In additon, the RF design of cavities for interaction region is described. So far, the mechanical design of this klystron has been completed and the fabrication is in progress.
Paper: MOPL080
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL080
About: Received: 16 Apr 2023 — Revised: 14 Jun 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL081
Transient beam loading and power analysis in the booster ring of CEPC
744
During the injection phase of the Higgs mode of CEPC, the stored energy of the cavity is low and beam loading is relatively high. The synchrotron radiation damping is weak compared to the growth rate of the untidamped mode. This will cause two types of trouble. Firstly, the transient beam loading caused phase-shift between the head and the tail of the beam will be too much. Secondly, the untidamped mode will grow too fast. Therefore, we performed a series of studies in order to put a quantified requirement on the strength of the damping mechanism and the power overhead.
Paper: MOPL081
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL081
About: Received: 04 May 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL082
Transient beam loading study in the storage ring of CEPC
747
During the on-axis injection process under the Higgs model, the transient beam loading in the CEPC storage ring will cause a phase shift between the head and the tail of one beam. Since the missing bunches are only extracted from one of the beams at a time, there will be a misalignment between the colliding bunches at the IP. In this paper, we presented the results of the study on this transient beam loading under different initial and extraction patterns and gave the preliminary analysis of the average luminosity loss due to this effect.
Paper: MOPL082
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL082
About: Received: 04 May 2023 — Revised: 14 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL083
Error correction for the high luminosity lattice of the CEPC
750
Circular Electron-Positron Collider (CEPC) is a 100 km circumference double-ring Collider, the high luminosity lattice in CEPC TDR is half lower emittance compared with the lattice in CEPC CDR. The dynamic aperture is strongly sensitive to the magnet misalignments and field errors. We present the study of the error correction for the CEPC TDR lattice and the dynamic aperture tracking after correction. The scheme of the correction and the resulting performance are discussed.
Paper: MOPL083
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL083
About: Received: 02 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL084
Beam background study at BEPCII
753
The Beijing Electron Positron Collider II will upgrade to achieve a higher beam energy and higher luminosity which need a higher beam current and smaller beam size. The consequent high beam background should be controlled within in a safety range. The beam related background at BEPCII is mainly from the Touschek effect and the beam gas effect. This paper presents the beam background study at BEPCII, which includes the recent results of experiment and simulation.
Paper: MOPL084
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL084
About: Received: 02 May 2023 — Revised: 24 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL085
DAFNE run for the SIDDHARTA-2 experiment
756
DAFNE, the Frascati electron-positron collider, based on the Crab-Waist collision scheme, has successfully completed the preliminary phase with the SIDDHARTA-2 detector aimed at testing and optimizing the performances of the machine and the experimental apparatus. In this configuration the collider has delivered to the experiment, using gaseous 4He targets, a data sample suitable to perform studies about the kaonic helium transitions with an accuracy which is the status of the art in the field. As a next step DAFNE is planning a new run finalized to deliver data to the detector in order to study the more elusive kaonic deuterium transition. In this context the setup and the performances of collider the are presented with special attention to the strategy adopted to reduce the background shower on the experimental apparatus.
Paper: MOPL085
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL085
About: Received: 03 May 2023 — Revised: 18 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL086
On positron beam dynamics an initial part of a large aperture FCC-ee capture linac
760
The application of HTS coils as a matching device and a large-aperture L-band linac make it possible to transport a substantial part of positrons generated in a positron production target through a capture linac. It raises a question of how to manage their large phase space to provide bunches matched to the damping ring acceptance. This paper presents the beam dynamics studies of the FCC-ee positron linac consisting of an adiabatic matching device (AMD) with theoretical field distribution combined with constant solenoidal field along $\frac{9}{10}\pi$ large aperture L-band accelerating sections. AMD field drop rate, as well as the RF field phase and accelerating section length, were varied to find features of a bunch formation. It was shown that 5D normalized beam brightness is a useful parameter to optimize the initial part of the capture linac. A higher beam brightness can be obtained for the higher AMD field drop rate. Starting from some accelerating section length, two peak structure appears in the normalized brightness dependence on the RF field phase. The peaks correspond to the acceleration of the head or the tail of the initial positron longitudinal distribution. The last one provides a higher positron yield.
Paper: MOPL086
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL086
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL089
Design and optimisation of an 800 MHz 5-cell elliptical SRF cavity for T¯t working point of the future circular Electron-Positron Collider
764
The Future Circular electron-positron Collider (FCC-ee) is planned to operate with beam energies from 45.6 to 182.5 GeV and beam currents from 5 to 1400 mA. This will enable precision physics at the four operational points, Z, W and Higgs boson and the top and anti-top quarks. This work will focus on the RF structure design for the ttbar operation point to reach a beam energy and current of 182.5 GeV and 5 mA, respectively. A 5-cell elliptical SRF cavity operating at 801.58 MHz is designed and optimized with a strong focus on minimizing higher-order modes impedances.
Paper: MOPL089
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL089
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
Design Progress for Accelerators of a Super Tau Charm Facility in China
Based on the key scientific questions in the frontier of particle physics field, the current status and future development trend globally and domestically of accelerator-based particle physics experiments, a Super Tau-Charm Facility (STCF) is proposed by taking into account the advantages in the relevant fields in China. The STCF is a new-generation electron-positron collider facility that has a center-of-mass energy of covering 2 to 7 GeV and a peak luminosity of 5×10^34cm^-2s^-1 at a center-of-mass energy of 4 GeV. It consists of an accelerator, including double storage rings of circumference approximately 800 meters and a linear injector of length approximately 400 meters, and a particle spectrometer. This paper discussed the key issues of accelerator physics and technologies. Also, the accelerator research progress of the projects are presented.
MOPL091
Design of a hybrid seven-bend-achromat-based lattice for a super tau charm facility
768
Super Tau Charm Facility (STCF) proposed in China, is a future electron-positron collider project with symmetric double ring. It’s designed to be operated in the center of mass energy (CME) range between 2 GeV and 7 GeV. The goal luminosity is beyond $0.5\times 10^{35} cm^{-2} s^{-1}$. Hybrid multi-bend-achromat (HMBA) concept, proposed to develop low emittance lattices with large dynamic aperture, has been adopted in some diffraction-limited storage ring (DLSR) designs. In this paper, we will show a lattice with hybrid 7BA arc for STCF. On the basis of last published lattice version, we optimize the interaction region, arc as well as technique region, add the damping wigglers and construct the geometry of double-ring.
Paper: MOPL091
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL091
About: Received: 03 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
MOPL094
Benchmarking the FCC-ee positron source simulation tools using the SuperKEKB results
772
For the Future Circular Collider (FCC-ee), particular attention is drowned to the crucial role of the positron source. Two positron production schemes are considered for the FCC-ee: conventional and crystal-based (hybrid), implying the use of channeling radiation in the oriented crystals. To design and optimize the positron production and capture by considering the positron injector parameters, including the electron drive beam and the final system acceptance, a start-to-end simulation toolkit should be developed. This paper will present the first results of benchmarking the FCC-ee positron source simulation tools using the SuperKEKB positron source currently in operation. The model starts with the production of positrons and target studies in Geant4. Then, a new tracking code RF-Track is used for capturing and tracking the generated positrons through the capture section composed of the matching device and several accelerating structures embedded in the solenoid field to accelerate the positrons until ~120 MeV. Afterward, the positrons are further accelerated to the energy of the Damping Ring (1.1 GeV).
