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SUMMARY:Approaches in centrality measurements of heavy ion collisions with
  forward calorimeters at MPD/NICA facility
DTSTART;VALUE=DATE-TIME:20201009T135500Z
DTEND;VALUE=DATE-TIME:20201009T141000Z
DTSTAMP;VALUE=DATE-TIME:20260309T211315Z
UID:indico-contribution-2329@cern.ch
DESCRIPTION:Speakers: Vadim Volkov (INR RAS\, MIPT)\nThe MPD/NICA heavy io
 n experiment is now under construction in Dubna\, Russia. The centrality i
 s the global characteristic of the nuclear interaction that reflects the d
 egree of the nuclei overlapping or the number of interacting nucleons.  On
 e of methods to measure the centrality is the determination of the number 
 of non-interacting projectile fragments or spectators\, which have the ver
 y forward/backward rapidity. In MPD setup these spectators would be detect
 ed by the two identical hadron calorimeters placed at the opposite sides o
 f the beam interaction point. Both forward hadron calorimeters (FHCal) hav
 e the central holes for the beam pipe. The most of heavy fragments escape 
 in these beam holes and are not detected by the calorimeters. As a consequ
 ence\, the central and peripheral collisions have the same spectator’s e
 nergy depositions that leads to the ambiguity in the determination of the 
 collision centrality. To resolve this ambiguity a few approaches are devel
 oped based on the Monte-Carlo simulations with a fragmentation models. In 
 first approach\, the transverse and longitudinal components of the energy 
 depositions in calorimeters are calculated. These two energy components ha
 ve different correlations for central and peripheral event and can be used
  for the measurements of the collision centrality. The second approach is 
 based on the subtraction of the pion contamination in FHCal. The number of
  produced pions is the maximum in the central events and it is minimum in 
 the peripheral ones. The pion energy fraction in FHCal can be subtracted t
 o accurately measure the spectator’s energy in calorimeters. The accurac
 y of the centrality measurements with these methods is discussed.\n\nThis 
 work was supported by the Russian Foundation of Basic Research (RFBR) Gran
 t No. 18-02-40065.\n\nhttps://indico.particle.mephi.ru/event/35/contributi
 ons/2329/
LOCATION:Zoom Heavy Ion
URL:https://indico.particle.mephi.ru/event/35/contributions/2329/
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