Author: Bruce, R.
Paper Title Page
MOPAB001 Power Deposition in Superconducting Dispersion Suppressor Magnets Downstream of the Betatron Cleaning Insertion for HL-LHC 37
 
  • A. Waets, C. Bahamonde Castro, E. Belli, R. Bruce, N. Fuster-Martínez, A. Lechner, A. Mereghetti, S. Redaelli, M. Sabaté-Gilarte, E. Skordis
    CERN, Meyrin, Switzerland
  
  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. 		 
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
 
  • J.B. Potoine, A. Apollonio, E. Belli, C. Bracco, R. Bruce, M. D’Andrea, R. García Alía, A. Lechner, G. Lerner, S. Morales Vigo, S. Redaelli, V. Rizzoglio, E. Skordis, A. Waets
    CERN, Meyrin, Switzerland
  • F. Wrobel
    IES, Montpellier, France
  
  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. 		 
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
 
  • R. Bruce, R. Alemany-Fernández, H. Bartosik, M.A. Jebramcik, J.M. Jowett, M. Schaumann
    CERN, Geneva, Switzerland
  
  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
 
  • R. Bruce, R. De Maria, M. Giovannozzi, N. Mounet, S. Redaelli
    CERN, Geneva, Switzerland
  
  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
 
  • C. Wiesner, W. Bartmann, C. Bracco, R. Bruce, J. Molson, M. Schaumann, C. Staufenbiel, J.A. Uythoven, M. Valette, J. Wenninger, D. Wollmann, M. Zerlauth
    CERN, Meyrin, Switzerland
  
  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
 
  • M. Sabaté-Gilarte, R. Bruce, F. Cerutti, A. Lechner
    CERN, Meyrin, Switzerland
  
  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. 		 
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
 
  • M. D’Andrea, R. Bruce, M. Di Castro, I. Lamas Garcia, A. Masi, D. Mirarchi, S. Redaelli, R. Rossi, B. Salvachua, W. Scandale
    CERN, Meyrin, Switzerland
  • F. Galluccio
    INFN-Napoli, Napoli, Italy
  • L.J. Nevay
    Royal Holloway, University of London, Surrey, United Kingdom
  
  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
 
  • J.R. Hunt, R. Bruce, F. Carra, F. Cerutti, J. Guardia, J. Molson
    CERN, Meyrin, Switzerland
  
  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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