Author: Zimmermann, F.
Paper Title Page
MOPWO010 Machine Protection Studies for a Crab Cavity in the LHC 906
 
  • B. Yee-Rendon, R. Lopez-Fernandez
    CINVESTAV, Mexico City, Mexico
  • T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: US-LARP and CONACYT
Crab cav­i­ties (CCs) apply a trans­verse kick that ro­tate the bunches so as to have a head-on col­li­sion at the in­ter­ac­tion point (IP). Such cav­i­ties were suc­cess­fully used to im­prove the lu­mi­nos­ity of KEKB. They are also a key in­gre­di­ent of the HL-LHC pro­ject to in­crease the lu­mi­nos­ity of the LHC. As CCs can rapidly change the par­ti­cle tra­jec­to­ries, ma­chine pro­tec­tion stud­ies are re­quired to as­sess the beam losses due to fast CC fail­ures. In this paper, we dis­cuss the ef­fect of rapid volt­age or phase changes in a CC for the HL-LHC lay­out using mea­sured beam dis­tri­b­u­tions from the pre­sent LHC. 		 
 
MOPWO036 Civil Engineering Feasibility Studies for Future Ring Colliders at CERN 969
 
  • J.A. Osborne, O.S. Brüning, M. Klein, S. Myers, S. Myers, L. Rossi, C.S. Waaijer, F. Zimmermann
    CERN, Geneva, Switzerland
  • M. Klein
    DESY Zeuthen, Zeuthen, Germany
  
  CERN civil en­gi­neers are study­ing the fea­si­bil­ity of fu­ture ring col­lid­ers to com­ple­ment the LHC. In­fra­struc­ture works typ­i­cally rep­re­sent one third of the cost of major physics pro­jects, so it's crit­i­cal that the con­struc­tion costs are well un­der­stood from the con­cep­tual stage. This poster pre­sents the first re­sults of the fea­si­bil­ity stud­ies for two po­ten­tial ring col­lid­ers at CERN: the race­track shaped Linac-Ring LHeC and an 80km cir­cu­lar tun­nel to house the High En­ergy LHC (SHE-LHC) and the TLEP. Some of the key civil en­gi­neer­ing chal­lenges faced in such large scale pro­jects are pre­sented with par­tic­u­lar em­pha­sis on ge­ol­ogy, de­sign and risk.  
 
MOPWO054 The LHeC as a Higgs Boson Factory 1017
 
  • F. Zimmermann, O.S. Brüning
    CERN, Geneva, Switzerland
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  
  The LHeC is de­signed to col­lide a new 60 GeV en­ergy elec­tron beam, from a 3-pass ERL, with the 7 TeV en­ergy LHC pro­ton beam. At the pre­sent tar­get ep lu­mi­nos­ity of 1033cm-2s-1, the LHeC would pro­duce a few 1000 Higgs bosons per year, al­low­ing for pre­ci­sion cou­pling mea­sure­ments, es­pe­cially of the H –> b bbar decay in charged cur­rent deep in­elas­tic scat­ter­ing (ep –> nu H X). With a sig­nif­i­cant in­crease of the lu­mi­nos­ity, rarer chan­nels be­come ac­ces­si­ble, as the charm decay. Here such an in­crease, to the level of 1034cm-2s-1 or even be­yond, is con­sid­ered from a com­bi­na­tion of im­prove­ments, namely with a smaller pro­ton beam emit­tance, with a fur­ther re­duc­tion of the pro­ton IP beta func­tion, an in­crease of the pro­ton bunch in­ten­sity and with dou­bling the lep­ton beam cur­rent, com­pared to the canon­i­cal val­ues as­sumed in the CDR.  
 
TUPFI002 Electron Cloud and Scrubbing Studies for the LHC 1331
 
  • G. Iadarola
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  • G. Arduini, V. Baglin, H. Bartosik, C.O. Domínguez, J.F. Esteban Müller, G. Iadarola, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, F. Zimmermann
    CERN, Geneva, Switzerland
  • C.O. Domínguez
    EPFL, Lausanne, Switzerland
  • G.H.I. Maury Cuna
    CINVESTAV, Mexico City, Mexico
  
