MC1: Circular and Linear Colliders
A24: Accelerators and Storage Rings, Other

Paper	Title	Page
WEPOPT005	Investigation of Polarized Proton Spin Coherence Time at Storage Rings	1832
SUSPMF004	use link to see paper's listing under its alternate paper code
	A.A. Melnikov, A.E. Aksentyev, Y. Senichev RAS/INR, Moscow, Russia A.E. Aksentyev MEPhI, Moscow, Russia E. Syresin JINR/VBLHEP, Dubna, Moscow region, Russia
	Funding: We appreciate a support of this study by the Russian Science Foundation grant 22-42-04419 and the ERC Advanced Grant of the European Union (proposal number 694340). The idea of the Elec­tric Di­pole Mo­ment (EDM) search using the stor­age ring with po­lar­ized beam de­mands long Spin Co­her­ence Time (SCT). It is the time dur­ing which the RMS spread of the ori­en­ta­tion of spins of all par­ti­cles in the bunch reaches one ra­dian. Long SCT is needed to ob­serve a co­her­ent ef­fect on po­lar­iza­tion in­duced by the EDM. The pos­si­bil­ity of get­ting a 1000 s SCT for deuterons has been shown ex­per­i­men­tally at COoler SYn­chro­tron (COSY), ac­cel­er­a­tor at FZJ Jülich, Ger­many. Reach­ing high val­ues of SCT for pro­tons is more chal­leng­ing due to a higher anom­alous mag­netic mo­ment. Ob­tain­ing suf­fi­cient pro­ton SCT is oblig­a­tory for planned EDM search ex­per­i­ments at COSY and the Pro­to­Type EDM Ring (PTR). It has been shown that the sec­ond order mo­men­tum com­paction fac­tor (al­pha1) has to be op­ti­mized along with chro­matic­i­ties to get high SCT. Three fam­i­lies of sex­tupoles have to be used. The op­ti­mal val­ues of chro­matic­i­ties and al­pha1 are dis­cussed. The race­track op­tion of PTR is in­ves­ti­gated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT005
About •	Received ※ 16 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 02 July 2022
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WEPOPT026	Possibilities for Upgrading to Polarized a SuperKEKB	1901
	Z.J. Liptak HU/AdSM, Higashi-Hiroshima, Japan
	The Su­perKEKB ac­cel­er­a­tor is cur­rently in op­er­a­tion in Tsukuba, Japan, with a planned long shut­down in 2026. Among the pos­si­ble up­grades being con­sid­ered dur­ing this pe­riod is the change to a po­lar­ized elec­tron beam in the High En­ergy Ring. Such a change would re­quire mod­i­fi­ca­tions in the source gen­er­a­tion and trans­port, geo­met­ri­cal and lat­tice vari­a­tions to pro­vide spin ro­ta­tion, and po­larime­try. A Po­lar­ized Su­perKEKB Work­ing Group has been formed from mem­bers of the Belle II ex­per­i­ment and the Su­perKEKB ac­cel­er­a­tor team to in­ves­ti­gate the pos­si­bil­i­ties and chal­lenges of these mod­i­fi­ca­tions. This pre­sen­ta­tion lays out the goals and mo­ti­va­tions of po­lar­iz­ing the elec­tron beam, con­sid­ers the nec­es­sary changes to the ex­ist­ing ac­cel­er­a­tor and their fea­si­bil­ity and re­ports progress in in­ves­ti­ga­tions to this point.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT026
About •	Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022
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WEPOPT054	Target Studies for the FCC-ee Positron Source	1979
	F. Alharthi, I. Chaikovska, R. Chehab, S. Ogur, A. Ushakov, S. Wallon Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France L. Bandiera, A. Mazzolari, M. Romagnoni, A.I. Sytov INFN-Ferrara, Ferrara, Italy J. Diefenbach, W. Lauth IKP, Mainz, Germany O. Khomyshyn Taras Shevchenko National University of Kyiv, Kyiv, Ukraine D.M. Klekots National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv, Ukraine V.V. Mytrochenko NSC/KIPT, Kharkov, Ukraine P. Sievers, Y. Zhao CERN, Meyrin, Switzerland M. Soldani Università degli Studi di Ferrara, Ferrara, Italy
