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| MOPAB001 | Power Deposition in Superconducting Dispersion Suppressor Magnets Downstream of the Betatron Cleaning Insertion for HL-LHC | 37 |
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Funding: Research supported by the HL-LHC project The power deposited in dispersion suppressor magnets downstream of the Large Hadron Collider (LHC) betatron cleaning insertion is governed by off-momentum particles scattered out of the primary collimators. In order to mitigate the risk of magnet quenches during periods of short beam lifetime in future High-Luminosity (HL-LHC) operation, new dispersion suppressor (DS) collimators are considered for installation (one per beam). In this paper, we present FLUKA simulations for both protons and Pb ions at 7 TeV, predicting the power deposition in the DS magnets, including the new higher-field dipoles 11T which are needed to integrate the collimator in the cold region next to the cleaning insertion. The simulated power deposition levels for the adopted HL-LHC collimator configuration and settings are used to assess the quench margin by comparison with the present estimated quench levels. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB001 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 16 August 2021 | |
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| MOPAB002 | Risk of Halo-Induced Magnet Quenches in the HL-LHC Beam Dump Insertion | 41 |
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Funding: Research supported by the HL-LHC project After the High Luminosity (HL-LHC) upgrade, the LHC will be exposed to a higher risk of magnet quenches during periods of short beam lifetime. Collimators in the extraction region (IR6) assure the protection of magnets against asynchronous beam dumps, but they also intercept a fraction of the beam halo leaking from the betatron cleaning insertion. In this paper, we assess the risk of quenching nearby quadrupoles during beam lifetime drops. In particular, we present an empirical analysis of halo losses in IR6 using LHC Run 2 (2015-2018) beam loss monitor measurements. Based on these results, the halo-induced power density in magnet coils expected in HL-LHC is estimated using FLUKA Monte Carlo shower simulations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB002 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 13 July 2021 issue date ※ 22 August 2021 | |
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| MOPAB005 | Studies for an LHC Pilot Run with Oxygen Beams | 53 |
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| Motivated by the study of collective effects in small systems with oxygen-oxygen (O-O) collisions, and improvements to the understanding of high-energy cosmic ray interactions from proton-oxygen (p-O) collisions, a short LHC oxygen run during Run 3 has been proposed. This article presents estimates for the obtainable luminosity performance in these two running modes based on simulations of a typical fill. The requested integrated luminosity, projected beam conditions, data-taking and commissioning times are considered and a running scenario is proposed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB005 | |
| About • | paper received ※ 17 May 2021 paper accepted ※ 25 May 2021 issue date ※ 19 August 2021 | |
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| MOPAB006 | Optics Configurations for Improved Machine Impedance and Cleaning Performance of a Multi-Stage Collimation Insertion | 57 |
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| For a two-stage collimation system, the betatron phase advance between the primary and secondary stages is usually set to maximise the absorption of secondary particles outscattered from the primary. Another constraint is the contribution to the ring impedance of the collimation system, which can be decreased through an optimized insertion optics, featuring large values of the beta functions. In this article we report on first studies of such an optics for the CERN LHC. In addition to a gain in impedance, we show that the cleaning efficiency can be improved thanks to the large beta functions, even though the phase advance is not set at the theoretical optimum. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB006 | |
| About • | paper received ※ 17 May 2021 paper accepted ※ 28 May 2021 issue date ※ 11 August 2021 | |
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| MOPAB023 | Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC | 115 |
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| The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this retraction has been proposed, and a proof-of-principle experiment was performed at the LHC. The method uses a long orbit bump to mimic the change of the beam trajectory caused by an asynchronous firing of the extraction kickers. It can, thus, be performed with circulating beam. This paper reports on the performed beam measurements, compares them with expectations and discusses the potential benefits of the new method for machine protection. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB023 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 24 August 2021 | |
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| WEXA06 | Study of Pb-Pb and Pb-p Collision Debris in the CERN LHC in View of HL-LHC Operation | 2528 |
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Funding: Research supported by the HL-LHC project For the first time, a full characterization of the Pb-Pb and Pb-p collision debris as well as its impact in terms of energy deposition in the long straight section (LSS) of CERN’s Large Hadron Collider has been carried out. By means of Monte Carlo simulations with FLUKA, both inelastic nuclear interaction and electromagnetic dissociation were taken into account as source term for lead ion operation, while for Pb-p operation only nuclear interaction is of importance. The radiation exposure of detectors exclusively destined for ion beam runs is assessed, allowing drawing implications of their use. This work gave the opportunity for an unprecedented validation of simulation results against measurement of beam loss monitors (BLM) in the experimental LSS during ion operation. Pb-Pb operation refers to the 2018 ion run at 6.37 TeV per charge with a +160 microrad half crossing angle in the vertical plane at the ATLAS interaction point. Instead, Pb-p operation was benchmarked for the 2016 ion run at 6.5 TeV per charge with -140 microrad half crossing angle in the vertical plane at the same location. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA06 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 05 July 2021 issue date ※ 22 August 2021 | |
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| WEPAB023 | Crystal Collimation of 20 MJ Heavy-Ion Beams at the HL-LHC | 2644 |
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| The concept of crystal collimation at the Large Hadron Collider (LHC) relies on the use of bent crystals that can deflect halo particles by a much larger angle than the standard multi-stage collimation system. Following an extensive campaign of studies and performance validations, a number of crystal collimation tests with Pb ion beams were performed in 2018 at energies up to 6.37 Z TeV. This paper describes the procedure and outcomes of these tests, the most important of which being the demonstration of the capability of crystal collimation to improve the cleaning efficiency of the machine. These results led to the inclusion of crystal collimation into the LHC baseline for operation with ion beams in Run 3 as well as for the HL-LHC era. A first set of operational settings was defined. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB023 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 27 August 2021 | |
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| WEPAB025 | Collimation Strategies for Secondary Beams in FCC-hh Ion-Ion Operation | 2652 |
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| The target peak luminosity of the CERN FCC-hh during Pb-Pb collisions is more than a factor of 50 greater than that achieved by the LHC in 2018. As a result, the intensity of secondary beams produced in collisions at the interaction points will be significantly higher than previously experienced. With up to 72 kW deposited in a localised region by a single secondary beam type, namely the one originated by Bound Free Pair Production (BFPP), it is essential to develop strategies to safely intercept these beams, including the ones from ElectroMagnetic Dissociation (EMD), in order to ensure successful FCC-hh Pb-Pb operation. A series of beam tracking and energy deposition simulations were performed to determine the optimal solution for handling the impact of such beams. In this contribution the most advanced results are presented, with a discussion of different options. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB025 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 02 July 2021 issue date ※ 18 August 2021 | |
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