Investigation of the Pulse Shape in a 3 He Counter under Neutron Irradiation

— The shape of pulses produced in a 3 He counter by thermal neutrons has been investigated. The electronics, which consist of a charge-sensitive preamplifier and a shaping amplifier, have been developed. The measured pulse shape is compared to the result of simulation of the 3 He counter signals under neutron irradiation. A new method for determining the pressure in a 3 He counter is proposed that is based on measurements of the total charge-collection efficiency and the maximum effective pulse width in the counter. This method is in good agreement with the direct measurement of the pressure in a 3 He counter using the transmission method.