S. Mazzoni, W. Andreazza, E. Balci, D. Belohrad, E. Bravin, N.S. Chritin, J.C. Esteban Felipe, T. Lefèvre, M. Martin Nieto, M. Palm
CERN, Meyrin, Switzerland
The Beam Rate of Neutrals (BRAN) is a monitor that provides a relative luminosity measurement for the four LHC experiments. BRANs are used during operations as a tool to find and optimise collision and to cross-check experiments luminosity monitors. While each LHC experiments is equipped with BRANs, in this contribution we will focus on the new monitors installed for ATLAS and CMS that will replace the current ageing gas chambers during LHC run 3. These will also serve as as prototypes for the future High Luminosity LHC monitors that will need to sustain an even higher collision rate. A description of the BRAN as well as the first results obtained during the LHC Run 3 start-up will be presented.
Electro-Optical BPM Development for High Luminosity LHC
181
S.M. Gibson, A. Arteche
Royal Holloway, University of London, Surrey, United Kingdom
T. Lefèvre, T.E. Levens
CERN, Meyrin, Switzerland
An Electro-Optic Beam Position Monitor (EO-BPM) is being developed as a high-frequency (up to 10 GHz) diagnostic for crabbing and Head-Tail intra-bunch detection at the HL-LHC. Following an earlier prototype at the SPS that demonstrated single-pickup signals, an upgraded design of an interferometric EO-BPM has been beam-tested at the HiRadMat facility for validation and characterisation studies. In the new design, the fibre-coupled Mach-Zehnder interferometer arms are modulated by lithium niobate waveguides integrated in an upgraded opto-mechanical arrangement that has been developed to produce a highly magnified image field replica of the passing Coulomb field. A new detection technique that is directly sensitive to the interferometric optical difference signal from opposite EO buttons has been applied to measure single-shot bunches for the first time. A transverse resolution study over a ±20 mm range at 3 GHz bandwidth produced the first successful electro-optic bunch-by-bunch position measurement at the HiRadMat in-air extraction line. The results of this campaign show promise for an in-vacuum design that is in production for beam tests at the SPS during Run-3 of the LHC.
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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.
Optimization Study of Beam Position and Angular Jitter Independent Bunch Length Monitor for Awake Run 2
465
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.
