Münster 2017 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 21: Heavy Ion Collisions and QCD Phases V
HK 21.3: Talk
Tuesday, March 28, 2017, 14:45–15:00, F 3
Reconstruction of neutral pions at CBM-RICH detector via conversion* — •Ievgenii Kres, Karl-Heinz Kampert, and Christian Pauly for the CBM collaboration — Wuppertal University
The Compressed Baryonic Matter (CBM) experiment at the future FAIR complex will investigate the phase diagram of strongly interacting matter at high baryon density and moderate temperatures in A+A collisions from 2-11 AGeV (SIS100). A central component of the proposed detector setup is a Ring Imaging Cherenkov Detector (RICH) using CO2 as radiator gas, a focussing optics with a large spherical mirror, and, as a result of recent CBM RICH geometry optimizations, a cylindrically shaped photon detection surface. As leptons are not affected by hadronic final state interactions, the dilepton spectrum, in particular dileptonic decays of light vector mesons like ρ or ω, offers the possibility to look into the dense fireball. At the low mass region, this spectrum is dominated by physical background from π0 and η mesons, mainly decaying into photons suffering subsequent conversion processes. The presented analysis aims at reconstructing π0 and η mesons via double conversion (π0 → γ (e+ e−) + γ (e+ e−)) inside the target or first detector layers in order to scale these background channels accurately in the integral e+ e− invariant mass spectrum. Proper counting of the pions requires an exact description of the combinatorical background below the pion invariant mass peak, which is achieved using the event mixing technique. First results of this conversion analysis are presented.
*gefördert durch BMBF 05P15PXFCA und GSI