Improvement of Capture Ratio for an X-Band Linac Based on Multi-Objective Genetic Algorithm
18
J.Y. Li, T. Hu, J. Yang, B.Q. Zeng
HUST, Wuhan, People’s Republic of China
H.G. Xu
SINR, Jiading, Shanghai, People’s Republic of China
Funding:This work was supported by National Natural Science Foundation of China (NSFC) under Project Numbers 11905074. Electron linear accelerators with an energy of ~MeV are widely required in industrial applications. Whereas miniaturized accelerators, especially those working at X-band, attract more and more attention due to their compact structures and high gradients. Since the performance of a traveling wave (TW) accelerator is determined by its structures, considerable efforts must be made for structure optimization involving numerous and complex parameters. In this context, functional key parameters are obtained through deep analysis for structure and particle motion characteristics of the TW accelerator, then a multi-objective genetic algorithm (MOGA) is successfully applied to acquire an optimized phase velocity distribution which can contribute to achieving a high capture ratio and a low energy spread. Finally, a low-energy X-band TW tube used for rubber vulcanization is taken as an example to verify the reliability of the algorithm under a single-particle model. The capture ratio is 91.2%, while the energy spread is 5.19%, and the average energy is 3.1MeV.
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Recent Improvements in the Beam Capture at Fermilab Booster for High Intensity Operation
23
C.M. Bhat, S. Chaurize, P. Derwent, M.W. Domeier, V.M. Grzelak, W. Pellico, J. Reid, B.A. Schupbach, C.-Y. Tan, A.K. Triplett
Fermilab, Batavia, Illinois, USA
Funding:This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Fermilab Booster is the oldest RCS in operation in the world. In current operations, it accelerates ~4.5E12ppp to 8 GeV at 15 Hz and will be upgraded to >6.7E12ppp at 20 Hz in the PIP-II era. Booster has 22 RF cavities with each capable of providing ~50 kV. These cavities are divided into two groups: A & B. In the tunnel, the cavities are cavities are placed in a BA, AB, ¿ sequence. At injection, A & B cavities have anti-parallel RF phase which results in a net zero RF voltage on the beam. During beam capture, the RF voltage is increased adiabatically by decreasing the relative phase between them. At the end of beam capture, the feedback is turned on for beam acceleration. It is vital that for current operations and in the PIP-II era that these cavities are properly matched in both magnitude and phase to preserve the longitudinal emittance during the early part of the beam cycle and to offer full RF voltage on the beam. In this paper we describe the how the cavities are distributed and how the phases are measured with beam and then corrected and balanced. Data with high intensity beam capture is also presented.
M. El Baz
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
J.-P. Carneiro, B.M. Hanna
Fermilab, Batavia, Illinois, USA
The PIP-II particle accelerator is a new upgrade to the Fermilab accelerator complex, featuring an 800-MeV H⁻ superconducting linear accelerator that will inject the beam into the present Fermilab Booster. A test accelerator known as PIP-II Injector Test (PIP2IT) has been built to validate the concept of the front-end of PIP-II. One of the paramount challenges of PIP2IT was to demonstrate a low longitudinal emittance at the end of the front end. Having a low longitudinal emittance is crucial in order to ensure the stability of the beam in the accelerator. We present a longitudinal emittance calculation at 14.3 MeV at the SSR1-8 cavity in the High Energy Transport line (HEBT). The signal is collected by a Fast Faraday Cup (FFC) at the end of HEBT and recorded by a high-bandwidth oscilloscope.
Status of the JAEA-ADS Superconducting LINAC Design
30
B. Yee-Rendón, Y. Kondo, F. Maekawa, S.I. Meigo, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
The Japan Atomic Energy Agency (JAEA) is working in the research and development of an Accelerator Driven Subcritical System (ADS) for the transmutation of nuclear waste. To this end, JAEA is designing a 30-MW cw proton linear accelerator (linac) with a beam current of 20 mA. The JAEA-ADS linac starts with a Normal Conducting (NC) up to an energy of 2.5 MeV. Then, five Superconducting (SC) sections accelerate the beam up to 1.5 GeV. The biggest challenge for this ADS linac is the stringent reliability required to avoid thermal stress in the subcritical reactor, which is higher than the achieved in present accelerators. For this purpose, the linac pursues a strong-stable design that ensures the operation with low beam loss and fault-tolerance capabilities to continue operating in case of failure. This work presents the beam dynamics results toward achieving high reliability for the JAEA-ADS linac.
