Ballistic deficit correction methods for large Ge detectors High counting rate study

A comparative study is carried out for different ballistic deficit correction methods versus input count rate (from 3 to 50 kcounts/s) using four large Ge detectors of about 70% relative efficiency. The present work shows that, at shaping time constants shorter or equal to 2 μs, the Tennelec TC245 linear amplifier in the BDC mode (Hinshaw method) is the best compromise for energy resolution and throughput. At low and moderate input count rates (≤10 kcounts/s) the Ortec 675 Ge resolution enhancer based on the Goulding/Landis method offers excellent energy resolution and throughput at 2 μs shaping time. The energy resolution obtained with the Intertechnique 7201 gated integrator is very sensitive to count rate which lowers the interest in this module. At 3 kcounts/s it works very satisfactorily. All correction methods lead to narrow sum-peaks indistinguishable from single γ lines. More than the classical throughput, the full energy peak throughput is found representative of the pile-up inspection dead time of the corrector circuits. A new synthetic representation, plotting simultaneously energy resolution and throughput versus input count rate, is proposed.