B. Keil, R. Ditter, F. Marcellini, G.M. Marinkovic, J. Purtschert, M. Rizzi, M. Roggli, D. Stephan, X. Wang
PSI, Villigen PSI, Switzerland
After more than 20 years of operation, the storage ring of the Swiss Light Source (SLS) will be replaced. The new ring called SLS 2.0 will have 40 times higher brilliance than SLS, thanks to an innovative low-emittance magnet lattice and a beam pipe with smaller aperture. For SLS 2.0, the ageing SLS BPM electronics will be incrementally replaced for the whole accelerator, including linac, booster, transfer lines and storage ring. This contribution presents the development status and latest prototype test results of the SLS 2.0 BPM system, including BPM pickups, mechanics, and electronics.
Q. Wang, Q.Y. Dong, L.T. Huang
DICP, Dalian, Liaoning, People’s Republic of China
Q. Luo
USTC/NSRL, Hefei, Anhui, People’s Republic of China
A nondestructive method to measure beam energy spread using the quadrupole modes within a microwave cavity is proposed. Compared with a button beam position monitor (BBPM) or a stripline beam position monitor (SBPM), the cavity monitor is a narrow band pickup and therefore has better signal-to-noise ratio (SNR) and resolution. In this study, a rectangular cavity monitor is designed. TM220 mode operating at 4.76 GHz in the cavity reflects the quadrupole moment of the beam. The cavity plans to be installed behind a bending magnet in Dalian Coherent Light Source (DCLS), an extreme ultraviolet FEL facility. In this position, the beam has a larger dispersion, which is beneficial to measure the energy spread. A quadrupole magnet, a fluorescent screen, and a SBPM with eight electrodes is installed near the cavity for calibration and comparison. The systematic framework and simulation results are also discussed in this paper.
SOLARIS linac currently operates at 540 MeV and is used as an injector to the storage ring, where after the accumulation the energy is ramped up to 1.5 GeV via two active RF cavities. Top-up injection would be of extreme benefits for user operation, therefore a new 1.5 GeV linac is being designed. The idea is to replace the current machine without infrastructural interventions in terms of tunnel expansion. Performed studies demonstrate that the best solution is provided by a Hybrid S-band/C-band LINAC. One of the main goals is to achieve bunch compression below the picosecond level and low-emittance beams for a future short-pulse facility or a Free Electron Laser. Within this presentation the results of performed simulations will be presented together with the concept of different diagnostics as BPMs, current transformers, YAG screens, coherent diffraction radiation monitor distribution.
D. Schneider, M. Arnold, U. Bonnes, A. Brauch, M. Dutine, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, G. Steinhilber
TU Darmstadt, Darmstadt, Germany
Funding:Work supported by DFG (GRK 2128), BMBF (05H21RDRB1), the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006) and the LOEWE Research Group Nuclear Photonics. The r-process fission cycle terminates the natural synthesis of heavy elements in binary neutron-star mergers. Fission processes of transuranium nuclides will be studied in electrofission reactions at the S-DALINAC*. Due to the minuscule fissile target, the experimental setup requires an active electron-beam-stabilization system with high accuracy and a beam position resolution in the submillimeter range. In this contribution, requirements and concepts of this system regarding beam-diagnostic elements, feedback control and readout electronics are presented. The usage of a beam position monitor cavity and optical transition radiation targets to monitor the required beam parameters will be discussed in detail. Additionally, various measurements performed at the S-DALINAC to assess requirements and limits for the beam-stabilization system will be presented. Finally, the option of using advanced machine learning methods such as neural networks and agent-based reinforcement learning will be discussed. *N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
I.D. Kittelmann, R.A. Baron, E.C. Bergman, E.M. Donegani, V. Grishin, H. Hassanzadegan, H. Kocevar, N. Milas, R. Miyamoto, M. Mohammednezhad, F. Nilen, D. Noll, K.E. Rosengren, T.J. Shea, R. Tarkeshian, C.A. Thomas
ESS, Lund, Sweden
Once constructed, the European Spallation Source (ESS) will be a 5MW pulsed neutron source based on a 2 GeV proton linac delivering 2.86 ms long pulses at a 14 Hz repetition rate. This paper focuses on the beam instrumentation performance during the recent linac beam commissioning up to drift tube linac (DTL) tank 4 with 74 MeV output energy. Instrumentation and measurement results will be presented for beam parameters such as current, position, energy, emittance and beam loss. Proposal by Peter, same proposal as ID 1283 by Wim. Alternative speaker Cyrille Thomas (ESS).