Paper: MOPL094
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL094
About: Received: 04 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
MOPL095
Update on the FCC-ee positron source design studies
776
The studies and R&D on the high-intensity positron source for the FCC-ee have been initiated for a while. The positrons are produced by a 6 GeV electron drive-beam incident on a target-converter at 200 Hz. The drive beam comes in 2 bunches spaced by 25 ns with a maximum charge of ~5 nC per bunch. Two scenarios using conventional and hybrid targets are being studied for positron production. According to the FCC CDR, the Flux Concentrator is used as the matching device for the capture system, followed by several accelerating structures embedded in the solenoidal field. Then, the positrons are further accelerated to be injected into the damping ring. Recently, the feasibility study on using a SC solenoid for the positron capture has been started, and the design based on the HTS technology is under investigation. In addition, the large aperture 2 GHz RF structures, which have been specially designed for the FCC-ee positron capture system, are used with the goal of demonstrating accepted positron yield values well beyond the values obtained with state-of-the-art positron sources. The purpose of this paper is to review the current status of the FCC-ee positron source design, highlighting the recent research into the positron production, capture system, primary acceleration, and injection into the damping ring.
Paper: MOPL095
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL095
About: Received: 05 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
MOPL096
Use of a superconducting solenoid as a matching device for the compact linear collider positron source
780
A matching device with a strong magnetic field is used to capture positrons in the positron source of future e+e- colliders such as the Compact LInear Collider (CLIC) and the Future Circular Collider (FCC-ee). Compared to conventional matching devices such as flux concentrators, superconducting (SC) solenoids can have a much higher peak field, improving the capture efficiency and the positron yield. In this paper, we tested an analytic SC solenoid field and simulated the matching device for the CLIC positron source. Furthermore, we optimised the coil parameters for maximum positron yield. The results from a study of the latest high temperature superconductor based solenoid designed by PSI for the FCC-ee positron source is also presented.
Paper: MOPL096
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL096
About: Received: 02 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL097
Coupling between transverse and longitudinal beam dynamics in the first-stage CLIC decelerator
784
In this paper we present the first results of full 6D multi-bunch tracking through the new Drive-Beam decelerator lattice for the first-stage of the Compact Linear Collider (CLIC). Using the new PLACET3 tracking code, we evaluate the coupling between transverse and longitudinal dynamics in the lattice finding an indirect impact of the Drive-Beam's transverse emittance in the Main-Beam performance.
Paper: MOPL097
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL097
About: Received: 01 May 2023 — Revised: 26 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL098
Helen: Traveling wave SRF Linear Collider Higgs factory
788
Travelling wave (TW) SRF accelerating structures offer several advantages over the traditional standing wave structures: substantially lower Hpk/Eacc and lower Epk/Eacc, ratios of peak magnetic field and peak electric field to the accelerating gradient, respectively, together with substantially higher R/Q. In this paper we discuss how a linear collider Higgs factory HELEN can be built using TW-based SRF linacs. We cover a plan to address technological challenges and describe potential ways to upgrade the collider luminosity and energy.
Paper: MOPL098
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL098
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL099
GaAs cathode activation with Cs-K-Sb thin film
792
GaAs cathode is a unique device generating a spin-polarized electron beam by photo-electron effect with a circularly polarized laser illumination. Negative Electron Affinity (NEA) surface which is artificially made has an essential role in spin polarization, but the NEA surface has limited vitality. In this study, we activated GaAs as NEA cathode by evaporating Cs, K, and Sb metal on its cleaned surface. The experimental results including the quantum efficiency spectrum and the lifetime will be presented.
Paper: MOPL099
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL099
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL100
Beam loading compensation of traveling wave LINAC to a multi-bunch pulse with gaps
796
In the electron-driven ILC positron source, the positron is generated a multi-bunch format with gaps, because it corresponds to a part of the damping ring fill pattern. The beam loading is compensated by amplitude modulation on the input RF (*). In this article, we derive the exact solution for the compensation with gaps. In addition, we evaluate the effect of the time constant (delay) of the input RF modulation due to klystron Q-value.
Paper: MOPL100
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL100
About: Received: 01 Apr 2023 — Revised: 10 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL101
Design, testing, and validating the CLIC module pre-alignment and alignment systems
800
In order to produce a high luminosity at the interaction point, the Compact Linear Collider (CLIC) accelerators must preserve low emittance beams along both the main 22km linacs. A key factor in preserving a low emittance beam is the mechanical alignment and stability of the accelerator components. The CLIC accelerators are divided into `Two Beam Modules’ (TBMs) which integrate a section of the power-delivering Drive Beam and the accelerating Main Beam. The Main Beam is accelerated within Acceleration Structures that require prealignment to within 14 µm of the Metrological Reference Network (MRN). To prevent a greater than 1% luminosity loss, the vertical jitter of the accelerator components must be kept below 1.4µm RMS when the TBMs are exposed to the ground noise within the tunnel, and other sources of vibration. A design of the TBMs is presented which includes active alignment, passive prealignment, and sufficient mechanical stability to meet the specification. Finite Element Analyses (FEA) are used to demonstrate the suitability of this design. The results of the testing of prototype SAS prealignment and active TBM positioning systems are discussed and shown to meet the CLIC alignment requirements. Opportunities for future testing and areas for further optimisation are identified and discussed.
Paper: MOPL101
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL101
About: Received: 06 Apr 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
Simulating Beam-Beam Collisions in Linear Colliders Using Particle-in-Cell Methods
The AAC community proposed linear collider concepts with energies extending to 15 TeV center-of-mass and luminosities up to 50E34 cm^-2 s^-1 as part of the Snowmass process. The beam power required to reach these energies and luminosities is prohibitive. We discuss the results of initial investigations of strategies to increase luminosity per beam power, a key figure-of-merit for linear colliders. We deploy a new tool for our studies, Particle-in-Cell simulations, in order to better understand collisions at high-energy and high-beamstrahlung parameters. The results of our studies will aid in the design of future linear colliders based on standard RF technologies and novel acceleration methods.
MOPL104
Design modelling of RF injector for ICS gamma-ray source system
803
High brightness beams are desired for application to Inverse Compton Scattering (ICS) systems for generation of high-quality x- and γ-rays. It opens new opportunities for nuclear physics research in fields such as nuclear photonics, nuclear astrophysics, photo-fission, production of exotic nuclei, applications in medicine, industry and space science. In ICS mechanism high energy electron is interacting with photon. It results in scattered photon with high energy. Results from computer simulations are presented. Different configurations of S-band injector were analysed. Photocathode RF electron source with diverse arrangement of magnetic devices for beam confinement, and standing wave cavity for initial particle acceleration were implemented. Electron beam parameters have been investigated with use of computer program for tracking particle beam through defined external electric and magnetic fields. Because cross-section of collision between electron and photon beam is very low, high brightness electron beam is crucial specification for gamma beam systems. Electron beam parameters of interest are emittance, beam spot size, average energy, energy spread, electron bunch length, Twiss parameters. Beam density, number of particles in bunch must find good compromise between optimum necessary for creation of high-performance gamma rays and limit in available technology.
Paper: MOPL104
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL104
About: Received: 10 May 2023 — Revised: 15 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL105
Orbit correction studies for the MINERVA 100 MeV proton accelerator
806
MINERVA entails the first phase of the MYRRHA programme, which aims at driving a nuclear reactor with a high-power proton accelerator, commonly referred to as an Accelerator Driven System(ADS). The purpose of MINERVA is to demonstrate the reliability requirements that are needed for a stable ADS, by the realization of a 100 MeV, 4mA proton beam. In order to transport the proton beam with minimal losses, a strategic placement and usage of orbit correctors, i.e. steering magnets, and Beam Position Monitors (BPMs) along the accelerator is paramount. With this in mind, error studies were carried out with TraceWin to determine an optimal steering strategy and put forward requirements on magnet design and alignment. In addition, orbit correction studies were performed with an in-house developed beam dynamics simulation code, PyAccel. Comparison of the results obtained with both software packages serves as an important benchmark towards future developments.
