Calibration of a 2D-CDB spectrometer using a reference 133Ba source

A procedure for calibrating a FAST-ComTec 2D-CDB spectrometer using a 133Ba source is presented. The energy calibration consisted of acquiring two-dimensional (2D) spectra by measuring simultaneously with two HPGe detectors the 356 and 511 keV peaks. As the 133Ba source only emits one photon per decay, the Ba contribution to the 2D spectra was built up by taking two successive and uncorrelated events, i.e. one from each detector (pseudo-coincidence technique). The FWHM of the spectrometer was estimated from the E1=E2 diagonal of the spectra.