J.A. Mock, A.S. Fisher, R.T. Herbst, P. Krejcik, L. Sapozhnikov
SLAC, Menlo Park, California, USA
Beam power at the LCLS-II linac and FEL can be as high as several hundered kW with CW beam rates up to 1 MHz. The new MPS has a latency of less than 100 µs to prevent damage when a fault or beam loss is detected. The MPS architecture encompasses the multiple FEL beamlines served by the SC linac and can mitigate a fault in one beamline without impacting the beam rate in a neighboring beamline. The MPS receives inputs from various devices including loss monitors and charge monitors as well as magnet power supplies and BPMs to pre-emptively turn of the beam if a fault condition is detected. Link nodes distributed around the facility gather the input data and stream it back to a central processor that signals other link nodes connected to beam rate control devices. Commmissioning and experience with the new system will be described.
I. Dolenc Kittelmann, V. Grishin
ESS, Lund, Sweden
P. Boutachkov
GSI, Darmstadt, Germany
E. Effinger, A.T. Lernevall, W. Viganò, C. Zamantzas
CERN, Meyrin, Switzerland
The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be a pulsed neutron source based on a proton linac. The ESS linac is designed to deliver a 2GeV beam with peak current of 62.5mA at 14 Hz to a rotating tungsten target for neutron production. One of the most critical elements for protection of an accelerator is a Beam Loss Monitoring (BLM) system. The system is designed to protect the accelerator from beam-induced damage and unnecessary activation of the components. The main ESS BLM system is based on ionization chamber (IC) detectors. The detector was originally designed for the LHC at CERN resulting in production of 4250 monitors in 2006-2008. In 2014-2017 a new production of 830 detectors with a modified design was carried out to replenish spares for LHC and make a new series for ESS and GSI. This contribution focuses on the results from a measurement campaigns performed at the HRM (High-Radiation to Materials) facility at CERN, where detector response of the ESS type IC has been studied. The results may be of interest for other facilities, that are using existing or plan to use new generation of LHC type IC monitors as BLM detectors.
A.S. Fisher, N. Balakrishnan, G.W. Brown, E.P. Chin, W.G. Cobau, J.E. Dusatko, B.T. Jacobson, S. Kwon, J.A. Mock, J. Park, J. Pigula, E. Rodriguez, J.I.D. Rudolph, D. Sanchez, L. Sapozhnikov, J.J. Welch
SLAC, Menlo Park, California, USA
A 4-GeV superconducting linac has been added to the LCLS x-ray FEL facility at SLAC. Its 120-kW, 1-MHz beam requires new beam-loss monitors (BLMs) for radiation protection, machine protection, and diagnostics. Long radiation-hard optical fibres span the full 4 km from the electron gun of the SC linac to the final beam dump. Diamond detectors at anticipated loss points provide local protection. Detector signals are continuously integrated with a 500-ms time constant and compared to a loss threshold. If crossed, the beam is halted within 0.1 ms. Commissioning began in March 2022 with the 100-MeV injector and with RF processing of the cryomodules. At IBIC 2022 last September, we presented commissioning results from the injector BLMs. In October, the beam passed through the full linac and the bypass transport line above the LCLS copper linac, stopping at an intermediate dump. In August it continued through the soft x-ray undulator and achieved first lasing. Here we present BLM commissioning at energies up to 4 GeV and rates up to 100 kHz. We discuss measurements and software using the fast diagnostic-waveform output to localize beam losses and to detect wire-scanner signals.
S. Kiy, P.M. Jung, T. Planche, O. Shelbaya, V.V. Verzilov
TRIUMF, Vancouver, Canada
A time-of-flight measurement system has been in use at ISAC-II since 2006 for the phasing of cavities and accurate ion beam velocity measurements across the nuclear chart. This system is heavily relied upon as the primary energy-time domain diagnostic downstream of the ISAC-II linac. Ongoing High Level Applications (HLA) development at TRIUMF has enabled the use of methods that are being applied to these measurements - both for processing and automation of data acquisition. An update will be provided on operational experience with the system over the past 10 years including its recent re-calibration and error analysis. A brief summary of the current HLA framework will be given, including a database for beam measurements and the ability to carry out sequential measurement processes. Finally, the way in which these developments enable beam-based calibration of cavity parameters and a shift to model-based tuning methods is discussed.