Paper: MOPL105
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL105
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL108
Study of a bunch train total energy spread in a Linac using SLED
810
A SLED (SLac Energy Doubler) RF pulse compressor is a passive RF component which increases the peak RF power level at the cost of reducing the pulse length. The Canadian Light Source (CLS) plans to replace the current 250 MeV Linac with a new one in mid-2024 by RI Research Instruments GmbH. The new Linac has a similar energy and two of its three 5.3 m TW constant-gradient accelerating structures are connecting to a SLED. Since a SLED output is not flat, this introduces additional energy variation along a bunch train, increasing the total energy spread. In addition, the energy spread acceptance of the CLS booster ring is below 0.5% FWHM, and it is critical to minimize the SLED non-flatness output effect by different methods. This paper will study the SLED effect on a multi-bunch train energy variation and consider the transient beam loading effect. Finally, we will show that by selecting proper RF phase switching and beam injection timing, and by alternating energy gain slope between the SLED-ed and non-SLED-ed Linac cavities can achieve the required energy spread.
Paper: MOPL108
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL108
About: Received: 02 May 2023 — Revised: 22 May 2023 — Accepted: 22 May 2023 — Issue date: 26 Sep 2023
MOPL111
An iterative algorithm to estimate the energy spectrum of an electron beam from PDD curves
814
Electron beam central-axis percentage depth dose (PDD) curves in water phantom are routinely employed to evaluate the electron beam energy at the phantom surface, in particular the mean and most probable energies from the values of R50 (half-value range) and Rp (practical range). However, these two quantities are not enough to evaluate important details of the energy distribution, such as the FWHM (Full Width Half Maximum) and the possible presence of a low-energy tail. This paper presents a numerical method that allows estimating the shape of the energy spectrum from a PDD curve. The algorithm uses a database consisting of a set of depth dose curves for monochromatic beams computed by FLUKA in the range 0.1-6.0 MeV by steps of 0.1 MeV and, using an adaptive iterative Monte Carlo process, reconstructs the incident energy spectrum by minimizing the distance between the measured PDD and the computed one. Applications of a MATLAB code based on this algorithm to simulated and real measurements of electron beams done at APAM lab (ENEA Frascati) are presented. This approach represents a strong simplification with respect to energy analysis based on the use of a magnetic spectrometer.
Paper: MOPL111
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL111
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL112
MAD-NG for final focus design
818
The CLIC Beam Delivery System (BDS) transports the lepton beams from the exit of the Main Linac to the Interaction Point (IP). The Final Focus System (FFS) is the last part of the BDS and its role is to focus the beam to the required size at the IP and to cancel the chromaticity of the Final Doublet (FD). MAD-X and MAD-NG are simulation codes for beam dynamics and optics that are used for particle accelerator design and optimization. This paper presents a comparison between the two codes to achieve the best performance of the design of the FFS, including the optimization methods, the speed performance and the physics accuracy.
Paper: MOPL112
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL112
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL113
Design of CLIC beam delivery system at 7 TeV
822
The Compact Linear Collider (CLIC) is a proposed linear accelerator designed to collide electrons and positrons at energies up to 3 TeV. In order to explore new physics and to be more competitive with other collider projects, CLIC is exploring the increase of the center-of-mass energy to 7 TeV. The CLIC Beam Delivery System (BDS) transports the lepton beams from the exit of the Main Linac to the Interaction Point (IP). This paper reports on the studies and the challenges of the new BDS design, such as minimizing the extent of trajectory bending for collimation and chromaticity correction to reduce the effects from synchrotron radiation, ensuring a good transverse aberration control at the IP.
Paper: MOPL113
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL113
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
A Booster Replacement Linac for the Future of High Energy Physics at Fermilab
After the PIP-II linac is commissioned as a new start of the Fermilab Acclerator Complex, the Booster will become a bottleneck for future high intensity particle physics research at Fermilab. An SRF linac is proposed as a replacement for the booster to enable future higher power proton beams in the Fermilab complex - this would include neutrino-based and muon-based studies, dark matter searches, and a platform for R&D for a muon collider. In this contribution, we overview the early conceptual accelerator design under development and discuss potential configuration options.
MOPL118
Status of the hydrogen gas stripper at the UNILAC at GSI
826
High intensity heavy ion beams are a main constituent of the FAIR research program. They will be provided by the UNILAC via the high current injector HSI. Generated in high current sources, these ions originally have low charge states. To allow for efficient acceleration in the UNILAC and SIS18, a gas stripper is located at the end of the HSI to reduce the mass-to-charge ratio below 8.5. An effort has been made to enhance the stripping by introducing hydrogen instead of nitrogen as stripping target, thereby increasing the stripping efficiency by up to 60%. The main focus of the project is now on transforming the experimental setup into a system suitable for regular operation. In 2022 the main effort was on the finalization of the technical and safety concept, which had been thoroughly revised last year and was awaiting final risk assessment. Additionally, solutions to some details had to be left open for discussion and decision with the help of external specialists. Both objectives were achieved and the technical and safety concept was approved with some modifications. Some of the planned safety measures were found to be unnecessary, resulting in a minor reduction of complexity and cost. The risk assessment was documented and the explosion safety document, relevant for later operation, compiled. Based on the design now being approved, the residual parts necessary for the gas stripper facility may be specified and procured and will be presented in this publication.
Paper: MOPL118
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL118
About: Received: 02 May 2023 — Revised: 12 May 2023 — Accepted: 21 Jun 2023 — Issue date: 26 Sep 2023
MOPL119
Automated RF-conditioning utilizing machine learning
829
RF-Conditioning of a room temperature cavity is a long and resource intensive process. The need for constant supervision by experienced personal to avoid damage to the cavity and used equipment makes it a very expansive endeavor. To reduce the workload of the experimentalist, it was decided to develop a program utilizing machine learning, which, once finished, should have the probabilities to greatly reduce the need for constant supervision by human personal or even to conduct a full RF-conditioning on its own. After a training with existing data of already conducted conditioning of room temperature cavities and a virtual cavity, it is planned to improve and expand the program during the RF-conditioning of 15 CH-cavities, designated for the MYRRHA project, with similar properties. In this paper, the outline of the program, as well as the existing and planned goals shall be given.
Paper: MOPL119
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL119
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL120
Beam injection issues at SuperKEKB
832
A high-charge, low-emittance injection beam is essential for SuperKEKB. For its both rings, HER and LER, the injection efficiencies and detector backgrounds have not been good enough up to the recent run. There are many reasons for the issues. For example, serious emittance growths are observed through the beam transport lines between the injector linac and both rings. It is considered that some parts of them are due to coherent synchrotron radiation as the observed horizontal emittance blowups depend on the bunch charge. Especially for the HER injection, physical aperture around the injection point and ring dynamic aperture also contribute, as both are narrower than the design. In this paper, we discuss the injection issues up to 2022 operation and outlook for the future to maximum collision currents.
Paper: MOPL120
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL120
About: Received: 03 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL122
Design of a 10.156 MHz pre-buncher for a heavy ion RFQ
836
LEAF (Low Energy heavy ion Accelerator Facility) is a low-energy high-intensity heavy-ion LINAC complex for multidiscipline research. At present, the beam repetition rate is the same as the LINAC frequency of 81.25 MHz. A lower frequency would be desirable for many types of experiments employing time of flight data acquisitions. A method of increasing the bunch spacing to 98 ns by combining a 10.156 MHz pre-buncher before the RFQ and an RF chopper after the RFQ has been proposed. This paper reports the design studies of such a low-frequency pre-buncher. A resonator-based buncher is the best choice since lumped circuit-based buncher cannot provide the high voltage we expect for the efficient bunching of ion beams with an A/q of 7. According to the simulation result, the bunching efficiency of a 3-harmonic buncher will merely increase by 1% compared to a 2-harmonic buncher. We decide to design a two-harmonic buncher based on the little improvement in bunching efficiency. We optimize the length of electrodes so that the utilization of the parasitic field is maximized. The beam dynamics analysis indicates that the voltage amplitude and the RF power can be lowered by 1.3 times and 2.2 times by optimizing the electrode length.
