Radiation Resistant Silicon Diode Neutron Detectors

Low-resistivity (10Ω-cm) silicon diodes were employed as fast-neutron monitors, using a ²³⁸U conversion foil. Resolved fission spectra were recorded in-pile at a fast-neutron flux of ≈ 10¹¹ n/(cm² sec) and up to an integrated flux of 4.6 × 10¹⁵ fast neutrons/cm². Preamplifiers designed especially for this work included a bias supply of very low dc impedance because of the large leakage currents in the radiation-damaged diodes. Despite this leakage, the damaged diodes were not very noisy and could withstand more bias (≈45V) than the undamaged diodes.