Commissioning and beam test of a high pressure time projection chamber

Abstract

Due to their large active volume and low energy threshold for particle detection Time Projection Chambers (TPCs) are promising candidates to characterise neutrino beams at the next generation long baseline neutrino oscillation experiments such as DUNE and Hyper-K. The higher target density for the incoming neutrino beam of a TPC filled with gas at High Pressure (HPTPC) will potentially allow a better neutrino-nucleus interaction measurements as compared with TPCs at atmospheric pressure.The HPTPC we built has an active volume of about 0.5m3 which is embedded into a pressure vessel rated up to 6bar absolute pressure. A cascade of three meshes amplifies the primary ionisations. The induced charge on each mesh is read out. In addition the photons emitted during the gas amplification are read out by four CCD cameras focused on the readout plane, which thus image the 2D projection of a particle’s tracks on the transverse plane. The third coordinate is reconstructed from the charge signal.We tested the HPTPC’s performance during a four week beam test at the CERN PS, measuring low momentum proton (≤0.5GeV) interactions with the counting gas. Several mixtures with Argon predominance have been tested for their light yield and gas gain. The aim is to calculate the proton-Ar cross-section from the data sample, which will enter the calculations of final state interactions in neutrino Ar scattering.