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Reduction of the Beam Jitter at the PIP2IT Test Accelerator
35
A.V. Shemyakin, G.W. Saewert, A. Saini
Fermilab, Batavia, Illinois, USA
Funding:This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Analysis of the beam position monitor (BPM) signals at the H⁻ test linear accelerator PIP2IT showed that a large portion of the signals scatter comes from the beam jitter. BPM position measurements of the jitter modes were compared with beam motion responses to perturbations excited by driving various beamline parameters in a low frequency sinusoidal manner. The main contributor to the jitter was found to be a low frequency noise in the input reference to the ion source high voltage (HV) power supply. Filtering the HV power supply reference signal decreased the rms scatter in BPM readings by a factor of 2-3.
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Resonance Compensation for High Intensity and High Brightness Beams in the CERN PSB
40
F. Asvesta, S.C.P. Albright, F. Antoniou, H. Bartosik, C. Bracco, G.P. Di Giovanni, E.H. Maclean, B. Mikulec, T. Prebibaj, E. Renner
CERN, Geneva, Switzerland
Resonance studies have been conducted during the recommissioning of the CERN Proton Synchrotron Booster (PSB) following the implementation of the LHC Injectors Upgrade (LIU) project. In particular, resonance identification through so-called loss maps has been applied on all four rings of the PSB, revealing various resonances up to fourth order. In a second step, compensation schemes for the observed resonances were developed using a combination of analytical methods, experimental data and machine learning tools. These resonance compensation schemes have been deployed in operation to minimize losses for reaching high intensity and high brightness, thereby achieving the target brightness for the LHC-type beams.
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Chromaticity Measurement Using Beam Transfer Function in High Energy Synchrotrons
46
X. Buffat, S.V. Furuseth, G. Vicentini
CERN, Geneva, Switzerland
S.V. Furuseth
EPFL, Lausanne, Switzerland
Control of chromaticity is often critical to mitigate collective instabilities in high energy synchrotrons, yet classical measurement methods are of limited use during high intensity operation. We explore the possibility to extract this information from beam transfer function measurements, with the development of a theoretical background that includes the impact of wakefields and by analysis of multi-particle tracking simulations. The investigations show promising results that could improve the operation of the HL-LHC by increasing stability margins.
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Recent Progress on Nonlinear Beam Manipulations in Circular Accelerators
52
F. Capoani, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy
In recent years, transverse beam splitting by crossing a stable resonance has become the operational means to perform MultiTurn Extraction (MTE) from the CERN PS to the SPS. This method delivers the high-intensity proton beams for fixed-target physics at the SPS. More recently, further novel manipulations have been studied, with the goal of devising new techniques to manipulate transverse beam properties. AC magnetic elements can allow beam splitting to be performed in one of the transverse degrees of freedom. Crossing 2D nonlinear resonances can be used to control the sharing of the transverse emittances. Furthermore, cooling the transverse emittance of an annular beam can be achieved through an AC dipole. These techniques will be presented and discussed in detail, considering future lines of research.
P.D. Hermes, R. Bruce, R. De Maria, M. Giovannozzi, A. Mereghetti, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland
G. Stancari
Fermilab, Batavia, Illinois, USA
Each of the two proton beams in the High-Luminosity Large Hadron Collider (HL-LHC) will carry a total energy of 720 MJ. One concern for machine protection is the energy stored in the transverse beam tails, estimated to potentially reach up to 5% of the total stored energy. Several failure scenarios could drive these tails into the collimators, potentially causing damage and therefore severely affecting operational efficiency. Hollow Electron Lenses (HEL) were integrated in the HL-LHC baseline to mitigate this risk by depleting the tails in a controlled way. A hollow-shaped electron beam runs co-axially to the hadron beam over about 3 m, such that halo particles at large amplitudes become unstable, while core particles ideally remain undisturbed. Residual fields from e-beam asymmetries can, however, induce emittance growth of the beam core. Various options for the pulsing of the HEL are considered and are compared using two figures of merit: halo depletion efficiency and core emittance growth. This contribution presents simulations for these two effects with different HEL pulsing modes using the final HL-LHC optics, that was optimized at the location of the lenses.
