Author: Alessio, F.
Paper Title Page
TUPZ031 Near Beam-gas Backgrounds for LHCb at 3.5 TeV 1876
 
  • D.R. Brett, R. Appleby
    UMAN, Manchester, United Kingdom
  • F. Alessio, G. Corti, R. Jacobsson
    CERN, Geneva, Switzerland
  • M.H. Lieng
    UNIDO, Dortmund, Germany
  • V. Talanov
    IHEP Protvino, Protvino, Moscow Region, Russia
  
  Funding: STFC
We con­sid­er the ma­chine in­duced back­grounds for LHCb aris­ing from col­li­sions of the beam with resid­u­al gas in the long straight sec­tions of the LHC close to the ex­per­i­ment. We con­cen­trate on the back­ground par­ti­cle flux­es ini­ti­at­ed by in­elas­tic beam-gas in­ter­ac­tions with a di­rect line of sight to the ex­per­i­ment, with the po­ten­tial im­pact on the ex­per­i­ment in­creas­ing for larg­er beam cur­rents and chang­ing gas pres­sures. In this paper we cal­cu­late the back­ground rates for pa­ram­e­ters fore­seen with LHC run­ning in 2011, using re­al­is­tic resid­u­al pres­sure pro­files. We also dis­cuss the ef­fect of using a pres­sure pro­file for­mu­lat­ed in terms of equiv­a­lent hy­dro­gen, through weight­ing of other resid­u­al gases by their cross sec­tion, upon the ra­di­al flux­es from the ma­chine and the de­tec­tor re­sponse. We pre­sent the ex­pect­ed rates and the error in­tro­duced through this ap­prox­i­ma­tion. 		 
 
THPS055 Controlling Beamloss at Injection into the LHC 3553
 
  • B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto
    CERN, Geneva, Switzerland
  • R. Appleby
    UMAN, Manchester, United Kingdom
  
  Loss­es at in­jec­tion into the su­per­con­duct­ing LHC can ad­verse­ly af­fect the ma­chine per­for­mance in sev­er­al im­por­tant ways. The high in­ject­ed beam in­ten­si­ty and en­er­gy mean that pre­cau­tions must be taken against dam­age and quench­es, in­clud­ing col­li­ma­tors placed close to the beam in the in­jec­tion re­gions. Clean in­jec­tion is es­sen­tial, to avoid spu­ri­ous sig­nals on the sen­si­tive beam loss mon­i­tor­ing sys­tem which will trig­ger beam dumps. In ad­di­tion, the use of the two in­jec­tion in­ser­tions to house down­stream high en­er­gy physics ex­per­i­ments brings con­straints on per­mit­ted beam loss lev­els. In this paper the sources of in­jec­tion beam loss are dis­cussed to­geth­er with the con­tribut­ing fac­tors and var­i­ous is­sues ex­pe­ri­enced in the first full year of LHC op­er­a­tion. Sim­u­la­tions are com­pared with mea­sure­ment, and the im­ple­ment­ed and planned mit­i­ga­tion mea­sures and di­ag­nos­tic im­prove­ments are de­scribed. An out­look for fu­ture LHC op­er­a­tion is given.