Author: Boccardi, A.
Paper Title Page
TUPC048 First Measurement Results of the LHC Longitudinal Density Monitor 1105
 
  • A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo
    CERN, Geneva, Switzerland
  • A.S. Fisher
    SLAC, Menlo Park, California, USA
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Funding: The primary author is funded by the E.U. under the DITANET Marie Curie network.
Knowl­edge of the lon­gi­tu­di­nal dis­tri­bu­tion of par­ti­cles is im­por­tant for var­i­ous as­pects of ac­cel­er­a­tor op­er­a­tion, for ex­am­ple to check the in­jec­tion qual­i­ty and to char­ac­ter­ize the de­vel­op­ment of ghost bunch­es be­fore and dur­ing the physics pe­ri­ods. A new de­tec­tor, the LHC Lon­gi­tu­di­nal Den­si­ty Mon­i­tor (LDM) is a sin­gle-pho­ton count­ing sys­tem mea­sur­ing syn­chrotron light by means of an avalanche pho­to­di­ode de­tec­tor. The un­prece­dent­ed en­er­gies reached in the LHC allow syn­chrotron light di­ag­nos­tics to be used with both pro­tons and heavy ions. The LDM is able to lon­gi­tu­di­nal­ly pro­file the whole ring with a res­o­lu­tion close to the tar­get of 50 ps. On-line cor­rec­tion for the ef­fects of the de­tec­tor dead­time, pile-up and af­ter­puls­ing allow a dy­nam­ic range of 105 to be achieved. The LDM op­er­at­ed dur­ing the 2010 lead ion run and dur­ing 2011 with pro­tons. Mea­sure­ments from both runs are pre­sent­ed in this con­tri­bu­tion along with an anal­y­sis of the LDM per­for­mance and an out­look for fu­ture up­grades.