M.U. Urbaniak, Y. Balkova, S.K. Kowalski, S. Puławski, K.W. Wójcik
University of Silesia in Katowice, Katowice, Poland
NA61/SHINE is a fixed-target experiment located at CERN Super Proton Synchrotron. The development of new beam position detectors is part of the ongoing upgrade of the detector system. Two types of detectors have been manufactured and tested. The first one is a scintillating fibers detector with photomultiplier as a readout. The scintillating fibers detector consists of two ribbons, which are arranged perpendicularly to each other. Each ribbon is made of two layers of 250 µm diameter fibers. The grouping method was used, which allows using of a single multichannel photomultiplier for one detector. The second type of detector is based on the single-sided silicon strip detector (SSD). In this project, Si strips produced by Hamamatsu (S13804) were used, where the pitch has a width equal to 190 um. The developed detectors must meet several requirements: should work efficiently with proton and lead beams with beam intensity on the level of 100 kHz, the detector’s material on the beamline should be minimized, the detectors should be able to determine the position of X and Y hit of each beam particle with maximum possible accuracy. During my speech I will present the results of our work.
A. Brauch, M. Arnold, J. Enders, L.E. Jürgensen, N. Pietralla, S. Weih
TU Darmstadt, Darmstadt, Germany
Funding:*Work supported by DFG (GRK 2128) and the State of Hesse within the Research Cluster ELEMENTS (Project ID 500/10.006). A high-quality beam is necessary for electron scattering experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC. An optimization of the bunch length to typical values of < 2 ps is performed to reach a high energy resolution of 1e-4. Currently, this is accomplished by inducing a linear momentum spread on the bunch in one of the accelerating cavities. The bunch length can then be measured with a target downstream. This method is time consuming and provides only an upper limit of the bunch length. Two new setups for bunch length measurements will improve the optimization process significantly. On the one hand, a new diagnostic beam line is set up in the low energy beam area. It includes a deflecting copper cavity used for measuring the bunch length by shearing the bunch and projecting its length on a target. On the other hand, a streak camera placed at different positions downstream the injector and the main linac will be used to measure the bunch length. Optical transition radiation from an aluminium coated kapton target is used to perform this measurement. The present layout of both systems and their current status will be presented in this contribution.
L.T. Stant, M.G. Abbott, L. Bobb, G. Cook, L. Hudson, A.F.D. Morgan, E.P.J. Perez Juarez, A.J. Rose, A. Tipper
DLS, Oxfordshire, United Kingdom
The UK national synchrotron facility, Diamond Light Source, is preparing for a major upgrade to the accelerator complex. Improved beam stability requirements necessitate the fast orbit feedback system be driven from beam position monitors with lower noise and drift performance than the existing solution. Short-term beam motion must be less than 2 nm/sqrt(Hz) over a period of one second with a data rate of 100 kHz, and long-term peak-to-peak beam motion must be less than 1 µm. A new beam position monitor is under development which utilises the pilot-tone correction method to reduce front-end and cabling perturbations to the button signal; and a MicroTCA platform for digital signal processing to provide the required data streams. This paper discusses the challenges faced during the design of the new system and presents experimental results from testing on the existing machine.
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S. Takano, T. Fujita, K. Fukami, H. Maesaka, M. Masaki, K. Soutome, M. Takao, T. Watanabe
JASRI, Hyogo, Japan
K. Fukami, T. Hiraiwa, H. Maesaka, K. Soutome, S. Takano, H. Tanaka, T. Watanabe
RIKEN SPring-8 Center, Hyogo, Japan
K. Ueshima
QST, Sendai, Miyagi, Japan
The alignment of sextupole magnets is one of the critical issues for the upcoming 4th generation light sources and future colliders. The alignment error of magnets and the beam offsets in sextupoles should be within a few 10 µm rms to ensure enough dynamic aperture for stable operation and minimize deterioration of beam quality. Considering that the quadrupole field in a sextupole is proportional to the displacement (normal Q for horizontal and skew Q for vertical), we propose a beam-based calibration (BBC) method to measure the sextupole centers by observing the betatron tune shift. The magnetic center is the point where the tune does not change regardless of the sextupole field strength. The key is increasing the XY coupling to obtain a tune shift large enough for the vertical calibration. We studied experimentally the feasibility of the sextupole BBC at SPring-8 and successfully demonstrated the principle for both horizontal and vertical calibration. The tune shift was monitored by bunch-by-bunch feedback electronics with approximately 1e-5 resolution. The measurement resolution of the sextupole center was approximately 10 µm std., which was sufficient for our requirement.
