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.
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.
please see instructions how to view/control embeded videos
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.
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.
please see instructions how to view/control embeded videos
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