A. Brauch, M. Arnold, M. Dutine, J. Enders, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, D. Schneider
TU Darmstadt, Darmstadt, Germany
Funding:Work supported by the State of Hesse within the Cluster Project ELEMENTS (Project ID 500/10.006) and by DFG (GRK 2128 AccelencE). The S-DALINAC is a thrice recirculating electron accelerator for high resolution electron scattering experiments with a continuous-wave beam at a frequency of 2.9972(1) GHz. Short bunches are crucial to enable tuning of the machine for operation as an energy-recovery linear accelerator* **. Currently, measurements of this beam parameter are accomplished by using the radio-frequency zero-crossing method: here, a momentum spread chirp is induced and the transverse beam profile in a downstream located dispersive section is measured with a scintillating screen providing an upper limit of the bunch length. Since this method is time consuming, a new setup for these measurements using a streak camera is developed. Optical transition radiation from an aluminum-coated Kapton target is used to map the bunch length information to a light pulse which enables an accurate measurement compared to a scintillating screen. The light pulse can then be evaluated with the streak camera by projecting its length onto the transverse dimension on a phosphor screen. This contribution will present the current status of the measurement setup as well as its design and properties. *Michaela Arnold et al., Phys. Rev. Acc. Beams 23, 020101 (2020). **F. Schliessmann et al., Nat. Phys. 19, 597-602 (2023).
W.L. Huang, X.J. Nie
IHEP CSNS, Guangdong Province, People’s Republic of China
M.Y. Liu, X.Y. Liu, Y.F. Sui
IHEP, Beijing, People’s Republic of China
Q.R. Liu
UCAS, Beijing, People’s Republic of China
Funding:Natural Science Foundation of Guangdong Province, 2021A1515010269 National Natural Science Foundation, 11475204 During the upgrade of linac in CSNS-II, the beam in-jection energy will increase from 80.1MeV to 300MeV and the beam power from 100kW to 500kW. A com-bined layout of superconducting spoke cavities and ellip-tical cavities is adopted to accelerate H− beam to 300MeV. Due to a ~10ps short bunch width at the exit of the spoke SC section, the longitudinal beam density dis-tribution will be measured by bunch shape monitors using low energy secondary emission electrons. As the most important part of a bunch shape monitor, a prototype 324MHz RF deflector is designed and tuned on the basis of a quasi-symmetric λ/2 325MHz coaxial resona-tor, which was fabricated for the C-ADS proton accelera-tor project. Preliminary parameters of the bunch shape monitor are presented. Simulation of the RF deflector and test results in the laboratory are described and analysed.
The lasing performance of a Free Electron Laser (FEL) strongly relies on a precise characterization of the electron bunch length and on the control and stabilization of the bunch compression settings of the machine under normal user operations. In a FEL driver linac, the so-called Bunch Compressor Monitors (BCMs) normally ensure the non-invasive monitoring of the electron bunch length. BCMs, being sensitive to the temporal coherent threshold of the radiation energy emitted by the electron beam crossing the last dipole of a magnetic chicane or a holed diffraction screen just downstream, can provide a bunch length dependent signal resulting from the integration of the detected radiation pulse energy over the acceptance frequency band of the detector. Thanks to the non-invasiveness, BCMs are primary diagnostics in a FEL to stabilize the bunch compression by feeding back the RF settings of the accelerating structure. In this contribution, we present a formal method to determine an absolute measurement of the electron bunch length from the analysis of a BCM signal (*). (*) G.L. Orlandi, Absolute and non-invasive determination of the electron bunch length in a Free Electron Laser using a Bunch Compressor Monitor, https://doi.org/10.48550/arXiv.2305.17042, https://doi.org/10.21203/rs.3.rs-3228455/v1
J.C. Dooling, A.R. Brill, N. Kuklev, I. Lobach, A.H. Lumpkin, N. Sereno, Y. Sun
ANL, Lemont, Illinois, USA
Funding:Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357. We report on measurements of beams from thermionic cathode (TC) rf guns in the Advanced Photon Source S-Band Linac. These measurements include the macropulse out of both new and existing TC guns as well as the observation of microbunching within the micropulses of these beams. A gun chopper limits the macropulse FWHM duration to the 10-ns range. Our objectives were to analyse the new TC gun and investigate microbunching within a TC-rf-gun-generated beam. Our diagnostics elucidated longitudinal beam structures from the ns to the fs time scales. Coherent transition radiation (CTR) interferometers responding to far-infrared wavelengths were employed after each compression stage to provide the autocorrelations of the sub-ps micropulse durations. The first compression stage is an alpha magnet and the second a chicane. A CCD camera was used to image the beam via optical transition radiation from an Al screen at the end of the linac and also employed to measure coherent optical transition radiation (COTR) in the visible range. The COTR diagnostic observations, implying microbunching on a fs time scale, are presented and compared with a longitudinal space-charge impedance model.
