THYGBD —  MC1 Orals   (03-May-18   11:00—12:30)
Chair: W. Fischer, BNL, Upton, Long Island, New York, USA
Paper Title Page
THYGBD1 FCC: Colliders at the Energy Frontier 2908
 
  • M. Benedikt, F. Zimmermann
    CERN, Geneva, Switzerland
  
  The in­ter­na­tional Fu­ture Cir­cu­lar Col­lider study, launched in 2014, is fi­nal­iz­ing a multi-vol­ume con­cep­tual de­sign re­port. The FCC de­vel­ops high-en­ergy cir­cu­lar col­lider op­tions based on a new 100 km tun­nel. Long-term goal is a 100 TeV pro­ton-pro­ton col­lider (FCC-hh). The study also in­cludes a high-lu­mi­nos­ity elec­tron-positron col­lider (FCC-ee), and it also ex­am­ines lep­ton-hadron sce­nar­ios (FCC-he). Civil en­gi­neer­ing and tech­ni­cal in­fra­struc­ture stud­ies were car­ried out. Global pro­grams ad­vance the de­vel­op­ment of high-field su­per­con­duct­ing mag­net tech­nol­ogy based on Nb3Sn, the op­ti­miza­tion of a suit­able large su­per­con­duct­ing RF sys­tem, and schemes for syn­chro­tron ra­di­a­tion han­dling. In ad­di­tion, the FCC study in­cludes the de­sign of the HE-LHC, housed in the LHC tun­nel, and based on the same high-field mag­net tech­nol­ogy as the FCC-hh. The FCC study fur­ther in­cludes an elab­o­ra­tion of the physics cases, in­clud­ing for heavy-ion col­li­sions, and de­tec­tor con­cepts, as well as stag­ing and im­ple­men­ta­tion sce­nar­ios. The FCC col­lab­o­ra­tion has grown to more than 120 in­sti­tutes from 30 coun­tries around the world. This in­vited talk sum­ma­rizes the study achieve­ments and the final de­signs.  
slides icon Slides THYGBD1 [12.503 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD1  
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THYGBD2 Results of UFO Dynamics Studies with Beam in the LHC 2914
 
  • B. Lindstrom, A. Apollonio, P. Bélanger, M. Dziadosz, A.A. Gorzawski, L. K. Grob, E.B. Holzer, A. Lechner, R. Schmidt, M. Valette, D. Valuch, D. Wollmann
    CERN, Geneva, Switzerland
  
  Mi­crom­e­ter sized par­ti­cles en­ter­ing the LHC beam (the so-called Uniden­ti­fied Falling Ob­jects or UFOs) are a known cause of lo­cal­ized beam losses since the be­gin­ning of high in­ten­sity beam op­er­a­tion, how­ever the ori­gin of these par­ti­cles is not fully known. Their ef­fect lim­its LHC avail­abil­ity by caus­ing pre­ma­ture dumps due to ex­ces­sive beam losses and oc­ca­sion­ally even mag­net quenches. This could be­come an im­por­tant lim­i­ta­tion for fu­ture ac­cel­er­a­tors such as the High Lu­mi­nos­ity up­grade of the LHC (HL-LHC) and the Fu­ture Cir­cu­lar Col­lider (FCC). The dy­nam­ics of these UFOs was in­ves­ti­gated in two ded­i­cated ex­per­i­ments. In the first ex­per­i­ment, it was shown that the trans­verse move­ments of these par­ti­cles can be stud­ied by ob­serv­ing bunch-by-bunch losses from bunches with dif­fer­ent hor­i­zon­tal and ver­ti­cal emit­tances. In the sec­ond ex­per­i­ment, UFO-like events around the 16L2 in­ter­con­nect in the LHC, which has seen in­tense UFO ac­tiv­ity in 2017, were stud­ied with the above method. This paper sum­ma­rizes the re­sults of both ex­per­i­ments.  
slides icon Slides THYGBD2 [1.357 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD2  
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THYGBD3 Beam-beam Studies for Super Proton-Proton Collider 2918
 
  • L.J. Wang, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  • K. Ohmipresenter
    KEK, Ibaraki, Japan
  
  In China, a two-stage cir­cu­lar col­lider pro­ject, CEPC-SPPC has been pro­posed. The first stage, CEPC (Cir­cu­lar Elec­tron Positron Col­lier, a so-called Higgs fac­tory) is fo­cused on the Higgs physics, and the sec­ond stage, SPPC (Super Pro­ton-Pro­ton Col­lider) will be an en­ergy fron­tier col­lider and a dis­cov­ery ma­chine. Lu­mi­nos­ity is a key fac­tor for any par­ti­cle-physics col­lid­ers. With the in­creas­ing bunch pop­u­la­tion, beam-beam in­ter­ac­tion is in­creas­ingly be­come the limit fac­tor of lu­mi­nos­ity im­prove­ment. The fi­nite cross­ing angle scheme is con­sid­ered firstly. Mean­while, long-range in­ter­ac­tion is an­other sig­nif­i­cant source of lu­mi­nos­ity de­grade. In this re­port, firstly, we don't con­sider long-range in­ter­ac­tions and study lu­mi­nos­ity de­grade with cross­ing angle and with­out cross­ing angle for hor­i­zon­tal cross­ing and hor­i­zon­tal-ver­ti­cal cross­ing. Sec­ondly we dis­cuss lu­mi­nos­ity decay with long-range in­ter­ac­tions for hor­i­zon­tal cross­ing and hor­i­zon­tal-ver­ti­cal cross­ing. Thirdly, we talk about emit­tance growth and lu­mi­nos­ity degra­da­tion using res­o­nance analy­sis for dif­fer­ent sce­nar­ios. Fi­nally the re­sult­ing beam-beam limit will be con­cluded for SPPC.  
slides icon Slides THYGBD3 [1.374 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD3  
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THYGBD4 Landau Damping by Electron Lenses 2921
 
  • A.V. Burov, Y.I. Alexahin, V.D. Shiltsev, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  Mod­ern and fu­ture par­ti­cle ac­cel­er­a­tors em­ploy in­creas­ingly higher in­ten­sity and brighter beams of charged par­ti­cles and be­come op­er­a­tionally lim­ited by co­her­ent beam in­sta­bil­i­ties. Usual meth­ods to con­trol the in­sta­bil­i­ties, such as oc­tu­pole mag­nets, beam feed­back dampers and use of chro­matic ef­fects, be­come less ef­fec­tive and in­suf­fi­cient. We show that, in con­trast, Lorentz forces of a low-en­ergy, mag­net­i­cally sta­bi­lized elec­tron beam, or "elec­tron lens", eas­ily in­tro­duces trans­verse non­lin­ear fo­cus­ing suf­fi­cient for Lan­dau damp­ing of trans­verse beam in­sta­bil­i­ties in ac­cel­er­a­tors. It is also im­por­tant to note that, un­like other non­lin­ear el­e­ments, the elec­tron lens pro­vides the fre­quency spread mainly at the beam core, thus al­low­ing much higher fre­quency spread with­out life­time degra­da­tion. For the pa­ra­me­ters of the Fu­ture Cir­cu­lar Col­lider, a sin­gle con­ven­tional elec­tron lens a few me­ters long would pro­vide sta­bi­liza­tion su­pe­rior to tens of thou­sands of su­per­con­duct­ing oc­tu­pole mag­nets.  
slides icon Slides THYGBD4 [4.502 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD4  
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