	FCC-ee in­jec­tor study fore­sees 3.5~nC elec­tron and positron bunches with 200 Hz rep­e­ti­tion and 2 bunches per linac pulse at 6~GeV ex­trac­tion en­ergy. Re­gard­ing the pos­si­ble op­tions of positron pro­duc­tion, we re­tain both of the con­ven­tional amor­phous tar­get and the hy­brid tar­get op­tions. The hy­brid scheme uses an in­tense pho­ton pro­duc­tion by 6 GeV elec­trons im­ping­ing on a crys­tal ori­ented along a lat­tice axis. In such a way, it in­volves two tar­gets: a crys­tal as a pho­ton ra­di­a­tor and an amor­phous tar­get-con­verter. There­fore, to avoid early fail­ure or dam­age of the tar­get, the can­di­date ma­te­ri­als for the crys­tal and con­ver­sion tar­gets have started to be tested by using the in­tense elec­tron beam at Mainzer Mikro­tron in Ger­many by the end of 2021. By ma­nip­u­lat­ing the beam in­ten­sity, fo­cus­ing, and chop­ping, a Peak En­ergy De­po­si­tion Den­sity in the tested tar­gets could be achieved close to that gen­er­ated by the elec­tron/pho­ton beam in the FCC-ee positron tar­get. Ra­di­a­tion-dam­age stud­ies of the crys­tal sam­ple have been also per­formed al­low­ing es­ti­mat­ing the ef­fect on the pho­ton en­hance­ment used in the hy­brid positron source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT054
About •	Received ※ 16 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 21 June 2022
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WEPOPT055	Linac3, LEIR and PS Performance with Ions in 2021 and Prospects for 2022	1983
	N. Biancacci, S.C.P. Albright, R. Alemany-Fernández, D. Alves, M.E. Angoletta, D. Barrientos, H. Bartosik, G. Bellodi, S.B. Bertolo, D. Bodart, M. Bozzolan, H. Damerau, F.D.L. Di Lorenzo, A. Frassier, D. Gamba, A. Huschauer, S. Jensen, V. Kain, T. Koevener, G. Kotzian, D. Küchler, A. Lasheen, G. Le Godec, T.E. Levens, N. Madysa, E. Mahner, O. Marqversen, C.M. Mastrostefano, P.D. Meruga, C. Mutin, M. O’Neil, G. Piccinini, R. Scrivens, P.S. Solvang, D. Valuch, F.M. Velotti, R. Wegner, C. Wetton, M. Zampetakis CERN, Meyrin, Switzerland
	CERN ac­cel­er­a­tors un­der­went a pe­riod of long shut­down from the end of 2018 to 2020. Dur­ing this time frame, sig­nif­i­cant hard­ware and soft­ware up­grades have been put in place to in­crease the per­for­mance of both pro­ton and ion ac­cel­er­a­tor chains in the High Lu­mi­nos­ity LHC era. In the con­text of the CERN lead ion chain, 2021 has been mainly de­voted to re­store the in­jec­tors’ per­for­mance and to suc­cess­fully prove the slip-stack­ing tech­nique in SPS. In this paper we sum­marise the key mile­stones of the ion beam com­mis­sion­ing and the achieved beam per­for­mance for the Linac 3 (in­clud­ing the source), LEIR and PS ac­cel­er­a­tors, to­gether with an out­look on 2022 op­er­a­tion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT055
About •	Received ※ 03 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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WEPOPT059	Corrections of Systematic Normal Decapole Field Errors in the HL-LHC Separation/Recombination Dipoles	1991
	J. Dilly, M. Giovannozzi, R. Tomás García, F.F. Van der Veken CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. Mag­netic mea­sure­ments re­vealed that the nor­mal de­ca­pole (b5) er­rors of the re­com­bi­na­tion dipoles (D2) could have a sys­tem­atic com­po­nent of up to 11 units. Based on pre­vi­ous stud­ies, it was pre­dicted that the cur­rent cor­rec­tions would not be able to com­pen­sate this, thereby lead­ing to a degra­da­tion of the dy­namic aper­ture by about 0.5 - 1 ’. On the other hand, the sep­a­ra­tion di­pole D1 is ex­pected to have a sys­tem­atic b5 com­po­nent of 6-7 units and its con­tri­bu­tion to the res­o­nance dri­ving terms will partly com­pen­sate the ef­fect of D2, due to the op­po­site field strength of the main com­po­nent. Sim­u­la­tions were per­formed with the HL-LHC V1.4 lat­tice to test these con­cerns and to ver­ify the com­pen­sa­tion as­sump­tion. In ad­di­tion, var­i­ous nor­mal de­ca­pole res­o­nance dri­ving terms were ex­am­ined for cor­rec­tion, the re­sults of which are pre­sented in this con­tri­bu­tion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT059