Paper: MOPL122
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL122
About: Received: 25 Apr 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL123
Design of a CW RFQ as axial injector of high intensity cyclotron
840
We propose to develop a compact superconducting cyclotron to accelerate H2+ ions for isotope production since using H2+ allows the use of a stripper foil after extraction from the cyclotron to remove the binding electron, thereby doubling the electrical beam current. An RFQ, partially embedded in the cyclotron yoke, will be used to bunch and axially inject the H2+ beam into the cyclotron’s central region because RFQ has excellent bunching capability. In this paper we are presenting the design of the RFQ, including beam dynamics, electromagnetic structure and geometrical cavity.
Paper: MOPL123
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL123
About: Received: 18 Apr 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL125
750 MHz IH-DTL for a proton therpy linac
844
750 MHz IH-DTL with the capability to accelerate protons from 3 to 10 MeV was proposed for the compact therpy linac that now under development in IMP. Four drift tube sections were housed in a single vacuum chamber and coupled with three large drift tubes which housing focusing triplet lens inside. In each drift tube section, there were 9 to 10 drift tubes, supported by the separated ridges. This cavity will be powered by a 1 MW klystron at 0.1% duty cycle, the kp factor is about 1.7 at the operation power level. The tank is now under construction and expected to be ready for beam commissioning in the middle of 2023. The overall cavity design and the status of the power cavity are presented in this paper.
Paper: MOPL125
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL125
About: Received: 02 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL126
Radio frequency system, power converters and cryomodule installation and tests as a Polish in-kind contribution to the European Spallation Source (ESS)
847
The European Spallation Source (ESS) project currently enters the final stage of installation. Since 2017, a group of engineers and technicians from The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Science (IFJ PAN) are involved in the project. The contribution to the project can be divided into three main tasks: Radio Frequency Distribution System (RFDS), RF (Radio Frequency) Power Stations and Cryomodules. The RFDS in ESS project is one of the largest installations of this type consisting of 155 RF high power systems. Engineers and technicians from IFJ PAN were responsible for preparation, installation and RF measurements of the above mentioned system. The team is also involved in preparation and conducting low and high power tests of the RF stations. The IFJ PAN team is also responsible for the preparation as well as vacuum and cryogenic tests for 9 Medium and 21 High Beta Cryomodules, before they are installed in the tunnel. The advanced quality control and quality assurance were mandatory for this work because the costs of failures, as well as potential delays, would have a huge impact in the project realisation. Therefore dedicated methods and approaches have been adapted to this work using experience gained by the IFJ PAN team on previous projects like LHC, XFEL and W7X.
Paper: MOPL126
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL126
About: Received: 11 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL127
Status and overview of the activities on ESS DTLs
851
The Drift Tube Linac (DTL) for the ESS Linac will accelerate H+ beams of up to 62.5 mA peak current from 3.62 to 90 MeV. The structure consists of five cavities. The first cavity (DTL1, 21 MeV) has been commissioned with beam in summer 2022. DTL2, 3 and 4 are installed in the tunnel since the end of 2022, ready for the conditioning and commissioning starting in 2023. DTL5 is under assembly and will be transported to the tunnel after the completion of beam commissioning up to 74 MeV. The paper wants to give an overview of the activities already done and ongoing on the five DTLs: from assembly to tuning, from conditioning to beam commissioning.
Paper: MOPL127
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL127
About: Received: 02 May 2023 — Revised: 09 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL128
The IFMIF RFQ as a resonant combiner: equivalent circuit and operational scenarios
855
The IFMIF RFQ has to accelerate a D+ beam of 125 mA from the source energy of 100 keV to its final energy of 5 MeV. For such a purpose, the needed RF power (approximately 600 kW dissipated power and 600 kW beam power) is injected in the RFQ from 8 amplifier chains with 8 coupling loops. In order to quantitatively understand the different circumstances which can occur, an equivalent circuit of the RFQ (that can be generalized to a generic multple-feed cavity) with all the feed lines and couplers will be described, and the expressions for cavity and reflected voltages and powers will be derived. Moreover, some operational scenarios that can occur will be analyzed. In particular errors in amplitude phase and coupling of each of the 8 feed lines of the RFQ itself will be introduced. This analysis is also useful as a guideline in determining the basic architecture of the amplitude/phase controls of the cavity feeds, for a given set of amplifier amplitude/phase characteristics.
Paper: MOPL128
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL128
About: Received: 03 May 2023 — Revised: 07 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL130
First installation of the upgraded vacuum control system for ALPI accelerator
858
At LNL (Laboratori Nazionali di Legnaro), the vacuum system of ALPI (Acceleratore Lineare Per Ioni) accelerator includes about 40 pumping groups installed in the 90s. Obsolescence and rigidity of the used hardware and deficit of spare parts required a complete renovation of the system and relative controls. In 2022 we made the first steps of the system renovation with the development and installation of the new high level control system part based on EPICS (Experimental Physics and Industrial Control System) and CSS (Control System Studio). Meanwhile, we designed a new flexible and configurable low level control system part running on a Siemens PLC and exploiting MOXA serial server to control the renewed pump groups and pressure gauges. Moreover we extended the EPICS control system to support both HW configurations, providing to users the same information and graphic interface. The plan for the next years is to replace the legacy hardware with new racks running the new control system, provide service continuity, retrieve spare hardware, debug the PLC software and extend the EPICS control system with new features. This paper describes the adopted strategy and the upgrade status.
Paper: MOPL130
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL130
About: Received: 20 Apr 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL131
The Frascati DAFNE LINAC modulator upgrade
862
The Frascati linear accelerator was used as electron and positron source for the DAFNE collider and the Beam Test Facility (BTF) where the fixed target experiments as PADME or irradiation test for space components are ongoing. Builded in 1996 an upgrade of the L-C traditional resonant charging system is started in 2018 and today 3 of the 4 RF power stations modulator are upgraded from the 3-phase variable phase control (SCR) based on a full-wave bridge diode assembly to a new 2 constant-current capacitor charging power supplies. This paper will discuss the design of the upgrade and the performances of the systems in operation
Paper: MOPL131
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL131
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL136
Manufacturing and testing of the 800 MHz RFQ at KAHVELab
866
An 800 MHz, Radio Frequency Quadrupole (RFQ) was designed to accelerate the proton beam to 2 MeV energy at a distance shorter than one meter in KAHVE-Lab, Turkey. A half-length test module was previously produced to investigate the local manufacturability of this RFQ cavity. The manufactured test module was subjected to mechanical, vacuum and electromagnetic tests to adjust the pressure, EM field and frequency parameters to the desired operational settings. Results from these tests were used to improve the final manufacturing process for the two modules of the RFQ which ended successfully in Q4 2022. The finished RFQ, after being fully assembled for the first time, will initially be subjected to vacuum tests followed by low-level RF and power tests. The KAHVE-Lab proton beamline is planned to be fully integrated and commissioned by the end of 2023. This study introduces a general framework about the current status of the 800 MHz RFQ, and discusses the ongoing commissioning studies.
Paper: MOPL136
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL136
About: Received: 03 May 2023 — Revised: 12 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
Magnetic lattice of PolFEL linac
The project of PolFEL free electron laser comprises 185 MeV cw-linac furnished with ASG electron gun and 4 Rossendorf-like cryomodules. Magnetic lattice has been designed applying alike air cooled quadrupole magnets. FODO quadrupoles in undulator section differ with trimmed coils. A variety of dipoles has been designed: 14 – degrees air and water cooled rectangular dipoles are used for low and high energy bunch compressors. 17 - degrees dipoles guide the beam towards a dump. The design of these dipoles bases on identical yoke, furnished with adequate coils and vacuum chambers. 45- degrees water cooled dipoles form a transfer section between FEL and Inverse Compton Scattering parts of the linac. Quadrupole poles design assumed parasitic multipoles strengths less than 10-4 relative to the main one. Dipoles field was assumed uniform within 10-4 of B0. Yokes and poles designs have been performed using 2D FEMM code and refined in 3D with Radia. Manufacturing of yokes and coils will be achieved in NCBJ workshop. Currently, the quadrupole prototype has been built and will be mechanically, electrically and magnetically verified.
