S. Nagaitsev, A.L. Romanov, A.V. Shemyakin, G. Stancari
Fermilab, Batavia, Illinois, USA
Funding:The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Two experiments were carried out to study the statistical properties of undulator radiation in the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The first experiment studied the turn-to-turn fluctuations in the power of the radiation generated by an electron bunch. The magnitude of these fluctuations depends on the 6D phase-space distribution of the electron bunch. In IOTA, we demonstrated that this effect can be used to measure some electron bunch parameters, small transverse emittances in particular. In the second experiment, a single electron was stored in the ring, emitting a photon only once per several hundred turns. In this regime, any classical interference-related collective effects were eliminated, and the quantum fluctuations could be studied in detail to search for possible deviations from the expected Poissonian photon statistics. In addition, the photocount arrival times were used to track the longitudinal motion of a single electron and to compare it with simulations. This allowed us to determine several dynamical parameters of the storage ring such as the rf cavity phase jitter and the dependence of the synchrotron motion period on amplitude.
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Time Resolved Dynamics of Transverse Resonance Island Buckets at SPEAR3
62
K. Tian, W.J. Corbett, J. Kim, J.A. Safranek
SLAC, Menlo Park, California, USA
The Transverse Resonance Island Buckets have been studied at SPEAR3 as an option for timing experiment mode operation of this third generation synchrotron radiation facility. In this mode, with proper optics setting, the electron beam is populated to island orbits with the excitation from a kicker. In this paper, we will report the experimental observation of the beam dynamics with turn by turn beam position monitors and a fast gated camera. The results are also compared with tracking simulations.
Development of a Scintillation Fibre Transverse Profile Monitor for Low-Intensity Ion Beams at HIT
67
R.L. Hermann, M. Galonska, Th. Haberer, A. Peters
HIT, Heidelberg, Germany
T. Gehrke
German Cancer Research Center (DKFZ), Heidelberg, Germany
B. Leverington
Universität Heidelberg, Heidelberg, Germany
Funding:Funded by Deutsche Forschungsgemeinschaft (DFG), project number 426970603. The Heidelberg Ion-Beam Therapy Center (HIT) pro-vides proton, helium, and carbon-ion beams with differ-ent energies and intensities for cancer treatment and oxy-gen-ion beams for experimentation. Below the intensities used for therapy, low-intensity ion beams (below 1·105 ions/s) are available for various experiments via manual-ly degrading of the beam. Since there is no built-in beam profile instrumentation device for this intensity region, the development of a transverse ion beam profile monitor for these intensities is therefore of interest. The principle of operation is based on scintillating fibres, particularly those with enhanced radiation hardness. The fibres transform the deposited energy of a traversing ion into photons, which are then converted and amplified via silicon pho-tomultipliers (SiPMs) into electric pulses. These pulses are recorded and processed by a novel and dedicated readout electronics: the front-end readout system (FERS) A5200 by CAEN. A prototype set-up consisting of all the above-mentioned parts was tested in beam and has proven to record the transverse beam profile successfully from intensities of 1·107 ions/s down to 1·102 ions/s.
X-Ray Pinhole Camera Spatial Resolution Using High Aspect Ratio LIGA Pinhole Apertures
71
N. Vitoratou, L. Bobb
DLS, Oxfordshire, United Kingdom
A. Last
KIT, Eggenstein-Leopoldshafen, Germany
G. Rehm
HZB, Berlin, Germany
X-ray pinhole cameras are employed to provide the transverse profile of the electron beam from which the emittance, coupling and energy spread are calculated in the storage ring of Diamond Light Source. Tungsten blades separated by shims are commonly used to form the pinhole aperture. However, this approach introduces uncertainties regarding the aperture size. X-ray lithography, electroplating and moulding, known as LIGA, has been used to provide thin screens with well-defined and high aspect ratio pinhole apertures. Thus, the optimal aperture size given the beam spectrum can be used to improve the spatial resolution of the pinhole camera. Experimental results using a LIGA screen of different aperture sizes have been compared to SRW-Python simulations over the 15-35 keV photon energy range. Good agreement has been demonstrated between the experimental and the simulation data. Challenges and considerations for this method are also presented.
