| Paper | Title | Page |
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| MOPAB283 | Simulations of Space-Charge and Guiding Fields Effects on the Performance of Gas Jet Profile Monitoring | 898 |
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| Gas jet based profile monitors inject a usually curtain shaped gas jet across a charged particle beam and exploit the results of the minimally invasive beam-gas interaction to provide information about the beam’s transversal profile. Such monitor will be installed as part of the High Luminosity LHC upgrade at CERN in the Hollow Electron Lens (HEL). The HEL represents a new collimation stage increasing the diffusion rate of halo particles by placing a high intensity hollow electron beam concentrically around the LHC beam. The gas jet monitor will use the fluorescence radiation resulting due to the beam-gas interaction to create an image of the profiles of both hollow electron and LHC beams However, the high beam space-charge and strong guiding magnetic field of the electron beam cause significant displacements of the excited molecules, as they are also ionized, and thus image distortions. This work presents preliminary simulation results showing expected fluorescence images of the hollow electron profile as affected by space-charge and guiding fields using simulation tools such as IPMsim. The influence of the estimated electron beam and gas jet curtain parameters are investigated. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB283 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 28 July 2021 issue date ※ 19 August 2021 | |
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| TUPAB280 | Quantum Gas Jet Scanner Based Beam Profile Monitors | 2128 |
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Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. A quantum gas jet scanner-based beam profile monitor is under development at the Cockcroft Institute (CI), the UK for beam diagnostics based on the principle of ionization detection induced in a quantum gas jet interacting with an ionizing primary beam that shall be characterized. It promises superior position resolution and high signal intensity resulting from a strongly focused quantum gas jet. In order to achieve the gas jet with a diameter of less than 100 µm, a novel focusing method exploiting the quantum wave function of the neutral gas atoms, generate an interference pattern with a single maximum acting as an ultra-thin gas jet. An ‘atom sieve’ has been designed for generating the interference pattern, applying the principle of a photon sieve. It will be analogous to a mechanical wire scanner though with a minimal interception. The idea of moving a quantum gas jet through the beam is proposed for transverse profiling. This contribution provides a general overview of the design, working principle, the results obtained from initial measurements carried out at CI and University of Bergen (Norway), for designing the same and possible methods for optimizing the scanner’s design. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB280 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 25 August 2021 | |
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| TUPAB281 | Gas-Mixing to Improve the Resolution of Non-Invasive Gas Jet-Based Ionization Profile Monitors | 2132 |
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Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. Ionization beam profile monitor using a supersonic gas jet is an attractive option for the characterization of low and medium energy beams. In this scheme, a primary beam crosses a 45-degree tilted thin gas curtain which causes ionization of gas molecules in the jet. The generated ions are then collected using an electrostatic extraction system to determine the 2D transverse profile of the primary beam. The most commonly used gases for the jet are neon and nitrogen. The signal from the gas jet is always super-imposed with the signal resulting from residual gases in the interaction chamber. CST simulations indicate that the gas jet speed is a key factor for the separation of the jet and the residual gas signals. To obtain a good signal separation, one can increase the velocity of the gas jet. This can be accomplished by generating a gas jet that mixes heavier and lighter gases. This contribution gives a general overview of the monitor design, discusses the effects of gas mixing and CST simulation results. It also presents experimental results obtained with Helium, and Nitrogen, as well as a mixture of them using different percentages and the impact on measurement resolution. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB281 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 13 August 2021 | |
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| FRXC05 | Gas Jet In-Vivo Dosimetry for Particle Beam Therapy | 4548 |
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Funding: This work is supported by the HL-LHC-UK project funded by STFC and CERN and the STFC Cockcroft core grant No. ST/G008248/1. Medical applications of charged particle beams require a full online characterisation of the beam to ensure patient safety, treatment efficacy, and facility efficiency. In-vivo dosimetry, measurement of delivered dose during treatment, is a significant part of this characterisation. Current methods offer limited information or are invasive to the beam, meaning measurements must be done offline. This contribution presents the development of a non-invasive gas jet in-vivo dosimeter for treatment facilities. The technique is based on the interaction between a particle beam and a supersonic gas jet curtain, which was originally developed for the high luminosity upgrade of the large hadron collider (HL-LHC). To demonstrate the medical application of this technique, an existing HL-LHC test system with minor modifications will be installed at the University of Birmingham’s 35 MeV proton cyclotron, which has properties comparable to that of a treatment beam. This contribution presents the design and development of this test setup, plans for initial benchmarking measurements, and plans for a future optimised medical accelerator gas jet in-vivo dosimeter. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC05 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 23 July 2021 issue date ※ 11 August 2021 | |
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| MOPAB279 | Non-Invasive Beam Profile Monitoring for the HL-LHC Hollow Electron Lens | 884 |
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Funding: This work was supported by the HL-LHC-UK phase II project funded by STFC under Grant Ref: ST/T001925/1 and the STFC Cockcroft core grant No. ST/G008248/1. A Hollow Electron Lens (HEL) is currently under development for the High-Luminosity upgrade of the Large Hadron Collider (HL-LHC). In this device, a hollow electron beam co-propagates with a central proton beam and provides active halo control in the LHC. To ensure the concentricity of the two beams, a non-invasive diagnostic instrument is currently being commissioned. This instrument is a compact version of an existing prototype that leverages beam induced fluorescence with supersonic gas curtain technology. This contribution includes the design features of this version of the monitor, recent progress, and future plans for tests at the Cockcroft Institute and the electron lens test stand at CERN. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB279 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 15 June 2021 issue date ※ 02 September 2021 | |
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