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H. Guerin, R. De Maria, R. Kersevan, B. Kolbinger, T. Lefèvre, M.T. Ramos Garcia, B. Salvant, G. Schneider, J.W. Storey
CERN, Meyrin, Switzerland
S.M. Gibson, H. Guerin
Royal Holloway, University of London, Surrey, United Kingdom
The Beam Gas Vertex (BGV) instrument is a novel non-invasive transverse beam profile monitor under development for the High Luminosity Upgrade of the Large Hadron Collider (HL-LHC). Its principle is based on the reconstruction of the tracks and vertices issued from beam-gas inelastic hadronic interactions. The instrument is currently in the design phase, and will consist of a gas target, a forward tracking detector installed outside the beam vacuum chamber and computing resources dedicated to event reconstruction. The transverse beam profile image will then be inferred from the spatial distribution of the reconstructed vertices. With this method, the BGV should be able to provide bunch-by-bunch measurement of the beam size, together with a beam profile image throughout the whole LHC energy cycle, and independently of the beam intensity. This contribution describes the design of the gas target system and of the gas tank of the future instrument.
R. Singh, P. Forck, T. Reichert, A. Reiter
GSI, Darmstadt, Germany
S. Klaproth
THM, Friedberg, Germany
G.O. Rodrigues
IUAC, New Delhi, India
Funding:This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE) The longitudinal charge profiles of the high intensity heavy ion beam accelerated at the GSI UNILAC upto 11.4 MeV/u can differ significantly in consecutive macro-pulses. Variations in bunch shape and mean energy were also observed within a single macro-pulse. In order to have an accurate and fast determination of bunch shape and its evolution within a macro-pulse, a study of fast Faraday Cup designs is underway at GSI. In this contribution, we present CST particle in cell (PIC) simulations of radially coupled co-axial Fast Faraday Cup (RCFFC) and conventional axially coupled FFC (ACFFC) design. The simulation results are compared to the measurements performed under comparable beam conditions primarily with RCFFCs. A rather large impact of secondary electron emission is observed in simulations and experiments. The biasing of the FFC central electrode as a mitigation mechanism on the measured profiles is discussed.
D.S. Levin, C. Ferretti, A. Kaipainen, N.A. Ristow
University of Michigan, Ann Arbor, Michigan, USA
P.S. Friedman
Integrated Sensors, LLC, Ottawa Hills, Ohio, USA
T.N. Ginter
NSCL, East Lansing, Michigan, USA
Funding:This work is funded by SBIR Phase-II Award No. DE-SC0019597, DOE Office of Science to Integrated Sensors, LLC. A high performance Scintillator Ion Beam Monitor (SBM)provides diagnostics across a range of isotopes, energies, and intensities. It uses a machine-vision camera and a magazine of thin scintillators, movable into the beam without breaking vacuum. Two proprietary scintillators are used: a semicrystalline polymer material (PM) tested over a thickness range of ~1 to 190 µm. The PM yields stronger signals than other commercial plastic scintillators tested and is radiation damage resistant; a 100-400 µm opaque wafer consisting of inorganic crystals in a polymer hybrid matrix (HM). Both PM and HM are non-hygroscopic and produce minimal secondary reflections. HM produces significantly larger signals than CsI with excellent radiation damage resistance. The SBM was staged at the FRIB (East Lansing) ion beam, demonstrating real-time beam profile and rate analysis spanning more than five orders-of-magnitude including visualization of single ion signals with ~10-20 µm spatial resolution. It is superior to and may replace the reference detectors: Faraday cup, silicon strips and a CCD camera beam imager. A proton test beam extended the dynamic range by four orders-of-magnitude.
