• D. Alesini, A. Battisti, O. Coiro, T. Demma, S. Guiducci, V. Lollo, C. Milardi, P. Raimondi, M. Serio, R.S. Sorchetti, M. Zobov
  INFN/LNF, Frascati (Roma)

Metal­lic clear­ing elec­trodes have been de­signed to ab­sorb the pho­to-elec­trons in the DAΦNE positron ring. They have been in­sert­ed in the wig­glers and dipoles vac­u­um cham­bers and have been con­nect­ed to ex­ter­nal high volt­age gen­er­a­tors. In the paper we pre­sent the de­sign of the de­vices and the re­sults of the elec­tro­mag­net­ic sim­u­la­tions re­lat­ed to both the trans­fer and lon­gi­tu­di­nal beam cou­pling impedances. We also pre­sent the re­sults of the RF mea­sure­ments and the first re­sults with the DAΦNE cir­cu­lat­ing positron beam.

• T. Demma
  INFN/LNF, Frascati (Roma)
• S. Petracca, A. Stabile
  U. Sannio, Benevento

The bunch-to-bunch evo­lu­tion of the elec­tron cloud den­si­ty can be mod­eled using a cubic map. The map ap­proach has been proved re­li­able for RHIC* and LHC**. The co­ef­fi­cients that pa­ram­e­ter­ize the map may be ob­tained by fit­ting from time con­sum­ing nu­mer­i­cal sim­u­la­tions. In this com­mu­ni­ca­tion we de­rive a sim­ple ap­prox­i­mate for­mu­la for the quadrat­ic co­ef­fi­cient, which de­ter­mines the sat­u­ra­tion of the cloud due to space charge, in the elec­tron cloud den­si­ty map, under the as­sump­tions of round cham­bers and free-field mo­tion of the elctrons in the cloud. Re­sults are com­pared with sim­u­la­tions for a wide range of pa­ram­e­ters gov­ern­ing the evo­lu­tion of the elctron cloud.

* U.Iriso, S.Peggs, Phys. Rev.STAB 8, 024403, 2005.
** T.Demma, S.Petracca, G.Rumolo, F.Ruggiero, F.Zimmermann, Phys. Rev.STAB 10, 114401, 2007.

• T. Demma
  INFN/LNF, Frascati (Roma)
• M.T.F. Pivi
  SLAC, Menlo Park, California

Some col­lec­tive ef­fects have been stud­ied for the Su­perB* high lu­mi­nos­i­ty col­lid­er. Es­ti­mates of the ef­fect of Intra Beam Scat­ter­ing on the emit­tance and en­er­gy spread growths have been car­ried up for both the High En­er­gy (HER, positrons) and the Low En­er­gy (LER, elec­trons) rings. Elec­tron cloud build up sim­u­la­tions for HER were per­formed with the ECLOUD code, de­vel­oped at CERN**, to pre­dict the cloud for­ma­tion in the arcs, tak­ing into ac­count pos­si­ble re­me­di­a­tion tech­niques such as clear­ing elec­trodes. The new code CMAD, de­vel­oped at SLAC***, has been used to study the ef­fect of this elec­tron cloud on the beam and as­sess the thresh­olds above which the elec­tron cloud in­sta­bil­i­ty would set in.

* M. E. Biagini, proceedings of PAC'09.
** F. Zimmermann, CERN, LHC-Project-Report-95, 1997.
*** M. Pivi, proceedings of PAC'09.

