Abstract: An apparatus for detecting the area and concentration of radioactive contamination on surfaces, objects and personnel is disclosed. The apparatus is capable of automatic adjustment without intervention by an operator, providing for self-calibration and avoiding the need for periodic calibration, source checking and maintenance by personnel. The apparatus is comprised of one or more position sensitive proportional counters coupled together to act as a single counter. A computer based acquisition system is used to collect the time, energy and position of an ionization event that is caused by the contamination. Collimated radiation sources are located inside of each position sensitive proportional counter. These sources act as stable artifacts in the position and energy spectra that the device acquires as a function of time.

Abstract: An apparatus for detecting the area and concentration of radioactive contamination on surfaces, objects and personnel is capable of automatic adjustment without intervention by an operator, providing for self-calibration and avoiding the need for periodic calibration, source checking and maintenance by personnel. The apparatus is comprised of one or more position sensitive proportional counters coupled together to act as a single counter. A computer based acquisition system is used to collect the time, energy and position of an ionization event that is caused by the contamination. Collimated radiation sources are located inside of each position sensitive proportional counter. These sources act as stable artifacts in the position and energy spectra that the device acquires as a function of time. The computer continuously adjusts parameters such as detector high voltage, amplifier gain and discrimination to keep the count rate, energy and position that the system measures for these check sources constant.