Machine learning and Bayesian optimization for pulse shaping on a linear induction accelerator
The Advanced Sources and Detectors project is building an advanced multi-pulse linear induction accelerator capable of generating a 1.4 kA electron beam at energies up to 24 MeV. The accelerator, named Scorpius after the brightest known x-ray source in the sky, will be unique in its use of solid-state pulsed power (SSPP) to generate the voltage pulse for the injector and accelerating gaps throughout the accelerator, giving Scorpius unique control of the pulse shape by independently triggering 45 individual stages stacked in each of nearly 1,000 line replaceable units (LRUs). To take full advantage of the SSPP flexibility, automated optimization of the pulse shape to a desired waveform is currently under development. To demonstrate this capability, nonlinear surrogate circuit models of the SSPP have been developed using the hybrid transmission line/modified nodal analysis code, CASTLE, that include parasitics and a dummy load to generate reflections. Data-efficient Bayesian optimizations calling CASTLE directly for each iteration are compared with results from a convolutional neural network or other machine learning model trained on data generated by CASTLE, and the effect of the number of stages on pulse flattening is discussed.
MOPL139
High Power Radiofrequency Operation of the Radiofrequency Quadrupoles in the Spallation Neutron Source
869
The Spallation Neutron Source (SNS) recently took delivery of a third Radiofrequency Quadrupole (RFQ03) that will ultimately be installed on the front-end (FE) of the SNS Linac. The first RFQ (RFQ01) operated in the SNS FE for more than a decade before being replaced with the second RFQ (RFQ02). RFQ01 was relocated to the Beam Test Facility (BTF) where it operated for five more years. The RFQ02 was initially installed in the BTF for high power testing and used with H- beam for BTF operation. It replaced RFQ01 in the SNS FE in 2017 and has been operating for beam production since then. There are some differences between the three RFQs. RFQ01 has a square cross-section with pi-mode stabilizing loops (PISLs) with the structure being fabricated using two layers of materials, GlidCop outside and OFHC inside. RFQ02 and RFQ03 has an octagonal cross-section with end-wall stabilizer rods and was fabricated using OFHC only. RFQ01 suffered some field flatness distortion incidents that resulted in degradation in beam transmission efficiency and required RF tuning. RFQ02 has performed well but had a melted RF seal in the high energy end wall, that was ultimately mitigated by a redesign of the end flange seals. The SNS decided to order RFQ03 that has a design that followed that of RFQ02 closely, but end-wall contacts were modified to prevent RF seal failure. This report presents the testing, installation, high power RF operation, and design improvements of the RFQ03.
Paper: MOPL139
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL139
About: Received: 01 May 2023 — Revised: 08 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL140
Design and fabrication of the waveguide Iris couplers for the Spallation Neutron Source drift tube linac
873
The Spallation Neutron Source (SNS) employs six cavities in the Drift Tube Linac (DTL) section to accelerate the H- ion beam to 87MeV. Each cavity is energized by a 2.5MW peak power klystron at 402.5MHz using rapid tapered waveguide iris couplers. All six original iris couplers have been in operation without replacement for over two decades. The increased RF power demands of the Proton Power Upgrade (PPU) project and operational problems, including arcing, temperature excursions, and vacuum bursts, have prompted the development of new iris coupler spares. The original iris couplers were made of GlidCop material, which is known to be mechanically strong and thermally stable, but is porous, expensive, and difficult to use in fabrication. To overcome these problems, the new spare couplers use Oxygen-Free Copper (OFC) and stainless steel (SS). This paper will discuss the mechanical, thermal and RF design, as well as challenges in the final coupler fabrication.
Paper: MOPL140
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL140
About: Received: 19 Apr 2023 — Revised: 08 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL141
The CLEAR user facility: a review of the experimental methods and future plans
876
The CERN Linear Accelerator for Research (CLEAR) is a test facility delivering an electron beam in the 30-220 MeV energy range to a diverse user community. In 2022, several hardware and software upgrades were done to the main installation, and procedures and methods were developed to address specific user requirements, including a further extension of the beam parameter ranges. In the paper, these improvements are described and the experimental activities during 2022/2023 are outlined. An outlook on future potential upgrades and on the planned experimental activities in the next years is also given.
Paper: MOPL141
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL141
About: Received: 03 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
Test Lab Klystron-Modulator System for RF Components Performance Test of PLS-II Linac
Recently, we completed a performance upgrade of Test Lab klystron-modulator system for PLS-II RF Linac as well as new developed S-Band 80-MW klystron test. PLS-II main linac system are under an operation of 17 RF stations including S-Band 80-MW klystron. It will be used as a test station for a performance test of RF components for PLS-II RF Linac. Klystron as RF sources is one of critical components for stable beam energy control since its RF power output affects the electron beam energy. Pulse-to-pulse stability of RF linac klystron modulators is one of important issues in 3rd generation synchrotron machine for the top-up operation of the PLS-II linac. This machine requires highly stable RF sources with a stability of 0.01% rms, to meet the beam stability requirements. By adopting a precision capacitor charging power supply (CCPS), we achieved the beam voltage with less than a 100 ppm stability for the MK system. This paper discusses an operational characteristics and measurement results of the Test Lab pulsed MK system.
MOPL144
Steering to a wakefield reduced trajectory using RF kick data in the SLAC linac
880
Wakefields kick the electron bunch to a non-linear tilt causing emittance growth. Any additional correlation like an energy chirp (energy vs z dependence) will filament the disturbance further causing a nearly unrecoverable bigger emittance. For C3 (Cool Copper Collider) the emittance preservation numbers seems to be about 1000 times more stringent than achieved. It is actually "only" about 30 times trickier (square root of 1000) which is still a big number. During two-bunch setups for LCLS (Linac Coherent Light Source) it was observed that the same transverse beam offset reduced the wakefield kick and at the same time the RF kick from the most probably misaligned accelerating structure. To turn this around an RF kick can be easily measured with RF on and off, or a phase scan using a single bunch. The plan is to test this at FACET-II where the emittance growth is quite high due to a high charge. Experimental results where RF kicks are locally minimized and therefore give a better starting value for emittance tuning will be presented in a later paper.
Paper: MOPL144
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL144
About: Received: 02 May 2023 — Revised: 11 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
MOPL147
Ultra-thin film yttria enhanced gold photocathodes
883
The performance requirements for next generation electron accelerators put ever increasing demand on the photocathode performance, where it fundamentally limits the achievable beam quality. Metal photocathodes are limited by their high work function and relatively low quantum efficiency, necessitating the use of high powered deep UV lasers. Metal oxide thin film interfaces have been shown to reduce the work function of the underlying metal photocathode, whilst maintaining the ease of use, high durability and fast response time. This leads to an improvement in quantum efficiency and spectral response to desirable incident laser sources. We present the characterisation of a thin film yttria (Y2O3) enhanced Au photocathode at various film thicknesses. Quantum efficiencies were measured at 265 nm along with surface compositions via X-ray photoelectron spectroscopy.
Paper: MOPL147
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL147
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL148
Study and simulation of cryogenic bi-periodic accelerating structure with TM02 mode
886
To further enhance the accelerating gradient of accelerators, we designed a cryogenic C-band standing wave bi-periodic accelerating structure for the Shanghai Soft X-ray Free Electron Laser Facility (SXFEL). According to the low-temperature environment, material characteristics and technological conditions, the design is completed and it is decided to design the accelerating structure into a bi-periodic magnetic coupling structure. It is a 17-cell structure consisting of 9 accelerating cavities and 8 coupling cavities. To guarantee the symmetry of the field, the structure is doubly-fed. Operating with the $\pi/2$ mode standing wave, it is much less sensitive than the standing-wave structure of $\pi$-mode. Additionally, the microwave mode is TM02 in coupling cavities that are larger and even less sensitive than the traditional bi-periodic structure. The shape of the coupling cavity can be redesigned to make it tunable.
