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SUMMARY:Performance and Radiation Damage Effects in the LHCb Vertex Locato
 r
DTSTART;VALUE=DATE-TIME:20140225T075500Z
DTEND;VALUE=DATE-TIME:20140225T081500Z
DTSTAMP;VALUE=DATE-TIME:20260613T062906Z
UID:indico-contribution-62@indico.inp.nsk.su
DESCRIPTION:Speakers: Tim Head (CERN)\nLHCb is a dedicated experiment to s
 tudy New Physics in the decays of heavy hadrons at the Large Hadron Collid
 er (LHC) at CERN. Heavy hadrons are identified through their flight distan
 ce in the Vertex Locator (VELO)\, and hence the detector is critical for b
 oth the trigger and offline physics analyses.\nThe VELO is the retractable
  silicon-strip detector surrounding the LHCb interaction point. It is loca
 ted only 7 mm from the LHC beam during normal LHC operation\, once moved i
 nto its closed position for each LHC fill when stable beams are obtained. 
 During insertion the detector is centred around the LHC beam by the online
  reconstruction of the primary vertex position. Both VELO halves comprise 
 21 silicon micro-strip modules each. A module is made of two n+-on-n 300 m
 um thick half-disc sensors with R-measuring and Phi-measuring micro-strip 
 geometry\, mounted on a carbon fibre support paddle. The minimum pitch is 
 approximately 40 mum. The detector is also equipped with the only n-on-p s
 ensors operating at the LHC.\nThe detectors are operated in vacuum and a b
 i-phase CO2 cooling system is used. The signals read out with analogue fro
 nt-end chips are subsequently processed by a set of algorithms in FPGA pro
 cessing boards.\nThe VELO has been performing very successfully during the
  first run of the LHC in 2010-12.\nPossible effects of radiation damage ha
 ve been monitored and studied in detail throughout this period. Indeed the
  VELO module sensors receive a large and non-uniform radiation dose having
  inner and outer radii of only 7 and 42 mm\, respectively. A maximum dose 
 of 1.2 x 1014 1 MeV neutron equivalent /cm2 was received in the innermost 
 region of the sensors for the combined 2010-12 run I (3.4 fb-1 of delivere
 d data). Being operated in an extreme and highly non-uniform radiation env
 ironment\, type-inversion of the inner part of the n-on-n sensors has alre
 ady been measured.\nThe radiation damage in the detector is monitored and 
 studied in three ways: (1) dependence of sensor currents on voltage and te
 mperature\; (2) measurement of the effective depletion voltage of the sens
 ors from the charge collection efficiency and from studying the noise vers
 us voltage behaviour\; and (3) cluster finding efficiency. Results will be
  presented in all three areas with the most recent results from the full r
 un I.\n\nhttps://indico.inp.nsk.su/event/0/contributions/62/
LOCATION:
URL:https://indico.inp.nsk.su/event/0/contributions/62/
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