Energy resolution and throughput of a new real time digital pulse processing system for x-ray and gamma ray semiconductor detectors

Abstract

New generation spectroscopy systems have advanced towards digital pulse processing (DPP) approaches. DPP systems, based on direct digitizing and processing of detector signals, have recently been favoured over analog pulse processing electronics, ensuring higher flexibility, stability, lower dead time, higher throughput and better spectroscopic performance. In this work, we present the performance of a new real time DPP system for X-ray and gamma ray semiconductor detectors. The system is based on a commercial digitizer equipped with a custom DPP firmware, developed by our group, for on-line pulse shape and height analysis. X-ray and gamma ray spectra measurements with cadmium telluride (CdTe) and germanium (Ge) detectors, coupled to resistivefeedback preamplifiers, highlight the excellent performance of the system both at low and high rate environments (up to 800 kcps). A comparison with a conventional analog electronics showed the better high-rate capabilities of the digital approach, in terms of energy resolution and throughput. These results make the proposed DPP system a very attractive tool for both laboratory research and for the development of advanced detection systems for high-rate-resolution spectroscopic imaging, recently proposed in diagnostic medicine, industrial imaging and security screening.

Silicon Photomultipliers for High-Performance Scintillation Crystal Readout Applications

“…The DPP firmware is based on a revised version of a DPP method, developed by our group and successfully used for both offline [10,[12][13][14][15] and online analysis [17,18]. The pulse detection is performed by using a fast-shaping mode, whereas the PSHA starts with a slow-shaping mode.…”

A digital approach for real time high-rate high-resolution radiation measurements

“…The width of each SDL pulse is calculated from the difference between the times when the leading and the falling edges cross the ARC threshold or the amplitude threshold. This width is a dead time for the system with a well-defined modeling (paralyzable dead time), allowing the estimation of the true ICR [25]. Moreover, the high-resolution estimation of the trigger allows the measurement of the time intervals between two consecutive events, helpful to validate Poisson statistics and for coincidence/anticoincidence measurements.…”

“…overlapped CSP pulses within the peaking time). Since, the peak pile-up pulses are characterized by a longer peaking time and a higher height than the single event pulse, it is possible to reduce their effects in the measured spectra by analyzing both the peaking time and the height (energy) distribution of the pulses [22][23][24][25].…”

“…the output signals from charge sensitive preamplifiers) are directly fed into fast digitizers and then processed by using digital algorithms. DPP systems are typically realized by using two different processing approaches: (i) a personal computer (PC) controls a simple digitizer, receives and records ADC data in files and performs offline processing [14,[17][18][19][20][21][22][23]; (ii) a PC controls a field programmable gate array (FPGA), equipped with local memory and digitizer; FPGA, wherein pulse processing algorithms are implemented (DPP firmware), receives and processes on-line ADC data, stores results in local memory, gets packets and sends them, when ready, to PC [6- 13,15,16,[24][25][26].…”

“…Data results are used for quick look processing (for on-line system running control) and are stored in PC files for much deeper off-line analysis [24,25].…”