Paper: MOPL148
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL148
About: Received: 20 Mar 2023 — Revised: 13 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL149
Low-level radio-frequency system integrated with feed-forward control and vector modulation
890
To provide a more accurate and stable Radio-Frequency (RF) signal in conditioning and processing test progress, it is necessary to design an Low-Level Radio-Frequency (LLRF) control system which can provide high precision RF driving signal based on meeting the amplitude and phase stabilization requirement. Through Feed-Forward operation, accurate phase adjustment and amplitude adjustment are realized inside the pulse, to realize the precision and automation of phase-inversion, amplitude stabilization, phase stabilization, and waveform adaptation matching. An LLRF System integrated with feed-forward control and vector modulation output was designed and built, the long term working stability of the LLRF system was verified during a new 50MW S band Klystron conditioning progress.
Paper: MOPL149
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL149
About: Received: 08 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL150
Wakefield effects on dark current bunches for LESA
893
Alongside the new LCLS-II facility, a new electron beamline known as Linac to End Station A (LESA) is under construction at SLAC. LESA will use field-emitted dark current from the new superconducting accelerator to search for MeV- to GeV-scale dark matter. To predict the behavior of the dark current in LESA, we must account for the effects of wakefields. In the conventional analysis of long-range wakefields, the bunches are both the sources and subjects of collective effects. Since the contribution of dark current to the wakefield is negligible, the dark bunches are passive recipients of the wakefield kicks. However, we also lose some simplifying assumptions. In contrast to the main bunches, which are generated at a low subharmonic of the RF frequency, dark current is generated on every RF cycle of the source cavity. The dark current bunches may also occupy a much larger proportion of each RF bucket – possibly the entire longitudinal acceptance of the accelerator. These complications lead to effects that are not seen in the main bunches, such as “beating” of the betatron amplitudes along the dark bunch train. In this work, we present the theory behind this interaction and apply it to LESA.
Paper: MOPL150
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL150
About: Received: 04 May 2023 — Revised: 08 Jun 2023 — Accepted: 08 Jun 2023 — Issue date: 26 Sep 2023
MOPL152
Positron beams at Ce+BAF
896
Positron beams would provide a new and meaningful probe for the experimental program at the Thomas Jefferson National Accelerator Facility (JLab). The JLab Positron Working Group, formed in 2018 and now with over 250 members from 75 institutions, continues to develop an experimental program with high duty-cycle positron beams including but not limited to future hadronic physics and dark matter experiments. Critical requirements involve generating positron beams with a high degree of spin polarization, sufficient intensity and a continuous-wave (CW) bunch train compatible with acceleration to 12 GeV at the Continuous Electron Beam Accelerator Facility (CEBAF). In this presentation we describe a start-to-end layout for positron beams at 12 GeV CEBAF utilizing the Low Energy Research Facility (LERF) at Jefferson Lab to build two new injectors. A GaAs dc high voltage photo-gun first generates >1 mA of polarized electrons which are then accelerated to 80-150 MeV and directed to a high-power spinning W target for polarized bremsstrahlung and positron pair creation. A second injector then collects, bunches and accelerates the positrons to 123 MeV. The positron beams are transported by a new beam line and injected into the CEBAF acceptance for acceleration to the end stations with energies up to 12 GeV. The layout is optimized to provide Users with positron spin polarization >60% and intensity greater than >100 nA, and with higher intensities when polarization is not required.
Paper: MOPL152
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL152
About: Received: 03 May 2023 — Revised: 09 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL154
Electromagnetic simulation of LANSCE chopper structure
900
An electromagnetic chopper is an important component of particle accelerators. It helps to provide users with different time structure beams. It is usually placed in the low energy beam sections of accelerators. In general, the chopper has rise and fall times of the order of a few nanoseconds. Due to this rise and fall time, post-chopper beam dynamics are affected. As part of this master thesis, the dependence of the beam parameter on the WNR chopper model (rise time, fall time, flat peak time) will be explored and CST software will be used for beam dynamics simulations.
Paper: MOPL154
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL154
About: Received: 06 May 2023 — Revised: 30 Jun 2023 — Accepted: 12 Jun 2023 — Issue date: 26 Sep 2023
MOPL156
Lattice design for the hadron storage ring of the Electron-Ion Collider
903
The electron-ion collider will utilize a major portion of the existing RHIC rings for its hadron storage ring (HSR). This paper describes the lattice design of the HSR. Presently, RHIC consists of two rings, each of which contains 6 straight sections, and between those straights are arcs, each consisting of 11 FODO cells. The HSR uses 7 of the existing RHIC arcs which are unmodified, other than powering changes to allow the beam to travel opposite to its direction in RHIC in selected arcs. We select the arc in one sextant to keep the orbit period of the HSR the same as that of the new electron storage ring, depending on whether we are operating at hadron energies around 41 GeV/u or in the range of 100 GeV/u to 275 GeV/u. We describe the purpose and lattice design of the 6 straight sections of the HSR.
Paper: MOPL156
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL156
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL157
Synchronizing the timing of the electron and Hadron storage rings in the Electron-Ion Collider
906
The Electron-Ion Collider has an electron storage ring (ESR) and a hadron storage ring (HSR) with beams traveling in opposite directions that collide initially at one but eventually at two interaction points. Our desired machine configurations require a wide range of energies for both rings: 5 to 18 GeV in the ESR, and 41 to 275 GeV/u in the HSR. The range of velocities in the HSR requires that we have a radial position in the arcs which depends on energy for energies from 100 to 275 GeV/u, and that we use a separate arc for a 41 GeV/u beam. We describe the requirements placed on our design to ensure synchronization for all these energies. When there are two detectors, the large beam-beam forces will not support having bunches colliding at both detectors simultaneously, so the design must ensure that bunches collide at only one IP. We describe the constraints this places upon our machine design and the bunch patterns that we use. We discuss the impacts on the timing of orbit manipulations that we expect to make in the ESR: the superbends that increase the radiation at 5~GeV and and orbit shifts to adjust damping partition numbers.
Paper: MOPL157
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL157
About: Received: 04 May 2023 — Revised: 11 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL158
Lattice design for the interaction region of the electron-ion collider
909
We present the lattice design for the interaction region (IR) for the Electron-Ion Collider. We specify the requirements that the IR must meet, both for the hadron and electron beams themselves and for the collision products and radiation that must be transmitted through the magnet apertures. We align the hadron magnets downstream of the detector to pass the collision products while minimizing stray fields in the electron line. We set the fields and gradients in the magnets near the IR to meet the required specifications at both the interaction point and the crab cavities. We describe how these magnet placements can be implemented in accelerator design codes. We match the hadron IR to the existing RHIC arcs, and describe the consequences for the spin manipulation snake and rotators.
Paper: MOPL158
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL158
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL162
Parameter ranges for a chain of rapid cycling synchrotrons for a muon collider complex
913
A facility for a muon collider brings the big advantages of a compact lepton collider and a collision energy up to several TeV, well above the energy reach of conventional electron circular accelerators. However, the short lifetime of muons drives the design of the accelerator complex and collider, which makes this complex unique. A high muon survival rate and luminosity requires an extremely fast energy increase in combination with intense and ultra-short bunches. The International Muon Collider Collaboration proposes a chain of rapid cycling synchrotrons (RCS) for acceleration from several tens of GeV to several TeV. The minimization of the muon decay during the acceleration process is driven by technological limitations like the maximum magnet ramp and field, and cavity gradient. We will consider different scenarios to reuse as much as possible the existing infrastructure at CERN. We will give some scaling laws for a hybrid RCS to evaluate the frequency shift due to a path variation and the trajectory variation. Finally, we will propose a preliminary parameter range for the different stages of an RCS chain.
