A gaseous detector for ultracold neutrons in the n2EDM project Student

Overview & Synopsis

The experimental arrangement of the n2EDM project, which aims at the measurement of the neutron electric dipole moment (dn), is in its construction phase. Currently, it is being evaluated for possible improvements that would lead to a greater ultra-cold neutron (UCN) counting efficiency and a larger sensitivity on the determination of dn. This work introduces a novel gaseous detector, which functioning is based on the absorption reaction n + 3He → 1H + 3H followed by the CF4 scintillation process. The counting capabilities for this detector are studied at two facilities that produce UCN from different mechanisms, one from spallation processes at the Paul Scherrer Institute (PSI), and the other from uranium fission at the TRIGA nuclear reactor in Mainz. Determination of parameters that optimize the UCN detection was also achieved, in particular, the gas pressure: 25 mbar for 3He and 400 mbar for CF4. Pulse shape discrimination techniques allowed the background events identification, estimated in a 2% of the total counts at PSI. The absolute comparison against a cascade detector shows that the new prototype is doubly more efficient, that converts it in one of the most suitable alternatives for the UCN counting in the upcoming n2EDM experiment.