• K.A. Brown, L. Ahrens, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, D. Bruno, C. Carlson, R. Connolly, T. D'Ottavio, R. De Maria, K.A. Drees, W. Fischer, W. Fu, C.J. Gardner, D.M. Gassner, J.W. Glenn, Y. Hao, M. Harvey, T. Hayes, L.T. Hoff, H. Huang, J.S. Laster, R.C. Lee, V. Litvinenko, Y. Luo, W.W. MacKay, M. Mapes, G.J. Marr, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, B. Oerter, F.C. Pilat, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, P. Sampson, J. Sandberg, T. Satogata, V. Schoefer, C. Schultheiss, F. Severino, K. Smith, D. Steski, S. Tepikian, C. Theisen, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York

Since the last suc­cess­ful RHIC Au+Au run in 2007 (Run7), the RHIC ex­per­i­ments have made nu­mer­ous de­tec­tor im­prove­ments and up­grades. In order to ben­e­fit from the en­hanced de­tec­tor ca­pa­bil­i­ties and to in­crease the yield of rare events in the ac­quired heavy ion data a sig­nif­i­cant in­crease in lu­mi­nos­i­ty is es­sen­tial. In Run7 RHIC achieved an av­er­age store lu­mi­nos­i­ty of <L>=12x10²⁶ cm^-2 s^-1 by op­er­at­ing with 103 bunch­es (out of 110 pos­si­ble), and by squeez­ing to β*=0.8 m. Our goal for this year's run, Run10, was to achieve an av­er­age of <L>=27x10²⁶ cm^-2 s^-1. The mea­sures taken were de­creas­ing β* to 0.6 m, and re­duc­ing lon­gi­tu­di­nal and trans­verse emit­tances by means of bunched-beam stochas­tic cool­ing. In ad­di­tion we in­tro­duced a lat­tice to sup­press in­tra-beam scat­ter­ing (IBS) in both RHIC rings, up­grad­ed the RF sys­tem, and sep­a­rat­ed tran­si­tion cross­ings in both rings while ramp­ing. We pre­sent an overview of the changes and the re­sults in terms of Run10 in­creased in­stan­ta­neous lu­mi­nos­i­ty, lu­mi­nos­i­ty life­time, and in­te­grat­ed lu­mi­nos­i­ty.

• C. Montag, L. Ahrens, M. Bai, J. Beebe-Wang, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, A.V. Fedotov, W. Fischer, G. Ganetis, C.J. Gardner, J.W. Glenn, H. Hahn, M. Harvey, T. Hayes, H. Huang, P.F. Ingrassia, J.P. Jamilkowski, A. Kayran, J. Kewisch, R.C. Lee, D.I. Lowenstein, A.U. Luccio, Y. Luo, W.W. MacKay, Y. Makdisi, N. Malitsky, G.J. Marr, A. Marusic, M.P. Menga, R.J. Michnoff, M.G. Minty, J. Morris, B. Oerter, F.C. Pilat, P.H. Pile, E. Pozdeyev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, T. Russo, T. Satogata, V. Schoefer, C. Schultheiss, F. Severino, M. Sivertz, K. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
  BNL, Upton, Long Island, New York

Dur­ing the sec­ond half of Run-9, the Rel­a­tivis­tic Heavy Ion Col­lid­er (RHIC) pro­vid­ed po­lar­ized pro­ton col­li­sions at two in­ter­ac­tion points with both lon­gi­tu­di­nal and ver­ti­cal spin di­rec­tion. De­spite an in­crease in the peak lu­mi­nos­i­ty by up to 40%, the av­er­age store lu­mi­nos­i­ty did not in­crease com­pared to pre­vi­ous runs. We dis­cuss the lu­mi­nos­i­ty lim­i­ta­tions and po­lar­iza­tion per­for­mance dur­ing Run-9.

• C. Montag, M. Blaskiewicz, J.M. Brennan, S. Tepikian
  BNL, Upton, Long Island, New York

Dur­ing the ac­cel­er­a­tion pro­cess, heavy ion beams in RHIC cross the tran­si­tion en­er­gy. When RHIC was col­lid­ing deuterons and gold ions dur­ing Run-8, lat­tices with dif­fer­ent in­te­ger tunes were used for the two rings. This re­sult­ed in the two rings cross­ing tran­si­tion at dif­fer­ent times, which proved ben­e­fi­cial for the "Yel­low" ring, the RF sys­tem of which is slaved to the "Blue" ring. For the sym­met­ric gold-gold run in FY2010, lat­tices with dif­fer­ent tran­si­tion en­er­gies but equal tunes were im­ple­ment­ed. We re­port the op­tics de­sign con­cept as well as op­er­a­tional ex­pe­ri­ence with this con­fig­u­ra­tion.

