laser
MOPC28
Status of the commissioning of the X-band injector prototype for AWAKE Run 2c
121
The status of commissioning of the electron injector intended for the next phase of the proton driven wakefield experiment (AWAKE) is presented, showing first experimental results from operating the brazing-free electron gun. To provide a high-quality electron beam, the UV laser was centered on the copper cathode, and a novel simplex and beam-based alignment of the focusing solenoid was performed. Measurements of the beam parameters and working points are addressed. The electron gun is shown to provide a high quality, stable and reproducible beam.
Paper: MOPC28
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC28
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPC37
Mechanical analysis and design for the LCLS-II-HE soft X-Ray undulator reconfiguration
142
As a part of the High Energy upgrade to the Linac Coherent Light Source II at SLAC, LBNL is responsible for the update of the undulators of the Soft X-Ray (SXR) line. In order to span the required photon energy range, the SXR undulators require longer magnetic period. This increased magnetic period leads to higher magnetic force, requiring updates to certain elements of the design. In contrast, many elements can safely remain unchanged. This presentation details the updates and analyses performed to support the adaptation to HE-SXR, as well as pre-production undulator results.
Paper: MOPC37
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC37
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPC47
Design and status of SHINE injector
164
Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) is an x-ray FEL facility, consisting of an 8 GeV CW superconducting linac and 3 FEL undulator lines, covering the spectral ranges 0.4-25 keV. Photoinjector using VHF gun is one of the key part of the facility. The installation of the electron gun section of the SHINE injector has been completed in August 2023. RF conditioning and commissioning were carried out from September to December. In this paper, we will introduce the installation progress of the injector and show some commissioning results of the electron gun section.
Paper: MOPC47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC47
About: Received: 15 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
MOPC52
Toward a long-lifetime polarized photoelectron gun for the Ce+BAF positron source
176
The addition of spin-polarized, continuous-wave (c.w.) positron beams to the 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) would provide a significant capability to the experimental nuclear physics program at Jefferson Lab. Based on bremsstrahlung and pair-production in a high-Z target, the positron source requires a 120 MeV spin-polarized c.w. electron beam of several milliamperes. While the beam dynamics of the high-current electron beam are tenable, sustaining this current for weeks of user operations requires an unprecedented charge lifetime from a high-polarization GaAs-based photocathode. A promising approach to exceed the kilocoulomb charge lifetime barrier is reducing the ion back-bombardment fluence at the photocathode. By increasing the laser size and managing the emittance growth with an adequate cathode/anode design, significantly enhanced charge lifetime may be achieved. Based upon a new simulation model that qualitatively explains the lifetime data previously measured at different spot sizes, we describe the practical implications on the parameter space available for a kilocoulomb-lifetime polarized photogun design.
Paper: MOPC52
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPC52
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG11
X-ray optics and diagnostics for the cavity-based X-ray free-electron laser project
319
The cavity-based x-ray free-electron laser (CBXFEL) R&D project utilizes a low-loss x-ray cavity (65.5 m long) to provide circulating monochromatized x-ray seeding for electrons from the Cu-linac at SLAC. The project aims to demonstrate the two-pass gain in x-ray regenerative amplifier and XFELO modes by 2024. Here, we report on the design, manufacture, and characterization of x-ray optical and diagnostic components for this project. The low-loss wavefront-preserving x-ray optical components include high-reflectivity C(400) diamond crystal mirrors, drumhead diamond crystal with thin membranes, beryllium refractive lenses, channel-cut Si monochromators, and exact-Backscattering C(440) diamond crystal. The x-ray diagnostics are designed to ensure the accuracy of beam alignment and to characterize and optimize CBXFEL performance. These include different types of x-ray beam position and profile monitors and x-ray beam intensity monitors, and a meV-resolution x-ray spectrograph. All x-ray optical and diagnostic components have been fully characterized with x-rays, and the mechanical installation of these components is expected to be finished soon.
Paper: MOPG11
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG11
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPG12
Thermoelastic response of Bragg crystals under MHz thermal loading
323
An x-ray free-electron laser oscillator (XFELO) is a promising candidate for producing fully coherent x-rays beyond the fourth-generation light sources. An R&D XFELO experiment (ANL-SLAC-Spring-8 collaboration) to demonstrate the basic principles and measure the two-pass FEL gain is expected to be accomplished by 2024. Beyond this R&D experiment, an XFELO user facility will be eventually needed to produce stable x-ray pulses with saturated pulse energy at MHz repetition rate. However, one of the outstanding issues for realizing an MHz XFELO is the possible Bragg crystal degradation due to the high-repetition-rate thermal loading of the high-pulse-energy x-rays. The deposited energy by one x-ray pulse induces temperature gradients and elastic waves in the crystal, where the deformed crystal lattice impacts the Bragg performance for subsequent x-ray pulses. Here, we report on the numerical study of the crystal thermoelastic response under thermal loading of x-ray pulse trains. The long-term decoupled thermoelastic behavior of the crystal and the possible mitigation of the thermal loading such as crystal cryogenical cooling will be discussed.
Paper: MOPG12
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG12
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG13
Simulation of CXFEL with MITHRA code
327
The CXFEL project at ASU will produce coherent soft x-ray radiation at a university-scale facility. Unlike conventional XFELs, the CXFEL will use an optical undulator in addition to nanobunching the electron beam instead of a static magnetic undulator. This reduces the undulator period from cm-scale to micron scale and lowers the requirements on the electron beam energy. CXFEL’s overtaking geometry design reduces the effective undulator period to 7.86 μm to produce 1 keV photons. This is accomplished by crossing the laser and electron beam at a 30 degree overtaking angle, and using a tilted laser pulse front to maintain temporal overlap between the electron beam and laser pulse. The inverse Compton scattering interaction between a microbunched electron beam and an optical undulator falls out of the range of most accelerator codes. We employ MITHRA, a FEL full-wave FDTD solver software package which includes inverse Compton scattering to simulate the FEL lasing process. We have adapted the code to the CXFEL instrument design to simulate the radiation/electron beam interactions and report results of studies including scaling of key parameters.
Paper: MOPG13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG13
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG14
The CXFEL project at Arizona State University
331
The CXFEL is designed to produce attosecond-femtosecond pulses of soft X-rays in the range 300-2500 eV using nanobunched electron beams and a very high power laser undulator. The project includes 5 X-ray endstations with applications in biology, quantum materials, and AMO science. The CXFEL Project overall includes both the CXFEL and the nonlasing hard X-ray CXLS that is described elsewhere in these proceedings. The CXFEL has recently completed a 3-year design phase and received NSF funding in March 2023 for construction over the next 5 years. Both CXFEL and CXLS instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.
Paper: MOPG14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG14
About: Received: 23 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG16
FLASH status – FEL user facility between two upgrade shutdowns
335
FLASH, the XUV and soft X-ray free-electron laser user facility at DESY, is in the transitional period between two substantial upgrade shutdowns within the FLASH2020+ upgrade project. FLASH consists of a common part FLASH0 (injector & superconducting linac), two FEL beamlines (FLASH1/2) and an experimental beamline FLASH3, accommodating the plasma wakefield experiment FLASHForward. The first (2021/22) shutdown was aimed at upgrading FLASH0 and install an APPLE-III undulator in the otherwise unchanged beamline FLASH2, enhancing the third harmonic at flexible output polarization. The next (2024/25) shutdown will focus on the complete exchange of the FLASH1 beamline to allow for externally seeded operation in the range from 60 nm down to 4 nm at 1 MHz bunch repetition rate (600 μs trains at 10 Hz train repetition rate). We report on the operation between the two shutdowns which was, to a large extend, dedicated to FEL operation for users and on the commissioning of the new features implemented in the last shutdown.
Paper: MOPG16
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG16
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG23
Characterization of FEL mirrors with long ROCs
350
FEL oscillators typically employ a two-mirror cavity with spherical mirrors. For storage ring FELs, a long, nearly concentric FEL cavity is utilized to achieve a reasonably small Rayleigh range, optimizing the FEL gain. A challenge for the Duke storage ring, with a 53.73 m long cavity, is the characterization of FEL mirrors with a long radius of curvature (ROC). The Duke FEL serves as the laser drive for the High Intensity Gamma-ray Source (HIGS). As we extend the energy coverage of the gamma-ray beam from 1 to 120 MeV, the FEL operation wavelength has expanded from infrared to VUV (1 micron to 170 nm). To optimize Compton gamma-ray production, the optimal value for the mirror's ROC needs to vary from 27.5 m to about 28.5 m. Measuring long mirror ROCs (> 10 m) with tight tolerances remains a challenge. We have developed two different techniques, one based on light diffraction and the other on geometric imaging, to measure the long ROCs. In this work, we present both techniques and compare their strengths and weaknesses when applied to measure mirror substrates with low reflectivity and FEL mirrors with high reflectivity.
Paper: MOPG23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG23
About: Received: 16 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPG24
High level software for operating an EEHG FEL
354
Reliable operation of a seeded Free Electron Laser requires the simultaneous control of several electron-beam, laser and accelerator parameters. With EEHG the complexity increases due to the second seed laser and the strong dependence of EEHG bunching to seeding parameters. With the recent upgrade of the FEL-1 line, FERMI is the first FEL facility to be operated in EEHG mode for users. This required a major work for developing software tools that could be used to easily set the FEL at the desired wavelength. We report here on the recent software developments at FERMI for the operations of the new FEL-1. An important prerequisite for EEHG is to determine both the electron beam energy spread and seed laser induced energy modulation. This is done by using HGHG time dependent bunching equations to match experimental parameters scans. With these data, optimal EEHG settings of the machine parameters are then calculated to reach the desired FEL wavelength. The requested parameters are then sent to interface tools that accurately control laser, undulator, chicane and electron beam.
Paper: MOPG24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG24
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG25
FERMI plans for a 2 nm seeded FEL
357
Most FELs employ the mechanism of self-amplified spontaneous emission (SASE) from a relativistic electron beam to generate intense femtosecond pulses in the x-ray spectral region. Such SASE FELs are characterized by a broad bandwidth and relatively poor longitudinal coherence, and offer a rather limited control over the spectro-temporal properties. The limitations of a SASE FEL can be overcome by using an external laser to trigger the amplification process. Echo-enabled harmonic generation (EEHG), alone or in combination with the high-gain harmonic generation scheme (HGHG) is currently the most promising candidate to extend the operation of externally-seeded FELs into the soft x-ray region. Here, we discuss the plan at FERMI for the upgrade of the second FEL line in order to reach ~2 nm at the fundamental emission wavelength. In the first step, coherent radiation at ~10 nm will be generated with an EEHG layout and used as a seed in an HGHG stage on a fresh part of the electron beam. The experience with EEHG at the FEL-1 line will be an important step towards the final realization of the FERMI FEL as a reliable source of highly coherent radiation at ~2 nm and below.
Paper: MOPG25
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG25
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPG31
Conceptual design of the laser-plasma accelerator based soft X-ray Free Electron Laser
368
The conceptual design of the laser-plasma-based soft X-ray Free Electron Laser at ELI-Beamlines involves the integration of a novel high-power, high-repetition-rate laser, plasma source, compact LPA-based electron beam accelerator, dedicated electron beam line with relevant diagnostics, undulator beam line, photon beam line with required diagnostics, as well as a photon beam distribution system. The proposed concept of the whole setup is optimized to produce high-quality, coherent X-ray pulses with femtosecond duration in the ‘water-window’ wavelength of the photon radiation, which will be used by the photon user community for expiring research in the field of biology to study biological structures and processes at the cellular and molecular level at high resolution. In addition, the laser-plasma-based soft X-ray FEL will extend the abilities of users in material science to study nanostructures and thin films. In the frame of this report, we present the conceptual design for the full setup, which will be incorporated into the existing infrastructure of ELI-Beamlines. Furthermore, we discuss the key obstacles and the role of this project in the EuPRAXIA joint activity.
