ADONIS : a new system for high count rate HPGe γ spectrometry

The ADONIS (Algorithmic Development framewOrk for Nuclear Instrumentation and Spectrometry) system is a new γ spectrometer which addresses high count rate metrology. It has been developed for count rate up to 10⁶ cps and beyond on HPGe detectors. The ADONIS system has been designed in order to: (1) maximize the (pile-up free) output count rate (OCR), (2) achieve both qualitative (i.e. Gaussian shape of spectrum peaks) and quantitative (i.e. reliable metrology) spectrometry, and (3) maintain these results even with time-varying activities. The actual instrument is based on a PC, hosting a PCI acquisition board, together with the standalone analog and digital front end module. The system allows data storage on hard disk for eventual off-line signal analysis. One of the main advantage of such a system is that there is no tuning depending on both input count rate (ICR) and charge collection duration. The accuracy of energy estimation naturally decreases as ICR increases. The same performances as conventional systems are reached at low ICR. For the user no trade-off between resolution and throughput has to be made.