Closed Form Formulas of the Indirect Space Charge Wake Function for Axisymmetric Structures
65
N. Mounet, E. Dadiani, E. Métral, C. Zannini
CERN, Geneva, Switzerland
A. Rahemtulla
EPFL, Lausanne, Switzerland
Indirect space charge contributes significantly to the impedance of non ultrarelativistic machines such as the LEIR, PSB and PS, at CERN. While general expressions exist in frequency domain for the beam coupling impedance, the time domain wake function is typically obtained numerically, thanks to an inverse Fourier transform. An analytical expression for the indirect space charge wake function, including the time dependence as a function of particle velocity, is nevertheless highly desirable to improve the accuracy of time domain beam dynamics simulations of coherent instabilities. In this work, a general formula for the indirect space charge wake function is derived from the residue theorem. Moreover, simple approximated expressions reproducing the time and velocity dependence are also provided, which can even be corrected to recover an exact formula, thanks to a numerical factor computed once for all. The expressions obtained are successfully benchmarked with a purely numerical approach based on the Fourier transform.
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Controlled Longitudinal Emittance Blow-Up for High Intensity Beams in the CERN SPS
71
D. Quartullo, H. Damerau, I. Karpov, G. Papotti, E.N. Shaposhnikova, C. Zisou
CERN, Geneva, Switzerland
D. Quartullo
Sapienza University of Rome, Rome, Italy
Controlled longitudinal emittance blow-up will be required to longitudinally stabilize the beams for the High-Luminosity LHC in the SPS. Bandwidth-limited noise is injected at synchrotron frequency sidebands of the RF voltage of the main accelerating system through the beam phase loop. The setup of the blow-up parameters is complicated by bunch-by-bunch differences in their phase, shape, and intensity, as well as by the interplay with the fourth harmonic Landau RF system and transient beam loading in the main RF system. During previous runs, an optimization of the blow-up had to be repeated manually at every intensity step up, requiring hours of precious machine time. With the higher beam intensity, the difficulties will be exacerbated, with bunch-by-bunch differences becoming even more important. We look at the extent of the impact of intensity effects on the controlled longitudinal blow-up by means of macro-particle tracking, as well as analytical calculations, and we derive criteria for quantifying its effectiveness. These studies are relevant to identify the parameters and observables which become key to the operational setup and exploitation of the blow-up.
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Understanding of the CERN-SPS Horizontal Instability with Multiple Bunches
77
C. Zannini, H. Bartosik, M. Carlà, K.S.B. Li, E. Métral, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland
L.R. Carver
ESRF, Grenoble, France
M. Schenk
EPFL, Lausanne, Switzerland
At the end of 2018, an instability with multiple bunches has been consistently observed during high intensity studies at the CERN-SPS. This instability could be a significant limitation to achieve the bunch intensity expected after the LHC Injector Upgrade (LIU). Therefore, a deep understanding of the phenomena is essential to identify the best mitigation strategy. Extensive simulation studies have been performed to explore the consistency of the current SPS model, give a possible interpretation of the instability mechanism and outline some possible cures.
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Influence of Transverse Motion on Longitudinal Space Charge in the CERN PS
83
A.J. Laut, A. Lasheen
CERN, Geneva 23, Switzerland
Particles in an intense bunch experience longitudinal self-fields due to space~charge. This effect, conveniently described by geometric factors dependent on a particle¿s transverse position, beam size, and beam pipe aperture, is usually incorporated into longitudinal particle tracking on a per-turn basis. The influence of transverse betatron motion on longitudinal space~charge forces is, however, usually neglected in pure longitudinal tracking codes. A dedicated tracking code was developed to characterize the CERN PS such that an effective geometric factor of a given particle could be derived from its transverse emittance, betatron phase~advance, and momentum~spread. The effective geometry factor is then estimated per particle by interpolation without the need for full transverse tracking and incorporated into the longitudinal tracker BLonD. The paper evaluates this effect under conditions representative of the PS, where space~charge is dominant at low energy and progressively becomes negligible along the acceleration ramp. The synchrotron frequency distribution is modified and the filamentation rate is moreover increased, which could suggest a stabilizing space~charge phenomenon.
