Neutron induced nuclear counter effect in Hamamatsu silicon PIN diodes and APDs

Neutron induced nuclear counter effect in Hamamatsu silicon PIN diodes and APDs was measured by irradiating fast neutrons from ²⁵²Cf and ²⁴¹Am-Be sources directly to these devices. It was found that the entire kinetic energy of these fast neutrons may be converted into electron signals in these devices, leading to anomalous signals of up to a few millions electrons in a single isolated readout channel. The overall rate of the neutron induced nuclear counter effect in APDs is found to be about a factor of ten less than that in PIN diodes. Increasing the APD gain was also found to reduce the neutron induced nuclear counter effect. An intelligent front-end chip capable of selecting uncontaminated signal is proposed to eliminate the nuclear counter effect completely without significant cost increase.