Method and apparatus for minimizing the effect of baseline depression in ionizing radiation measuring equipment

A radiation analysis system for detection of radiation from a relevant ionizing radiation source in a background radiation environment, the apparatus comprising:

• a radiation detector exposed to ambient radiation, the radiation detector configured to detect at least a first and a second ionizing radiation region of interest, wherein the first ionizing radiation region of interest includes detectable emissions from the relevant ionizing radiation source and the second ionizing radiation region of interest substantially excludes emissions from the relevant ionizing radiation source;
• a triggering system configured to generate a first data acquisition trigger when the detector is exposed to ambient radiation comprising the background radiation environment without radiation from the relevant ionizing radiation source and configured to generate a second data acquisition trigger when the detector is exposed to ambient radiation comprising the background radiation environment and a potentially shielded relevant ionizing radiation source;
• a data acquisition system in operable communication with the radiation detector and with the triggering system, wherein:
• the data acquisition system is configured to acquire from the radiation detector a background radiation measurement after the triggering system generates the first data acquisition trigger, the background radiation measurement comprising a first background ionizing radiation measurement in the first ionizing radiation region of interest and a second background ionizing radiation measurement in the second ionizing radiation region of interest, and
• the data acquisition system is further configured to acquire from the radiation detector a test radiation measurement after the triggering system generates the second data acquisition trigger, the test radiation measurement comprising a first total ionizing radiation measurement in the first ionizing radiation region of interest and a second total ionizing radiation measurement in the second ionizing radiation region of interest;
• and
• a computer in operable communication with the data acquisition system, the computer configured to normalize the second background ionizing radiation measurement to the first background ionizing radiation measurement to determine a calibration constant, and configured to apply the calibration constant to normalize the second total ionizing radiation measurement to determine a normalized second total ionizing radiation measurement and configured to subtract the normalized second total ionizing radiation measurement from the first total ionizing radiation measurement to determine a net difference there between to indicate the presence of the relevant ionizing radiation source.