• M.A. Palmer, J.P. Alexander, M.G. Billing, J.R. Calvey, C.J. Conolly, J.A. Crittenden, J. Dobbins, G. Dugan, N. Eggert, E. Fontes, M.J. Forster, R.E. Gallagher, S.W. Gray, S. Greenwald, D.L. Hartill, W.H. Hopkins, D.L. Kreinick, B. Kreis, Z. Leong, Y. Li, X. Liu, J.A. Livezey, A. Lyndaker, J. Makita, M.P. McDonald, V. Medjidzade, R.E. Meller, T.I. O'Connell, S.B. Peck, D.P. Peterson, G. Ramirez, M.C. Rendina, P. Revesz, D.H. Rice, N.T. Rider, D. L. Rubin, D. Sagan, J.J. Savino, R.M. Schwartz, R.D. Seeley, J.W. Sexton, J.P. Shanks, J.P. Sikora, E.N. Smith, C.R. Strohman, H.A. Williams
  CLASSE, Ithaca, New York
• F. Antoniou, S. Calatroni, M. Gasior, O.R. Jones, Y. Papaphilippou, J. Pfingstner, G. Rumolo, H. Schmickler, M. Taborelli
  CERN, Geneva
• D. Asner
  Carleton University, College of Natural Sciences, Ottawa, Ontario
• L. Boon, A.F. Garfinkel
  Purdue University, West Lafayette, Indiana
• J.M. Byrd, C.M. Celata, J.N. Corlett, S. De Santis, M.A. Furman, A. Jackson, R. Kraft, D.V. Munson, G. Penn, D.W. Plate, M. Venturini
  LBNL, Berkeley, California
• B.T. Carlson
  Grove City College, Grove City, Pennsylvania
• T. Demma
  INFN/LNF, Frascati (Roma)
• R.T. Dowd
  ASCo, Clayton, Victoria
• J.W. Flanagan, P. Jain, K. Kanazawa, K. Kubo, K. Ohmi, H. Sakai, K. Shibata, Y. Suetsugu, M. Tobiyama
  KEK, Ibaraki
• D. Gonnella
  Clarkson University, Potsdam, New York
• W. Guo
  BNL, Upton, Long Island, New York
• K.C. Harkay
  ANL, Argonne
• R. Holtzapple
  CalPoly, San Luis Obispo, CA
• J.K. Jones, A. Wolski
  Cockcroft Institute, Warrington, Cheshire
• D. Kharakh, J.S.T. Ng, M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• M.C. Ross, C.-Y. Tan, R.M. Zwaska
  Fermilab, Batavia
• L. Schächter
  Technion, Haifa
• E.L. Wilkinson
  Loyola University, Chicago, Illinois

The Cor­nell Elec­tron Stor­age Ring (CESR) has been re­con­fig­ured as a test ac­cel­er­a­tor (Ces­r­TA) for a pro­gram of elec­tron cloud (EC) re­search at ultra low emit­tance. The in­stru­men­ta­tion in the ring has been up­grad­ed with local di­ag­nos­tics for mea­sure­ment of cloud den­si­ty and with im­proved beam di­ag­nos­tics for the char­ac­ter­i­za­tion of both the low emit­tance per­for­mance and the beam dy­nam­ics of high in­ten­si­ty bunch trains in­ter­act­ing with the cloud. Fi­nal­ly a range of EC mit­i­ga­tion meth­ods have been de­ployed and test­ed. Mea­sure­ments of cloud den­si­ty and its im­pact on the beam under a range of con­di­tions will be pre­sent­ed and com­pared with sim­u­la­tions. The ef­fec­tive­ness of a range of mit­i­ga­tion tech­niques will also be dis­cussed.

Slides

• M.E. Biagini, D. Alesini, R. Boni, M. Boscolo, T. Demma, A. Drago, M. Esposito, S. Guiducci, F. Marcellini, G. Mazzitelli, M.A. Preger, P. Raimondi, C. Sanelli, M. Serio, A. Stecchi, A. Stella, S. Tomassini, M. Zobov
  INFN/LNF, Frascati (Roma)
• M.A. Baylac, J.-M. De Conto, Y. Gomez-Martinez, N. Monseu, D. Tourres
  LPSC, Grenoble
• K.J. Bertsche, A. Brachmann, Y. Cai, A. Chao, M.H. Donald, A.S. Fisher, D. Kharakh, A. Krasnykh, N. Li, D.B. MacFarlane, Y. Nosochkov, A. Novokhatski, M.T.F. Pivi, J. Seeman, M.K. Sullivan, A.W. Weidemann, J. Weisend, U. Wienands, W. Wittmer, A.C. de Lira
  SLAC, Menlo Park, California
• S. Bettoni
  CERN, Geneva
• B. Bolzon, L. Brunetti, A. Jeremie
  IN2P3-LAPP, Annecy-le-Vieux
• J. Bonis, G. Le Meur, B.M. Mercier, F. Poirier, C. Prevost, C. Rimbault, F. Touze, A. Variola
  LAL, Orsay
• F. Bosi
  INFN-Pisa, Pisa
• A. Chancé, F. Méot, O. Napoly
  CEA, Gif-sur-Yvette
• R. Chehab
  IN2P3 IPNL, Villeurbanne
• I. Koop, E.B. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov, S.V. Sinyatkin
  BINP SB RAS, Novosibirsk
• S.M. Liuzzo, E. Paoloni
  University of Pisa and INFN, Pisa

