F. Fienga, G. Breglio, A. Irace, V.R. Marrazzo, L. Sito
University of Napoli Federico II, Napoli, Italy
N. Beni, G. Breglio, S. Buontempo, F. Carra, F. Fienga, F. Giordano, V.R. Marrazzo, B. Salvant, L. Sito, Z. Szillasi
CERN, Meyrin, Switzerland
N. Beni, Z. Szillasi
Atomki, Debrecen, Hungary
S. Buontempo
INFN-Napoli, Napoli, Italy
The passage of a high-intensity particle beam inside accelerator components generates heating, potentially leading to degradation of the accelerator performance or damage to the component itself. It is therefore essential to monitor such beam-induced heating in accelerators. This paper showcases the capabilities of iPipe, which is a set of Fiber Bragg Grating sensors stuck on the inner beam pipe of the Compact Muon Solenoid (CMS) experiment installed in the CERN Large Hadron Collider (LHC). In this study, the wavelength shift, linked directly to the temperature shift, is measured and is compared with the computed dissipated power for a set of LHC fills. Electromagnetic and thermal simulations were also coupled to predict the beam-induced temperature increase along the beam pipe. These results further validate the sensing system and the methods used to design accelerator components to mitigate beam-induced heating.
D. Lipka, M. Holz, S. Vilcins
DESY, Hamburg, Germany
The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) hosts various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD facility, also called ARES (Accelerator Research Experiment at SINBAD), is a conventional S-band linear RF accelerator allowing the production of low charge ultra-short electron bunches within a range between 0.5 pC and 1000 pC. The positions of the low charge bunches will be detected by cavity beam position monitors. The principal design is based on the experience from the EU-XFEL cavity beam position monitors. It consists of a 316 LN stainless steel body with a design loaded quality factor of 70, a resonance frequency of 3.3 GHz and a relative wide gap of 15 mm to reach a high peak position sensitivity of 4.25 V/(nC mm). This poster covered, the manufacture of the individual mechanical parts, as well as presents the special features in the manufacture of customer designed UHV feedthroughs.
M. Colja, S. Carrato
University of Trieste, Trieste, Italy
G. Brajnik, R. De Monte
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
Digital processing systems have been proven to often outperform analog elaboration. Indeed, thanks to high-density DSPs and FPGAs, operations in digital domain give results that are impossible to achieve in other ways. On the other side, dealing with this great performance and flexibility is not always straightforward: the processing chain needs to be accurately planned to reach the desired goals, avoiding erratic behaviours in the digital domain. In this paper, we focus on the design and implementation of an FPGA-based digital processor that will be used in the electron beam position monitors of Elettra 2.0. After digitizing the 500 MHz beam signals from the pickups, the system executes a digital down conversion, followed by several filtering and demodulating stages, in order to have a selectable data rate that is suitable for both diagnostics and feedback. The position calculation is also performed in FPGA as well, with the well-known difference-over-sum algorithm. According to results provided by a fixed-point simulation, the overall system has been implemented in an Intel Arria 10 FPGA, demonstrating the correct design functionality that meets the specified requirements.
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.
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.
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.
S. Maier, M. Brosi, H.J. Cha, A. Mochihashi, A.-S. Müller, M.J. Nasse, P. Schreiber, M. Schwarz
KIT, Karlsruhe, Germany
Funding:Supported by the DFG project 431704792 in the ANR-DFG collaboration project ULTRASYNC and by the Doctoral School KSETA. Two parallel, corrugated plates will be installed at the KIT storage ring KARA (KArlsruhe Research Accelerator). This impedance manipulation structure can be used to study and eventually control the electron beam dynamics and the emitted coherent synchrotron radiation (CSR) at KARA. In this contribution, we present the design of the impedance manipulation structure with corrugated plates, simulation results showing the influence of different corrugation parameters on its impedance, and the impact of this additional impedance source on the temporal changes in the emitted CSR in the presence of the microbunching instability.
M.C. Paniccia, S.L. Clark, D.M. Gassner, R.L. Hulsart, P. Thieberger
BNL, Upton, New York, USA
Attenuation in a lossy coaxial cable increases over distance and varies over frequency. Having a model of these variations can help predict the expected loss and distortion of a signal. This paper discusses a free web-based application developed to provide accurate SPICE models for various coaxial cable types. The user can specify a length and select between different cable types, or upload their own cable attenuation curve, and receive a SPICE model for that cable. These simulation models have been used to assist the design and development of new instrumentation systems for the future Electron Ion Collider (EIC).
The beam quadrupole moment of stored beams can be measured with a four-plate quadrupole pick-up. The frequency spectrum of the quadrupole moment contains not only the usual first-order dipole modes (the betatron tunes) but also the second-order coherent modes, comprising of (1.) (even) normal envelope modes, (2.) odd (skew) envelope modes and (3.) dispersion modes. As a novel diagnostic tool, the measured frequencies and amplitudes provide direct access to transverse space charge strength through the tune shift as well as linear coupling (and mismatch thereof), along with the benefit of a non-invasive beam-based measurement. Technically, quadrupole moment measurements require a pick-up with non-linear position sensitivity function. We discuss recent developments and depict measurements at the GSI SIS18 heavy-ion synchrotron.
