He jishu (Dec 2023)
Performance of the electromagnetic calorimeter module in the NICA-MPD based on Geant4
Abstract
BackgroundThe barrel-sampled electromagnetic calorimeter (Ecal) is an important part of the Multi-Purpose Detector (MPD) in Nuclotron-based Ion Collider fAcility (NICA) that is being built in Russia. It is primarily used to detect energy, time, and position information of electrons and photons in the energy domain from 10 MeV to a few GeV. MPD-Ecal is comprised of 2 400 modules with 16 towers per module. Each tower is made up of alternating layers of 211 scintillator sheets and 210 lead sheets, as well as 16 wave-length shift fibers.PurposeThis study aims to evaluate the performance, such as energy resolution, time resolution, and coordinate resolution, etc., of the Ecal by simulation.MethodsThe Geant4 software was employed to simulate single-energy electron incident on Ecal to examine the effects of several parameters on the performance of Ecal. Influences of the position of the particle incidence point, the number and thickness of the scintillator and lead layers, the polish of the optical fibre end-face, and the energy and type of incident particles on the energy deposition and resolution, time distribution and time resolution, and coordinate resolution were investigated in details. Finally, the time resolution of a single tower was simulated using the natural cosmic ray package, and the tower's expected time resolution in the cosmic ray test was obtained.ResultsAs the electron incidence position moves from the edge to the center of the module, the energy deposition within the scintillator rises from 718 MeV to 758 MeV. With a limited tower length of 415.5 mm, increasing the number of scintillator layers decreases the energy resolution of the module, improves the time resolution of the tower, and worsens the coordinate resolution of the Ecal. Taking into account the performance of the Ecal gauge, the optimal number of scintillator layers in the tower is 211. SiPM detects 42% more photoelectrons at a polish of 0.6 when the fiber end is coated with a reflective material than when it is not. As the polish of the fiber end-face increases, so does the number of photoelectrons detected by the SiPM, and the time resolution of the tower improves. When the fibre end-face polish is 1.0, the time resolution of the tower is less than 103 ps while time resolution of the tower (with 211 layers) in the cosmic ray is 185 ps.ConclusionsThe time and coordinate resolutions of Ecal improve with increasing electron energy under the same circumstances.
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