The PS Booster Alignment Campaign and a New Tune Control Implementation After the LHC Injectors Upgrade at CERN
89
F. Antoniou, F. Asvesta, H. Bartosik, J.F. Comblin, G.P. Di Giovanni, M. Hostettler, A. Huschauer, B. Mikulec, J.-M. Nonglaton, T. Prebibaj
CERN, Meyrin, Switzerland
The CERN PS Booster (PSB) has gone through major upgrades during the Long Shutdown 2 (LS2) and the recommissioning with beam started in December 2020. Two of the aspects leading to improved operation will be described in this paper: a new tune control implementation; and a full re-alignment campaign. The operation of the PSB requires a large range of working points to be accessible along the acceleration cycle. As part of the LIU project, the PSB main power supply was upgraded to raise the extraction energy from 1.4 GeV to 2 GeV, in order to improve the brightness reach of the downstream machines. A new tune control implementation was necessary to take into account saturation effects of the bending magnets and the reconfiguration of the main circuits, as well as the additional complexity of the new H⁻ charge exchange injection. The first part of the paper describes the implementation of the new tune control and its experimental verification and optimization. The second part describes the results of the PSB alignment campaign after LS2, giving emphasis to the method developed to perform a combined closed orbit correction through quadrupole alignments.
Threshold for Loss of Longitudinal Landau Damping in Double Harmonic RF Systems
95
L. Intelisano, H. Damerau, I. Karpov
CERN, Meyrin, Switzerland
Landau damping is a natural stabilization mechanism to mitigate coherent beam instabilities in the longitudinal phase space plane. In a single RF system, binominal particle distributions with a constant inductive impedance above transition (or capacitive below) would lead to a vanishing threshold for the loss of Landau damping, which can be avoided by introducing an upper cut-off frequency to the impedance. This work aims at expanding the recent loss of Landau damping studies to the common case of double harmonic RF systems. Special attention has been paid to the configuration in the SPS with a higher harmonic RF system at four times the fundamental RF frequency, and with both RF systems in counter-phase (bunch shortening mode). Refined analytical estimates for the synchrotron frequency distribution allowed to extend the analytical expression for the loss of Landau damping threshold. The results are compared with semi-analytical calculations using the MELODY code, as well as with macroparticle simulations in BLonD.
New Analytical Criteria for Loss of Landau Damping in Longitudinal Plane
100
I. Karpov, T. Argyropoulos, E.N. Shaposhnikova
CERN, Meyrin, Switzerland
S. Nese
University of Bergen, Bergen, Norway
Landau damping is a very important stabilization mechanism of beams in circular hadron accelerators. In the longitudinal plane, Landau damping is lost when the coherent mode is outside of the incoherent synchrotron frequency spread. In this paper, the threshold for loss of Landau damping (LLD) for constant inductive impedance ImZ/k is derived using the Lebedev matrix equation (1968). The results are confirmed by direct numerical solutions of the Lebedev equation and using the Oide-Yokoya method (1990). For more realistic impedance models of the ring, new definitions of an effective impedance and the corresponding cutoff frequency are introduced which allow using the same analytic expression for the LLD threshold. We also demonstrate that this threshold is significantly overestimated by the Sacherer formalism based on the previous definition of an effective impedance using the eigenfunctions of the coherent modes.
End-to-End Longitudinal Simulations in the CERN PS
106
A. Lasheen, H. Damerau, K. Iliakis
CERN, Meyrin, Switzerland
In the context of the LHC Injector Upgrade (LIU) project, the main longitudinal limitations in the CERN PS are coupled bunch instabilities and uncontrolled emittance blow-up leading to losses at injection into the downstream accelerator, the SPS. To complement beam measurements, particle tracking simulations are an important tool to study these limitations. However, to avoid excessive runtime, simulations are usually targeting only a fraction of the cycle assuming that bunches are initially matched to the RF bucket. This ignores all initial perturbations that could seed an instability. Simulations were therefore performed along the full PS cycle by using the BLonD tracking code optimized with advanced parallelization schemes. They include beam manipulations with several RF harmonics (batch compression, merging, splittings), controlled emittance blow-up, a model of the beam coupling impedance covering a wide frequency range, as well as beam and cavity feedbacks. A large number of macroparticles is required as well as arrays to store beam induced voltage spanning several revolutions to account for long range wakefields.
Injection Chicane Beta-Beating Correction for Enhancing the Brightness of the CERN PSB Beams
112
T. Prebibaj, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, E.H. Maclean, B. Mikulec, E. Renner
CERN, Meyrin, Switzerland
T. Prebibaj
IAP, Frankfurt am Main, Germany
In the context of the LHC Injectors Upgrade Project (LIU), the Proton Synchrotron Booster (PSB) developed an H⁻ charge exchange injection system. The four short rectangular dipoles of the injection chicane induce focusing errors through edge focusing and Eddy currents. These errors excite the half-integer resonance 2Qy = 9 and cause a dynamically changing beta-beating in the first milliseconds after injection. Using the beta-beating at the positions of two individually powered quadrupoles, measured with k-modulation, correction functions based on a model response matrix have been calculated and applied. Minimizing the beta-beating at injection allows the machine to be operated with betatron tunes closer to the half-integer resonance and therefore with larger space charge tune spreads. In this contribution the results of the beta-beating compensation studies and the impact on the achievable beam brightness limit of the machine are presented.