About •	Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022
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WEPOPT060	Controlling Landau Damping via Feed-Down From High-Order Correctors in the LHC and HL-LHC	1995
SUSPMF005	use link to see paper's listing under its alternate paper code
	J. Dilly, E.H. Maclean, R. Tomás García CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. Am­pli­tude de­tun­ing mea­sure­ments in the LHC have shown that a sig­nif­i­cant amount of de­tun­ing is gen­er­ated in Beam 1 via feed-down from de­ca­pole and do­de­ca­pole field er­rors in the triplets of the ex­per­i­ment in­ser­tion re­gions, while in Beam 2 this de­tun­ing is neg­li­gi­ble. In this study, we in­ves­ti­gate the cause of this be­hav­ior and we at­tempt to find cor­rec­tions that use the feed-down from the non­lin­ear cor­rec­tors in the in­ser­tion re­gion for am­pli­tude de­tun­ing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT060
About •	Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022
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WEPOPT061	A Flexible Nonlinear Resonance Driving Term Based Correction Algorithm with Feed-Down	1999
	J. Dilly, R. Tomás García CERN, Meyrin, Switzerland
	Funding: This work has been supported by the HiLumi Project and been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Re-search. The op­tics in the in­ser­tion re­gions of the LHC and its up­grade pro­ject the High Lu­mi­nos­ity LHC are very sen­si­tive to local mag­netic er­rors, due to the ex­tremely high beta-func­tions. In col­li­sion op­tics, the non-zero closed orbit in the same re­gion leads to a "feed-down" of high-or­der er­rors to lower or­ders, caus­ing ad­di­tional ef­fects detri­men­tal to beam life­time. An ex­ten­sion to the well-es­tab­lished method for cor­rect­ing these er­rors by lo­cally sup­press­ing res­o­nance dri­ving terms has been un­der­taken, not only tak­ing this feed-down into ac­count, but also adding the pos­si­bil­ity of uti­liz­ing it such that the pow­er­ing of higher-or­der cor­rec­tors will com­pen­sate for lower order er­rors. Ex­ist­ing cor­rec­tion schemes have also op­er­ated on the as­sump­tion of (anti-)sym­met­ric beta-func­tions of the op­tics in the two rings. This as­sump­tion can fail for a mul­ti­tude of rea­sons, such as in­her­ently asym­met­ric op­tics and un­evenly dis­trib­uted er­rors. In this re­spect, an ex­ten­sion of this cor­rec­tion scheme has been de­vel­oped, re­mov­ing the need for sym­me­try by op­er­at­ing on the two sep­a­rate op­tics of the beams si­mul­ta­ne­ously.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT061
About •	Received ※ 07 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022
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WEPOPT062	Optimisation of the FCC-ee Positron Source Using a HTS Solenoid Matching Device	2003
	Y. Zhao, S. Döbert, A. Latina, S. Ogur CERN, Meyrin, Switzerland B. Auchmann, P. Craievich, J. Kosse, R. Zennaro PSI, Villigen PSI, Switzerland I. Chaikovska, R. Chehab Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France M. Duda IFJ-PAN, Kraków, Poland P.V. Martyshkin BINP SB RAS, Novosibirsk, Russia
	In this paper, we pre­sent the sim­u­la­tion and op­ti­mi­sa­tion of the FCC-ee positron source, where a high-tem­per­a­ture su­per­con­duct­ing (HTS) so­le­noid is used as the match­ing de­vice to col­lect positrons from the tar­get. The "con­ven­tional" tar­get scheme is used which sim­ply con­sists of amor­phous tung­sten. The tar­get is placed in­side the bore of the HTS so­le­noid to im­prove the ac­cepted positron yield at the en­trance of the damp­ing ring and the lo­ca­tion of the tar­get is op­ti­mised. The lat­est rec­om­mended base­line beam pa­ra­me­ters are used and pre­sented. An op­ti­mi­sa­tion of the ideal positron yield using the an­a­lytic SC so­le­noid on-axis field is also per­formed and shows that the de­sign of the HTS so­le­noid is op­ti­mal as far as the ac­cepted positron yield is con­cerned.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT062