Commissioning of the Renewed Long Radial Probe in PSI Ring Cyclotron
76
M. Sapinski, R. Dölling, M. Rohrer
PSI, Villigen PSI, Switzerland
PSI’s Ring cyclotron is a high intensity proton cyclotron producing 2 mA beam. The beam is accelerated over about 180 turns from 72 MeV to 590 MeV. The Long Radial Probe, called RRL, scans the beam along the range of beam radii from 2048 mm to 4480 mm. A replacement for the RRL has been developed in the last years*. The recently installed new probe drives three carbon fibers with 30 ’m diameter through the turns and measures secondary electron currents, providing information on horizontal and vertical beam shape. Additional drives are available for a later extension of measurement capabilities. The main challenges are a coupling of the device elements to RF fields leaking from the accelerating cavities, plasma interfering with the measured signal and performance of the carbon fibers in harsh environment with high intensity beam. We report on commissioning of the probe with RF and beam and discuss measurement results. * doi:10.18429/JACoW-IBIC2020-WEPP33
First Results of PEPITES, A New Transparent Profiler Based on Secondary Electrons Emission for Charged Particle Beams
80
C. Thiebaux, L. Bernardi, F. Gastaldi, Y. Geerebaert, R. Guillaumat, F. Magniette, P. Manigot, M. Verderi
LLR, Palaiseau, France
É. Delagnes, F.T. Gebreyohannes, O. Gevin
CEA-IRFU, Gif-sur-Yvette, France
F. Haddad, N. Servagent
SUBATECH, Nantes, France
F. Haddad, C. Koumeir, F. Poirier
Cyclotron ARRONAX, Saint-Herblain, France
Funding:This study is supported by two programs of the Agence Nationale de la Recherche, ANR-17-CE31-0015 and ANR-11-EQPX-0004. The PEPITES project* consists of a brand new operational prototype of an ultra-thin, radiation-resistant profiler capable of continuous operation on mid-energy (O(100 MeV)) charged particle accelerators. Secondary electron emission (SEE) is used for the signal because it only requires a small amount of material (10 nm); very linear, it also offers good dynamics. The lateral beam profile is sampled using segmented electrodes, constructed by thin film methods. Gold strips, as thin as the electrical conductivity allows (~ 50 nm), are deposited on an insulating substrate as thin as possible. While crossing the gold, the beam ejects the electrons by SEE, the current thus formed in each strip allows the sampling. SEE was characterized at ARRONAX with 68 MeV proton beams and at medical energies at CPO**. Electrodes were subjected to doses of up to 109 Gy without showing significant degradation. A demonstrator with dedicated electronics (CEA) is installed at ARRONAX and will be used routinely with proton beams of 17-68 MeV for intensities of 100fA to 100nA. An overview of the design and first measurements will be presented, and system performances will be assessed. *LLR, ARRONAX cyclotron and CEA **Orsay Protontherapy Center (Institut Curie)
Development of New Beam Position Detectors for the NA61/SHINE Experiment
84
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.
Recent LHC SR Interferometer Simulations and Experimental Results
88
D. Butti, E. Bravin, G. Trad
CERN, Meyrin, Switzerland
S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
At the CERN Large Hadron Collider (LHC), among the different systems exploiting Synchrotron Radiation (SR) for beam diagnostics, interferometry is under study as a non-invasive technique for measuring absolute beam transverse sizes. Extensive numerical simulations, recently completed for characterising the spatial coherence of the LHC SR source, facilitated the optimisation of the LHC interferometer design and the existing prototype system tested in the past has been refurbished to include the new simulation findings. This contribution describes the simulation specificity and then focuses on first measurements performed at the beginning of the LHC run 3. Such experiments allowed to obtain a first validation of the expected system performance at the injection energy of 450 GeV. A complete benchmark of the simulations will be carried out in 2022 as soon as the LHC will reach its top energy of 6.8 TeV.
Test of a Prototype for Modular Profile and Position Monitors in the Shielding of the 590 MeV Beam Line at HIPA
92
R. Dölling, F. Marcellini, M. Sapinski
PSI, Villigen PSI, Switzerland
A new generation of monitor plugs is under develop-ment as spares for the ageing wire profile monitors and beam position monitors inserted into massive shielding in the target regions of the 590 MeV proton beam line at HIPA. A prototype was installed recently in the beam line to the ultra-cold neutron source UCN, to test the perfor-mance of wire monitor, BPM and modular mechanical design in a low-radiation environment. We report on first measurements with beam.