Paper: MOPG31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG31
About: Received: 18 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG32
Plasma accelerator based free electron laser program at ELI-ERIC (ELI-Beamlines)
372
The plasma accelerator-based Free Electron Laser research program at ELI-ERIC (ELI-Beamlines, Czech Republic) intends to utilize the unique qualities of plasma accelerators to build FELs with remarkable brightness, coherence, and pulse length. The program is based on the novel high-power, high-repetition-rate laser system, which is under preparation at ELI-Beamlines. The program entails expanding the LUIS experimental setup to test and validate the performance of the laser-plasma accelerator-based extreme ultra-violet (EUV) FEL, integrating a high-power laser, plasma source, and electron beam transport line with relevant diagnostics to create a comprehensive test bed for the development of the EuPRAXIA LPA-based FEL. The plasma accelerator-based FEL development program at ELI-Beamlines represents an innovative effort to expand the capabilities of FEL technology and open new possibilities for scientific research and industrial applications. In the frame of this report, we provide an overview of the relevant developments at ELI-ERIC (ELI-Beamlines) as well as the main challenges of this program.
Paper: MOPG32
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG32
About: Received: 18 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPG47
Characterization of low-emittance electron beams generated by a new photocathode drive laser system NEPAL at the European XFEL
388
An ultrafast laser system for driving the photocathode RF gun at the European XFEL has been recently put into operation. The new laser system, NExt generation PhotocAthode Laser (NEPAL) is capable of providing drive laser pulses of variable pulse lengths and shapes, supporting the facility to extend its capabilities to operate in multiple user-desirable FEL modes. In this paper, we present a preliminary characterization of the low-emittance electron beams produced by NEPAL in the photoinjector. Both experimental and numerical results will be presented and discussed.
Paper: MOPG47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG47
About: Received: 06 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG55
The UK XFEL conceptual design and options analysis: mid-term update
400
The UK XFEL project is now mid-way through its three-year Conceptual Design and Options Analysis (CDOA) phase. The purpose of this phase is to develop concepts to meet the required ‘next-generation’ XFEL capabilities identified in the project’s peer-reviewed Science Case, developed by UK scientists. The envisaged next-generation features are a step-change in both the number of simultaneous experiments and in their capability – through multiple, combinable FEL sources delivering transform limited pulses across a wide range of photon energies and pulse durations, together with a comprehensive array of synchronised sources including high power lasers and particle beams. The project is assessing options to achieve this either via a new UK-based facility or by investment at existing XFELs, based on criteria that include performance, cost, and environmental sustainability. The project is holding a series of Town Hall meetings and workshops around the UK (see https://xfel.ac.uk) and is expanding collaborations nationally and internationally.
Paper: MOPG55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG55
About: Received: 15 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPG65
Towards short-pulse generation at FLASH via laser-assisted electron bunch manipulation
404
The FLARE project aims to investigate special operation modes of the laser heater at the free-electron laser FLASH in Hamburg that enable the generation of few- or possibly sub-femtosecond soft X-ray pulses. To this end, laser pulses of the laser heater are split and then recombined after one pulse has been delayed. By controlling the interference of both pulses via their temporal overlap, a longitudinally non-uniform heating of the electron bunches can be achieved. Utilizing this, two short-pulse generation schemes are to be implemented as part of the FLARE project. In the first scheme, the energy spread of the bunch is increased to a degree that inhibits lasing, leaving only a small unheated region which emits a short FEL pulse. The second scheme works by imprinting an energy modulation with a linearly increasing amplitude onto the longitudinal phase-space distribution of the bunch. In subsequent magnetic chicanes, this phase-space structure results in a localized compression of the bunch, creating an extremely short current spike, which might be used to produce an X-ray pulse on the same time scale. The FLARE setup as well as first experimental results are presented.
Paper: MOPG65
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG65
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPG66
EUV FEL light source based on energy recovery linac with on-orbit laser plasma injection
408
We report on a week-long study of a conceptual design of EUV FEL light source based on an energy recovery linac with on-orbit laser plasma accelerator injection scheme. We carried out this study during USPAS Summer 2023 session of Unifying Physics of Accelerators, Lasers and Plasma applying the art of inventiveness TRIZ. An ultrashort Ti-sapphire laser accelerates electron beams from a gas target with mean energy of 20 MeV, which are then ramped up to 1 GeV in a five-turn scheme with a series of fixed field alternating magnets and two superconducting RF cavities (100 MeV per cavity per turn). The electron beam is then bypassed to an undulator line optimized to generate EUV light of 13.5 nm at kW level in a single pass.
Paper: MOPG66
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG66
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG69
Simulations of dielectric-lined waveguide seeding option for THz FEL at PITZ
420
The first operational high peak and average power THz self-amplified spontaneous emission (SASE) free electron laser (FEL) at the Photo Injector Test facility at DESY in Zeuthen (PITZ) has demonstrated up to 100 uj single pulse energy at a center frequency of 3 THz from electron bunches of 2-3 nC. The measured shot-to-shot radiation pulse energy has a fluctuation of 10%. Shot-to-shot stability and temporal coherence in FELs can be greatly enhanced by the seeding method. In this paper, we propose the use of dielectric-lined waveguides (DLW) to enhance the initial seeding signal. Simulations of using electromagnetic wakefield in DLW to introduce energy modulation to the beam, controlling the conversion between energy modulation and density modulation, and space charge dominated beam matching in the chicane bunch compressor and the undulator will be presented.
Paper: MOPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG69
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPG70
Early lasing at LCLS and its implications for future cavity-based XFELs
424
Cavity-based XFEL, or CBXFEL, is a future photon source concept under intense development at SLAC. It is considered a path towards full 3D coherence at angstrom wavelength, delivering another 2-3 orders of magnitude leap in source brightness compared to current XFELs configurations. In a first phase of the project, one of the goals is to demonstrate the regenerative amplification by returning and amplifying the seed pulse from 7 LCLS Hard X-ray Undulators (HXUs) with a rectangular crystal cavity. In this paper, we report on the recent measurement of early stage XFEL lasing characteristics at 9.831 keV photon energy by using 7 LCLS HXUs under e-beam conditions close to those chosen for the first phase of CBXFEL gain demonstration.
Paper: MOPG70
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG70
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
MOPG72
Study on high energy coupling efficiency of laser-electron interaction via vortex beam
431
Manipulation electron beam phase space technology by laser-electron interaction has been widely used in accelerator-based light sources. The energy of the electron beam can be modulated effectively under resonant conditions by using an intense external laser beam incident into the undulator together with the electron beam. Enhancing the modulation efficiency is crucial for the performance of high repetition rate seeded free electron lasers (FELs) and other related devices. In this paper, we propose a new scheme to augment the efficiency of laser-electron interaction by employing the interaction between a vortex beam and an electron beam within a helical undulator. Three-dimensional time-dependent simulation results indicate that the modulation repetition rate of laser-electron interaction using a vortex beam can be improved by one order of magnitude over the conventional Gaussian beam at the same input power.
Paper: MOPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG72
About: Received: 09 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPG76
A compact water window X-ray source based on inverse Compton scattering
441
X-rays in the water window (2.33 nm to 4.40 nm wavelength) can be used to provide high quality images of wet biological samples. Given the limited availability of current generation light sources in this energy range, table-top water window X-ray sources have been proposed as alternatives. We present start-to-end simulations in RF-Track of a water window X-ray source based on inverse Compton scattering. A brazing-free electron gun with a maximum beam energy of 7 MeV is considered, providing photon energies covering the full water window range. Performance estimates for the gun operating with copper and cesium telluride cathodes are presented. The cesium telluride cathode, combined with a burst mode Fabry-Perot cavity, allows for an increase in flux by orders of magnitude compared to single bunch copper cathode operation. A beamline of 1 m was determined to be sufficient to produce a high photon flux.
Paper: MOPG76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPG76
About: Received: 14 May 2024 — Revised: 28 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPR17
Advanced accelerator concepts for dark sector searches and fast muon acceleration
489
Dielectric laser acceleration (DLA) is a promising approach to accelerate single electrons at a high repetition rate to GeV energies, for indirect dark matter searches. Relevant concepts include the integration of the dielectric structure inside the laser oscillator. To efficiently use muons for high energy physics applications, they need to be accelerated rapidly, before they decay. Plasma acceleration achieves GV/m accelerating fields and could be ideal for accelerating to muon-collider energies. Single muons could also be accelerated in DLAs for dark matter searches. They could be injected from existing low-intensity muon sources, such as the one at PSI. A workshop organized in the frame of the EU project “Innovation Fostering in Accelerator Science and Technology” (I.FAST) focused on GHz Rate & Rapid Muon Acceleration for Particle Physics to address these topics. We report highlights and future research directions.
Paper: MOPR17
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR17
About: Received: 13 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR38
An LWFA injector for AWAKE Run 2 experiment
535
A beam physics design has been carried out for a 200 MeV-LWFA injector to the AWAKE Run 2 experiment as an alternative to the reference RF injector. It is composed of a laser-plasma acceleration stage and a transport line. In addition to specific environment constraints that impose a dogleg configuration, the electron beam must feature unprecedented performances for a plasma-based accelerator: 100 pC charge, a few mm·mrad emittance, and a few % energy spread. Thanks to an integrated beam physics study assigning specific roles to each section of the accelerator, all the requirements are successfully met in numerical simulations, paving the way for plasma-based accelerators to be competitive with conventional accelerators.
Paper: MOPR38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR38
About: Received: 14 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR43
Experimental characterization of the timing-jitter effects on a beam-driven plasma wakefield accelerator
553
Plasma wakefield acceleration is nowadays very attractive in terms of accelerating gradient, able to overcome conventional accelerators by orders of magnitude. However, this poses very demanding requirements on the accelerator stability to avoid large instabilities on the final beam energy. In this study we analyze the correlation between the driver-witness distance jitter (due to the RF timing jitter) and the witness energy gain in a plasma wakefield accelerator stage. Experimental measurements are reported by using an electro-optical sampling diagnostics with which we correlate the distance between the driver and witness beams prior to the plasma accelerator stage. The results show a clear correlation due to such a distance jitter highlighting the contribution coming from the RF compression.
Paper: MOPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR43
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR56
Design and modeling of HOFI plasma channels for laser plasma accelerators
565
Structured plasma channels are an essential technology for driving high-gradient, plasma-based acceleration and control of electron and positron beams for advanced concepts accelerators. Laser and gas technologies can permit the generation of long plasma columns known as hydrodynamic, optically-field-ionized (HOFI) channels, which feature low on-axis densities and steep walls. By carefully selecting the background gas and laser properties, one can generate narrow, tunable plasma channels for guiding high intensity laser pulses. We present on the development of 1D and 2D simulations of HOFI channels using the FLASH code, a publicly available radiation hydrodynamics code with specific improvements to model plasma channels. We explore sensitivities of the channel evolution to laser profile, intensity, and background gas conditions. We examine efforts to benchmark these simulations against experimental measurements of plasma channels. Lastly, we discuss ongoing work to couple these tools to community PIC models to capture variations in initial conditions and subsequent coupling for laser wakefield accelerator applications.
Paper: MOPR56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR56
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR58
UV-Soft X-ray betatron radiation characterization from laser-plasma wakefield acceleration
573
The spontaneous emission of radiation from relativistic electrons within a plasma channel is called betatron radiation and has great potential to become a compact x-ray source in the future. We present an analysis of the performance of a broad secondary radiation source based on a high-gradient laser-plasma wakefield electron accelerator. The purpose of this study is to assess the possibility of having a new source for a non-destructive X-ray phase contrast imaging and tomography of heterogeneous materials. We report studies of compact and UV-soft X ray generation via betatron oscillations in plasma channel and in particular measurement of the radiation spectrum emitted from electron beam is analyzed from a grazing incident monochromator at Centro de Laseres Pulsados Ultraintensos (CLPU).
Paper: MOPR58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR58
About: Received: 22 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPR62
First results from the EuPRAXIA doctoral network: paving the way for next-generation particle accelerators
576
This contribution presents the initial findings from the 3.2 Million Euro EuPRAXIA Doctoral Network. European Plasma Research Accelerator with eXcellence In Applications (EuPRAXIA) is at the forefront of advanced particle accelerator research, focusing on the development of plasma-based accelerator technologies. The EuPRAXIA Doctoral Network, a collaborative effort among leading research institutions, is dedicated to exploring and advancing the frontiers of plasma-based particle acceleration. The network’s research involves a wide range of topics, from beam diagnostics and optimization techniques to new applications. Here, we present the innovative approaches and methodologies employed to achieve very high acceleration gradients, improve the energy sharpness and overall beam quality. Some of the early results of this new network are discussed, showcasing the progress made across the network’s three scientific work packages. The contribution also gives an overview of the initial training provided to the network’s Fellows.
