Cherenkov Detector for Beam Quality Measurement  

A.  E.  Dabrowski1,  R.Loos1,  S.  S.  Orfanelli1,2,  J.Mans3,  R.  Rusack3,  K.  S?@er3,  D.  P.  S?ckland4,  F.  Fabbri5,  A.  Montanari5,  N.Tosi5  

1.  CERN,  2.  Na?onal  Technical  University  of  Athens,  3.  University  of  Minnesota,  4.Princeton  University,  5.  INFN  Bologna    

Beam  Halo  Monitor  in  CMS:    novel,  fast  &  direc8onal    

•  Beam Halo Monitor (BHM) is a new monitor to measure online bunch-by-bunch beam background in the CMS experiment at LHC.

•  BHM will provide feedback to the LHC about the beam quality. •  Since Cherenkov radiation is emitted in a forward cone around the charged

particle’s trajectory, BHM can distinguish the low rate of machine induced background from collision products.    

backward   forward  

Installa8on  &  first  beams  results  

Time [UTC+2:00]12:57:00

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(Fill 3679, 5 May 2015)

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-Z BHM ratebeam 1 collimator

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(Fill 3679, Circulating Beams, 5 May 2015)!

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The  increase  in  BHM  rate  occurs,  as  expected,  when  the  collimator  gap  is  reduced.  

The  BHM  units  in  blue  as  installed  parallel  to  the  beam  pipe  around  the  CMS  rota=ng  shielding  at  radius  ~180  cm  from  beam  pipe,  20.6  m  from  IP.  Twenty  detectors  were  installed  per  end.    

The  BHM  units  in  blue  as  installed  parallel  to  the  beam  pipe  around  the  CMS  rota=ng  shielding  at  radius  ~180  cm  from  beam  pipe,  20.6  m  from  IP.