Transverse Emittance Measurement in Injector of RAON
E.H. Lim
Korea University Sejong Campus, Sejong, Republic of Korea
Y.S. Chung, G.D. Kim, J.W. Kwon
IBS, Daejeon, Republic of Korea
E.-S. Kim
KUS, Sejong, Republic of Korea
It is important to measure the transverse emittance, a beam characteristic for beam dynamics calculation. There are several methods for measuring transverse emittance. The emittance is calculated from the phase space distribution of the beam measured by Allison scanner. Quadrupole scan with wire scanner or multi wire scanner for RAON injector were also performed to compare with these data. RAON injector consists of ECR-IS, LEBT, RFQ, MEBT. Various diagnostic devices such as 8 Wire Scanners and 1 Allison Scanner were installed in beam transport line. Each diagnostic device was driven by PLC and the current was measured with microTCA-based DAQ system. EPICS was used to control the diagnostic system, and each device was driven and measured according to the sequencer module. In this paper, the measurement result of each diagnostic device and result of the emittance measurement on Ar-40 beam are presented.
New Gas Target Design for the HL-LHC Beam Gas Vertex Profile Monitor
252
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.
FOCUS: Fast Monte-CarlO Approach to Coherence of Undulator Sources
257
M. Siano
Università degli Studi di Milano, Milano, Italy
D. Butti, T. Lefèvre, S. Mazzoni, G. Trad
CERN, Meyrin, Switzerland
G. Geloni
EuXFEL, Schenefeld, Germany
U. Iriso, A.A. Nosych, L. Torino
ALBA-CELLS, Cerdanyola del Vallès, Spain
B. Paroli, M.A.C. Potenza
Universita’ degli Studi di Milano & INFN, Milano, Italy
"Fast Monte-CarlO approach to Coherence of Undulator Sources" (FOCUS) is a new GPU-based code to compute the transverse coherence of X-ray radiation from undulator sources. The code relies on scaled dimensionless quantities and analytic expressions of the electric field emitted by electrons in an undulator, obtained in the frequency domain under paraxial approximation (justified by the assumption of ultra-relativistic electrons) and free space propagation, with the addition of the resonance approximation. We describe the core structure of the code, which exploits GPUs for massively parallel computations. We validate our approach by direct comparison with SRW (Synchrotron Radiation Workshop) simulations. The benchmarks prove that FOCUS yields similar results with respect to SRW, while at the same time reducing the computation times by five orders of magnitude. Finally, we show examples of applications to beam size diagnostics. The aim of the code is to fast evaluating the transverse coherence properties of undulator X-ray radiation as a function of the electron beam parameters, and to support and help preparing more rigorous numerical simulations with traditional codes like SRW.
HL-LHC Beam Gas Fluorescence Studies for Transverse Profile Measurement
261
O. Sedláček, M. Ady, C. Castro Sequeiro, A.R. Churchman, S. Mazzoni, G. Schneider, K. Sidorowski, R. Veness
CERN, Meyrin, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
M. Sameed
European Organization for Nuclear Research (CERN), Geneva, Switzerland
O. Sedláček, O. Stringer, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
O. Sedláček, O. Stringer, C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
In a gas jet monitor, a supersonic gas curtain is injected into the beam pipe and interacts with the charged particle beam. The monitor exploits fluorescence induced by beam-gas interactions, thus providing a minimally invasive transverse profile measurement. Such a monitor is being developed as part of the High Luminosity LHC upgrade at CERN. As a preliminary study, the fluorescence cross section of relevant gases must be measured for protons at 450 GeV and 6.8 TeV (i.e. the LHC injection and flat top energies). In these measurements, neon, or alternatively nitrogen gas, will be injected into the LHC vacuum pipe by a regulated gas valve to create an extended pressure bump. This work presents the optical detection system that was installed in 2022 in the LHC to measure luminescence cross-section and horizontal beam profile. Preliminary measurements of background light and first signals are presented in this paper.