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J.C. Dooling, M. Borland, A.M. Grannan, C.J. Graziani, Y. Lee, R.R. Lindberg, G. Navrotski
ANL, Lemont, Illinois, USA
N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
D.W. Lee
UCSC, Santa Cruz, California, USA
Funding:Work supported by Hard X-ray Sciences LDRD Project 2021-0119 and by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The reduced emittance and concomitant increase in electron beam intensity in Fourth Generation Storage Ring (4GSR) light sources lead to the challenging machine protection problem of how to safely dispose of the circulating charge during unplanned whole-beam loss events. Two recent experiments conducted to study the effects of 4GSR whole-beam dumps showed that damage to candidate collimator materials can be severe. This is a paradigm shift for SR light source machine protection. Typically the biggest threat to the machine is from CW synchrotron radiation. The choice of collimator material is important. High-Z, high-density materials such as tungsten may appear effective for stopping the beam in static simulations; however, in reality, short radiation lengths will cause severe destructive hydrodynamic effects. In our experiments, significant damage was observed even in low-Z aluminum. Thus unplanned, whole-beam dumps cannot be stopped in a single collimator structure. In this tutorial, alternatives such as multiple collimators and fan-out abort kicker systems will be discussed. Collimator design strategy and foreseen diagnostics for their operation will also be presented.
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S. Strokov, M. Holz, G. Kube, D. Lipka, S. Vilcins
DESY, Hamburg, Germany
A new diffraction limited light source PETRA IV (DESY, Germany) with ultra-low emittance is currently being designed as an upgrade of the 3rd generation light source PETRA III. For transverse beam position measurements, beam position monitors (BPMs) will be used as an essential part of the beam diagnostic system. There will be a total of about 800 BPMs distributed along the 2.3 km storage ring. The inner diameter of the standard beam pipe, and therefore of most of the BPM chambers, will be 20 mm. The primary purpose of the systems is to provide high-resolution measurements of the transverse position of the electron beam. By specification, the impact of the mechanical tolerances on the position readings should be below 150 microns which is essential for the commissioning of the machine. To achieve this goal, the dependence of the accuracy of the beam position measurement on the tolerances of each manufactured part of the BPM was studied. This paper summarizes the development and optimization of each part of the BPM by using EM simulations performed with CST Studio Suite.
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.
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.
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.
A bunched beam intensity measurement system for the CERN Extra Low ENergy Antiproton (ELENA) ring, using a cylindrical shoe-box electrostatic pick-up from the existing orbit system [1], is presented. The system has been developed to measure very challenging beam cur-rents, as low as 200nA corresponding to intensities of the order of 107 antiprotons circulating with a relativistic beta of the order of 10-2. In this work we derive and show that the turn-by-turn beam intensity is proportional to the baseline of the sum signal and that, despite the AC-coupling of the system, the installed front-end electronics, based on a charge amplifier, not only guarantees the preservation of the bunch shape (up to a few tens of MHz), but also allows for an absolute calibration of the system. In addition, the linearity of the intensity measurements and their inde-pendence with respect to average beam position is evalu-ated using a standard electromagnetic simulation tool. Finally, experimental measurements throughout typical antiproton deceleration cycles are presented and their accuracy and precision are discussed.
C. Lannoy, D. Alves, N. Mounet
CERN, Meyrin, Switzerland
C. Lannoy, T. Pieloni
EPFL, Lausanne, Switzerland
K. Łasocha
Jagiellonian University, Kraków, Poland
We introduce a method for building Schottky spectra from macro-particle simulations performed with the PyHEADTAIL code, applied to LHC beam conditions. In this case, the use of a standard Fast Fourier Transform (FFT) algorithm to recover the spectral content of the beam becomes computationally intractable memory-wise, because of the relatively short bunch length compared to the large revolution period. This would imply having to handle an extremely large amount of data for performing the FFT. To circumvent this difficulty, a semi-analytical method was developed to compute efficiently the Fourier transform. The spectral content of the beam is calculated on the fly along with the macro-particle simulation and stored in a compact manner, independently from the number of particles, thus allowing the processing of one million macro-particles in the LHC, over 10’000 revolutions, in a few hours, on a regular computer. The simulated Schottky spectrum is then compared against theoretical formulas and measurements of Schottky signals previously obtained with lead ion beams in the LHC.
Y. Levinsen, R.A. Baron, E.M. Donegani, M. Eshraqi, A. Garcia Sosa, H. Hassanzadegan, B. Jones, N. Milas, R. Miyamoto, D. Noll, I. Vojskovic, R.H. Zeng
ESS, Lund, Sweden
M. Akhyani
EPFL, Lausanne, Switzerland
I. Bustinduy
ESS Bilbao, Zamudio, Spain
F. Grespan
INFN/LNL, Legnaro (PD), Italy
The installation and commissioning of the European Spallation Source is currently underway at full speed, with the goal to be ready for first neutron production by end of 2024. This year we accelerated protons through the first DTL tank. This included the RFQ, 3 buncher cavities in the medium energy beam transport as well as the DTL tank itself as RF elements. At the end of the DTL tank we had a Faraday cup acting as the effective beam stop. This marks the first commissioning when RF matching is required for beam transport. In this paper we discuss the phase scan measurements and analysis of the buncher cavities and the first DTL tank.