Paper: MOPR62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR62
About: Received: 09 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR68
Development of liquid lithium target in crucible for laser ion source
595
A liquid lithium target system is being developed for laser ion sources. Existing laser ion sources are operated at the repetition rate of the order of 1 Hz. The limitation stems from the use of solid laser targets because of the craters created and the need to provide a fresh surface by either repositioning the laser beam or the target. In addition, an enormously large surface area is needed for long-term operation. This limits the total yield of lithium ions and the application of laser ion sources. To dramatically increase the repetition rate, we propose the use of a liquid lithium target in a crucible because a liquid surface shape is recovered by itself after laser irradiation. The establishment of a liquid target system is an important objective for the development of the intense lithium beam driver for a clean compact source of a directional neutron beam. In the conference, the concept and design of experimental apparatus for the development will be presented.
Paper: MOPR68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR68
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR69
Highly charged Mg ion production using laser ablation ion source at Brookhaven National Laboratory
598
We are researching the development of an ultra-high intensity heavy ion source based on laser ablation ion source (LIS) technology coupled with a unique beam injection technique called Direct Plasma Injection Scheme (DPIS). A metallic target is ablated using a Q-switched Nd:YAG laser to generate a pulsed high-density plasma, which is then injected and accelerated by a radio-frequency quadrupole (RFQ) linear accelerator. The ion source enables the production of rare isotopes, the use of particle beams in cancer treatment, and nuclear physics experiments. The exploration of multiple charge states for Mg production is currently underway. The measurement of beam current is conducted using a Faraday cup positioned at the end of the beam line. Following the RFQ acceleration, the beam is transported by multiple quadrupole magnets and a steerer, and a dipole magnet then directs the beamline into the Faraday cup. Notably, we have accomplished an ion beam current of about 20 mA for Mg10+ ions and a current exceeding 10 mA for fully stripped Mg12+ ions. In this presentation, I will discuss the operation of the LIS at Brookhaven National Laboratory (BNL) and the outcomes of Mg ion production.
Paper: MOPR69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR69
About: Received: 16 May 2024 — Revised: 24 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR71
An ultimate single-ion source using a Coulomb crystal in a Paul trap
606
An ion cloud confined in a Paul trap eventually reaches a Coulomb crystalline state when strongly cooled toward absolute zero. The normalized emittance of the Coulomb crystal can be in the sub-femtometer range. The trap is thus usable as a unique ion source for nano-beam production, though the available beam intensity is limited. This new concept was first discussed nearly 20 years ago* and later experimentally demonstrated by several research groups (**, ***). In this paper, we report on the result of a recent experiment where an attempt was made to extract Ca+ or N2+ ions one by one from a compact linear Paul trap. In addition to the regular extraction scheme based on a string Coulomb crystal, the possibility of using a multi-shell crystalline structure is explored in detail.
Paper: MOPR71
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR71
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
MOPR72
Transport and dosimetry of laser-driven proton beams for radiobiology at the BELLA center
610
Laser-driven ion accelerators (LDIAs) are well-suited for radiobiological research on ultra-high dose rate effects due to their high intensity. For this application, a transport system is required to deliver the desired beam intensity and dose distribution while online dosimetry is required due to the inherent shot-to-shot variability of LDIAs. At the BELLA Center's iP2 beamline, we implemented two compact, permanent magnet-based beam transport configurations for delivering 10 or 30 MeV protons to a biological sample, along with a suite of diagnostics used for dosimetry. These diagnostics include multiple integrating current transformers (ICTs) for indirect online dose measurements and calibrated radiochromic films (RCFs) to measure the dose profile and calibrate the ICT dosimetry. Benchmarked Monte-Carlo (MC) simulations of the beamline allow us to predict the dose received by the sample and correct the linear energy transfer (LET)-dependent response of the RCFs. This work not only further establishes the practicality of utilizing LDIAs for radiobiological research but also highlights the BELLA Center's capacity to accommodate further experiments in this domain.
Paper: MOPR72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR72
About: Received: 17 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPR74
Tunable laser Doppler spectroscopy of LANSCE H- ion source
614
Plasma temperature dynamics provide significant insight when evaluating ion source performance. Quantities such as beam emittance, or mean transverse energy, are strongly correlated with the source plasma temperature. At LANSCE there is currently no method implemented for measuring initial source emittance or implementing tunability of mean transverse energy through ion source control parameters. In this work we will discuss our demonstration of a new laser diagnostic tool for measuring H- beam emittance on the LANSCE H- ion source laser diagnostic stand. Our investigated method will be an extension of systems outlined for NIFS, and will be optimized for rapid response times, scanning the Doppler broadened Hydrogen-alpha emission line at a rate 10x faster than the plasma ignition time window (800 microseconds). We will show that our real-time, non-intrusive measurement approach will enable characterization and study of source control parameter effects on source plasma temperature for future emittance optimization.
Paper: MOPR74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR74
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
MOPR76
Studies of photoemission in the high-field regime in an X-band photoemission RF gun
622
A program is underway at the Argonne Wakefield Accelerator (AWA) facility, in collaboration with Euclid Techlabs and Northern Illinois University (NIU), to develop a GV/m-scale photocathode gun, to produce bright electron bunches. The novel X-band (11.7 GHz) photoemission gun (Xgun) is powered by high-power, short RF pulses (9 ns) generated by the AWA drive beam in a wakefield structure. In the first series of experiments, the Xgun demonstrated peak fields of ~400 MV/m on the photocathode surface. As a first step towards achieving a complete understanding of the Xgun’s performance in the high-field regime, we studied the photoemission mechanism by measuring the quantum efficiency (QE) and thermal emittance across a large range of operating fields on the photocathode surface from 60 MV/m to values exceeding 300 MV/m. In this work, we will present the results of our experimental measurements and simulation studies on examining photoemission at high fields on the photocathode surface.
Paper: MOPR76
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR76
About: Received: 20 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPR78
PHOtocathode Epitaxy and Beam Experiments laboratory at Cornell: current status and future work
630
High-efficiency alkali antimonide photocathodes degrade with little oxidation, making them hard to characterize and test outside their growth chamber. In this proceeding, we report on the design and performance of the PHOtocathode Epitaxy and Beam Experiments (PHOEBE) laboratory at Cornell University, where the growth, characterization, and testing of alkali photocathodes in vacuum has been successfully integrated. The growth of photocathodes is characterized in-situ by measuring the QE and by looking at the photocathode’s reflection high energy electron diffraction (RHEED) pattern. Once the desired photocathode is obtained, it is moved to a storage chamber to collect spectral response data, after which it is moved to the cryogenic emittancediagnostic beamline via a vacuum suitcase. A rapid cathode exchange system in the diagnostic beam can efficiently transfer alkali-antimonide photocathodes to beamline operation with little QE loss. Using this beamline, the mean transverse energy of the photocathode can be measured at various photoexcitation wavelengths in the visible spectrum and sample temperatures within 20 - 300 K.
Paper: MOPR78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR78
About: Received: 16 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
MOPR89
Framework for a multiphysics model of optical field emission from extended nanostructures
664
Laser-field emission, or optical field emission, is a process that can produce electron beams with high charge density and high brightness with ultrafast response times. Using an extended nanostructure, such as a nanoblade, permits plasmonic field enhancement up to 80 V/nm with an incident ultrafast laser of wavelength 800 nm. Stronger ionizing fields lead to higher current densities, so understanding how this field is attained will aid in further increasing brightness. In this paper we lay the framework to study the nanoblade system thermomechanically and plasmonically. We show that, in the moving frame following the laser driver, a steady state is reached, allowing us to reduce the computational complexity of the multiphysics calculation. We derive Maxwell's equations and the current dynamical equation for the steady state in such a moving frame. We also derive the eigenproblem for finding plasmonic modes in the structure with a nonlinear dielectric. The planned calculations to come will allow us to predict peak attainable fields and optimal experimental parameters. We leave off with a discussion of directions for numerical implementation.
Paper: MOPR89
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR89
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
MOPR90
Optical pump generation for long-wave infrared lasers for advanced acceleration
668
The favorable wavelength scaling of ponderomotive interactions indicates that long-wave infrared (LWIR) lasers are well suited for applications such as laser wakefield acceleration and high harmonic generation. CO2 amplifiers are the primary source of such wavelengths, able to generate TW peak powers with sub-ps pulse lengths. However, a limiting factor for these amplifiers is the necessity of using electrical discharges to pump the gain medium, reducing the maximum repetition rate and energy stability. This can be mitigated by instead optically pumping the CO2 at 4.5 μm. We demonstrate a proof of principle of the generation of this wavelength by utilizing stimulated Raman scattering, a process where photons inelastically scatter from a material. For this wavelength, we employ a novel class of material known as ionic liquids as the Raman medium. We demonstrate efficient conversion from a 532 nm frequency doubled Nd:YAG laser to 603 nm in the ionic liquid EMIM DCA, followed by performing difference frequency generation to produce the 4.5 μm pump.
Paper: MOPR90
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR90
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
MOPR91
Particle motion in spatio-spectrally iso-diffracting ultrabroadband pulsed beams
672
An analytical form is derived using the Faddeeva function to represent terahertz-frequency pulses generated by optical rectification of ultrashort laser pulses. Spectra of these pulses can be described by a Gaussian fall-off at high frequencies and a power-law as DC is approached. A set of pulsed beams based on this form is also derived for the special case of propagation-invariant spatio-temporal coupling (iso-diffracting). Motion of charged particles in these pulsed beams is considered analytically and numerically and energy gain is computed and compared with ponderomotive force laws. Particle motion in more complex pulsed-beam fields is also considered.
Paper: MOPR91
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPR91
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS50
Simulation studies of laser cooling for the Gamma Factory proof-of-principle experiment at the CERN SPS
832
The proof-of-principle (PoP) experiment at the Super Proton Synchrotron (SPS) at CERN aims at demonstrating laser cooling of high energy Li-like Pb79+ in a synchrotron. First laser cooling simulations with realistic laser and beam parameters of the Gamma Factory proof-of-principle experiment (PoP) in the Super Proton Synchrotron (SPS) at CERN are presented. Furthermore, we investigate the expected cooling performance for various laser-pulse types, such as Fourier-limited and continuous wave lasers, and compare their performance metrics such as emittance reduction and the required laser power.
Paper: MOPS50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS50
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
MOPS58
First-principle simulations of a laser-assisted bunch compression scheme
852
High brightness electron beams with high peak current are critical to reducing the size of XFEL. A promising approach consists in combining low emittance beam generated high-frequency photoinjector with a laser-assisted bunch compression scheme. Such a compression consists in using an infrared laser to modulate the electron beam energy in a planar undulator and a low R56 chicane to compress these modulations and produced a micro-bunched beam. We present first-principle simulations of this compression process including the impact of coherent synchrotron radiation (CSR) on the beam dynamics. These simulations were performed using the large-scale self-consistent LW3D code for two compression configurations under study for compact XFEL designs.
Paper: MOPS58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS58
About: Received: 24 May 2024 — Revised: 25 May 2024 — Accepted: 28 May 2024 — Issue date: 01 Jul 2024
MOPS62
Generation of attosecond electron bunches through terahertz regulation
863
Obtaining ultrashort electron bunches is the key to the studies of ultrafast science, yet second and higher order nonlinearities limits the bunch length to a few femtoseconds after compression. Traditional regulation methods using rf higher order harmonics have already optimized the bunch length to sub-fs scale, yet the energy loss and rf jitter are not negligible. In this paper we demonstrate the second order regulation with THz pulses through a dielectric-loaded wave-guide. Simulations suggest that with higher order correction, the MeV electron bunches with tens of fC charges can be compressed to a 679 attoseconds rms and the second order distortion can be compensated. The transverse beam size is also optimized to 16.8 um rms. This scheme is feasible for a wide range of electron charges. The relatively short bunch length is expected to find a better time resolution in UED, UEM and other ultrafast, time-resolved studies.
