The P̄ANDA Barrel-TOF Detector

Abstract

The P̄ANDA experiment is a fixed target experiment in which antiprotons collide with stationary hydrogen atoms. The main physics program of the experiment is to study open questions in hadron physics by performing charmonium spectroscopy and precisely measuring the width, mass and decay branches, and investigating possible exotic states like glueballs and hybrids. The Barrel Time-of-Flight detector (Barrel TOF), located between the DIRC detector and the electromagnetic calorimeter (EMC), which is built in the P̄ANDA target spectrometer, has been designed to measure the time at which a charged particle transits the detector with a resolution superior to the other sub-detectors of P̄ANDA. A time resolution below 100 ps (sigma) is mandatory for this sub-detector to fulfil the requirements of good event separation and particle identification below the Cherenkov threshold. The implementation of the Barrel TOF is based on very fast organic scintillator tiles with a size of 87 x 29.5 x 5 mm3 coupled to Silicon Photomultipliers. The total of 1920 tiles are read out by 8 SiPMs each and cover almost the full azimuthal range and polar angles from 22.5∘ to 140∘ and an area of about 5 m2. The current prototypes achieve ∼60 ps, well below the design goal. The detector R&D is now in a matured stage.