High-Resolution Interferometric Beam-Size Monitor For Low-Intensity Beams
265
B. Alberdi-Esuain, J.-G. Hwang, T. Kamps
HZB, Berlin, Germany
T. Kamps
HU Berlin, Berlin, Germany
Plasma-based accelerator technology is reaching a mature state, where applications of the beam for medical sciences, imaging, or as an injector for a future large-scale accelerator-driven light source become feasible. Particularly, the requirements for beam injection into a storage-ring-based light source are very strict with regards to beam quality and reliability. A non-invasive diagnostics greatly helps to reduce the commissioning time of the machine. We present a device suitable for online, non-destructive monitoring of the transverse spot size of the injected beam. In order to measure lateral beam sizes with a few-micrometer resolution, the technique uses an interferometric regime of coherent synchrotron radiation that is enabled by a sub-femtosecond short bunch-length. Simulations of the photon flux and the retrieval of the beam spot-size are performed for different bandwidth filters in order to define the bandwidth acceptance. Results show the potential of the proposed system that achieves precise retrieval of the complex degree of coherence at an extremely low photon intensity similar to those expected towards the plasma-acceleration injectors.
Visible Range Polarized Imaging for High Resolution Transverse Beam Size Measurement at SOLEIL
269
M. Labat, A. Bence, A. Berlioux, B. Capitanio, G. Cauchon, J. Da Silva, N. Hubert, D. Pédeau, M. Thomasset
SOLEIL, Gif-sur-Yvette, France
SOLEIL storage ring is presently equipped with three diagnostics beamlines: two in the X-ray range (pinhole cameras) and one in the visible range. The visible range beamline relies on a slotted copper mirror extracting the synchrotron radiation from one of the ring dipoles. The extracted radiation is then transported down to a dedicated hutch in the experimental hall. Up to now, this radiation was split into three branches for rough monitoring of the beam transverse stability, bunch length measurements and filling pattern measurements. In the framework of SOLEIL’s upgrade, we now aim at developing a new branch for high resolution beam size measurement using polarized imaging. This work presents the various modifications recently achieved on the beamline to reach this target, including a replacement of the extraction mirror, and preliminary results towards transverse beam size measurement.
Correction for Systematic Errors in Transverse Phase Space Measurements at PITZ
273
C.J. Richard, Z. Aboulbanine, G.D. Adhikari, N. Aftab, P. Boonpornprasert, G.Z. Georgiev, M. Groß, A. Hoffmann, M. Krasilnikov, X.-K. Li, A. Lueangaramwong, R. Niemczyk, H.J. Qian, F. Stephan, G. Vashchenko, T. Weilbach
DESY Zeuthen, Zeuthen, Germany
Funding:This work was supported by the European XFEL research and development program The Photo Injector Test Facility at DESY in Zeuthen (PITZ) characterizes and optimizes electron sources for use at FLASH and European XFEL. AT PITZ, the transverse phase space is measured using a single slit scan and scintillator screen method. With the trend in photoinjectors towards lower current and emittance, these measurements become increasingly influenced by systematic errors including camera resolution and scintillator response due to smaller spot sizes. This study investigates the effects and corrections of the systematic errors for phase space measurements at PITZ.
A.I. Novokshonov, G. Kube, S. Strokov
DESY, Hamburg, Germany
Z. Aboulbanine, G.D. Adhikari, N. Aftab, P. Boonpornprasert, G.Z. Georgiev, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, A. Lueangaramwong, D. Melkumyan, F. Mueller, A. Oppelt, H.J. Qian, F. Stephan, G. Vashchenko, T. Weilbach
DESY Zeuthen, Zeuthen, Germany
A standard technique to measure beam profiles in linear accelerators are screen monitors using scintillating screens. This technique is used e.g. at the European XFEL in order to overcome coherence effects in case of OTR usage [*]. During the XFEL commissioning it was found out that screens based on LYSO:Ce as scintillating material revealed a nonproportional light output [**]. Reason for it is the high particle beam density. As consequence it was decided to exchange LYSO:Ce by GAGG:Ce scintillators because the excitation carriers can rapidly transfer their energy to excited states of gadolinium, and a rapid migration of this energy among the Gd sub-lattice is expected. Driven by the observations at XFEL a series of measurements was started to investigate the properties of various scintillator materials (LYSO:Ce, YAP:Ce, YAG:Ce, LuAG:Ce and GAGG:Ce). The last measurement campaign was carried out at PITZ which allows to operate at higher beam charge and lower electron energy compared to the XFEL. The present work summarizes the results of these measurements. * S.Wesch and B.Schmidt, in Proc. DIPAC’11, Hamburg, WEOA01, pp. 539-543. ** G.Kube, A.Novokshonov, S.Liu, M.Scholz, in Proc. FEL’19, Hamburg, WEB01, pp. 301-306.