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Optimised Transverse Painting Schemes for the New 160 MeV H⁻ Injection System at CERN
118
E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, B. Mikulec, T. Prebibaj, F.M. Velotti
CERN, Meyrin, Switzerland
A major aspect of the LHC Injectors Upgrade (LIU) project at CERN is the Proton Synchrotron Booster (PSB) connection to the newly built Linac4 and the related installation of a new 160 MeV H⁻ charge exchange injection. This contribution presents the first operational experience with the new injection system and its flexibility of applying horizontal phase space painting to tailor different beams to the respective user-defined brightness targets. The presented measurement and multi-particle simulation results focus on the optimisation of the required transverse injection settings to reduce losses when producing high-intensity beams, i.e. for the ISOLDE experiment. In this context, feasibility studies towards applying numerical optimisation algorithms for improving and efficiently adapting the respective injection settings online are presented.
Space Charge Resonance Analysis at the Integer Tune for the CERN PS
124
F. Schmidt, F. Asvesta
CERN, Meyrin, Switzerland
In the context of the LHC Injectors Upgrade (LIU) project, a series of studies have been performed in order to better understand the beam brightness limitations imposed by resonances and space charge effects. Space charge simulations using the analytic (frozen) space charge solver as implemented in the MAD-X code conducted for the CERN Proton Synchrotron (PS) show that a particle approaching the integer tune of Qx = 6 demonstrates a resonant behavior. The analysis of the single particle transverse motion reveals the excitation of a second order resonance. The interplay of the space charge effect and the optics perturbation in the regime of the integer tune on this excitation was further investigated. The simulations were complemented with the analysis of the resonance driving terms coming from the space charge potential derived in a classical perturbative approach.
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3D Symplectic Space Charge Implementation in the Latest Mad-X Version
129
F. Schmidt, A. Latina, H. Renshall
CERN, Meyrin, Switzerland
Y.I. Alexahin
Fermilab, Batavia, Illinois, USA
In 2018 as part of a collaboration between CERN and FNAL, the space charge (SC) implementation has been upgraded in a test version of MAD-X. The goal has been to implement the 3D symplectic SC kick together with a number of new features and benchmark it with earlier MADX-SC versions. Emphasis has given to the use of the Sigma Matrix approach that allows to extend MAD-X optics calculations. In the meantime, significant effort has been made to fully debug and optimize the code and in particular to achieve a speed-up of the simulations by a factor of 2. The code has been ported to the latest MAD-X version, the elaborated set-up procedures have been automated and a user manual has been written.
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A Dedicated Wake-Building Feedback System to Study Single Bunch Instabilities in the Presence of Strong Space Charge
135
R. Ainsworth, A.V. Burov, N. Eddy, A. Semenov
Fermilab, Batavia, Illinois, USA
Recent advances in the theoretical understanding of beam stability in the presence of strong space charge, has suggested a new class of instabilities known as convective instabilities. A novel approach to excite and study these instabilities will be to install a ‘waker’ system, a dedicated wake-building feedback system. The System was installed in the Fermilab Recycler and commissioned during 2021. The first results are presented.
Coupled Bunch Instabilities Growth in the Fermilab Booster During Acceleration Cycle
140
C.M. Bhat, N. Eddy
Fermilab, Batavia, Illinois, USA
Funding:This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The Fermilab Booster is an RCS with h=84 and gammaT =5.47 and, during standard operation it accelerates ~4.5E12ppBc from 400 MeV to 8 GeV at 15 Hz. The Booster is being upgraded to handle higher beam intensity >6.7E12ppBc and repetition rate of 20Hz. In the current mode of operation, we perform multi-turn beam injection and capture beam in h=84 system adiabatically. However, we have observed coupled bunch (CB) instabilities in the extracted beam. This issue is expected to worsen at higher beam intensities. In principle, for h=84 one expects 41 modes of oscillations contributing to these CB instabilities. Currently, we have a digital mode damper to mitigate prominent CB modes [1]. We would like to understand at what time in the beam cycle a particular mode is going to originate and how much it contributes at a different time of the cycle. In this regard, we have collected wall current monitor data from injection to extraction and looked for the start of a particular mode of CB instability and its growth for different intensities. This paper presents the results from this study and future plans to mitigate the CB instability in Booster. [1] Nathan Eddy (private communications, 2020).