D. Lipka, T. Lensch, Re. Neumann, M. Werner
DESY, Hamburg, Germany
The ARES facility (Accelerator Research Experiment at SINBAD) is an accelerator to produce low charge ultra-short electron bunches within a range of currently 0.5 pC to 200 pC. Especially for eFLASH experiments at ARES an absolute, non-destructive charge measurement is required. To measure an absolute charge of individual bunches different types of monitors are installed. A destructive Faraday Cup is used as reference charge measurement device. To measure the charge non-destructively 2 Toroids, 1 Turbo-ICT and 2 cavity monitors are installed. The latter system consists of the cavity, front-end electronics with logarithmic detectors and µTCA ADCs. The laboratory calibration of the cavity system is performed by using an arbitrary waveform generator which generate the same waveform like the cavity with beam. This results in a non-linear look-up table used to calculate the ADC amplitude in charge values independent of beam-based calibration. The measured charges from the cavity monitors agree very well within few percent in comparison with the Faraday Cup results.
H. Hassanzadegan, R.A. Baron, S. Gabourin, H. Kocevar, M. Mohammednezhad, J.F.J. Murari, S. Pavinato, K.E. Rosengren, T.J. Shea, R. Zeng
ESS, Lund, Sweden
K. Czuba, P.K. Jatczak
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
The ESS BCM system is not only used for beam measurement but it also plays an important role for machine protection particularly in the normal-conducting part of the linac. During the previous beam commissionings to the MEBT and DTL1 FCs and before the cavities were fully conditioned, RF breakdowns and other types of discharges in the cavities had a major impact on beam availability due to the Fast machine protection functions of the BCM. Following an investigation on the root cause of the beam trips, the configuration of the machine protection functions was modified to improve beam availability in the more recent beam commissioning to the DTL4 FC. In addition to this, some optimizations were made in the BCM system to improve beam measurement, and a few more functions were added based on new requirements. This paper reports on these improvements and the results obtained during the beam commissioning through the DTL4.
S.T. Littleton
Stanford University, Stanford, California, USA
A.S. Fisher, C. Huang, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
The LESA beamline is designed to transport dark current from the LCLS-II and LCLS-II-HE superconducting linacs to the End Station A for various fixed target experiments. The primary experiment is expected to be the Light Dark Matter eXperiment (LDMX) which required beam currents of a few pA. The operation of the beam line much be parasitic to the LCLS-II / LCLS-II-HE FEL operation. The dark current in the LCLS-II is expected to be at the nA-level which will be below the resolution of most of the LCLS-II diagnostics (it will be degraded before the experiments as necessary). This paper will describe a possible non-destructive diagnostic using synchrotron radiation that could be applied at multiple locations along the LCLS-II and the LESA beamline.
J. Marroncle, P. Abbon, F. Belloni, F. Bénédetti, T. Hamelin, J.-Ph. Mols, L. Scola
CEA-DRF-IRFU, France
B. Bolzon, N. Chauvin, D. Chirpaz-Cerbat, M. Combet, M.J. Desmons, Y. Gauthier, C. Lahonde-Hamdoun, Ph. Legou, O. Leseigneur, Y. Mariette, V. Nadot, M. Oublaid, G. Perreu, F. Popieul, B. Pottin, Y. Sauce, J. Schwindling, F. Senée, O. Tuske, S. Tzvetkov
CEA-IRFU, Gif-sur-Yvette, France
I. Dolenc Kittelmann, A.A. Gevorgyan, H. Kocevar, R. Tarkeshian, C.A. Thomas
ESS, Lund, Sweden
Several Non-invasive Profile Monitors are being in-stalled along the accelerator to support the commissioning, tuning and operation of the powerful proton based ESS linear accelerator. In the low energy parts of the ESS linac (3.6 MeV to 90 MeV), the residual gas pressure is high enough to measure the transverse beam profile by using fluorescence induced by the beam on the gas molecules. However, in the ESS linac sections above 90 MeV, protons are accelerated by superconductive cavities working at cryogenic temperatures and high vacuum. Therefore, the signal based on the fluorescence process is too weak, while ionization can counteract this drawback. We have provided five IPM (Ionization Profile Monitors) pairs for energies ranging from 100 to 600 MeV. The design of such monitors is challenging due to weak signal (as a result of high proton energy and low pressure <10-9 mbar), tight space constraints inside the vacuum chamber, space charge effect, ISO-5 cleanliness requirement, and electrode polarization at ±15 kV. This publication will detail the development we followed to fulfil the ESS requirements.
