Research Investigation of p-I-n- Electron Junction Detectors

摘要

Various types of radioactive sources containing the isotopes thallium-204, phosphorous-32, and sulfur-35 have been utilized in carefully specified geometries for the purpose of comparing the response of silicon lithium-drifted p-i-n junction of detectors with extrapolation chamber measurements of the surface absorbed dose rate in polystyrene. Specifically, data has been obtained showing the ratio of detector response (open-circuit voltage or count rate) to surface absorbed dose rate in polystyrene as a function of distance from the source for various source and detector areas for both thick and thin sources. 'Infinitely thick' solutions of thallium-204 and phosphorous-32 having circular areas of 1.04, 10.0, and 100 sq cm and 'thin' dry (7.6 sq cm area) sources of all three isotopes were used. Detector open-circuit voltage measurements were made for all these source configurations using a number of moderately thin window p-i-n junction detectors having areas of 0.04, 0.24, 1.0, and 11.9 sq cm. One of these detectors (0.24 sq cm) has been used for count rate measurements with all of the thick source configurations. The large (11.9 sq cm) detector was used only with the 10.0-sq cm-thick phosphorous-32 source. Further measurements are now in progress. For all of the detector and source configurations studied, the response of the p-i-n detectors relative to absorbed dose rate increased with distance between source and detector. (Author)