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C. Davut
The University of Manchester, Manchester, United Kingdom
Ö. Apsimon
The University of Liverpool, Liverpool, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
T. Lefèvre, S. Mazzoni
CERN, Meyrin, Switzerland
G.X. Xia
UMAN, Manchester, United Kingdom
In this paper, a study using the Polarization Current Approach (PCA) model is performed to optimize the design of a short bunch length monitor using two dielectric radiators that produce coherent Cherenkov Diffraction Radiation (ChDR). The electromagnetic power emitted from each radiator is measuring a different part of the bunch spectrum using Schottky diodes. For various bunch lengths, the coherent ChDR spectrums are calculated to find the most suitable frequency bands for the detection system. ChDR intensities measured by each detector are estimated for different impact parameters to explore the dependence of bunch length monitor on beam position and angular jitter. It is found that, in the present configuration, the effects of beam position and angular jitter are negligibly small for bunch length measurement. * Shevelev, M. V., & Konkov, A. S. (2014). Journal of Experimental and Theoretical Physics, 118(4), 501-511. ** Curcio, A. et al. (2020). Physical Review Accelerators and Beams, 23(2), 022802.
L. Parsons França, M. Duraffourg, F. Roncarolo, F.M. Velotti
CERN, Meyrin, Switzerland
E. Kukstas, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
Funding:This work was supported by CERN and the STFC Liverpool Centre for Doctoral Training on Data Intensive Science (LIV. DAT) under grant agreement ST/P006752/1. The CERN fixed target experimental areas have recently acquired new importance thanks to newly proposed experiments, such as those linked to Physics Beyond Colliders (PBC) activities. Secondary Emission Monitors (SEMs) are the instruments currently used for measuring beam current, position and size in these areas. Guaranteeing their reliability, resistance to radiation and measurement precision is challenging. This paper presents the studies being conducted to understand ageing effects on SEM devices, to calibrate and optimise the SEM design for future use in these beamlines. These include feasibility studies for the application of machine learning techniques, with the objective of expanding the range of tools available for data analysis.
F. Roncarolo, P.A. Arrutia Sota, D. Belohrad, E. Calvo Giraldo, E. Effinger, M.A. Fraser, V. Kain, M. Martin Nieto, S. Mazzoni, I. Ortega Ruiz, J. Tan, F.M. Velotti, C. Zamantzas
CERN, Meyrin, Switzerland
M. Bergamaschi
MPI-P, München, Germany
At the CERN Super Proton Synchrotron (SPS) the proton beam is supplied to the fixed target experiments in the North Area facility (NA) via a slow extraction process, taking place at 400 GeV. The monitoring of the spill quality during the extraction, lasting 4.8 seconds with the present SPS setup, is of high interest for minimising beam losses and providing the users with uniform proton-on-target rates. The monitor development challenges include the need for detecting, sampling, processing and publishing the data at rates ranging from few hundred Hz to support the present operation to several hundreds of MHz to serve future experiments proposed within the Physics Beyond Collider (PBC) programme. This paper will give an overview of the ongoing studies for optimizing the existing monitors performances and of the R&D dedicated to future developments. Different techniques are being explored, from Secondary Emission Monitors to Optical Transition Radiation (OTR), Gas Scintillation and Cherenkov detectors. Expected ultimate limitations from the various methods will be presented, together with 2022 experimental results, for example with a recently refurbished OTR detector.
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R. Kitamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
At J-PARC Linac, bunch shape monitors (BSMs) have been used to measure a longitudinal profile of high power H− beam. Operational principle of the monitor is similar to that of the streak-camera. The BSM inserts a biased-solid target into H− beam to extract and accelerate secondary electrons. These electrons are then modulated with synchronized RF. After passing through dipole B field, a longitudinal profile is converted to a transverse one. For the BSM, a choice of target material is essential to reduce beam loss and to have sufficient tolerance for breakage by the interaction with high power beams. The BSM with graphite target realized the measurement of high-power 3 MeV beam for the first time.
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