• M. Benedikt, J. Gutleber, M. Palm, W. Pirkl
  CERN, Geneva
• U. Dorda, A. Fabich
  EBG MedAustron, Wr. Neustadt

MedAus­tron is a syn­chrotron based ac­cel­er­a­tor fa­cil­i­ty for can­cer treat­ment in Aus­tria cur­rent­ly in the de­vel­op­ment phase. The de­sign is based on the PIMMS study* and CNAO** syn­chrotron. In ad­di­tion to the clin­i­cal ap­pli­ca­tion, the ac­cel­er­a­tor will also pro­vide beams for non­clin­i­cal re­search in the fields of med­i­cal ra­di­a­tion physics, ra­di­a­tion bi­ol­o­gy and ex­per­i­men­tal physics with an ex­tend­ed pro­ton en­er­gy range be­yond med­i­cal re­quire­ments to 800 MeV. The dif­fer­ences to oth­ers med­i­cal ac­cel­er­a­tor-based fa­cil­i­ties will be elab­o­rat­ed, specif­i­cal­ly the used source tech­nolo­gies and con­fig­u­ra­tion (start­ing up with pro­tons (p) and car­bon ions (C⁶⁺) al­low­ing a later up­grade to ion species up to neon) and the on­line ver­i­fi­ca­tion of all rel­e­vant beam pa­ram­e­ters. The cur­rent pro­ject sta­tus is pre­sent­ed.

* PIMMS Proton-ion medical machine study, Bryant, Philip J (ed.) et al., CERN, 2000.
** CNAO, www.cnao.it

• K.L.F. Bane, G.V. Stupakov, U. Wienands
  SLAC, Menlo Park, California
• M. Benedikt, A. Grudiev, E. Mahner
  CERN, Geneva

In order for the LHC to reach an ul­ti­mate lu­mi­nos­i­ty goal of 10³⁵, CERN is con­sid­er­ing up­grade op­tions for the LHC in­jec­tor chain, in­clud­ing a new 50 GeV syn­chrotron of about 1.3 km length for pro­tons and heavy ions, to be called the PS2. In this ring the pro­ton en­er­gy is ramped from 4 GeV in 1.2 s, and the de­sign (pro­ton) cur­rent is 2.7 A. The pre­sent base­line of the vac­u­um sys­tem con­sid­ers el­lip­ti­cal stain­less steel cham­bers bake­able up to 300°C, var­i­ous coat­ings to mit­i­gate elec­tron cloud are under study. For a bare stain­less steel or In­conel cham­ber, the re­sis­tive wall wake alone will lead to mul­ti-bunch in­sta­bil­i­ty, where­as for trans­verse mode cou­pling (TMCI), the thresh­old is above the de­sign beam cur­rent, though this in­sta­bil­i­ty may be­come an issue once other impedance con­tri­bu­tions are taken into ac­count. A cop­per layer of vary­ing thick­ness is shown to raise the TMCI thresh­old but to have rel­a­tive­ly lit­tle ef­fect on the mul­ti-bunch re­sis­tive-wall growth rate un­less the coat­ing is very thick. We are also study­ing the ef­fect of the cop­per coat­ing on the pen­e­tra­tion of the guide field dur­ing the en­er­gy ramp, which sets an upper limit on the al­low­able thick­ness.

• C. Heßler, W. Bartmann, M. Benedikt, B. Goddard, M. Meddahi, J.A. Uythoven
  CERN, Geneva

With­in the scope of the LHC in­jec­tor up­grade, it is pro­posed to re­place the pre­sent in­jec­tor chain by new ac­cel­er­a­tors, Linac4, SPL and PS2, for which new beam trans­fer lines are re­quired. The beam prop­er­ties and re­quire­ments for each of the lines are sum­ma­rized. The orig­i­nal de­sign of the beam lines has been fully re­con­sid­ered due to the very de­mand­ing con­straints on the beam line lay­outs at the PS2 in­jec­tion / ex­trac­tion re­gions and a new straight sec­tion of the PS2 which led to a much im­proved beam line ge­om­e­try. The rel­e­vant mod­i­fi­ca­tions and op­tics de­signs are de­scribed and a pre­lim­i­nary spec­i­fi­ca­tion of the beam line equip­ment is also given.

• Y. Papaphilippou, W. Bartmann, H. Bartosik, M. Benedikt, B. Goddard, A. Lachaize
  CERN, Geneva
• Y. Senichev
  FZJ, Jülich

The PS2 ring is de­signed with neg­a­tive mo­men­tum com­paction arc cells and dou­blet straights. In this paper, dif­fer­ent lat­tice ge­ome­tries are con­sid­ered. In par­tic­u­lar, a two-fold sym­met­ric lat­tice with dis­per­sion sup­pres­sors and a 3-fold sym­met­ric one with res­o­nant arc cells are com­pared with re­spect to their op­tics prop­er­ties, and abil­i­ty to sat­is­fy space and mag­net con­straints. The tun­ing flex­i­bil­i­ty of rings based on these two op­tions is pre­sent­ed. Fi­nal­ly, the im­pact of dif­fer­ent ge­ome­tries on res­o­nance ex­ci­ta­tion and dy­nam­ic aper­ture is eval­u­at­ed.

• H. Bartosik, W. Bartmann, M. Benedikt, B. Goddard, Y. Papaphilippou
  CERN, Geneva

The PS2 lat­tice, based on Neg­a­tive Mo­men­tum Com­paction (NMC) arc cells is being op­ti­mized in order to ac­com­mo­date a new all-dou­blet long-straight sec­tion (LSS) de­sign. Apart from smooth­ing the op­tics and en­abling dif­fer­ent tun­ing so­lu­tions for H^- in­jec­tion, the op­ti­miza­tion fo­cus­es on in­creas­ing the avail­able mag­net-to-mag­net drift space and re­duc­ing the quadrupole types and strengths. The vari­a­tion of lat­tice pa­ram­e­ters for a wide range of work­ing points is pre­sent­ed.

• H. Bartosik, M. Benedikt, Y. Papaphilippou
  CERN, Geneva

This paper de­scribes a de­tailed anal­y­sis of var­i­ous non-lin­ear ef­fects of the nom­i­nal Neg­a­tive Mo­men­tum Com­paction lat­tice for PS2. Chro­matic­i­ty and orbit cor­rec­tion schemes to­geth­er with dy­nam­ic aper­ture stud­ies are pre­sent­ed. The im­pact of mag­net er­rors is being as­sessed and tol­er­ances are eval­u­at­ed. Fre­quen­cy and dif­fu­sion maps are pro­duced and, com­bined with non-lin­ear driv­ing terms anal­y­sis, are used for work­ing point op­ti­miza­tion.