Paper: MOPS62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS62
About: Received: 11 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
MOPS63
Research on spatial alignment of laser and electron beam in the generation of ultra-short electron pulses by laser modulation
866
The utilization of laser modulation techniques shows potential in producing sub-femtosecond electron beams within photoinjector electron guns. The precise spatial alignment between the modulated laser and electron beam is crucial for the stable emission of sub-femtosecond electron beams. In practical applications, inevitable lateral positional fluctuations are present in both the modulated laser and electron beam pulses, resulting in uneven and suboptimal modulation effects of the laser on the electron beam. Photocathode electron guns commonly utilize solenoid focusing for transverse electron beam concentration, inducing transverse phase space coupling and causing the laser-induced transverse jitter in the electron gun to not accurately reflect the transverse jitter of the electron beam. This study seeks to employ coherent lasers and devise a solenoid coil to disentangle the transverse phase space of the electron beam, ensuring that the transverse jitter of the electron beam aligns with the jitter of the modulated laser at the focal point.
Paper: MOPS63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-MOPS63
About: Received: 10 May 2024 — Revised: 19 May 2024 — Accepted: 19 May 2024 — Issue date: 01 Jul 2024
TUCN3
Results from CXLS commissioning
981
The Compact X-ray Light Source (CXLS) is a compact source of femtosecond pulses of x-rays that is now commissioning in the hard x-ray energy range 4-20 keV. It collides the beams from recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency, and recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 200 mJ. These instruments are designed to drive a user program in time-resolved x-ray studies such as SAXS/WAXS, XES and XAS, femtosecond crystallography as well as imaging. The different technical systems also act as prototypes for the more advanced CXFEL discussed elsewhere in these proceedings. We present the performance of the CXLS technical components and initial x-ray results.
Paper: TUCN3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUCN3
About: Received: 20 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC19
High-current DC gun for low energy RHIC cooler project
1047
Electron cooling of ion beams employing RF-accelerated electron bunches was successfully used for the RHIC physics program in 2020 and 2021. Electron cooler LEReC uses a high-voltage photoemission electron gun with stringent requirements for beam current, beam quality, and stability. The electron gun has a photocathode with a high-power fiber laser, and a novel cathode production, transport, and exchange system. It has been demonstrated that the high-voltage photoemission gun can continually produce a high-current electron beam with a beam quality suitable for electron cooling. We describe the operational experience with the LEReC dc photoemission gun in RHIC and discuss the important aspects needed to achieve the required beam current, beam quality, and stability. We also present recent gun tests in which stable operation at 50 mA CW beam current was established, as well as future plans.
Paper: TUPC19
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC19
About: Received: 08 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPC29
Optimization of nanostructured plasmas for laser wakefield acceleration using a Bayesian algorithm
1064
Nanostructures are currently attracting attention as a medium for obtaining ultra-high-density plasmas for beam-driven or laser-driven acceleration. This study investigates Bayesian optimization in Laser Wakefield Acceleration (LWFA) to enhance solid-state plasma parameters towards achieving extremely high gradients on the order of TV/m or beyond, specifically focusing on nanostructured plasmas based on arrays of carbon nanotubes. Through Particle-In-Cell (PIC) simulations via EPOCH and custom Python scripts, we conducted a parameter analysis for various configurations of carbon nanotube arrays. Utilizing the open-source machine learning library BoTorch for optimization, our work resulted in a detailed database of simulation results. This enabled us to pinpoint optimal parameters for generating effective wakefields in these specialized plasmas. Ultimately, the results demonstrate that Bayesian optimization is an excellent tool for significantly refining parameter selection for nanostructures like carbon nanotube arrays, thus enabling the design of promising nanostructures for LWFA.
Paper: TUPC29
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC29
About: Received: 14 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPC47
SoC based time-resolved scaler DAQ and amplifier-discriminator upgrade for laser spectroscopy
1115
The BEam COoler and LAser spectroscopy (BECOLA) is a collinear laser spectroscopy facility at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. Time resolved laser spectroscopy experiments are performed here to study the nuclear structure of radioactive isotopes. The current data acquisition (DAQ) system being used is based on AMD Spartan 6 field programmable gate array (FPGA) and has a time resolution of 8 ns. There was a need to upgrade existing hardware to meet the requirements for higher time resolution of fast ion detectors. A new DAQ system with AMD Zynq System on Chip (SoC) FPGA based time-resolved scaler was designed, developed and fabricated. It achieves a time resolution of 2 ns. The current amplifier-discriminator has an output pulse resolution of 10 ns. To address this constraint and fully leverage the 2 ns time resolution provided by the new SoC FPGA, a new AD with an output pulse resolution of 1 ns was designed. A brief overview of the upgraded DAQ system will be discussed in this paper, including its features, improvements and future updates.
Paper: TUPC47
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC47
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC78
Normalized uniformity-based common points layout optimization method for alignment installations
1196
The alignment installation work of Hefei Advanced Light Facility (HALF) is usually carried out in tunnels. Calculate the key component points to the global coor-dinate system through coordinate conversion, and accu-rately adjust them to the corresponding coordinate values for alignment and installation. However, long and narrow tunnels can easily cause dense common points, resulting in a loss of accuracy. Therefore, to quickly and accurately obtain the coordinate transformation parameters, this article proposes a common point selection method with uniformity normalization and selects the optimal com-mon points set based on the normalized uniformity in different directions. The feasibility of this method was verified based on experimental data. The results show that the conversion parameters solved by this method are more accurate, avoiding accuracy loss due to aggregation in a certain direction, and are suitable for long and narrow tunnels.
Paper: TUPC78
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC78
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPC80
Radiation to electronics studies for CERN gamma factory-proof of principle experiment in SPS
1202
The Physics Beyond Colliders is a CERN exploratory study aimed to fully exploit the scientific potential of its accelerator complex. In this initiative, the Gamma Factory experiment aims to produce in the Large Hadron Collider (GF@LHC) high-intensity photon beams in the energy domain up to 400 MeV. The production scheme is based on the collisions of a laser with ultra-relativistic atomic beam of Partially Stripped Ions (PSI) circulating in a storage ring. The collision results in a resonant excitation of the atoms, followed by the spontaneous emission of high-energy photons. A Proof of Principle (PoP) experiment is being planned to study the GF scheme generating X-rays, in the range of keV, from lithium-like lead PSI stored at the CERN Super Proton Synchrotron (SPS). GF-PoP has undergone a series of exhaustive radiation effect studies in view of Radiation to Electronics (R2E) risks. With the use of FLUKA Monte Carlo code, the radiation environment in the laser room and its premises has been estimated during proton and PSI runs. Recorded data from beam instruments has been used to appropriately scale the computed results and to verify the compliance with general R2E limits.
Paper: TUPC80
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPC80
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG43
Light source top-up through direct generation of electron beam based on LPA technology
1330
Laser plasma acceleration (LPA) technology is advancing day by day, getting ready for user facility applications. LPA might be applicable to a generation of electron beams directly within the light-source storage-ring vacuum chamber. Typical injector of the light source facility consists of linac and synchrotron booster (or simply a full energy linac). It can be replaced by a laser plasma cell and a driving laser system that can generate multi-GeV electron beams through so-called self injection. The electron beam out of plasma cell has typically a large energy spread. In this application, however, we do not require small energy spread since the storage ring can accept off-energy electrons of up to ±5% or so. It can also have a transverse angular acceptance of a few hundred micro radian. Therefore, a large fraction of generated electrons can be eventually accepted by the storage ring. LPA system, which replaces the conventional injector, may contribute to significant energy saving.
Paper: TUPG43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG43
About: Received: 10 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPG50
Echo-enabled harmonic generation at the DELTA storage ring
1354
Echo-enabled harmonic generation (EEHG) has been proposed as a seeding method for free-electron lasers but can also be employed to generate ultrashort radiation pulses at electron storage rings. With a twofold laser-electron interaction in two undulators, each followed by a magnetic chicane, an electron density pattern with a high harmonic content is produced, which gives rise to coherent emission of radiation at short wavelengths. The duration of the coherently emitted pulse is given by the laser pulse lengths. Thus, the EEHG pulse can be three orders of magnitude shorter and still more intense than conventional synchrotron radiation. At the 1.5-GeV synchrotron light source DELTA at TU Dortmund University, the worldwide first implementation of EEHG at a storage ring was achieved by reconfiguring an electromagnetic undulator. The paper reviews the experimental setup and describes the present status of the project.
Paper: TUPG50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG50
About: Received: 15 May 2024 — Revised: 13 Jun 2024 — Accepted: 13 Jun 2024 — Issue date: 01 Jul 2024
TUPG53
Initial status report on BNL ATF AE131 experiment harmonic nonlinear inverse Compton scattering
1365
Recent progress of basic study on Harmonic nonlinear Compton scattering in Brookhaven National Laboratory Accelerator Test Facility (BNL ATF) will be reported. Experiment is conducted by counter collision of a multi TW CO2 laser and 60-70 MeV electron beam having 300-600 pC of charge per pulse. Experiment AE131 is intended for two aspects of experimental demonstrations. A: Nonlinear bi harmonic effect seen in external lasers having shorter wavelength such as Nd:YAG laser induced by a long wavelength intense CO2 laser at scattered photon energy of 100 keV range. B: Detailed study on the harmonic radiation induced by circularly polarized multi TW CO2 laser which potentially contain the Orbital Angular Momentum at photon energy of 10 keV range.
Paper: TUPG53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG53
About: Received: 15 May 2024 — Revised: 27 May 2024 — Accepted: 27 May 2024 — Issue date: 01 Jul 2024
TUPG64
Integrated Hall probe and stretched wire measurement system for an in-vacuum undulator
1398
Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Several in-vacuum undulators are expected to be installed before the end of 2024. Before installation in the storage ring, an in-vacuum undulator's magnetic field has been measured at operational gaps. In order to assess the performance of the in-vacuum undulator, we integrated two measurement methods in the vacuum chamber: one is the SAFALI (Self Aligned Field Analyzer with Laser Instrumentation) system to measure the magnetic field, and the other is the stretched wire system to measure the magnetic field integral. In this work, we designed a stretched wire measurement system integrated with the SAFALI system inside the vacuum chamber. This measurement system was applied to the in-vacuum undulator with a period of 22mm and a magnetic length of 2 m.
Paper: TUPG64
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG64
About: Received: 08 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
TUPG69
Tunable laser pulses enable the generation of femtosecond electron beams with controllable lengths
1409
In ultrafast electron diffraction experiments, the electron beam's length is crucial as it determines the timescale for observing ultrafast dynamic changes. Therefore, achieving continuous control over the length of these beams within a specific range is paramount for broadening the research scope in ultrafast science. This regulation ensures the accuracy of diffraction images from diverse samples, precise electron beam length measurement, and effective generation of terahertz radiation. Currently, typical methods employ radio frequency (RF) cavity compression to manage electron beam length. Nonetheless, this approach introduces time jitter and encounters challenges in continuously adjusting the electron beam length due to constraints of the RF cavity structure. This paper focuses on compressing femtosecond laser pulse methods to obtain laser pulses with continuously adjustable pulse widths. Subsequently, further controlling the distribution of photoemission electron beams can enhance the temporal resolution of ultrafast electron diffraction.
Paper: TUPG69
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG69
About: Received: 14 May 2024 — Revised: 07 Jun 2024 — Accepted: 07 Jun 2024 — Issue date: 01 Jul 2024
TUPG72
An electron beam modulation laser for steady-state microbunching
1413
Steady-state microbunching (SSMB) represents an innovative scheme for generating high-power coherent radiation. This approach is expected to generate kilowatt-scale extreme ultraviolet (EUV) radiation for lithography in the semiconductor industry. During the second phase of the SSMB proof-of-principle experiment (SSMB PoP II), the creation of quasi-steady-state microbunches requires specific modulation of the electron beam. This modulation is achieved through a phase-locked laser with a high repetition rate, which enables the detection of continuous coherent radiation over multiple turns. To meet the requirements of SSMB PoP II, a high-power, high-repetition-rate, phase-stabilized pulsed laser has been developed. The single-frequency pulsed laser has been achieved using an electro-optic modulator stage, three amplification stages, and a phase-locked feedback system. Here we report on the development and test results of the electron beam modulation laser.
