Principles of an Electronic Neutron Dosemeter Using a PIPS Detector

Abstract

This laboratory has already studied fast and thermal neutron dosimetry with the help of a passive dosemeter composed of a boron implanted polyethylene (CH2)n converter placed on a solid state nuclear track detector (SSNTD), CR-39. With the development of semiconductor detector technology, real-time dosimetry is now being considered. The principle of the dosemeter is to detect the secondary particles from the converter using a PIPS (passivated implanted silicon) detector for which the registered pulses are processed to be proportional to the dose equivalent. Theory shows the neutron dose equivalent response (dosimetric efficiency) with the optimum thickness of converter and calculated for an isotropic incident neutrons beam, to be fairly independent of neutron energy (range 0.2 MeV - 5 MeV). Many experiments (accelerator, Am-Be source) show the response of the electronic device to be greater than that of a passive detector. The response of the device to gamma rays and background is overcome by adoption of a differential method, using a similar PIPS detector without converter.