  Elec­tron cloud build-up re­sult­ing from beam-in­duced mul­ti­pact­ing is one of the major lim­i­ta­tions for the op­er­a­tion of the LHC with beams with close bunch spac­ing. Elec­tron clouds in­duce un­wanted pres­sure rise, heat loads on the beam screens of the su­per­con­duct­ing mag­nets and beam in­sta­bil­i­ties. Op­er­a­tion with bunch spac­ing of 50 ns in 2011 and 2012 has re­quired de­creas­ing the Sec­ondary Elec­tron Yield of the beam screens below the mul­ti­pact­ing thresh­old for beams with this bunch spac­ing. This was achieved by con­tin­u­ous elec­tron bom­bard­ment in­duced by op­er­at­ing the ma­chine with high in­ten­sity beams with 50 and 25 ns spac­ing dur­ing ded­i­cated pe­ri­ods at in­jec­tion en­ergy (450 GeV) and at top en­ergy (3.5 and 4 TeV). The evo­lu­tion of the Sec­ondary Elec­tron Yield dur­ing these pe­ri­ods, at dif­fer­ent sec­tions of the ma­chine, can be es­ti­mated by pres­sure, heat load and by bunch-by-bunch RF sta­ble phase mea­sure­ments. The ex­per­i­men­tal in­for­ma­tion on the scrub­bing process will be dis­cussed and a pos­si­ble “scrub­bing strat­egy” to allow the op­er­a­tion with 50ns and 25ns beams after the Long Shut­down in 2013-2014 will be pre­sented.  
 
TUPFI005 Synchrotron-Radiation Photon Distribution for Highest Energy Circular Colliders 1340
 
  • G.H.I. Maury Cuna
    CINVESTAV, Mérida, Mexico
  • G. Dugan, D. Sagan
    CLASSE, Ithaca, New York, USA
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Funding: Acknowledgements to CINVESTAV, CERN and EPLANET project.
At high en­er­gies, beam-in­duced syn­chro­tron ra­di­a­tion is an im­por­tant source of heat­ing, beam-re­lated vac­uum pres­sure in­crease, and pri­mary pho­to­elec­trons, which can give rise to an elec­tron cloud. The pho­ton dis­tri­b­u­tion along the beam pipe wall is a key input to codes such as ECLOUD and PyE­CLOUD, which model the elec­tron cloud build-up. For fu­ture high-en­ergy col­lid­ers, like TLEP or SHE-LHC, pho­ton stops and an­techam­bers are con­sid­ered in order to fa­cil­i­tate cool­ing and vac­uum pres­sure con­trol. We use the Syn­rad3D code de­vel­oped at Cor­nell to sim­u­late the pho­ton dis­tri­b­u­tion for the LHC. 		 
 
TUPFI030 LHC Machine Developments in 2011-12 1406
 
  • G. Papotti, R.W. Aßmann, F. Zimmermann
    CERN, Geneva, Switzerland
  
  In 2011 and 2012 LHC ma­chine de­vel­op­ment (MD) ses­sions were per­formed dur­ing ded­i­cated slots of beam time. These MD stud­ies were sched­uled and planned well in ad­vance. Study top­ics re­flected the pre­vi­ously agreed pri­or­i­ties, such as fur­ther op­ti­miz­ing ma­chine per­for­mance, ex­plor­ing beam pa­ra­me­ters be­yond de­sign tar­gets, as­sess­ing ma­chine lim­i­ta­tions, test­ing new con­cepts and ma­chine set­tings, prepar­ing fu­ture LHC run­ning in view of the 2013/14 LHC shut­down and the re-com­mis­sion­ing of the LHC at nom­i­nal beam en­ergy in 2014/15. We de­scribe the plan­ning, prepa­ra­tion, ex­e­cu­tion, re­view, and doc­u­men­ta­tion of these LHC beam stud­ies and high­light some key re­sults.  
 
TUPFI042 Beam Parameters and Luminosity Time Evolution for an 80-km VHE-LHC 1442
 
  • C.O. Domínguez, F. Zimmermann
    CERN, Geneva, Switzerland
  
  The Very High En­ergy LHC (VHE-LHC) is a re­cently pro­posed pro­ton-pro­ton col­lider in a new 80-km tun­nel. With a di­pole field of 15-20 T it would pro­vide a col­li­sion en­ergy of 76-100 TeV c.m. We dis­cuss the VHE-LHC beam pa­ra­me­ters and com­pute the time evo­lu­tion of lu­mi­nos­ity, beam cur­rent, emit­tances, bunch length, and beam-beam tune shift dur­ing a physics store. The re­sults for VHE-LHC are com­pared with those for HE-LHC, a 33-TeV (20-T field) col­lider lo­cated in the ex­ist­ing LHC tun­nel.  
 
