Speaker
Alexander Izvestnyy
(Institute for Nuclear Research of the Russian Academy of Sciences)
Description
A modular hadron calorimeter, the Projectile Spectator Detector (PSD) at
CBM is aimed to determine a collision centrality and to reconstruct the
event plane orientation in collisions of heavy nuclei. PSD is a hadron
lead/scintillator sandwich calorimeter with the sampling ratio providing
the compensation condition. The calorimeter includes 44 individual
modules. Each module consists of 60 lead/scintillator sandwiches with the
4 mm thickness of each scintillator plate and 16 mm lead plate. Each
module has ten longitudinal sections and, respectively, ten compact
photodetectors, the avalanche photodiodes MPPC with active area 3x 3 mm2.
The modules after assembling were tested with the cosmic muons to evaluate
the light yield of each longitudinal section. At first stage, the module
was installed in the vertical position and the data were collected for a
few hours. Clean peaks in amplitude spectra were observed in all 10
sections. At the second stage, the module was placed back into horizontal
position and the data were collected in self-triggering mode. In the last
case, the cosmic muons pass different lengths in the scintillator plates
depending on the angular distribution of the muons. Therefore, no clear
peaks were observed in the amplitude spectra. To select the muon tracks
with the similar pass-lengths in the scintillator plates the track
selection algorithms were used. In the simplest way, the events with the
energy depositions in 3 neighbor sections were selected. These events
correspond to the almost horisontal muon tracks crossing a few
longitudinal sections in the module.
The different algorithms of the energy calibration and the light yields of
the calorimeter modules are discussed.
Primary author
Alexander Izvestnyy
(Institute for Nuclear Research of the Russian Academy of Sciences)