Funding:This study is supported by The Scientific and Technological Research Council of Turkey (TUBITAK), Project No: 119M774 In Kandilli Detector, Accelerator, and Instrumentation Laboratory, a proton accelerator system is produced using local resources consists of 2 types of ion sources, a low energy beam transfer line (LEBT)and a 1-meter-long RFQ that will operate at 800 MHz. A bespoke Python program calculated the space charge effect created by internal interactions of the beam along the line before entering the RFQ. The results were validated with CERN’s TRAVEL program. The growth of the beam with a 1.4 mA current value in the transverse axis due to the effect of space charge has been calculated with a maximum margin of error of 4% for different current and frequency values. Studies using different emittance calculation methods on emittance growth due to space charge dominance continues to be developed. In addition, studies on comparing new methods’ findings with outputs of A Space Charge Tracking Algorithm (ASTRA) and RF-Track Programs are ongoing and aim to finalize by the end of 2023.
Investigating the Transverse Dynamics of Electron Bunches in Laser-Plasma Accelerators
348
A. Koehler
DLR, Berlin, Germany
The demonstrations of GeV electron beams and FEL radiation driven by a centimeter-scale device illustrate the tremendous progress of laser-plasma accelerators. In such applications, beam divergence and size, along with beam energy and charge, are critical parameters of electron beams. An insight on the transverse parameters and their dynamics such as beam decoherence can be obtained by diagnostics complemented by betatron radiation detectors. This talk will also provide a brief overview of recent techniques for accessing the transverse phase space.
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Angular-Resolved Thomson Parabola Spectrometer for Laser-Driven Ion Accelerators
352
C. Salgado-López, A. Curcio, G. Gatti, J.L. Henares, J. Imanol Apiñaniz, J.A.P. Pérez-Hernández, L. Volpe, D. de Luis
CLPU, Villamayor, Spain
Funding:LASERLAB-EUROPE V (Grant Agreement No. 871124, EU Horizon 2020). IMPULSE (Grant Agreement No. 871161, EU Horizon 2020). Equipment Grant No. EQC2018-005230-P, Junta de CyL (Grant No. CLP263P20). Laser-plasma driven accelerators have become reliable sources of low-emittance, broadband and multi-species ion sources, with cut-off energies above the MeV-level*. We report on the development, construction, and experimental test of an angle resolved Thomson parabola spectrometer for laser-accelerated multi-MeV ion beams able to distinguish between ionic species with different q/m ratio. The angular resolving power, which is achieved due to an array of entrance pinholes, can be simply adjusted by modifying the geometry of the experiment and/or the pinhole array itself. The analysis procedure allows for different ion traces to cross on the detector plane, which greatly enhances the flexibility and capabilities of the detector. A full characterization of the TP magnetic field has been implemented into a relativistic code developed for the trajectory calculation of each beamlet. High repetition rate compatibility is guaranteed by the use of a MCP as active particle detector. We describe the first test of the spectrometer at the 1PW VEGA 3 laser facility at CLPU, Salamanca (Spain), where up to 15MeV protons and carbon ions from a 3-micron laser-irradiated metallic foil are detected**. *A. Macchi et. al., Rev. Mod. Phys. 85, 751 (2013) **C. Salgado et. al., Sensors 22, 3239 (2022).