Paper: TUPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPG72
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
TUPR58
Analysis of laser engineered surface structures’ roughness and surface impedance
1564
This study examines Laser Engineered Surface Structures (LESS) in the context of their potential application within particle accelerators. These structures are investigated due to their efficient reduction of secondary electron yield to counteract the formation of electron clouds, a phenomenon detrimental to accelerator performance. A critical aspect of their evaluation involves understanding their radio-frequency characteristics to determine their influence on beam impedance. LESS involves intricate surface modifications, integrating etched grooves and deposited particulates, resulting in a complex surface topology. Measurements are conducted on two distinct surface patterns, from which particulates are then removed with incremental cleaning. Acquired data form the basis for mathematical models elucidating observed results. Novel approaches are investigated in addition to several established surface roughness models, including analysis of geometrical attributes of the surface topology and the associated electric currents. The aim is to develop a framework that describes roughness's influence across varying scales to assist in selecting appropriate treatment parameters.
Paper: TUPR58
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPR58
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
TUPS77
Applications of machine learning in ultrafast laser control
1862
In our pursuit to tailor a precise electron bunch with a photoinjector, fine-tuning laser parameters, especially those influencing the photocathode pulse, is pivotal. Our ongoing research integrates machine learning, training neural networks with experimental data from ATF. The first approach involves generating a downstream photocurrent image to replicate the emission profile, serving as a fitness function for neural network training. The second approach employs an emittance scan during each iteration of the neural network-controlled laser profile, using magnetic optics and beam profile monitors, with calculated beam emittance as an additional fitness function. Our research aims to demonstrate the potential superiority of the neural network in achieving precise laser shaping for electron beam optimization. Leveraging real data, our goal is to reduce electron beam emittance through optimized laser profiles, underscoring the impactful applications of machine learning in advancing photoinjector technology.
Paper: TUPS77
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS77
About: Received: 09 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
TUPS82
Characterization of meter-scale Bessel beams for plasma formation in a plasma wakefield accelerator
1865
A large challenge with Plasma Wakefield Acceleration lies in creating a plasma with a profile and length that properly match the electron beam. Using a laser-ionized plasma source provides control in creating an appropriate plasma density ramp. Additionally, using a laser-ionized plasma allows for an accelerator to run at a higher repetition rate. At the Facility for Advanced Accelerator Experimental Tests, at SLAC National Accelerator Laboratory, we ionize hydrogen gas with a 225 mJ, 50 fs, 800 nm laser pulse that passes through an axicon lens, imparting a conical phase on the pulse that produces a focal spot with an intensity distribution described radially by a Bessel function. This paper overviews the diagnostic tests used to characterize and optimize the focal spot along the meter-long focus. In particular, we observe how wavefront aberrations in the laser pulse impact the peak intensity of the focal spot. Furthermore, we discuss the impact of nonlinear effects caused by a 6 mm, CaF2 vacuum window in the laser beam line.
Paper: TUPS82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS82
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS84
PIP-II laser beam profile monitor laser system
1869
Fermilab is currently engaged in the development of an 800 MeV superconducting RF linac, aiming to replace its existing 400 MeV normal conducting linac. PIP-II is a warm front-end producing 2 mA of 2.1 MeV H-, followed by a sequence of superconducting RF cryomodules leading to 800 MeV. To mitigate potential damage to the superconducting RF cavities, PIP-II uses laser-based monitors for beam profiling via photoionization. This abstract provides an update on the project’s beam profiling, focusing on advancements made since the initial prototype. The prototype profile monitor featured a high-repetition-rate, low-power fiber laser and fiber optic transport that was tested with a 2.1 MeV H- beam at the PIP-II Injector Test (PIP2IT) accelerator. Since then, the fiber laser and fiber transport have been upgraded to a diode laser based system and free-space optical transport. This highlights a significant evolution in the laser system, enhancing its efficiency and adaptability. This paper will focus on an alternative laser system for the transverse beam measurements. The new system will use a variable pulse-width drive laser system via gain-switching, and the newly implemented free-space propagated optical beam
Paper: TUPS84
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS84
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
TUPS85
Recent progress in laser wire-based H⁻ beam diagnostics at the SNS linac
1873
Laser wire has been used for nonintrusive profile and emittance measurements of operational hydrogen ion (H-) beam at the SNS linac. In this talk, we will describe the following recent developments in the laser wire system. 1) An upgraded light source and laser transport line which enables novel measurement capabilities including longitudinal profile measurement and high-energy proton beam extraction over potentially an entire macropulse. 2) A dual-detector emittance measurement scheme that boosted the dynamic range by an order of magnitude. 3) Design and implementation laser-wire-based nonintrusive longitudinal phase space measurement system.
Paper: TUPS85
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS85
About: Received: 17 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
TUPS87
Time-resolved evaluation of the transient responses of crystal optics to instantaneous heat deposition for wavefront integrity
1876
Our focus centers on numerical investigation into the transient response of optics when subjected to instantaneous heat deposition. The heat load deposited onto crystal optics, coupled with the emission of strain waves, has the potential to induce crystal deformation and vibrations. These phenomena carry detrimental consequences for optic performance, particularly in terms of wavefront preservation—an essential criterion for coherent XFEL beams. Our research involves an evaluation of optical performance in terms of the Strehl ratio at delay time. Ultimately, we aim to provide recommendations for establishing upper bounds on pulse energy and repetition rates during XFEL operation. These guidelines will play a pivotal role in optimizing XFEL performance while safeguarding wavefront integrity, thus advancing the capabilities of coherent X-ray beams in scientific and technological applications.
Paper: TUPS87
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-TUPS87
About: Received: 18 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEAD2
Orbital angular momentum beams research using a free-electron laser oscillator
1885
Orbital angular momentum (OAM) photon beams are excellent tools for non-contact optical manipulation of matter in a broad photon energy range. A free-electron laser (FEL) oscillator is well-suited for studying OAM beams with various features including a wide spectral coverage, wavelength tunability, two-color lasing, etc. Here, we report the first experimental demonstration of superposed OAM beams from an oscillator FEL. Lasing at around 458 nm, we have generated superposed OAM beams up to the fourth order as a superposition of two pure OAM modes with opposite helicities. These generated beams have a high beam quality, a high degree of circular polarization, and high power. Using external rf modulation with frequencies from 1 to 30 Hz, we also developed a pulsed mode operation of the OAM beams with a highly reproducible temporal structure. FEL operation showcased in this work can be extended to higher photon energies, e.g. using a future x-ray FEL oscillator. The operation of such an OAM FEL also paves the way for the generation of OAM gamma-ray beams via Compton scattering.
Paper: WEAD2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEAD2
About: Received: 14 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEAD3
Echo-enabled harmonic generation at FERMI FEL-1: commissioning and initial user experience
1889
The FERMI free-electron laser (FEL) facility has recently achieved a significant milestone with the successful implementation of the echo-enabled harmonic generation (EEHG) scheme in the FEL-1 amplifier line. This advancement is part of a broader upgrade strategy aiming at expanding the covered spectral range of the facility to the entire water window and beyond. Through this upgrade, the maximum photon energy of FEL-1 has been doubled and spectral quality has been enhanced. The updated FERMI FEL-1 is the first user facility operating in the spectral range 20-10 nm utilizing the EEHG scheme. It will serve also as the ideal test bench for conducting new machine studies in the perspective of future developments. In this contribution, we present the results obtained during the commissioning phase and the first user experiments.
Paper: WEAD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEAD3
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEBD3
Technologies and concepts for the next generation of heavy ion synchrotrons
1919
New technical approaches are under investigation to further push the intensity frontier of the next generation heavy ion synchrotrons. Residual gas dynamics and corresponding charge exchange processes are key issues which need to be overcome by means of advanced UHV system technologies, but also by a focused design of the synchrotron as a whole. Cryogenics and superconductivity enable high field operation but in synergy also enable technologies for stabilizing the dynamic vacuum. Beam loss usually implicated as driver for activation and damages is as well an important initiator for residual gas pressure dynamics. Advanced superconducting cables promise lower energy consumption, fast ramping and higher average beam intensities. The cryo-pumping properties of specially developed cryogenic inserts, can also be used to upgrade existing synchrotrons and enable operation with lower charge states and higher intensities. The advancement of laser technologies may be applied as new devices in heavy ion synchrotrons for advanced manipulations, e.g. non-liouville injection or laser cooling. With FAIR, GSI has expanded its competence for the design of novel high intensity heavy ion synchrotrons.
Paper: WEBD3
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEBD3
About: Received: 04 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC03
Bubble-beam accelerators: breaking the paradigm
1957
Most particle accelerators utilize beams with a charge density concentrated in the center of the bunch in real 3-dimensional space and the 6-dimensional phase space. In this work, by enhancing the space-charge forces in the photo-cathode injector of the Compact Linear Electron Accelerator for Research (CLEAR) at CERN, we produce electron bunches with a “bubble-like” shape, with a charge density mostly concentrated on the outside shell. We demonstrate that the dynamics of such beams can be tailored to achieve stable uniformity in the coordinate and momentum transverse planes simultaneously. This would allow reaching a uniform dose distribution without a severe loss of particles which is of the great interest in the irradiation community. Additionally, we investigate the potential benefits of bubble-beams across several accelerator pillars: for driving light sources, for advanced acceleration technologies, and for particle colliders.
Paper: WEPC03
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC03
About: Received: 14 May 2024 — Revised: 19 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
WEPC13
Status of the RUEDI UK national facility design
1979
RUEDI (Relativistic Ultrafast Electron Diffraction & Imaging) is a proposed facility which will deliver single-shot, time-resolved, imaging with MeV electrons, and ultrafast electron diffraction down to 10 fs timescales. RUEDI is being designed to enable the following science themes: dynamics of chemical change; materials in extreme conditions; quantum materials; energy generation, storage, and conversion; and in vivo biosciences. RUEDI is proposed to be built at STFC’s Daresbury Laboratory in the UK.
Paper: WEPC13
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC13
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC23
Overview of inverse Compton scattering feasibility studies at MESA
2014
Johannes Gutenberg University Mainz is currently constructing a new electron accelerator that employs an energy recovery scheme. The Mainz Energy Recovery Superconducting Accelerator (MESA) will provide two modes of operation: the Energy Recovery (ER) mode, which will supply an internal gas target experiment, and the Extraction Beam (EB) mode, primarily used in the P2 experiment where MESA's spin-polarized electrons will be directed towards a target. As an Energy Recovery Linac (ERL), MESA shows potential as an accelerator for an Inverse Compton Scattering (ICS)-based gamma source. To anticipate the impact of the scattering on electron beam parameters, significant for energy recovery, a novel quasi-analytical simulation code, "COMPARSE", has been developed and used for the feasibility studies. The investigations examine various applications of ICS sources at MESA. This paper gives an overview of the results as well as the limitations and possibilities of the underlying mathematical approach.
Paper: WEPC23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC23
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPC24
Optimization of bunch charge distribution for space charge emittance growth compensation in the PERLE injector
2018
Low energy electron bunches experience emittance growth due to space charge. This effect can lead to large emittances which are unacceptable for a facility like PERLE at IJCLab. PERLE will be an ERL test facility circulating a high current electron beam. The traditional method to reduce emittance due to this effect is already planned for the PERLE injector, this has a limit of how small the emittance can be reduced to. This limit is defined by the quality of the bunch as it is upon production at the cathode. The transverse and longitudinal properties of the laser pulse incident on the cathode defines some characteristics of the bunch, to which the space charge effect is related. In addition, the complex evolution of the bunch along the injector could result in optimal laser parameters which are different from the simple flattop distribution currently simulated. Presented here are simulation-based studies of the bunch charge distribution at the cathode and its subsequent evolution along the injector. An optimization of the laser parameters which create the bunch is also performed. We find that there is an optimal bunch charge shape which corresponds to minimal emittance growth.
Paper: WEPC24
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC24
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPC39
Picometer scale emittance from plasmonic spiral photocathode for particle accelerator applications
2046
In this work we demonstrate the generation of a record low root mean square normalized transverse electron emittance of less than 40 pm-rad from a flat metal photocathode – more than an order of magnitude lower than the best emittance that has been achieved from a flat photocathode. This was achieved by using plasmonic focusing of light to a sub-diffraction regime using plasmonic Archimedean spiral structures resulting in a 50 nm root mean square electron emission spot. The emitted electrons show free electron dispersion with ∼90% of the total kinetic energy in the transverse direction. Such nanostructured electron sources exhibiting simultaneous spatio-temporal confinement to nanometer and femtosecond levels can be used for developing advanced electron sources to generate unprecedented electron beam brightness for various accelerator applications.