TUPFI043 Matching Antisymmetric Arc Optics to Symmetric Interaction Region 1445
 
  • J.L. Abelleira, F. Zimmermann
    CERN, Geneva, Switzerland
  • J.L. Abelleira
    EPFL, Lausanne, Switzerland
  
  Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
Con­sid­er­ing a generic dou­ble-ring col­lider, we dis­cuss the match­ing from an an­ti­sym­met­ric op­tics in the arcs to a sym­met­ric op­tics in the in­ter­ac­tion re­gion (IR) by means of an an­ti­sym­met­ric match­ing sec­tion (MS). As an ex­am­ple, we pre­sent an ap­pli­ca­tion to the LHC, for which a sym­met­ric IR with ex­tremely flat beams is under study. 		 
 
TUPFI044 LHC Optics with Crab-waist Collisions and Local Chromatic Correction 1448
 
  • J.L. Abelleira, S. Russenschuck, F. Zimmermann
    CERN, Geneva, Switzerland
  • C. Milardi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  
  Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
We re­port the sta­tus of the op­tics de­sign for a local chro­matic cor­rec­tion with ex­tremely-flat beams at the LHC. To­gether with a Large Pi­win­ski angle, this op­tics opens up the pos­si­bil­ity of crab-waist col­li­sions at the LHC, for which a new lay­out of the LHC in­ser­tion re­gion (IR) is needed. We pre­sent a com­plete op­tics and dis­cuss the pa­ra­me­ters of the final "dou­ble-half" quadru­pole. 		 
 
TUPFI045 Electron-cloud Maps for LHC Scrubbing Optimization 1451
 
  • C.O. Domínguez, F. Zimmermann
    CERN, Geneva, Switzerland
  
  Elec­tron-cloud maps as al­ter­na­tive to de­tailed build-up sim­u­la­tions have al­ready been ap­plied in the past for a few ac­cel­er­a­tors, e.g. RHIC and the LHC at 7 TeV. We here re­port a first ap­pli­ca­tion of maps to op­ti­mize the "beam scrub­bing" of the LHC arcs at in­jec­tion en­ergy: Maps are used to ef­fi­ciently de­ter­mine the op­ti­mum bunch fill­ing pat­tern which max­i­mizes the elec­tron flux on the cham­ber wall, while re­spect­ing con­straints on the cen­tral cloud den­sity to en­sure beam sta­bil­ity. In ad­di­tion, new fea­tures have been ex­plored, e.g. by in­tro­duc­ing thresh­olds which di­vide re­gions where ei­ther lin­ear maps or cubic maps best de­scribe the build-up and the decay of an elec­tron cloud. In the near fu­ture we plan to ex­tend the map for­mal­ism to in­di­vid­ual slices in a di­pole file in order to rep­re­sent the ver­ti­cal "stripes".  
 
TUPME011 Simulated Beam-beam Limit for Circular Higgs Factories 1586
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  We re­port sim­u­la­tion stud­ies of the beam-beam limit for two pro­posed cir­cu­lar e+e− Higgs fac­to­ries with cir­cum­fer­ence of 27 and 80 km, re­spec­tively, called LEP3 and TLEP. In par­tic­u­lar we in­ves­ti­gate the de­pen­dence of the steady-state lu­mi­nos­ity and trans­verse beam sizes on the syn­chro­tron tune (or mo­men­tum com­paction fac­tor) and on the be­ta­tron tunes, as well as the con­se­quences of the strong ra­di­a­tion damp­ing and the im­pli­ca­tions of the large hour­glass ef­fect.  
 
TUPME040 TLEP: High-performance Circular e+e− Collider to Study the Higgs Boson 1658
 
  • M. Koratzinos, O. Brunner, A.C. Butterworth, J.R. Ellis, P. Janot, E. Jensen, J.A. Osborne, F. Zimmermann
    CERN, Geneva, Switzerland
  • R. Aleksan
    CEA/DSM/IRFU, France
  • A.P. Blondel
    DPNC, Genève, Switzerland
  • M. Zanetti
    MIT, Cambridge, Massachusetts, USA
  