• G. Wang, M. Blaskiewicz, V. Litvinenko
  BNL, Upton, Long Island, New York

We re­port re­cent pro­gress­es on an­a­lyt­i­cal stud­ies of Co­her­ent Elec­tron Cool­ing. The phase space elec­tron beam dis­tri­bu­tion ob­tained from the 1D FEL am­pli­fi­er is ap­plied to an in­fi­nite elec­tron plas­ma model and the elec­tron den­si­ty evo­lu­tion in­side the kick­er is de­rived. We also in­ves­ti­gate the ve­loc­i­ty mod­u­la­tion in the mod­u­la­tor and ob­tain a closed form so­lu­tion for the cur­rent den­si­ty evo­lu­tion for in­fi­nite ho­mo­ge­neous elec­tron plas­ma.

• A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, W. Fischer, C.J. Liaw, W. Meng
  BNL, Upton, Long Island, New York
• A.X. Custer, M.Y. Erickson, N.Z. Jamshidi, H.J. Poole
  PVI, Oxnard
• N. Sochugov
  Institute of High Current Electronics, Tomsk

Elec­tron clouds, which can limit ma­chine per­for­mance, have been ob­served in many ac­cel­er­a­tors in­clud­ing RHIC at BNL. They can be sup­pressed by low sec­ondary elec­tron yield beam pipe sur­faces. Ad­di­tion­al con­cern for the RHIC ma­chine, whose vac­u­um cham­ber is made from rel­a­tive­ly high re­sis­tiv­i­ty 316LN stain­less steel, is high wall re­sis­tiv­i­ty that can re­sult in un­ac­cept­ably high ohmic heat­ing for su­per­con­duct­ing mag­nets. The high re­sis­tiv­i­ty can be ad­dressed with a cop­per (Cu) coat­ing; a re­duc­tion in the sec­ondary elec­tron yield can be achieved with a TiN or amor­phous car­bon (a-C) coat­ing. Ap­ply­ing such coat­ings in an al­ready con­struct­ed ma­chine is rather chal­leng­ing. We start­ed de­vel­op­ing a robot­ic plas­ma de­po­si­tion tech­nique for in-situ coat­ing of long, small di­am­e­ter tubes. The tech­nique en­tails fab­ri­cat­ing a de­vice com­pris­ing of staged mag­netrons mount­ed on a mo­bile mole for de­po­si­tion of about 5 μm (a few skin depths) of Cu fol­lowed by about 0.1 μm of a-C. As a first step, a 15-cm Cu cath­ode mag­netron is being de­signed and fab­ri­cat­ed, after which, 30-cm long sam­ple of the RHIC pipe are to be Cu coat­ed. De­po­si­tion rates and af­fects on RF re­sis­tiv­i­ty are to be mea­sured.

• V. Ptitsyn, M. Blaskiewicz, W. Fischer, R.C. Lee, S.Y. Zhang
  BNL, Upton, Long Island, New York

A fast tran­si­tion in­sta­bil­i­ty pre­sents a lim­it­ing fac­tor for ion beam in­ten­si­ty in RHIC. Sev­er­al pieces of ev­i­dence show that elec­tron clouds play an im­por­tant role in es­tab­lish­ing the thresh­old of this in­sta­bil­i­ty. In RHIC Runs 7 and 8 ded­i­cat­ed mea­sure­ments of the in­sta­bil­i­ty, using dif­fer­ent beam in­stru­men­ta­tion tools (But­ton BPM, Wall Cur­rent Mon­i­tor, tran­si­tion mon­i­tors) were done in order to ob­serve the in­sta­bil­i­ty de­vel­op­ment over hun­dreds turns. The pa­pers pre­sents and dis­cuss­es the re­sults of those mea­sure­ments in time and fre­quen­cy do­mains.

• G. Wang, M. Blaskiewicz, A.V. Fedotov, Y. Hao, J. Kewisch, V. Litvinenko, E. Pozdeyev, V. Ptitsyn
  BNL, Upton, Long Island, New York

We pre­sent our stud­ies on var­i­ous as­pects of the beam dy­nam­ics in 'race­track' de­sign of the first stage elec­tron-ion col­lid­er at RHIC (eRHIC), in­clud­ing trans­verse beam break up in­sta­bil­i­ties, elec­tron beam emit­tance growth and en­er­gy loss due to syn­chrotron ra­di­a­tion, elec­tron beam loss­es due to Tou­schek ef­fects and residue gas scat­ter­ing, beam-beam ef­fects at the in­ter­ac­tion re­gion and emit­tance growth of ion beam due to elec­tron bunch to bunch nois­es. For all ef­fects con­sid­ered above, no show­stop­per has been found.