Paper: WEPC39
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC39
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
WEPC42
Pulsed laser deposition assisted growth of alkali-based photocathodes
2057
Alkali-based semiconductor photocathodes are widely used as electron sources and photon detectors. The prop-erties of alkali-based semiconductor materials such as crystallinity and surface roughness fundamentally de-termine the performance merits like quantum efficiency and thermal emittance. In BNL, pulsed laser deposition (PLD) was utilized to assist the growth of alkali-based photocathode materials, providing precise control of material growth and improving film quality. In the pre-sented work, films prepared with thermal and PLD sources are compared. The film quality of K2CsSb, Cs3Sb and Cs2Te grown with PLD assisted technique are reported.
Paper: WEPC42
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC42
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC43
An upgrade for the CeC cathode deposition system: co-deposition of K₂CsSb and CsTe/GaAs for CeC use
2060
Properties such as high quantum efficiency (QE), low thermal emittance, and longevity are crucial features for the rapidly developing electron accelorators. Compared to the traditional sequential deposition, the co-evaporation method is reported to yield better surface roughness, film crystallinity, and high quantum efficiency for photocath-ode materials. Here we present the effort in upgrading the coherent electron cooling (CeC) photocathode deposition system to adapt the co-evaporation growth method, the development of the co-evaporation recipe, and the prepa-ration of K-Cs-Sb photocathode using the developed system. QE of about 6.3% at wavelength 532 nm was obtained for co-deposited K2CsSb photocathode, where stoichiometry was determined by the deposition rate of each element. The system upgrade also enables the prepa-ration of GaAs photocathodes activating with Cs-Te. In our study, both CsTe and CsTe/CsO activated GaAs are prepared using the “yo-yo” method. QE of about 3.6% and 5% at wavelength 532 nm are obtained respectively. Lifetime measurements are performed and results are reported.
Paper: WEPC43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC43
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC50
GaAs cathode activation with Cs-CsO-Sb thin film
2076
GaAs cathodes are unique devices which generate a spin-polarized electron beam by the photoelectric effect when illuminated with a circularly polarized laser. Thin-film Negative Electron Affinity (NEA) surfaces have an essential role in spin polarized beam production, but they have limited lifetimes. In this study, we activate GaAs as an NEA cathode by evaporating Cs, Cs-O, and Sb metal on its cleaned surface. Here we present the latest experimental results of quantum efficiency measurements taken after evaporative deposition of multi-alkali thin-film surfaces.
Paper: WEPC50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC50
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC53
Unconventional high-voltage insulator in DC photoemission sources
2083
Especially when a high average current of 1 mA and more is required, it is important to protect photocathodes from overheating due to the absorbed laser power. Heat must be dissipated via the surrounding components and materials. This is largely limited by the low heat conductivity of usual high-voltage insulators, e.g. made of aluminum oxide. At the Johannes Gutenberg University in Mainz, we have successfully tested an insulating structure from boron nitride. Due to its physical properties, boron nitride fulfills both requirements: good heat conduction and high-voltage resistance. The results of high voltage tests and of the heat transfer capabilities will be presented.
Paper: WEPC53
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC53
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC55
A laser heated thermionic cathode
2090
There is increasing interest in developing accelerator technologies for space missions, particularly for fundamental science. In order to meet these mission needs, key accelerator technologies must be redesigned to be able to function more reliably and efficiently in a remote and harsh environment. In this work we focus on a modest electron injector system, specifically the traditional thermionic cathode. Typically such cathodes are resistively heated by a power supply that is floated at the cathode accelerating negative high voltage. This can increase engineering complexity and add a significant load to the accelerating voltage supply. We pursue laser heating a thermionic cathode in order to remove the heater power supply from the injector system, allowing for reduced engineering complexity and power requirements for the injector. To date we have shown that a simple tantalum disk cathode can be heated by a laser with similar emission performance to the same disk resistively heated.
Paper: WEPC55
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC55
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC67
NaKSb photocathode tests in a high gradient S-band photoinjector
2126
We report on initial characterization of NaKSb photocathodes in the Pegasus high gradient S-band RF photoinjector. These cathodes were grown at Cornell and transported by air to UCLA. Preliminary characterization was done in the UV and yielded a quantum efficiency of 1.5% and a mean transverse energy of 0.7±0.2 eV measured by solenoid scan. Photocathode response at different wavelengths as well as measurements of other important parameters such as cathode life-time, dark current levels and the time response are being planned.
Paper: WEPC67
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC67
About: Received: 28 May 2024 — Revised: 29 May 2024 — Accepted: 29 May 2024 — Issue date: 01 Jul 2024
WEPC81
Shanghai laser electron gamma source beamline in Shanghai synchrotron radiation facility
2159
Quasi-monochromatic gamma-ray beams are produced in the laser Compton slant-scattering at the Shanghai Laser Electron Gamma Source (SLEGS) of the Shanghai Synchrotron Radiation Facility(SSRF) [1,2]. The laser Compton slant-scattering was pioneered to produce X rays as early as in 1996 [3] and has more recently been used to produced gamma rays in the MeV region at UVSOR [4]. The slant-scattering makes the usage of energy-tunable gamma-ray beams compatible with that of the synchrotron radiation in synchrotron radiation facilities operated at a fixed electron beam energy worldwide. The SLEGS is designed to produce gamma rays in the energy range of 0.66 – 21.7 MeV with a flux of 1e+5 - 1e+7 photons/s [2]. We have conducted test runs of the slant-scattering in the commissioning of the beamline to confirm the designed energy tunability and flux [5]. After a more careful measurement and data processing of the γ ray energy spectra in 2023, the newest experiment results of the quality of gamma-ray beams in flux and bandwidth is obtained and will be present in this report. The gamma-ray flux is in a range of 1e+4 - 3e+5 cps in 60° - 120° and the energy-resolution is in the range of 6 - 18%.
Paper: WEPC81
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC81
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPC82
Gamma beam modulation in Shanghai Laser Electron Gamma Source
2162
The Shanghai Laser Electron Gamma Source (SLEGS) is one of the beamlines of the Shanghai Synchrotron Radiation Facility, which dedicate to producing gamma beams in the slant-scattering for the first time. After produced in the interaction area, gamma rays pass through a carefully designed Gamma Modulation System (GMS), which consists of a double collimator system, attenuator system, and X/gamma imaging system. The quasi-monochromatic gamma beams with an energy spread of 4.2-4.6% are produced at the target position by using an aperture of 2 mm of the double collimator system*. The flux of gamma beams is regulated by the gamma attenuator system. X/gamma imaging system is equipped with two beam-spot monitors, an X-ray camera MiniPIX and the gamma spot monitor. MiniPIX is used for imaging electron-induced bremsstrahlung to reflect the position of gamma beam indirectly. The gamma spot monitor is used to reflect the gamma spatial distribution directly. With the GMS the gamma beam have been successfully implemented on SLEGS, the obtained high-quality gamma beam has been applied to photoneutron validation experiments. The expected results confirm the reliability of SLEGS gamma quality.
Paper: WEPC82
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPC82
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG05
CXLS inverse Compton scattering interaction point chamber
2183
The Inverse Compton Scattering Interaction Point (ICS-IP) vacuum chamber provides a UHV environment where the electron and IR laser beams are overlapped in space and time to generate hard X-rays between 4 and 20 keV. The chamber has over two dozen motorized stages that position YAG screens with ~10 nm precision utilizing the EPICS framework for instrumentation interface. Using agile programming methods, MATLAB GUIs were created to control all the motors inside the chamber. Each YAG screen has a linear array of holes ranging between 10 microns and 2 mm that are imaged by cameras mounted on top of the chamber. Programmable focus lenses and IR mirrors are positioned to focus the IR laser at the interaction point. An X-ray optic is mounted onto a six degree of freedom nano-positioner enabling capture and collimation of X-rays coming from the IP. The X-ray optic can also be extracted from the beam path to transport the freely diverging X-rays to the experiment hutch for imaging experiments. We present the systems integration of the chamber, diagnostics elements, and control software and comment on its performance during instrument commissioning.
Paper: WEPG05
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG05
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG21
Updates on the Cornell cryo-MTE-meter beamline
2236
A critical factor in determining the limit of the brightness of an electron beam is the mean transverse energy (MTE) of its source, which describes the spread in transverse momentum of electrons at the moment of emission from the source. To increase beam brightness, there has been much work in growing novel photocathodes with low MTE and high quantum efficiency (QE) near threshold photoemission excitation energies. Therefore, it is important to have a testing platform for accurately measuring the MTE of a cathode over a range of cryogenic temperatures and photoexcitation energies, with self-consistent results across multiple measurement techniques. Here, we will discuss the characterization and operation of the Cornell Cryo-MTE-Meter beamline which aims to fulfill these criteria for a robust photocathode testing platform.
Paper: WEPG21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG21
About: Received: 17 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG22
Slice energy spread measurements of a 20 MeV electron beam at PITZ
2240
Due to improvements of the performance of FELs, the measurements of the beam’s slice energy spread is becoming increasingly important for optimization of the brightness. Of particular interest are measurements of the uncorrelated energy spread near the gun as this determines the lower limit of the energy spread for the rest of the machine. At the Photo Injector Test facility at DESY in Zeuthen (PITZ), the uncorrelated energy spread is measured of an electron beam generated from an L-band electron gun and accelerated to 20 MeV with a booster cavity. The energy spread of the central time slice is measured using a transverse deflecting structure (TDS) and a dispersive arm to image the longitudinal phase space. Scans of the TDS voltage and quadrupole strengths are used to remove the contributions from the TDS, transverse emittance, and imaging resolution. Presented is an overview of the measurement procedure, resolution, and results of measurements tests.
Paper: WEPG22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG22
About: Received: 16 May 2024 — Revised: 20 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPG38
Geant4 simulations on Faraday cup design for PIP-II Laser wire scanner system
2295
The Proton Improvement Plan-II (PIP-II) accelerator upgrade at Fermilab represents a groundbreaking leap forward in high-energy physics research. This ambitious initiative involves enhancing Fermilab's accelerator complex by replacing the current linear accelerator with a warm front end (WFE) capable of accelerating H- beams up to 2.1 MeV. Subsequently, a superconducting linac further accelerates these beams up to 800 MeV. To pre-cisely measure the transverse beam profile, a combination of traditional wire scanners at the WFE section and Laser wire scanners along the superconducting linac are planned for implementation. This investigation centers on refining the Faraday cup design for the PIP-II Laser wire scanners by utilizing GEANT4, a Monte Carlo simulation toolkit. Leveraging this method enables a comprehensive analysis of particle trajectories, energy deposition, secondary electron emission, backscattering, etc., facilitating optimization through adjustments to cup geometries, materials, and placement to maximize its efficacy in beam diagnostics.
Paper: WEPG38
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG38
About: Received: 17 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG50
Investigations of a potential 5D detector system for a laserwire instrument on the front end test stand
2331
A laserwire diagnostic capable of measuring 5D phase space is to be installed on the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory. The FETS beamline is a hydrogen ion source and the laserwire operates on the principle of photodetachment. A conventional tranverse laserwire is capable of 4D transverse profiling and emittance reconstruction. The FETS laserwire has a pulse duration shorter than the bunch temporal length enabling longitudinal profiling. A detector capable of measuring the laserwire signal is under development. One scheme being considered is a modular detector system. The initial section of the detector would consist of a scintillator to absorb the incoming beam, emitting photons. Following this an optical system will direct the signal to a CCD. Simulations for the photon production for a range of scintillators are compared. A configuration to remove the CCD from the direct line of the accelerator using an optical transport system is considered along with the impact on potential measurements. The expected signal to the CCD and reconstruction of beam size, temporal distribution, and transverse emittance are presented.