Paper: MOPL162
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL162
About: Received: 27 Apr 2023 — Revised: 11 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL163
Thermodynamic characteristics of hydrogen in an ionization cooling channel for muon colliders
917
Ionization cooling is the only suitable approach to reduce the phase space volume occupied by a muon beam on a timescale compatible with the muon lifetime. Small normalized transversal emittances can be achieved by using hydrogen (H) as an absorber and high solenoid fields at low beam energy. The strong focusing suppresses emittance growth due to scattering occurring from muon beam interaction with nuclei in the absorber's atoms. This leads to very small beam sizes and therefore the deposition of energy in small volumes causing a high peak energy density. Temperature changes in H can cause pressure rises that may damage the absorber's H containment windows. This work presents the acceptable temperature ranges in liquid H and discusses an alternative method with low density H-gases.
Paper: MOPL163
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL163
About: Received: 03 May 2023 — Revised: 13 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL165
Comparison of tracking codes for beam-matter interaction
921
The interaction of particle beams with materials is important for muon colliders, as it causes particle scattering, energy loss and energy-straggling processes. Such interactions are also relevant in high-precision applications such as radiation oncology treatment planning, where the beam travels through air before reaching the patient, and are also the crucial mechanism for ionization cooling processes, such as those required for generating high-brightness beams for muon colliders. Few particle tracking codes integrate such effects in an environment suitable for lattice design. This work presents the simulation of these effects in the beam tracking program RF-Track (v2.1), compares the beam-matter interactions with the tracking programs ICOOL (v331.1) and G4Beamline (v3.08) and discusses the results.
Paper: MOPL165
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL165
About: Received: 03 May 2023 — Revised: 10 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL166
Neutrino generated radiation from a high energy muon collider
925
Muons circulating in a muon collider decay and generate neutrinos within a small solid angle, which reach the earth’s surface. One of the challenges of a high energy muon collider is to ensure that showers created by such neutrinos interacting close to the earth’s surface result in very low radiation levels. The neutrino radiation cone from a muon beam without divergence is estimated through a combination of analytical estimates and FLUKA simulations. Such neutrino cones have to be combined with the properties of the lattice to obtain the possible radiation levels at the earth’s surface. Studies of mitigation measures will be presented, combining the installation of the collider deep underground with a careful choice of the orientation, and with periodic variations of the muon beam trajectory either within the machine aperture or by deforming the whole machine in the vertical plane.
Paper: MOPL166
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL166
About: Received: 02 May 2023 — Revised: 05 Jun 2023 — Accepted: 05 Jun 2023 — Issue date: 26 Sep 2023
MOPL170
The ESSvSB+ project
929
The European Spallation Source neutrino Super Beam plus (ESSνSB+) project has recently been approved by the EU for a 4-year design study. It aims at measuring the neutrino-nucleus cross-section, which represents the dominant systematic uncertainty in the measurement, in the energy range of 0.2 – 0.6 GeV, as well as perform searches for sterile neutrinos using a Low Energy nuSTORM (LEnuSTORM) and a Low Energy Monitored Neutrino Beam (LEMNB). ESSnuSB+ follows the ESSnuSB design study project 2019-2022 that resulted in a conceptual design of ESSnuSB and an evaluation of its high performance for leptonic CP violation measurements which is due to that the measurements will be made at the second, rather than the first, oscillation maximum, where the sensitivity of the experiment is close to 3 times higher than at the first maximum. This paper reviews the ESSnuSB design-study results and presents the planned ESSnuSB+ design study.
Paper: MOPL170
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL170
About: Received: 08 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL172
Prototyping of a disk-loaded structure for muon acceleration
933
The muon linear accelerator is under development at J-PARC for precise measurement of muon anomalous magnetic moment and electric dipole moment. Four 2592 MHz disk-loaded structures (DLSs) operating in the TM01-2pi/3 mode take charge of the acceleration of high-velocity muon from 70% to 94% of the speed of light. They have disk-iris apertures tapered to generate a quasi-constant gradient of 20 MV/m. Gradual variation in disk space at each cell is one of the structural features of the DLS for muon to synchronize the accelerating phase with the changing speed of muon. Therefore, the dimensions of both end cells are significantly different. Two prototypes of RF couplers and two 9-cell reference cavities with shapes of the end cells of the DLS at the first stage have been fabricated and tested. We validate our design RF parameters and establish a method for tuning the DLS in this paper.
Paper: MOPL172
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL172
About: Received: 03 May 2023 — Revised: 06 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPL173
Development of the diagnostic beamline for muon acceleration test with APF IH-DTL
937
The muon-dedicated linear accelerator is being developed for the muon g-2/EDM experiment at J-PARC. To suppress the decay loss during acceleration, the alternative phase focusing (APF) method inter-digital H-mode drift tube linac (IH-DTL) is adopted in the low-velocity region following a radio-frequency quadrupole linac (RFQ). We are planning to accelerate muons in 2024 using the RFQ and the IH-DTL which will accelerate muons from 8% to 30% of the speed of light with an operating frequency of 324 MHz. After the IH-DTL, a diagnostic beamline will be placed to measure the beam energy and quality after acceleration, and its design, which consists of magnets and bunchers, is underway. In this poster, we will report on the development status of the diagnostic beamline.
Paper: MOPL173
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL173
About: Received: 03 May 2023 — Revised: 12 May 2023 — Accepted: 15 Jun 2023 — Issue date: 26 Sep 2023
MOPL175
Considerations for a new damping ring design of the FCC-ee pre-injector complex
941
The current injector complex design of the FCC-e+e− project consists of e+/e− linacs, which accelerate the beams up to 6 GeV, a damping ring at 1.54 GeV, a pre-booster ring, accelerating the beam up to 16 GeV and a booster synchrotron ring integrated in the collider tunnel accelerating the beams up to the collision energies. The purpose of the damping ring is to accept the 1.54 GeV beam coming from the linac-1, damp the positron/electron beams and provide the required beam characteristics for the injection into the linac-2. The purpose of this paper is to provide a new layout of the damping ring. In this study, the beam parameters are established, including the optics design, layout and consideration for non-linear dynamics optimization.
Paper: MOPL175
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL175
About: Received: 03 May 2023 — Revised: 05 May 2023 — Accepted: 11 May 2023 — Issue date: 26 Sep 2023
MOPL176
Slow Extraction Techniques from Fixed Field Accelerators
945
Fixed Field Accelerators are a candidate for future hadron cancer therapy facilities as their high repetition rate and large energy acceptance enables novel treatment modalities such as high dose rate FLASH. However, conventional dose delivery mechanisms are still necessary, requiring continuous beam delivery over 1--30s. This work is the first study of slow extraction from a scaling Fixed Field Accelerator, using the LhARA facility for baseline parameters. At a horizontal tune of 10/3, the intrinsic sextupole strength of the nonlinear FFA magnetic field is sufficient to excite the resonance, although extraction is better controlled using an additional excitation sextupole at a tune close to 8/3, with radiofrequency knock-out extraction. Including considerations of issues due to nonlinear fields and limitations required to keep the tune energy-independent, slow extraction from Fixed Field Accelerators is successfully demonstrated.
Paper: MOPL176
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL176
About: Received: 31 Mar 2023 — Revised: 16 Jun 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL177
Status of error correction studies in support of FFA@CEBAF
949
In this work, we examine the beam correction requirements for the FFA@CEBAF energy upgrade. Both hardware and software diagnostic and corrector components are under investigation; in particular the relationship between hardware and software optimization will be developed. To generate a representative sample of errors---from the machine lattice and other beam properties---we construct a Markov Chain Monte Carlo (MCMC) sampler which considers different probability distributions for different types of errors. This sample is used to investigate the statistical sensitivity of the beam to various diagnostic and corrective schema. Once statistics are acquired, we plan to use a variety of optimization techniques to minimize correction time for the electron beam in the FFA arcs designed for the CEBAF upgrade.
