Use of Compact CZT Detectors for On-Line Monitoring of the Activity Collected and Facility Operation Performance Improvement at CERN-MEDICIS

The CERN MEDical Isotopes Collected from Isotope Separator On Line Device (ISOLD) (CERN-MEDICIS) facility is dedicated to the production of unconventional radionuclides by mass separation for medical research. Efficient real-time monitoring of radionuclide collection is crucial for optimizing production and ensuring high purity levels. This study investigates the use of compact cadmium zinc telluride (CZT) detectors, specifically the Kromek GR-1 and GR-05, for on-line gamma-ray spectrometry during radionuclide collection at CERN-MEDICIS. The performance of these detectors is assessed through efficiency calibration, comparing results using different collection foils (NaCl-covered Al foils, further referred to as Al/NaCl, and Al-covered Au foils, further referred to as Au/Al). The GR-1 detector, positioned in front of the collection chamber, demonstrates higher efficiency and accuracy in detecting activity changes, while the GR-05 serves as a backup with lower efficiency. Calibration results highlight material-dependent variations in detection efficiency, particularly at low gamma-ray energies, where Al/NaCl foils exhibit higher efficiency due to reduced self-absorption. The study also validates the real-time assessment of collected activity by comparing CZT detector measurements with high-purity germanium spectrometry results, ensuring the reliability of on-line monitoring for future radionuclide production and mass separation facilities.