| Paper | Title | Other Keywords | Page |
|---|---|---|---|
| MOPOST043 | Testing the Global Diffusive Behaviour of Beam-Halo Dynamics at the CERN LHC Using Collimator Scans | collider, proton, emittance, hadron | 172 |
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| In superconducting circular particle accelerators, controlling beam losses is of paramount importance for ensuring optimal machine performance and an efficient operation. To achieve the required level of understanding of the mechanisms underlying beam losses, models based on global diffusion processes have recently been studied and proposed to investigate the beam-halo dynamics. In these models, the building block of the analytical form of the diffusion coefficient is the stability-time estimate of the Nekhoroshev theorem. In this paper, the developed models are applied to data acquired during collimation scans at the CERN LHC. In these measurements, the collimators are moved in steps and the tail population is re-constructed from the observed losses. This allows an estimate of the diffusion coefficient. The results of the analyses performed are presented and discussed in detail. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST043 | ||
| About • | Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022 | ||
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| MOPOPT045 | Beam Loss Localisation with an Optical Beam Loss Monitor in the CLEAR Facility at CERN | photon, electron, detector, experiment | 351 |
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| A prototype of a Beam Loss Monitor based on the detection of Cherenkov light in optical fibres is being developed to measure beam losses in the CERN Super Proton Synchrotron. Several testing campaigns have been planned to benchmark the simulations of the system and test the electronics in the CLEAR facility at CERN. During the first campaigns, the emission of Cherenkov light inside optical fibres and the photodetector characterisation were studied. Fibre-based Beam Loss monitors continuously monitor beam losses over long distances. The localisation of the beam loss could be calculated from the timing of the signals generated by the photosensors coupled at both ends of the optical fibre. The experimental results of an optical fibre Beam Loss Monitor installed in the CLEAR facility are reported in this paper. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT045 | ||
| About • | Received ※ 03 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 24 June 2022 | ||
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| MOPOPT046 | Linearity and Response Time of the LHC Diamond Beam Loss Monitors in the CLEAR Beam Test Facility at CERN | target, detector, electron, operation | 355 |
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| Chemical Vapour Deposition (CVD) diamond detectors have been tested during the Run 2 operation period (2015-2018) as fast beam loss monitors for the Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) at CERN. However, the lack of raw data recorded during this operation period restrains our ability to perform a deep analysis of their signals. For this reason, a test campaign was carried out at the CLEAR beam test facility at CERN with the aim of studying the linearity and response time of the diamond detectors against losses from electron beams of different intensities. The signal build-up from multi-bunched electron beams was also analyzed. The conditions and procedures of the test campaign are explained, as well as the most significant results obtained. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT046 | ||
| About • | Received ※ 08 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 07 July 2022 | ||
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| MOPOPT051 | Optical Fiber Based Beam Loss Monitor for SPS Machine | radiation, injection, septum, operation | 374 |
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| At the Siam Photon Source (SPS) beam loss monitors based on PIN diode have been used. The existing system allow beam loss detection very locally at the monitor position close to the vacuum chamber. For optical fiber, Cherenkov radiation can be detected when a lost particle travel in the fiber. Thus optical fiber based loss monitor with sufficient length can cover parts of the machine conveniently. Fast beam loss event can be detected with more accurate position. In this paper, the design and result of the optical fiber based beam loss monitor system at SPS machine are discussed. The system will be a prototype for the new 3 GeV machine SPS-II. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT051 | ||
| About • | Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 08 July 2022 | ||
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| TUPOST041 | Experience with Computer-Aided Optimizations in LINAC4 and PSB at CERN | linac, MMI, extraction, cavity | 945 |
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| Accelerator optimization is routinely performed with the help of computer algorithms that fully automate these tasks. However, their efficiency, speed, and time to implement varies greatly depending on the algorithms used. In LINAC4 some of the automatic optimization routines were programmed using different algorithms to find the most suitable. We present the problems for which the computer algorithms were used and the results of our comparative study. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST041 | ||
| About • | Received ※ 09 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 08 July 2022 | ||
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| WEPOPT013 | Effect of a Spurious CLIQ Firing on the Circulating Beam in HL-LHC | luminosity, simulation, collimation, collider | 1862 |
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| The High Luminosity LHC (HL-LHC) will reach a nominal, levelled luminosity of §I{5e34}{\per\cm\square\per\second} and a stored energy of nearly §I{700}{MJ} in each of the two proton beams. The new large-aperture final focusing Nb3Sn quadrupole magnets in IR1 and IR5, which are essential to achieve the luminosity target, will be protected using the novel Coupling Loss Induced Quench (CLIQ) system. A spurious discharge of a CLIQ unit will impact the circulating beam through higher order multipolar field components that develop rapidly over a few turns. This paper reports on dedicated beam tracking studies performed to evaluate the criticality of this failure on the HL-LHC beam. Simulations for different machine and optics configurations show that the beam losses reach a critical level after only five machine turns following the spurious CLIQ trigger, which is much faster than assumed in previous simulations that did not consider the higher order multipolar fields. Machine protection requirements using a dedicated interlock to mitigate this failure are discussed. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT013 | ||
| About • | Received ※ 08 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 01 July 2022 | ||
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| WEPOPT014 | The Effect of a Partially Depleted Halo on the Criticality and Detectability of Fast Failures in the HL-LHC | simulation, luminosity, collider, dipole | 1866 |
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| In the High Luminosity LHC (HL-LHC) era, the bunch intensity will be increased to νm{2.2e11} protons, which is almost twice the nominal LHC intensity. The stored energy in each of the two beams will increase to §I{674}{MJ}. The HL-LHC will feature beams whose transverse halos are partially depleted by means of a hollow electron lens. The reduced stored energy in the beam tails will significantly change the development of losses caused by failures. This paper reports on beam tracking simulations evaluating the effect of a partially depleted halo on the criticality and detection of failures originating from the superconducting magnet protection systems. In addition, the effect of the transverse damper operating as a coherent excitation system leading to orbit excursions on a beam with a partially depleted halo is discussed. The results in terms of time-dependent beam losses are presented. The margins between the failure onset, its detection, and the time to reach critical loss levels, are discussed. The results are extrapolated to failure cases of different origins that induce similar beam loss dynamics. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT014 | ||
| About • | Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022 | ||
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| THPOMS024 | A Novel Intensity Compensation Method to Achieve Energy Independent Beam Intensity at the Patient Location for Cyclotron Based Proton Therapy Facilities | cyclotron, proton, optics, emittance | 3004 |
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Funding: This work is supported by a PSI inter-departmental funding initiative (Cross) In cyclotron-based proton therapy facilities, an energy selection system is typically used to lower beam energy from the fixed value provided by the accelerator (250/230MeV) to the one needed for the treatment (230-70MeV). Such a system has drawback of introducing an energy-dependent beam current at the patient location, resulting in energy-dependent beam intensity ratios of about 103 between high and low energies. This complicates treatment delivery and challenges patient safety systems. As such, we propose the use of a dual-energy degrader method that can reduce beam intensity for high-energy beams. The first degrader is made of high Z material and the second is made of low Z material and are placed next to each other. For high energies (230-180MeV), we use only first degrader to increase beam emittance after degrader and thus lose intensity in emittance selection collimators. For intermediate energy beams (180-100MeV) we use the combination of both degraders, whereas for low energy beams (100-70MeV), only the second degrader limits the increase in emittance. With this approach, energy-independent beam intensities can be achieved, whilst localizing beam losses around the degrader. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS024 | ||
| About • | Received ※ 16 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 14 June 2022 | ||
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