The Su­perB pro­ject is an in­ter­na­tion­al ef­fort aim­ing at build­ing in Italy a very high lu­mi­nos­i­ty e⁺e^- (10³⁶ cm^-2 sec^-1) asym­met­ric col­lid­er at the B mesons cm en­er­gy. The ac­cel­er­a­tor de­sign has been ex­ten­sive­ly stud­ied and changed dur­ing the past year. The pre­sent de­sign, - based on the new col­li­sion scheme, with large Pi­win­s­ki angle and the use of 'crab' sex­tupoles, which has been suc­cess­ful­ly test­ed at the DAPHNE Phi-Fac­to­ry at LNF Fras­cati, - pro­vides larg­er flex­i­bil­i­ty, bet­ter dy­nam­ic aper­ture and in the Low En­er­gy Ring spin ma­nip­u­la­tion sec­tions, need­ed for hav­ing lon­gi­tu­di­nal po­lar­iza­tion of the elec­tron beam at the In­ter­ac­tion Point. The In­ter­ac­tion Re­gion has been fur­ther op­ti­mized in terms of aper­tures and re­duced back­grounds in the de­tec­tor. The in­jec­tor com­plex de­sign has been also up­dat­ed. A sum­ma­ry of the de­sign sta­tus, in­clud­ing de­tails on lat­tice and spin ma­nip­u­la­tion will be pre­sent­ed in this paper.

• C. Milardi, D. Alesini, M.E. Biagini, C. Biscari, R. Boni, M. Boscolo, F. Bossi, B. Buonomo, A. Clozza, G.O. Delle Monache, T. Demma, E. Di Pasquale, G. Di Pirro, A. Drago, M. Esposito, A. Gallo, A. Ghigo, S. Guiducci, C. Ligi, F. Marcellini, G. Mazzitelli, L. Pellegrino, M.A. Preger, L. Quintieri, P. Raimondi, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, S. Tomassini, C. Vaccarezza, M. Zobov
  INFN/LNF, Frascati (Roma)
• S. Bettoni
  CERN, Geneva
• E.B. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov
  BINP SB RAS, Novosibirsk

Re­cent­ly the peak lu­mi­nos­i­ty achieved on the DAΦNE col­lid­er has been im­proved by al­most a fac­tor 3 by im­ple­ment­ing a novel col­li­sion scheme based on large Pi­win­s­ki angle and Crab-Waist. This en­cour­ag­ing re­sult opened new per­spec­tives for physics re­search and a new run with the KLOE-2 de­tec­tor has been sched­uled to start by spring 2010. The KLOE-2 in­stal­la­tion is a com­plex op­er­a­tion re­quir­ing a care­ful de­sign ef­fort and a sev­er­al months long shut­down. The high lu­mi­nos­i­ty in­ter­ac­tion re­gion has been deeply re­vised in order to take into ac­count the ef­fect on the beam caused by the solenoidal field of the ex­per­i­men­tal de­tec­tor and to en­sure back­ground re­jec­tion. The shut­down has been also used to im­ple­ment sev­er­al other mod­i­fi­ca­tions aimed at im­prov­ing beam dy­nam­ics: the wig­gler poles have been dis­placed from the mag­net axis in order to can­cel high order terms in the field, the feed­back sys­tems have been equipped with stronger power sup­plies and more ef­fi­cient kick­ers and elec­trodes have been in­sert­ed in­side the wig­gler and the dipole vac­u­um cham­bers, in the positron ring, to avoid the e-cloud for­ma­tion. A low level RF feed­back has been added to the cav­i­ty con­trol in both rings.

• M.T.F. Pivi, L. Wang
  SLAC, Menlo Park, California
• C.M. Celata, M.A. Furman, M. Venturini
  LBNL, Berkeley, California
• J.A. Crittenden, G. Dugan, M.A. Palmer
  CLASSE, Ithaca, New York
• T. Demma, S. Guiducci
  INFN/LNF, Frascati (Roma)
• K.C. Harkay
  ANL, Argonne
• O.B. Malyshev
  Cockcroft Institute, Warrington, Cheshire
• K. Ohmi, K. Shibata, Y. Suetsugu
  KEK, Ibaraki
• Y. Papaphilippou, G. Rumolo
  CERN, Geneva

As part of the In­ter­na­tion­al Lin­ear Col­lid­er (ILC) col­lab­o­ra­tion, we have com­pared the elec­tron cloud ef­fect for dif­fer­ent Damp­ing Ring de­signs re­spec­tive­ly with 6.4 km and 3.2 km cir­cum­fer­ence and in­ves­ti­gat­ed the fea­si­bil­i­ty of a short­er damp­ing ring with re­spect to the elec­tron cloud build-up and re­lat­ed beam in­sta­bil­i­ty. These stud­ies were car­ried out with beam pa­ram­e­ters of the ILC Low Power op­tion. A re­duced damp­ing ring cir­cum­fer­ence has been pro­posed for the new ILC base­line de­sign and would allow to con­sid­er­ably re­duce the num­ber of com­po­nents, wig­gler mag­nets and costs. We also briefly dis­cuss the plans for fu­ture stud­ies in­clud­ing the lu­mi­nos­i­ty up­grade op­tion with short­er bunch spac­ing, the eval­u­a­tion of mit­i­ga­tions and the in­te­gra­tion of the Ces­r­TA re­sults into the Damp­ing Ring de­sign.