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 16 June 2022
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WEPOTK009	Processes and Tools to Manage CERN Programmed Stops Applied to the Second Long Shutdown of the Accelerator Complex	2048
	E. Vergara Fernandez, A. Ansel, M. Barberan Marin, M. Bernardini, S. Chemli, J. Coupard, K. Foraz, D. Hay, J.M. Jimenez, D.J. Mcfarlane, F. Pedrosa, M. Pirozzi, J.Ph.G.L. Tock CERN, Meyrin, Switzerland
	The prepa­ra­tion and fol­low-up of CERN ac­cel­er­a­tor com­plex pro­grammed stops re­quire clear processes and method­olo­gies. The LHC and its In­jec­tors were stopped in De­cem­ber 2018, to main­tain, con­sol­i­date and up­grade the dif­fer­ent equip­ment of the ac­cel­er­a­tor chain. Dur­ing the Long Shut­down 2 (LS2), major pro­jects were im­ple­mented such as the LHC In­jec­tors up­grade and the LHC Dipoles Diodes con­sol­i­da­tion. The in­stal­la­tion of some equip­ment of the HL-LHC pro­ject took also place. This paper pre­sents the ap­pli­ca­tion to the LS2 of the processes and tools to man­aged CERN pro­grammed stops: it cov­ers the prepa­ra­tion, im­ple­men­ta­tion and fol­low up phases, as well as the KPIs, the tools used to build a co­her­ent sched­ule and to fol­low up and re­port the progress. The de­scrip­tion of the method­ol­ogy to cre­ate a lin­ear sched­ule, as well the con­struc­tion of au­toma­tised bro­ken lines and progress curves are de­tailed. It also de­scribes the or­ga­ni­za­tional set-up for the co­or­di­na­tion of the works, the main ac­tiv­i­ties and the key mile­stones. The im­pact of the COVID-19 on the long shut­down will be de­scribed, es­pe­cially the strat­egy im­ple­mented to min­imise its con­se­quences.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK009
About •	Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 17 June 2022
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WEPOMS052	Impacts of an ATS Lattice on EIC Dynamic Aperture	2373
	J.E. Unger, J.A. Crittenden, G.H. Hoffstaetter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA D. Marx BNL, Upton, New York, USA
	The Elec­tron-Ion Col­lider (EIC) pro­ject at Brookhaven Na­tional Lab­o­ra­tory has ex­plored strate­gies for in­creas­ing the en­ergy aper­ture of the Elec­tron Stor­age Ring (ESR) to meet the goal of 1\% for the 90 de­gree lat­tice at 18 GeV. Cur­rent strate­gies use a four sex­tu­pole fam­ily per arc cor­rec­tion scheme to in­crease the en­ergy aper­ture and to keep the trans­verse aper­ture suf­fi­ciently large as well. A scheme called Achro­matic Tele­scopic Squeez­ing (ATS), first in­tro­duced for the Large Hadron Col­lider, in­tro­duces a beta-beat into se­lect arcs, al­low­ing dy­namic aper­ture op­ti­miza­tions with dif­fer­ent sex­tu­pole strengths. The ATS scheme’s mix of some higher beta-func­tion and some lower sex­tu­pole strengths in the arcs has the po­ten­tial to in­crease the en­ergy aper­ture. Basic chro­matic cor­rec­tions and nu­meric op­ti­miza­tions were used to com­pare the ATS op­tics to a non-ATS scheme. In all cases, the ATS scheme per­formed sim­i­larly or bet­ter than the more com­mon schemes. How­ever, this in­crease in en­ergy aper­ture from the ATS op­tics also has neg­a­tive ef­fects, such as an in­crease in emit­tance which poses com­pli­ca­tions for the cur­rent ESR de­sign.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS052
About •	Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 05 July 2022
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