Compensation of Ultimate Space Charge with Electron Lenses
E.G. Stern, Y.I. Alexahin, A.V. Burov, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA
Space-charge effects set stringent limits on the performance of frontier high power proton accelerators. They manifest themselves in beam losses and emittance growth. Compensation of the space-charge effects in positively charged proton beams is possible by propagating the beam through negatively charged electron lenses which employ high brightness magnetized and externally controlled electron beams. While the method was previously assessed theoretically and in simplified tracking simulations, it has never been modeled by PIC codes to get reliable quantitative estimates of the efficiency of the compensation. Here we report on the first evidence using the Synergia particle-in-cell simulation code that a suitable number of electron lens type elements can protect the machine from emittance growth caused by space-charge forces in a model beam optics lattice with imperfections. For effective electron lens space-charge compensation, the compensating elements must be placed within not too large betatron phase advance from each other. Electron lens elements could become the basis of new generation of high power proton and ion rapid cycling synchrotrons.
Simulating Magnetized Electron Cooling for EIC with JSPEC
S.J. Coleman, D.T. Abell, D.L. Bruhwiler, B. Nash, I.V. Pogorelov
RadiaSoft LLC, Boulder, Colorado, USA
H. Zhang
JLab, Newport News, Virginia, USA
We present a possible electron cooling configuration for the proposed Electron Ion Collider (EIC) facility, developed using a Nelder-Mead Simplex optimization procedure built into JSPEC, an electron cooling code developed at Jefferson Lab. The time evolution of the emittance of the ion beam in the presence of this cooler is evaluated assuming the ion distribution remains Gaussian. We also show that bi-gaussian distributions emerge in simulations of ion macro-particles, where Gaussian distributions are not enforced. The Sirepo/JSPEC and Sirepo/Jupyter apps will be presented, with instructions enabling the community to reproduce our simulations
Status of Layout Studies for Fixed-Target Experiments in Alice Based on Crystal-Assisted Halo Splitting
146
M. Patecki, D. Kikoła
Warsaw University of Technology, Warsaw, Poland
A.S. Fomin, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland
Funding:This project has received funding from the European Union’s Horizon 2020 research and innovation programme. The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 TeV and 2.76 TeV, respectively. ALICE is one of the detector experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is considered to collide a portion of the beam halo split by means of a bent crystal with an internal target placed a few meters upstream of the detector. Fixed-target collisions offer many physics opportunities related to hadronic matter and the quark-gluon plasma to extend the research potential of the CERN accelerator complex. This paper summarises our progress in preparing the fixed-target layout consisting of crystal assemblies, a target and downstream absorbers. We discuss the conceptual integration of these elements within the LHC ring, impact on ring losses, conditions for a parasitic operation and expected performance in terms of particle flux on target.
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The Design and Implementation of Fast Machine Protection System for CSNS
151
P. Zhu, Y.C. He, D.P. Jin, Y.L. Zhang
IHEP, Beijing, People’s Republic of China
L. Wang, X. Wu, K. Xue
IHEP CSNS, Guangdong Province, People’s Republic of China
The high-quality of fast machine protection system(FPS) is one of the significant conditions for the stable and reliable operation of the Chinese Spallation Neutron Source (CSNS) accelerator. Based on the design concept of high availability, high reliability and high maintainability, we adopt the distributed architecture based on "high-performance Field Programmable Gate Array (FPGA) chip + Gigabit Transceiver with Low Power (GTP)+ VME bus read and write by real-time", which is demonstrated the superior performance to satisfy the requirements of the CSNS accelerator during commissioning and operation. The main design and implementation include: (1) develop diversity signal interface boards achieving a flexible interaction; (2) explore and realize protection strategies improving beam efficiency; (3) self-define and implement the creative and practical functions enhancing the robustness of the system, such as signal heartbeat monitoring, fail-safe mechanism, automatic reset, and so on. The CSNS accelerator fast machine protection system has been put into operation for nearly five years with strong operability and availability, thorough traversal and response time-consuming tests.