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LINAC4 Laser Profile and Emittance Meter Commissioning
357
A. Goldblatt, O.Ø. Andreassen, T. Hofmann, F. Roncarolo, J. Tagg
CERN, Meyrin, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
The LINAC4 is now equipped with two laser profile and emittance meters, basically non destructive and not limited by beam power density. A pulsed laser is transported through fibres and focused into the 160 MeV H− beam. Its interaction with the H− ions detaches electrons that are collected by an electron-multiplier, while the resultingH0 particles, after being separated from the main H− beam by a dipole magnet, are recorded by a diamond strip detector, few meters away from the interaction point. The emittance and profile are reconstructed from the laser step by step scan of the beam. After several years of feasibility tests and prototyping, this paper will present all details about the final HW and SW implementation and the 2022 experimental results.
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A High Performance Scintillator Ion Beam Monitoring System
362
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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First Observation of Quasi-Monochromatic Optical Cherenkov Radiation in a Dispersive Medium (Quartz)
A.I. Novokshonov
DESY, Hamburg, Germany
Spectral properties of optical Cherenkov radiation (ChR) were studied both theoretically and experimentally. This type of radiation has a continuous spectral distribution which allows to use it in different fields of physics. By exploiting the frequency dependence of the target permittivity it is possible to observe quasi-monochromatic radiation. A theoretical model based on a surface current approach is presented. In order to test the predictions, an experiment was carried out using 855 MeV electrons and a 0.2 mm thick quartz target as radiator. Quasi-monochromatic ChR was observed with a spectrometer, and tilting the radiator crystal offered the possibility to tune the radiation wavelength. The monochromatization effect is attributed to the frequency dependence of the quartz permittivity, and taking into account the refraction law it is possible to deduce a dispersion relation which connects ChR wavelength and target tilt angle for fixed observation angle. Dispersion relation and model description are confirmed in the experiment. Exploiting the ChR monochromatization mechanism might offer versatile tools which can find applications in beam diagnostics.
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An X-Ray Beam Property Analyzer Based on Dispersive Crystal Diffraction
366
N. Samadi, G. Lovric, C. Ozkan Loch
PSI, Villigen PSI, Switzerland
X. Shi
ANL, Lemont, Illinois, USA
The advance in low-emittance x-ray sources urges the development of novel diagnostic techniques. Existing systems either have limited resolution or rely heavily on the quality of the optical system. An x-ray beam property analyzer based on a multi-crystal diffraction geometry was recently introduced. By measuring the transmitted beam profile of a dispersive Laue crystal downstream of a double-crystal monochromator, the system can provide a high-sensitivity characterization of spatial source properties, namely, size, divergence, position, and angle in the diffraction plane of the system at a single location in a beamline. In this work, we present the experimental validation at a super-bending magnet beamline at the Swiss Light Source and refine the method to allow for time-resolved characterization of the beam. Simulations are then carried out to show that the system is feasible to characterize source properties at undulator beamlines for fourth-generation light sources.
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U. Iriso, A.A. Nosych, M. Zeus
ALBA-CELLS, Cerdanyola del Vallès, Spain
A.C. Cazorla
ICMAB, Bellatera, Spain
I. Mases Solé
CERN, Meyrin, Switzerland
ALBA is currently equipped with two x-ray pinhole cameras for continuous beam size monitoring using the synchrotron radiation from two different bending magnets. The first pinhole was installed in day-1 and it is working properly since 2012 as the work-horse for the ALBA emittance measurements, while the second one has been commissioned in beginning 2021 for redundancy purposes. This paper summarizes the exercises to characterize the Point Spread Function (PSF) of both pinhole cameras using analytical calculations, SRW simulations, and experimental measurements using the beam lifetime.
Electron Emission (SEM) Grids for the FAIR Proton Linac
426
J. Herranz
Proactive Research and Development, Sabadell, Spain
I. Bustinduy, Á. Rodríguez Páramo
ESS Bilbao, Zamudio, Spain
P. Forck, T. Sieber
GSI, Darmstadt, Germany
A. Navarro Fernandez
CERN, Meyrin, Switzerland
New SEM-Grid has been developed for FAIR Proton Linac, the instrument consists of 2 harps fixed together in an orthogonal way. This SEM-Grid will provide higher resolution and accuracy measurements as each harp consists of 64 tungsten wires 100 micro-meter in diameter and 0.5 mm pitch. Each wire is fixed to a ceramic PCB with an innovative dynamic stretching system, this system assures wire straightness under typical thermal expansion due to beam heat deposition. Electric field distribution has been performed, 3 main parameters have been optimized, wires distribution, quantity of polarization electrodes and distance between electrodes and wires. The design and production of the SEM-Grids have been performed by the company Proactive R&D that has count on the expertise of ESS-Bilbao to define safe operation limits and signal estimation by means of a code developed specifically for this type of calculations. Preliminary validations of the first prototypes shown good values of electric field behaviour signal. After additional beam test validations to be performed on June 2022, final series of the SEM-Grid will be produced and installed on FAIR proton LINAC.
