Abstract: A method, apparatus, and computer program products for controlling gain in a scintillation detector. Calibration count rates, each representing an integral count rate above a different threshold, are obtained from a photomultiplier tube. Photomultiplier tube gain is adjusted if a result from evaluating a relationship of calibration count rates varies from an expected result based on integral count rate versus threshold for a reference peak in the energy spectrum of the radiation source. An additional, different relationship may also be evaluated and an additional gain adjustment performed when a result indicates that the calibration count rates are not from the reference peak. A same radiation source may be used for collecting test counts and calibration counts.

Abstract: A method, apparatus, and computer program products for controlling gain in a scintillation detector. Calibration count rates, each representing an integral count rate above a different threshold, are obtained from a photomultiplier tube. Photomultiplier tube gain is adjusted if a result from evaluating a relationship of calibration count rates varies from an expected result based on integral count rate versus threshold for a reference peak in the energy spectrum of the radiation source. An additional, different relationship may also be evaluated and an additional gain adjustment performed when a result indicates that the calibration count rates are not from the reference peak. A same radiation source may be used for collecting test counts and calibration counts.