J. Yang, P. Boutachkov, P. Forck, T. Milosic, R. Singh, S. Sorge
GSI, Darmstadt, Germany
Funding:This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under GA No 101004730. The quality of slowly, typically several seconds, extracted beams from the GSI synchrotron SIS18 is characterized with respect to the temporal beam stability, the so-called spillμstructure on the 100 µs scale. A pilot experiment was performed utilizing transverse emittance exchange to reduce the beam size in the extraction plane, and the improvement of spillμstructure was found. Important beam instrumentation comprises an Ionization Profile Monitor for beam profile measurement inside the synchrotron and a plastic scintillator at the external transfer line for ion counting with up to several 106 particles per second and 20 µs time slices. The performant data acquisition systems, including a scaler and a fast Time-to-Digital Converter (TDC), allow for determining the spill quality. The application of the TDC in the measurement and related MAD-X simulations are discussed.
S.H. Mirza, A. Aloev, H.T. Duhme, B. Dursun, A. Eichler, S. Jabłoński, J. Klute, F. Ludwig, S. Pfeiffer, H. Schlarb, B. Szczepanski
DESY, Hamburg, Germany
G. Rehm
HZB, Berlin, Germany
PETRA IV is the upcoming low-emittance, 6 GeV, fourth- generation light source at DESY Hamburg. It is based upon a six-bend achromat lattice with additional beamlines as compared to PETRA III. Stringent stability of the electron beam orbit in the ring will be required to achieve diffraction- limited photon beam quality. In this regard, the requirements and the proposed topology of the global orbit feedback system are discussed for expected perturbations. An initial analysis based upon system requirements, design and modelling of the subsystems of the orbit feedback system is also presented
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.
M. Reißig, E. Bründermann, S. Funkner, B. Härer, A.-S. Müller, G. Niehues, M.M. Patil, R. Ruprecht, C. Widmann
KIT, Eggenstein-Leopoldshafen, Germany
Funding:Supported by the Doctoral School KSETA. C. W. achnowledges funding by BMBF contract number 05K19VKD. FCCIS is funded by the EU’s Horizon 2020 research and innovation programme under grant No 951754. At the KIT electron storage ring KARA (Karlsruhe Research Accellerator) an electro-optical (EO) near-field monitor is in operation performing single-shot, turn-by-turn measurements of the longitudinal bunch profile using electro-optical spectral decoding (EOSD). In context of the Future Circular Collider Innovation Study (FCCIS), a similar setup is investigated with the aim to monitor the longitudinal bunch profile of each bunch for dedicated top-up injection at the future electron-positron collider FCC-ee. This contribution presents the status of a monitor design adapted to cope with the high-current and high-energy lepton beams foreseen at FCC-ee.
G.O. Rodrigues, S. Kumar, K. Mal, R. Mehta, C.P. Safvan
IUAC, New Delhi, India
R. Singh
GSI, Darmstadt, Germany
Fast Faraday Cups (FFCs) are interceptive beam diagnostic devices used to measure fast signals from sub-nanosecond bunched beams and the operation of these devices is a well-established technique. However, for short bunch length measurements in non-relativistic regimes with ion beams, the measured profile is diluted due to field elongation and distortion by the emission of secondary electrons. Additionally, for short bunches with the expected intensities envisaged in the High Current Injector at the Inter University Accelerator Centre, the impedance matching of the EM structure puts severe design constraints. This work presents a detailed study on the modification of a radially-coupled coaxial FFC [1]. The field dilution and secondary electron emission aspects are modelled through EM simulations and techniques to minimise these effects are explored. This has resulted in a new design, which has a better signal to noise ratio and benefits from a more accurate bunched beam measurement. [1] Carneiro, J.-P., et al. ’Longitudinal Beam Dynamics Studies at the Pip-II Injector Test Facility.’ International Journal of Modern Physics A, vol. 34, no. 36, 2019, p.1942013
S. Preston, L. Bobb, A.F.D. Morgan, T. Olsson
DLS, Oxfordshire, United Kingdom
In the Diamond storage ring, the vertical emittance is kept at 8 pm rad by an emittance feedback which modifies the strengths of skew quadrupoles. A new feedback using a stripline kicker to control the vertical emittance by exciting the beam resonantly at a synchrotron sideband is planned to avoid modification of the optics. This is crucial for the anticipated Diamond-II upgrade of the storage ring, which will have a much smaller equilibrium emittance than the existing machine. A larger coupling is therefore needed to keep the vertical emittance at the same level, potentially reducing the off-axis injection efficiency and lifetime. Measurements of the beam oscillation and emittance have been performed at the existing storage ring to characterise the effects of chromaticity and impedance on the optimal excitation frequency, where the emittance is increased significantly while the beam oscillation is kept low. The implications for simulating the emittance feedback for the Diamond-II storage ring are also discussed.
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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