Paper: MOPL177
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL177
About: Received: 02 May 2023 — Revised: 07 May 2023 — Accepted: 16 Jun 2023 — Issue date: 26 Sep 2023
MOPL178
Short pulsed beam extraction from Kurns FFAG
952
Short pulsed proton beams of 8 ns has been extracted from FFAG accelerator in KURNS. Bunch rotation after adiabatic debunching was used at highest energy orbit.
Paper: MOPL178
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL178
About: Received: 03 May 2023 — Revised: 06 Jun 2023 — Accepted: 06 Jun 2023 — Issue date: 26 Sep 2023
MOPL179
A conceptual design of FFA ring for super heavy element production adopting the ERIT mechanism.
955
Production of super heavy elements of which atomic number is larger than 118 can provide new prospects in the field of nuclear physics. Extremely low production rate of these elements makes the experiments time consuming. This difficulty can be solved by using the energy recovery internal target, so-called ERIT, because the number of interactions can be increased as a circulating beam hits the target located in the ERIT ring. Here, we present a conceptual design of the FFA ring for super heavy element production adopting the ERIT mechanism.
Paper: MOPL179
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL179
About: Received: 03 May 2023 — Revised: 25 May 2023 — Accepted: 25 May 2023 — Issue date: 26 Sep 2023
MOPL180
Proton and electron RLA optics design
958
We describe optics designs of the key components of proton and electron Recirculating Linear Accelerators (RLAs). They are presented in the context of a high-power hadron accelerator being considered at ORNL and a CEBAF electron energy doubling study, FFA@CEBAF, being developed at Jefferson Lab. Both concepts rely on the Fixed-Field Alternating gradient (FFA) arc optics designs where multiple beam passes are transported by a single beam line.
Paper: MOPL180
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL180
About: Received: 13 May 2023 — Revised: 16 May 2023 — Accepted: 19 Jun 2023 — Issue date: 26 Sep 2023
MOPL182
CEBAF 22 GeV FFA energy upgrade
962
Extending the energy reach of CEBAF by increasing the number of recirculations, while using the existing linacs is explored. This energy upgrade is based on the multi-pass acceleration of electrons in a single non-scaling Fixed Field Alternating Gradient (FFA) beam line, using Halbach-style permanent magnets. Encouraged by the recent successful demonstration of CBETA, a proposal was formulated to nearly double the energy of CEBAF from 12 to 22~GeV by replacing the highest energy arcs with FFA transport. The new FFA arcs would support simultaneous transport of an additional 6 passes spanning roughly a factor of two in energy. One of the challenges of the multi-pass (11) linac optics is to assure uniform focusing over a wide range of energies. Here, we propose a triplet lattice that provides a stable periodic solution covering an energy ratio of 1:33. The current CEBAF injection at 123 MeV, makes optical matching in the first linac impossible due to the extremely high energy ratio (1:175). Replacement of the current injector with a 650 MeV recirculating injector will alleviate this issue. Orbital and optical matching from the FFA arcs to the linacs is implemented as a compact non-adiabatic insert. The design presented here is anticipated to deliver a 22 GeV beam with normalized emittance of 76 mm·mrad and a relative energy spread of 1×10^{-3}. Further recirculation beyond 22 GeV is limited by the large (974 MeV per electron) energy loss due to synchrotron radiation.
Paper: MOPL182
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL182
About: Received: 03 May 2023 — Revised: 08 May 2023 — Accepted: 12 May 2023 — Issue date: 26 Sep 2023
MOPL183
Designing the spreaders and splitters for the FFA@CEBAF energy upgrade
965
The FFA@CEBAF energy upgrade study aims to approximately double the final energy of the electron beam at the Continuous Electron Beam Accelerator Facility (CEBAF). It will do this by replacing the highest-energy recirculating arcs with fixed-field alternating gradient (FFA) arcs, allowing for several more passes to circulate through the machine. This upgrade necessitates the re-design of the vertical spreader sections, which separate each pass into different recirculation arcs. Additionally, the FFA arcs will need horizontal splitter lines to correct for time of flight and R56. This work will present the current state of the spreader re-design and splitter design.
Paper: MOPL183
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL183
About: Received: 02 May 2023 — Revised: 23 May 2023 — Accepted: 23 May 2023 — Issue date: 26 Sep 2023
MOPL184
Multicell dielectric disk accelerating structure design and low power results
969
Utilizing short RF pulses ($\sim$9 ns) with Dielectric Disk Accelerators (DDA) is a way to improve the energy efficiency of a linear accelerator and decrease the required footprint while still achieving large energies. A DDA is an accelerating structure that utilizes dielectric disks to improve the shunt impedance while still achieving large accelerating gradients. A single cell clamped DDA structure was designed and high power tested at the Argonne Wakefield Accelerator, reaching an accelerating gradient of 102~MV/m. A multicell clamped DDA structure has been designed and fabricated. Simulation results for this new structure show a 108~MV/m accelerating gradient with 400~MW of input power with a high shunt impedance and group velocity. Engineering designs have been improved from the single cell structure to improve the consistency of clamping over the entire structure. The multicell structure has been fabricated, assembled, and low power tested with high power testing to come.
Paper: MOPL184
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL184
About: Received: 03 May 2023 — Revised: 11 May 2023 — Accepted: 20 Jun 2023 — Issue date: 26 Sep 2023
MOPL185
High beam energy recovery simulations for space charged based collector in Neutral beam injection application
973
Energy recovery of residual ions may be needed to increase the energy efficiency of Neutral Beam (NB) injectors for fusion plants as DEMO while a deflection-based system has been proposed. A compact beam energy recovery system, composed of 2 Farady Cups (FC) with holes for D0 passage, based on space charge effects, very effective to recover ions with low residual energy, has been proposed recently to replace the Electrostatic Residual Ion Dump (ERID) designed for ITER to dump the residual D- and D+ before the NB injection in the tokamak plasma [1]. New more accurate simulations on the proposed recovery system, however, presented some collection efficiency problems for very high initial beam kinetic energy (Eki=0.5÷ 1 MeV) when a very low residual (few keV) energy in the planned device. In this contribution, all parameter tunings for optimized simulation results are described and discussed. The collection of high Eki ions at low energy (a few percent of the full neutral beam energy Eki) remain possible although it could be done with lower efficiencies.
Paper: MOPL185
DOI: reference for this paper: 10.18429/JACoW-IPAC2023-MOPL185
About: Received: 04 May 2023 — Revised: 12 May 2023 — Accepted: 23 Jun 2023 — Issue date: 26 Sep 2023
Advanced accelerators for high energy physics and Snowmass AF06
New R\&D concepts for particle acceleration, generation, and focusing at ultra high acceleration gradients (GeV/m and beyond) have the potential to enable future e+e- and $\gamma - \gamma$ colliders to and beyond 15 TeV energies. In addition to proven high gradient and ultra-bright beam generation, these systems have the potential to increase luminosity per unit beam power via short beams, for practical energy recovery to extend the reach of high energy physics, and for fast cooling. They hence have potential to reduce the dimensions, CO$_2$ footprint, and costs of future colliders, with added potential to reduce power consumption. The last decade has seen tremendous experimental progress in performance, together with development of concepts to address potential collider issues. Conceptual parameter sets for colliders have been developed for e+e- and $\gamma \gamma$ colliders at a range of energies, which present potentially competitive options with prospects for future cost reduction. In addition to a strengthened ongoing R$\&$D program, continuing to develop these collider concepts in interaction with the collider and high energy physics communities, starting with an integrated set of parameters, is important; as is development of technologies through nearer-term applications. Progress in these concepts, next steps, and results of Snowmass Accelerator Frontier topical group # 6, Advanced Accelerator Concepts (https://doi.org/10.48550/arXiv.2208.13279) will be discussed.