SAUNA system beta-gamma detector calibration stability monitoring and correction

An algorithm and implementing software has been developed to automatically monitor and correct for electronic drifting in the energy calibration of the betaand gamma detectors of the SAUNA system. Quality control measurements done between each sample (or background) measurement are analyzed using full-spectrum fitting to a template created at the time of calibration. Any detected drifting is corrected by a change in electronics gain before the next measurement starts. Initial and long-term testing under different conditions indicate that the method allows the spectral stability to be maintained to within better than about 1 % for the electron detectors and about 0.1 % for the photon detector. Analysis of the corrective actions taken by the system indicates that the maximum deviation during the testing period (in the absence of correction) would have been about 15 %.