Funding:This study is supported by Istanbul University Scientific Research Commission Project ID 33250 and TUBITAK Project no : 119M774. A testbeam using a Radio Frequency Quadrupole (RFQ) operating at 800 MHz, to accelerate a 1.5mA proton beam to 2MeV energy has been designed, manufactured and is currently being commissioned at KAHVELab, Istanbul. The beam from the microwave discharge ion source (IS) must be matched to the RFQ via an optimized Low Energy Beam Transport (LEBT) line which also contains an integrated measurement station, called MBOX. The MBOX is designed to measure the beam current and profile, as well as the beam emittance, to ensure an accurate match between IS and RFQ. It includes a number of diagnostic tools: a Faraday Cup, a scintillator screen, and a pepper pot plate (PPP). During the commissioning, beam images were taken at different points on the beamline. Other measurements were also taken with different screen materials and different plates in the MBOX box. The analysis software was also developed and tested for the PP photo analysis. This contribution will present the proton beamline components, MBOX diagnostic tools and will focus on the measurements, especially on the PPP emittance analysis.
A Raster Scanning Laser-Sculptor for Hydrogen Ion Beam Diagnostics
S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
S.E. Alden
JAI, Egham, Surrey, United Kingdom
Funding:We acknowledge funding by the STFC Grant ST/P003028/1 and the John Adams Institute’ at Royal Holloway, University of London. A novel scheme for laser sculpting a neutralised hydrogen beam from a parent beam of hydrogen ions circulating in a racetrack accelerator was proposed at IPAC19*. Such a method was shown in simulation to produce a particle beam with reduced transverse emittance, based on a simple static laser sculptor geometry. This paper investigates effects of translating or raster scanning a focussed laser-sculptor transversely within the hydrogen ion beam, which creates new possibilities for non-invasive beam diagnostics of the transverse phase space. The optimisation of the optical geometry, intensity and the temporal characteristics of the laser beam are investigated for laser-induced extraction of neutralised beamlets, from which the beam profile and emittance can be reconstructed. Photo-detachment simulations are performed in a photon-particle interaction framework that has been implemented in BDSIM, a Geant4 based particle tracking code**. We evaluate the design of a potential experimental demonstration at a hydrogen ion linac, the Front End Test Stand, at Rutherford Appleton Laboratory, UK. * Laser sculpted cool proton beams, S. Gibson, S. Alden, L. Nevay. ** A simulation framework for photon-particle interactions for laserwires and further applications S. Alden, L. Nevay, S. Gibson
M. Marongiu, G. Kube, M. Lantschner, A.I. Novokshonov, K. Wittenburg
DESY, Hamburg, Germany
The PETRA IV project will be a Diffraction Limited Light Source designed to be the successor of PETRA III, the 6 GeV 3rd generation hard X-Ray synchrotron light source at DESY in Hamburg. It will operate at a beam energy of 6 GeV with a design emittance of 20/4 pm rad. For a precise emittance online control, two dedicated diagnostics beamlines will be built up to image the beam profile with synchrotron radiation in the X-Ray region. With two beamlines, it will be possible to extract both the transverse beam emittances and the beam energy spread. Both beamlines will be equipped with two interchangeable X-Ray optical systems: a pinhole camera system to achieve high dynamic range and a Fresnel Diffractometry system for high resolution measurements in the range 1-18 um. This paper describes the planned setup and deals with the possible limitations.