  The re­cent dis­cov­ery of a light Higgs boson has opened up con­sid­er­able in­ter­est in cir­cu­lar e+e− Higgs fac­to­ries around the world. We re­port on the progress of the “TLEP3” con­cept since last year. Two op­tions are con­sid­ered: LEP3, a 240 GeV cen­tre-of-mass (Ecm) e+e− ma­chine in the LHC tun­nel with cost only a frac­tion of the cost of an equiv­a­lent lin­ear col­lider, due to the use of ex­ist­ing in­fra­struc­ture and the two gen­eral-pur­pose LHC de­tec­tors, and TLEP, an e+e− ma­chine in a new 80 km tun­nel that can op­er­ate up to an Ecm of 350 GeV. Both con­cepts enjoy the ex­ten­sive know-how on cir­cu­lar col­lid­ers and how to de­liver their de­sign lu­mi­nos­ity, and the ex­is­tence of up to four in­ter­ac­tion points. The at­tain­able lu­mi­nosi­ties are 1034/cm2/s and 5x1034/cm2/s per in­ter­ac­tion point for LEP3 and TLEP re­spec­tively. Both ma­chines can op­er­ate as Tera-Z and Mega-W boson fac­to­ries, giv­ing de­ci­sive op­por­tu­ni­ties for over-con­strain­ing the elec­troweak sec­tor of the Stan­dard Model. The tech­ni­cal chal­lenges and pos­si­ble ways to im­prove the per­for­mance fur­ther will be dis­cussed.  
 
TUPME055 Strawman Optics Design for the CERN LHeC ERL Test Facility 1694
 
  • A. Valloni, O.S. Brüning, R. Calaga, E. Jensen, M. Klein, R. Tomás, F. Zimmermann
    CERN, Geneva, Switzerland
  • S.A. Bogacz, D. Douglas
    JLAB, Newport News, Virginia, USA
  
  In prepa­ra­tion for a fu­ture Large Hadron elec­tron Col­lider (LHeC) at CERN, an ERL test fa­cil­ity is fore­seen as a test bed for SRF de­vel­op­ment, cryo­gen­ics, and ad­vanced beam in­stru­men­ta­tion, as well as for stud­ies of ERL-spe­cific beam dy­nam­ics. The CERN ERL test fa­cil­ity would com­prise two linacs, each con­sist­ing of 4 su­per­con­duct­ing 5-cell cav­i­ties at 802 MHz, and two re­turn arcs on ei­ther side. With an RF volt­age of 75 MeV per linac a final elec­tron en­ergy of about 300 MeV is reached. The av­er­age beam cur­rent should be above 6 mA to ex­plore the pa­ra­me­ter range of the fu­ture LHeC. In this paper we pre­sent a pre­lim­i­nary op­tics lay­out.  
 
TUPME056 3.5 GeV Superconducting Stacking Ring for Compton Based Polarized Positrons Source of CLIC 1697
 
  • E.V. Bulyak, P. Gladkikh, A.A. Kalamayko
    NSC/KIPT, Kharkov, Ukraine
  • T. Omori, J. Urakawa, K. Yokoya
    KEK, Ibaraki, Japan
  • L. Rinolfi, F. Zimmermann
    CERN, Geneva, Switzerland
  
  This paper de­scribes 3.5 GeV su­per­con­duct­ing stor­age ring ded­i­cated to positron ac­cu­mu­la­tion as part of a po­lar­ized positron source for CLIC, based on Comp­ton scat­ter­ing in a Comp­ton stor­age ring. The su­per­con­duct­ing stack­ing ring can pro­vide a syn­chro­tron damp­ing time of order 250 mi­crosec­onds. To­gether with com­bined in­jec­tion scheme in the lon­gi­tu­di­nal and trans­verse plane, such a ring may solve the prob­lem of ac­cu­mu­lat­ing a positron beam with ef­fi­ciency close to 95 % and with the beam in­ten­sity re­quired for CLIC.  
 
TUPWA050 Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings 1823
 
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • J. Urakawa
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  Fast cool­ing of bunches cir­cu­lat­ing in a Comp­ton ring is achieved by plac­ing the col­li­sion point be­tween elec­tron bunches and laser pulses in a dis­per­sive sec­tion and by, in ad­di­tion, in­tro­duc­ing a trans­verse off­set be­tween the laser pulse and the elec­tron-beam closed orbit. Growth of the emit­tance in the dis­per­sive trans­ver­sal di­rec­tion due to the ad­di­tional ex­ci­ta­tion of be­ta­tron os­cil­la­tions lim­its this type of cool­ing. Here we pre­sent the re­sults of fur­ther stud­ies on the fast cool­ing process, look­ing at the ef­fect of the cou­pling of the trans­verse (be­ta­tron) os­cil­la­tions. We first show the­o­ret­i­cally that the trans­verse be­ta­tron cou­pling short­ens the cool­ing time and hence re­duces the steady-state en­ergy spread of the elec­tron beam, as well as the quan­tum losses. The the­o­ret­i­cal es­ti­mates are then val­i­dated by sim­u­la­tions. Fi­nally, a proof-of-prin­ci­ple ex­per­i­ment at the KEK ATF Damp­ing Ring is pro­posed.