Paper: WEPG50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG50
About: Received: 15 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPG54
Electro-optical spectral decoding of THz pulses at MHz repetition rates
2347
A far-field electro-optical (EO) setup based on a balanced detection scheme has been set up to measure the coherent synchrotron radiation (CSR) at the Karlsruhe Research Accelerator (KARA). To enable the readout with a spectrally decoded scheme (EOSD), a KALYPSO based line array camera sensitive to NIR operating at a readout rate of 2.7 MHz has been included in the set-up. In this contribution, measurement results with the KALYPSO based spectrometer in combination with a commercial THz emitter are presented.
Paper: WEPG54
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG54
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
WEPG56
Simulations of an electro-optical in-vacuum bunch profile monitor and measurements at KARA for use in the FCC-ee
2354
The Karlsruhe Research Accelerator (KARA) is an electron storage ring for accelerator research and the synchrotron of the KIT light source at the Karlsruhe Institute of Technology (KIT). KARA features an electro-optical (EO) in-vacuum bunch profile monitor to measure the longitudinal bunch profile in single shot on a turn-by-turn basis using electro-optical spectral decoding (EOSD). A simulation procedure has been set up to evaluate its suitability as a beam instrumentation for the operation of the future electron-position collider FCC-ee. In order to assess the simulations, this contribution focuses on a comparison to EO sampling (EOS) measurements at KARA and a study on the heat load of the EO crystal due to the expected high bunch repetition rate envisioned for FCC-ee.
Paper: WEPG56
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG56
About: Received: 15 May 2024 — Revised: 18 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPG68
Sub-femtosecond resolution electro-optical arrival-time measurement of relativistic electron bunches in a free-electron laser
2386
SwissFEL is a normal conducting linear accelerator driving two separate free-electron laser (FEL) lines – one for soft and one for hard x-rays. We report jitter and correlation measurements of two electro-optical Bunch Arrival-Time Monitors (BAMs), which use directly the pulses from a mode-locked laser oscillator. The arrival-time is encoded in the amplitude of one single reference laser pulse in a fiber coupled Mach-Zehnder modulator driven by a fast RF-transient from a button pick-up. Using the modulation slope and the laser amplitude jitter, we demonstrate <1 femtosecond resolution at 200 pC bunch charges for the BAM with a 16 mm pick-up beam pipe diameter and <10 fs at 10 pC for the BAM with 8 mm pick-up beam pipe diameter. We also report a jitter correlation measurement of two independent BAMs over 1 min at 100 Hz machine repetition rate as well as a similar correlation measurement of one single BAM station with 8 mm pick-up beam pipe diameter and having two identical high resolution channels. The measured correlations are as low as 1.3 fs rms resulting in sub-femtosecond resolution of the optical detection scheme.
Paper: WEPG68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG68
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 17 May 2024 — Issue date: 01 Jul 2024
WEPG72
Fast laser focal position correction using deployed models
2393
Ultrafast high repetition-rate laser systems are essential to modern scientific and industrial applications. Variations in critical figures of merit, such as focal position, can significantly impact efficacy for applications involving laser plasma interactions, such as electron beam acceleration and radiation generation. We present a diagnostic and correction scheme for controlling and determining laser focal position by utilizing fast wavefront sensor measurements from multiple positions to train a focal position predictor. We present the deployment and testing of this scheme at the BELLA Center at Lawrence Berkeley National Laboratory. Online optical adjustments are made to a telescopic lens to provide the desired correction on millisecond timescales. A framework for generating a low-level hardware description of ML-based correction algorithms on FPGA hardware is coupled directly to the beamline using the AMD Xilinx Vitis AI toolchain in conjunction with deployment scripts.
Paper: WEPG72
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPG72
About: Received: 16 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPR43
Experimental evidence of the effect of transverse Landau damping on the microbunching instability
2590
The mechanisms that drive short-range modulations in the longitudinal phase space of accelerated electron bunches, otherwise known as the microbunching instability, have undergone intensive study. The various collective interactions between charged particles within the bunch, and their environment, can degrade the quality of these bunches, eventually making them unsuitable to drive light sources such as free-electron lasers (FELs). Although the most common method for removing this instability at X-ray FELs – namely, the laser heater – has proven to be very useful in improving the performance of these facilities, alternative methods to achieve this goal are active areas of research. In this contribution, we present experimental evidence of the influence of transverse Landau damping on mitigating the microbunching instability.
Paper: WEPR43
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPR43
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
WEPS04
A faster initial cesium transfer for the LANSCE H⁻ ion source
2698
The LANSCE H- Ion Source utilizes a cesium coated converter to induce H- surface conversion. To achieve an optimal cesium coating, a heated cesium reservoir and transfer tube vaporizes cesium onto the converter surface. An initial coating of cesium is done via an initial cesium transfer. During this process, the cesium heater is brought to a high initial temperature (250°C) and is slowly lowered to the operational temperature (~190°C) over six hours, followed by a static conditioning for another 18 hours to get the cesium converter coating optimal for H- surface conversion. Any reduction in the 24-hour cesium transfer process would allow more for experimental time for LANSCE experiments. Thus, there is high value in seeking to reduce the initial Cs transfer time. The LANSCE H- Ion Source Laser Diagnostic Stand was recently utilized to take cesium density measurements inside the H- Ion Source as a function of cesium reservoir temperature. A comparison of the measured cesium densities to the theoretical cesium vapor pressure values will be presented. Also, results using the measured cesium densities to calculate and run a faster cesium transfer process will be discussed.
Paper: WEPS04
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS04
About: Received: 15 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPS50
Progress on the autonomous event detection system for the laser particulate counter
2810
Field emission is one of the most important issues that limits the performance of the superconducting radio fre-quency (SRF) systems and leads to SRF cavity trips at the Continuous Electron Beam Accelerator Facility at Jeffer-son Lab. Studies have confirmed that particulates are the dominant source of field emitters and the particulates can be transported into a cavity from other parts of the accel-erator. To monitor the transportation of the particulates, a prototype of a novel, non-invasive laser particulate coun-ter (LPC) has been developed and tested. Experiments have been done to validate the capability of the LPC. We are developing autonomous event detection system to continuously monitor the readout from the LPC and to recognize real events generated by particulates from noises using machine learning model. In this report, we will present how the data are prepared and how the model is trained. We will also discuss the performance of the model.
Paper: WEPS50
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS50
About: Received: 13 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
WEPS68
Development and test of a large-aperture Nb3Sn cos-theta dipole coil with stress management
2858
The stress-managed cos-theta (SMCT) coil is a new concept which was proposed and is being developed at Fermilab in the framework of US Magnet Development Program (US-MDP) for high-field and/or large-aperture accelerator magnets based on low-temperature and high-temperature superconductors. A 120-mm aperture two-layer Nb3Sn SMCT dipole coil has been developed at Fermilab to demonstrate and test the SMCT concept including coil design, fabrication technology and performance. The first SMCT demo coil was fabricated and assembled with 60-mm aperture Nb3Sn coil inside a dipole mirror configuration and tested separately and in series with the insert coil. This paper summarizes the design, parameters, and quench performance of the 120-mm aperture SMCT coil in a dipole mirror configuration.
Paper: WEPS68
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS68
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
WEPS79
Optimization studies on accelerator sample components for energy management purposes
2887
The large amount of energy required to operate large-scale facilities with particle accelerators within has been considered as one of the important research topics over the past years. This sheds light on the importance of the research field of energy management that entitles, with a view to long-term operations, the implementation of smart and sustainable technologies. One of the key technologies in accelerators are superconductor (SC)-based designs. The vanishing electrical resistance together with the ability to provide field values well above those from conventional conductors is the main motivation behind exploiting superconducting wires in building coils and magnets for large-scale accelerators. However, these superconductors can also quench under certain conditions, driving the wires into the normal state and potentially allowing for overheating and destruction of the conductor material and/or the whole design. This work will present the results of optimization-based analyses performed on accelerator SC-sample components aiming at goal designs that are more energy efficient at a reference operational field or current. A compromise between getting the best performance for excellent science from a design (with superconductivity preserved and safe operation maintained) and reducing its power consumption (and eventually its effective cost) will be addressed too.
Paper: WEPS79
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS79
About: Received: 15 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
WEPS83
Passively stable pulsed optical timing distribution at 1030-nm wavelength using hollow core optical fibers
2903
New generation X-ray free electron lasers require reliable and precise synchronization of pulsed laser sources across various locations. This demands stable timing distribution to preserve ultra-low timing jitter, ultrashort pulse duration, and high peak power*. Fiber optic delivery, compared to free-space optics, offers advantages in flexibility, laser safety, ease of deployment and superior output beam quality. However, standard fibers with silica glass core face challenges like high dispersion, nonlinear pulse shaping and environmental sensitivity, causing excess timing jitter. Emerging anti-resonant hollow core fibers that guide light though a central hole have significantly lower environmental sensitivity, high nonlinearity threshold and low dispersion, while achieving attenuation similar to glass-core fibers**. This makes them an improved medium for low-noise transmission of fs pulses with high peak powers. Here, we experimentally demonstrate passively stable timing distribution of femtosecond pulses at 1030-nm center wavelength using sealed hollow core fibers with-out vacuum components. We have achieved a timing precision of 0.3 fs RMS from 1 Hz to 1 MHz and < 250 fs peak-to-peak for 12 hours with a hollow core fiber length of 72 m without requiring any transmission delay stabilization.
Paper: WEPS83
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-WEPS83
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THAN2
Beam profile measurement of the ultra-slow muon for the transmission muon microscope
2933
We have performed a beam profile measurement of the ultra-slow muon for the transmission muon microscope, which is being developed at the Japan Proton Accelerator Research Complex (J-PARC). A laser ionization of thermal muonium generates the ultra-slow muon. The generated ultra-slow muon is extracted by an electrostatic lens and transported to the beam profile monitor, which consists of a micro-channel plate and delay-line anode. In this paper, the results of profile measurements and the beam commissioning status of the ultra-slow muon beamline are reported.
Paper: THAN2
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THAN2
About: Received: 13 May 2024 — Revised: 18 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC08
Beam-based alignment of magnetic system in AREAL linear accelerator
2978
In this paper the beam-based alignment for solenoid and quadrupole magnets in the AREAL linear accelerator is presented. The AREAL accelerator, at this stage, operates with one solenoid, one quadrupole, corrector, and dipole magnets. The adjustment of solenoid and quadrupole magnets is crucial for the stable operation of the accelerator and for forming the desired beam required for the AREAL upgrade program. This work also takes into account the influence of the RF field radial component on the off-axis beam parameters and trajectory due to laser spot misalignment on the cathode. The study involves theoretical, simulation, and experimental comparisons.
Paper: THPC08
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC08
About: Received: 13 May 2024 — Revised: 19 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPC31
Dynamics study of laser stripping injection of H- beam in the SNS
3053
A Laser Assisted Charge Exchange (LACE) injection in the Spallation Neutron Source (SNS) is under development. By utilizing powerful lasers and magnetic fields, electrons are stripped out of the H- beam without foils. Such a process avoids any foil-based charge exchange injection problems, such as foil degradation and beam loss, especially for future multi-megawatt power beams. Proof-of-principle of LACE has been experimentally demonstrated in the SNS in a transport line. Integration of the LACE injection into the SNS accumulator ring is in progress. In this paper, we present preliminary results of optics design and beam dynamics study.
Paper: THPC31
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC31
About: Received: 21 May 2024 — Revised: 23 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPC74
Generation femtosecond proton beam for laser plasma acceleration
3202
Laser plasma accelerators have a great potential to accelerate a charged particle beam to high energy within a short distance due to their extraordinarily high accelerating gradient. However, in order to effectively use the laser plasma accelerator, the input beam has to be moving at relativistic velocities, with a duration 100 femtoseconds or less. In this study, we propose a scheme to generate a femtosecond proton beam for the laser plasma acceleration. The self-consistent simulation including the three-dimensional space-charge effects was used to verify this concept in a simplified version.