Merits of Pulse Mode Operation of Residual Gas Ionization Profile Monitor for J-PARC Main Ring
434
K. Satou, Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
S. Igarashi
KEK, Ibaraki, Japan
Funding:Accelerator and Beamline Research and Technology Development for High-Power Neutrino Beams in the U.S.-Japan Science and Technology Cooperation Program in High Energy Physics. The measurement accuracy of the ionization profile monitor (IPM) of J-PARC main ring (MR) depends on the flatness and stability of the gain of the position-sensitive microchannel plate (MCP). The flatness of the MCP deteriorates after long-term operation; the gain of the central area selectively decreases as the integrated output charge increases. The beam-based calibration, where the local bump shifts the beam and the reconstructing beam profiles determine the gain distribution, is used to calibrate the flatness. The immediate gain drop occurs when the output current from the MCP becomes comparable to the bias current is problematic. This gain drop depends on the bias voltage and the output current; thus, it is difficult to calibrate. A pulsed HV module of 30 kV, which collects ionized electrons and ions, was installed to solve these problems. The pulse mode operation can modulate the averaged output current from the MCP to improve gain stability. Profiles of the intense beam up to 3.3·1013 ppb were measured and compared with those measured by destructive profile monitors in beam transport lines 3’50 BT, and the Abort line. Estimated emittances were consistent at ±20%.
Experimental Investigation of Gold Coated Tungsten Wires Emissivity for Applications in Particle Accelerators
438
A. Navarro Fernandez, M. Martin Nieto, F. Roncarolo
CERN, Meyrin, Switzerland
The operation of wire grids and wire scanners as beam profile monitors can be heavily affected, both in terms of measurement accuracy and wire integrity, by the thermal response of the wires to the energy deposited by the charged particles. Accurate measurements of material emissivity are crucial, as Radiative Cooling represent the most relevant cooling process. In this work, we present a method for emissivity measurements of gold-coated tungsten wires based on calorimetric techniques. The dedicated electrical setup allowed allowed transient and steady state measurements for temperatures up to 2000 K. A theoretical description of the measurement technique will be followed up by the electrical set up description and a detailed discussion about the measured results and uncertainties.
Assessing the Performance of the New Beam Wire Scanners for the CERN LHC Injectors
443
S. Di Carlo, W. Andreazza, D. Belohrad, J. Emery, J.C. Esteban Felipe, A. Goldblatt, D. Gudkov, A. Guerrero, S. Jackson, G.O. Lacarrere, M. Martin Nieto, A.T. Rinaldi, F. Roncarolo, C. Schillinger, R. Veness
CERN, Meyrin, Switzerland
The ability of reliably measuring the transverse beam profile in its injectors is essential for the operation of the LHC. This report aims to assess the reliability, stability, and reproducibility of the new generation of beam wire scanners developed at CERN in the framework of the LHC Injectors Upgrade (LIU). The study includes data from the over 60000 scans performed in 2021 and 2022, with a special focus on reproducibility, investigation of optimal operational settings to ensure a large dynamic range, and evaluation of absolute accuracy through comparison with other instruments present in the injectors.
Simulated Behavior of CNT Wires Irradiated in the HiRadMat Experimental Line at CERN
527
A. Mariet, B. Moser, R. Veness
CERN, Meyrin, Switzerland
M. Devel, J.E. Groetz
UFC, Besançon, France
A. Mikhalchan, J.J. Vilatela
IMDEA, Madrid, Spain
With the planned increase of luminosity at CERN for HL-LHC and FCC, instruments for beam quality control must meet new challenges. The current wires, made up of plain carbon fibers and gold-plated tungsten would be damaged due to their interactions with the higher luminosity beams. We are currently testing a new and innovative material, with improved performance: carbon nanotube fibers (CNTF). The HiRadMat (High Radiation for Material) experimental line at the output of the SPS is a user facility which can irradiate fix targets up to 440 GeV/c. CNTF with various diameters were irradiated in HiRadMat with different intensities, later imaged with a SEM microscope and tested for their mechanical properties. In addition, simulations have been carried out with the FLUKA particle physics Monte-Carlo code, in order to better understand the mechanisms and assess the energy deposition from protons at 440 GeV/c in those CNTF wires, depending mainly on their diameters and densities. This could lead to a good estimation of the CNTF temperature during irradiation. In this contribution, we first present the HiRadMat experimental setup and then we discuss the results of our FLUKA simulations.
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