Experimental investigation of the ADC sampling rate effect on the digital gamma spectrometry

Abstract

Gamma spectrometer is not available in many laboratories because it is very expensive. Analog to digital converter ADC is the basic component of digital gamma spectrometers. The sampling rate of the ADC plays an important role in determining the performance and the cost of the gamma spectrometers. This paper investigates experimentally the ADC's sampling rate effect on the performance of the gamma spectroscopy. The conducted experiment started by sampling a real pre-amplifier output. Then, the acquired samples have been processed at different sampling rates to build the dedicated gamma spectrums. During the processing of the sampled signals, three different digital filters have been tested to distinguish their effect on the energy resolution when the sampling rate is reduced. The results of this experimental investigation will help later in proposing new low-cost and efficient gamma spectrometer prototypes.

Development of low-cost digital gamma spectrometer using ARM Cortex-M Type Microcontroller Unit

“…First the ready buffer is scanned. If an event is detected, a busy time interval (BTI) [5] is started. Then a fast scan within the BTI interval is done to check two things: first, to check that there are no other events presented; second, to check that the detected pulse is within the dynamic range of the ADC.…”

“…The SAM3X8E MCU repeats this process until a stop command is received from the computer. The pulse detection is done using the previously proposed algorithm in [5]. In this algorithm, three points of the shifted and subtracted (SS) data are checked to be above a certain threshold [5].…”

“…The pulse detection is done using the previously proposed algorithm in [5]. In this algorithm, three points of the shifted and subtracted (SS) data are checked to be above a certain threshold [5]. Two filters are implemented to be used in extracting the height of the detected pulse.…”

“…As the sampling rate of the ADC decreases, the required memory and operating clock frequency of the DPP unit decrease which in turn lowers the cost of the DPP unit in expense of some sort of degradation in its performance. In [5], we have investigated experimentally the effect of lowering the ADC's sampling rate on the energy resolution of the gamma spectrum when computed. We concluded in [5] that the energy resolution of the computed spectrum is not affected dramatically by lowering the ADC's sampling rate down to 1 MS/s especially when the moving average and trapezoidal filters are used.…”

“…In [5], we have investigated experimentally the effect of lowering the ADC's sampling rate on the energy resolution of the gamma spectrum when computed. We concluded in [5] that the energy resolution of the computed spectrum is not affected dramatically by lowering the ADC's sampling rate down to 1 MS/s especially when the moving average and trapezoidal filters are used.…”