Paper: THPC74
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPC74
About: Received: 14 May 2024 — Revised: 20 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPG14
Automation upgrade of the CXLS photoinjector
3275
The automation upgrade of the photoinjector for the Compact X-Ray Light Source (CXLS) at Arizona State University is described. As the accelerator vault of the CXLS is only 10 meters long, the photoinjector drive laser is located in an enclosure inside the vault. Since ionizing radiation is present in this room during operations, it necessitates remote control of all devices used to optimize the laser spot. This includes multiple shutters, Galil motors, picomotors, a mirror flipper, LEDs, and remote lens controllers. To actuate these devices, a GUI was created with the use of MATLAB AppDesigner which communicates with the hardware through EPICS (Experimental Physics and Industrial Control System). Challenges with this GUI are described, along with the team’s efforts to finalize the control software. After these upgrades, the photoinjector laser characteristics can be adjusted remotely during operation and changes to the drive laser’s position, shape, and intensity can be made without interrupting beam time.
Paper: THPG14
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG14
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPG23
Novel clock and trigger solutions with ultra-high precision delay to support time-resolved experiments at TPS
3305
The TPS (Taiwan Photon Source) is a third generation 3 GeV synchrotron light source. Some beamlines use synchrotron pulses in conjunction with laser pulses for pump-probe experiments, which is a time-resolved experiment method for capturing the temporal evolution of the pumped process. Periodic X-ray pulses are provided by the synchrotron light source as detecting light (Probe), and laser pulses can be used as a pump to excite a target, which changes a certain property when excited. Pump-probe experiments re-quire a synchronized laser system to alter the delay time between X-ray pulses and laser pulses. It has been built a laser synchronizer and timing support system. One direct digital synthesizer (DDS) with fine delay adjustment can change the laser pump pulse relative to the X-ray pulse. The clock fanout buffer with output dividers provides the synchronized clocks required by the laser oscillator and laser source. An SBC (single-board computer) is employed as a control interface The software architecture is created using the EPICS framework, which is compatible with the TPS control system, and a GUI with the ability to adjust the time delay is created. The efforts will be described in this report.
Paper: THPG23
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG23
About: Received: 14 May 2024 — Revised: 16 May 2024 — Accepted: 16 May 2024 — Issue date: 01 Jul 2024
THPG35
Generation of symmetrical optical caustic beams for precise alignment
3333
Generating layers of symmetrical optical caustic beams using a specific configuration of cylindrical lenses is an innovative idea with potential application in precision alignment and other fields. The technique allows the generation of layers of non-diffracting beams with opposite accelerating directions. This approach can be extended in two dimensions or to create rotationally symmetric beams. Prior methods have produced similar beams using spatial light modulators, but the presented approach with cylindrical lenses reduces setup complexity and cost, thereby opening the possibility for new applications. In the context of particle accelerators, these include particle acceleration using high-power lasers and alignment of accelerator components. The presented research emphasizes the possibility for this technique to be used as a reference line for precise alignment. It allows the generation of reference lines with a thickness in the order of millimeters for distances of tens to hundreds of meters, which is advantageous for large accelerator facilities. A brief description of the sensors used to detect misalignment is also presented.
Paper: THPG35
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG35
About: Received: 14 May 2024 — Revised: 22 May 2024 — Accepted: 24 May 2024 — Issue date: 01 Jul 2024
THPG41
CXLS ionizing and laser radiation safety interlock systems
3352
The Compact X-ray Light Source (CXLS) requires the acceleration of electron bunches to relativistic energies, which collide with focused IR laser pulses to produce X-rays which are then transported to the experiment hutch. A class 4 UV laser is used at the photocathode to liberate the electrons that are generated via the photoelectric effect. During electron acceleration bremsstrahlung radiation (gamma and neutron) is generated through electron interactions with solid matter. In the experiment hutch the X-rays then interact with the sample under test in pump-probe configuration where the pump laser is another class 4 laser with a wide spectral range from deep UV to THz. Interlock systems have been designed and deployed to protect users of the facility from exposure to these ionizing and laser radiation hazards. We present the design architecture of CXLS interlock systems. In this description we make clear what systems are independent, and which are interdependent and what administrative override modes are made available and why. We also provide an overview of our monthly interlock system testing protocols and conclude with comments on overall system performance.
Paper: THPG41
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPG41
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR44
Study of stripping magnets for LACE at the SNS
3607
We study possibility of laser assisted charge exchange injection at the SNS. The realistic injection of LACE injection and accumulation into the Ring of SNS is considered. The design of stripping magnets at the injection area is one of the most challenging problems toward operational scheme of LACE at the SNS. Basic requirements and needed parameters of stripping magnets are studied. Based on this study the possibility of real stripping magnet design is considered.
Paper: THPR44
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR44
About: Received: 15 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPR54
The Laser-hybrid Accelerator for Radiobiological Applications (LhARA): an update towards the conceptual design
3639
LhARA, the Laser-hybrid Accelerator for Radiobiological Applications, is a proposed facility designed to advance radiobiological research by delivering high-intensity beams of protons and ions in unprecedented ways. Designed to serve the Ion Therapy Research Facility (ITRF), LhARA will be a two-stage facility that will employ laser-target acceleration in the first stage, generating proton bunches with energies around 15 MeV via the TNSA mechanism. A series of Gabor plasma lenses will efficiently capture the beam, directing it to an in-vitro end station. In the second stage, protons will be accelerated in a fixed-field alternating gradient ring, reaching up to 127 MeV, while ions can achieve up to 33.4 MeV/u. The resulting beams will be directed to either an in-vivo end station or a second in-vitro end station. The demonstrated technologies have the potential to shape the future of hadron therapy accelerators, offering versatility in time structures and spatial configurations, with instantaneous dose rates surpassing the ultra-high dose rates required for studies into the FLASH effect. Here, we present a status update of the LhARA accelerator as we approach a full conceptual design.
Paper: THPR54
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR54
About: Received: 15 May 2024 — Revised: 19 May 2024 — Accepted: 23 May 2024 — Issue date: 01 Jul 2024
THPR63
Thermal diffusivity and acoustic properties of Nb thin films studied by time-domain thermoreflectance
3667
The thermal diffusion and acoustic properties of Nb impacts the thermal management of devices incorporating Nb thin films such as superconducting radiofrequency (SRF) cavities and superconducting high-speed electronic devices. The diffusion and acoustic properties of 200-800 nm thick Nb films deposited on Cu substrates were investigated using time-domain thermoreflectance (TDTR). The films were examined by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The grain size and thermal diffusivity increase with film thickness. The thermal diffusivity increased from 0.100± 0.002 cm2s-1 to 0.237± 0.002 cm2s-1 with the increase in film thickness from 200 nm (grain size 20±6 nm) to 800 nm (grain size 65±16 nm). Damped periodic photoacoustic signals are detected due to laser heating generated stress in the Nb film, which results in an acoustic pulse bouncing from the Nb/Cu and the Nb/vacuum interfaces. The period of the acoustic oscillation gives a longitudinal sound velocity of 3637.3 ms-1 inside the Nb films, which is in good agreement with the values reported in the literature.
Paper: THPR63
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR63
About: Received: 07 May 2024 — Revised: 17 May 2024 — Accepted: 18 May 2024 — Issue date: 01 Jul 2024
THPR86
The gamma activation measurements at Shanghai Laser Electron Gamma Source (SLEGS)
3714
SLEGS is a Laser Compton Scattering gamma source. The gamma energy is 0.66 to 21.7 MeV, and the gamma flux is approximately 4.8e+5 to 1.5e+7 phs/s. Gamma activation method is used in beam flux monitor, medical isotpoe production and nuclear astrophysics in SLEGS*. Gamma beam flux under different collimated apertures has been checked by gamma activation method by using various half-life nuclide targets with an online activation and offline measurement platform. It is consistent with the flux measured with direct method by the LaBr3 detector. The activation method will be uniquely advantageous for monitoring gamma beam with short-life nuclide in a short time.A series of potential medical isotopes giant resonance production cross sections are measured by gamma activation method, which will provide key data for medical isotopes production by photonuclear reactions. The p-nuclei’s photonuclear cross sections**, for example Ru, are measured by photoneutron and gamma activation, which can provide favorable data on the much larger abundance of 98Ru, 96Ru. The activation experiment of SLEGS provides a reliable option for different experimental research objectives in photonuclear physics.
Paper: THPR86
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPR86
About: Received: 17 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPS02
Upgrade of the SPARC_LAB low level radiofrequency system
3722
SPARC_LAB facility was born in 2004 as an R&D activity to develop a high brightness electron photo-injector dedicated to FEL experiments and exploration of advanced acceleration techniques. The electron source consists in a brazefree 1.6-cell S-band RF gun with a peak electric field of 120 MV/m and a metallic copper photocathode. The gun injects particles into two S-band sections, the initial section acting as an RF compressor using the velocity bunching technique, with built-in solenoid coils that enhance magnetic focusing and control emittance. A subsequent C-band acceleration section acts as a booster to achieve the desired kinetic energy. The Lazio Regional government recently funded the SABINA project for the consolidation of SPARC_LAB facility. The reference and the distribution systems and the Low Level radiofrequency (LLRF) system will also undergo a significant upgrade, involving the replacement of the original analogue S-band and digital C-band radiofrequency systems with commercial, temperature-stabilized, FPGA-controlled LLRF digital systems provided by Instrumentation Technologies in order to improve performance in terms of amplitude, phase resolution, and stability.
Paper: THPS02
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS02
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 21 May 2024 — Issue date: 01 Jul 2024
THPS21
Strain measurements of the Apple-X SABINA undulator with fiber Bragg grating
3777
The SABINA project will add a user facility to SPARC_LAB at INFN in Frascati (Rome). For the THz line, an electron beam is transported to the APPLE-X undulators to produce photon pulses in the ps range, with energy of tens of µJ, with linear or elliptical polarization. Each undulator has four magnetic arrays that can be moved radially simultaneously to set the operating gap. Two arrays can also move longitudinally for phase displacement. A structural analysis of this unique mechanical structure has been performed by the production company (KYMA S.p.a) to ensure good field quality and beam trajectory. To support those, a set of tests has been performed with FBG acting as strain sensors in Frascati. An FBG is a phase grating inscribed in the core of a single-mode fiber, whose Bragg-diffracted light propagates back along the fiber. Any deformation of the grating affects its pitch, which changes the diffracted Bragg wavelength thus giving information about the occurred deformation. Application of the technique at the state-of-the-art level allows to perform strain measurements with 1 µStrain resolution. Such analysis and results will be presented in this contribution.
Paper: THPS21
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS21
About: Received: 15 May 2024 — Revised: 20 May 2024 — Accepted: 20 May 2024 — Issue date: 01 Jul 2024
THPS22
Design study of a compact superconducting undulator based on laser-structured HTS tapes
3781
Undulators are X-ray sources which are widely used in synchrotron storage rings or in future light sources such as free-electron lasers. Due to sustainability and energy efficiency the development envisages small-scale high-field and compact undulators with short period lengths (<10 mm) and narrow magnetic gaps (<4 mm). Therefore, high-temperature superconducting (HTS) tapes, which can provide both large critical current densities and high critical magnetic fields, are widely used and investigated at KIT. A new concept of superconducting undulators (SCUs) was introduced and further developed by laser-scribing a meander pattern into the superconducting layer to achieve quasi-sinusoidal current path through the tape. In this contribution, we present our results from the design study in respect of the cooling concept for a compact SCU. The foreseen cooling is based on the one hand on calculations of the different heat loads through synchrotron radiation, impedance, and current supplies and on the other hand on the design of the liner including the tapering.
Paper: THPS22
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS22
About: Received: 15 May 2024 — Revised: 21 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024
THPS62
Perspectives and recent achievements on additive manufacturing technologies for accelerators
3890
This paper reports the exploratory studies on advanced accelerator technologies performed within the I.FAST (Innovation Fostering in Accelerator Science and Technology) EU project, and in particular the key results of the additive manufacturing Task 10.2 – “Additive Manufacturing – applications and potential developments” and Task 10.3 – “Repair of damaged accelerator components by AM technologies”. This includes results of two surveys targeted to the accelerator community: a) on current additive manufacturing applications in accelerators and expected new developments, b) on current additive manufacturing repair technologies for accelerator and list of possible applications. The paper is outlining potential additive manufacturing applications in accelerators and overall strategies applicable to accelerator components repairs benefiting from additive manufacturing technology.
Paper: THPS62
DOI: reference for this paper: 10.18429/JACoW-IPAC2024-THPS62
About: Received: 18 May 2024 — Revised: 22 May 2024 — Accepted: 22 May 2024 — Issue date: 01 Jul 2024