K.P. Wootton, W. Berg, M. Borland, A.R. Brill, J.M. Byrd, S. Chitra, J.T. Collins, J.C. Dooling, J.N. Edwards, L. Erwin, G.I. Fystro, T. Grabinski, M.J. Henry, E.E. Heyeck, J.E. Hoyt, R.T. Keane, S.H. Lee, J. Lenner, I. Lobach, A.H. Lumpkin, A. Puttkammer, V. Sajaev, N. Sereno, Y. Sun, J. Wang, S.G. Wang, A. Zholents
ANL, Lemont, Illinois, USA
Funding:This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The Linac Extension Area has been developed into a beamline area for testing accelerator components and techniques. Beginning commissioning activities in February 2023, we have delivered the first electron beam to the Linac Extension Area at the Advanced Photon Source at 425 MeV. In the present work, we outline the stages of re-commissioning the electron beamline. We summarise measurements of the electron beam transport through the accelerator. We outline scenarios used to verify the adequacy of radiation shielding of the beamline, and measured shielding performance.
E. Yamakawa, S. Machida, A. Pertica, D.W. Posthuma de Boer
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
Y. Ishi
Kyoto University, Research Reactor Institute, Osaka, Japan
A.P. Letchford
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
T. Uesugi
Kyoto University, Institute for Integrated Radiation and Nuclear Science, Osaka, Japan
To confirm the use of Fixed Field Alternating gradient accelerator (FFA) as a high power pulsed neutron spallation source, a prototype called FETS-FFA is studied at Rutherford Laboratory (RAL). A single Wire Scanner Monitor (WSM) is planned to be used to measure a beam position and a beam profile in the ring. One of the concerns of this monitor is the thermal damage on the Carbon Nano Tube (CNT) wire due to high energy deposition of low energy proton beam in FETS-FFA (3 - 12 MeV). Furthermore, to measure a beam profile during beam acceleration in the ring, a diameter of CNT wire needs to be smaller than the orbit displacements in turns. To confirm whether a single WSM is suitable for FETS-FFA ring, two different beam tests were performed at RAL and at the Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS). Both measurements demonstrated that the single WSM is applicable for FETS-FFA ring if the diameter of CNT is smaller than the orbit separation in turns. In this paper, the detail of the design study of the single WSM as well as the performance tests are presented.
R.M. Thurman-Keup, M. El Baz, V.E. Scarpine
Fermilab, Batavia, Illinois, USA
Funding:This work was produced by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The Proton Improvement Plan - II (PIP-II) is a new linear accelerator (LINAC) complex being built at Fermilab. It is based on superconducting radiofrequency cavities and will accelerate H− ions to 800 MeV kinetic energy before injection into the existing Booster ring. Measurements of the profile of the beam along the LINAC must be done by non-intercepting methods due to the superconducting cavities. The method chosen is photoionization of a small number of H− by a focused infrared laser, aka laserwire. The number of ionized electrons is measured as a function of laser position within the H− beam. To aid in the design of the collection mechanism, a simulation was written in MATLAB with input from the commercial electromagnetic simulation, CST. This simulation calculates the number and positions of the liberated electrons and tracks them through the magnetic collection and H− beam fields to the collection point. Results from this simulation for various points along the LINAC will be shown.
H. Shaker, A. Bertwistle, E.J. Ericson, Y. Yousefi Sigari
CLS, Saskatoon, Saskatchewan, Canada
E. Soltan, Y. Yousefi Sigari
University of Saskatchewan, Saskatoon, Canada
There is a plan in the Canadian Light Source (CLS) to replace the current Linac with a new one from Research Instruments GmbH in mid-2024. The first straight section of LTB (Linac-To-Booster) was upgraded to have two BPMs with a 4.79m drift between them, and two phosphor screens were replaced by YAG screens. A new BPM and a YAG-based screen station upgraded the following 90-degree achromat beamline. These upgrades help us to measure the current and future Linac beam parameters, including the beam twiss parameters, energy, and energy spread. In this paper, we discussed how we could use these three BPMs for non-destructive energy measurement, which will be a part of the active energy correction system.
C. Bianchini Mattison, K.H. Kim, P. Krejcik, M. Weaver, S. Zelazny
SLAC, Menlo Park, California, USA
The new timing system for the LCLS-II SC linac and FEL meets the challenging requirements for delivering multiple interleaved timing patterns to a number of different destinations at rates up to 1 MHz. The timing patterns also carry information on bunch charge and beam energy to prevent inadvertent selection of beam dumps beyond their rated beam power. Beamline instruments are equipped with a timing receiver that performs bunch-by-bunch synchronous data acquisition based on the timing pattern for that location. Data is buffered in on-board memory for up to 106 machine pulses (1 second at 1 MHz). The large data volume can be locally processed and and analysed before transmission to clients on the network. Commissioning and experience with the new system will be presented.
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