FPGA implementation of a real-time digital pulse processing analysis for radiation detectors

The high performance parameterization for deep learning in pulse shaping

In high energy physics, front-end data acquisition systems based on analog-to-digital converters (ADC) can provide multiple aspects (time, energy, position) of information when an incident particle is detected. To process the shaped semi-Gaussian pulses from ADCs, multi-layer neural networks (aka. deep learning recently) show excellent accuracy and promising real-time capability. However, several factors, such as sampling rate and precision, neural network quantization bits, and intrinsic noise, complicate the problem and make it hard to find a cost-effective solution with high performance. In this article, we analyze above factors in a systematic way to study the effect of each one on the performance of the network individually when other factors are controlled. Moreover, the proposed network architecture can provide both the time and energy information from a single pulse. When the sampling rate is 2.5 MHz, sampling precision is 5-bit, the network tested in this work with an 8-bit encoder and a 16-bit decoder (designated as N2) achieved the best comprehensive performance in all conditions.

Compact Back-End Electronics with Temperature Compensation and Efficient Data Management for In Situ SiPM-Based Radiation Detection

A compact back-end interface for silicon photomultipliers (SiPMs) implementing Zener diode-based temperature compensation has been developed for the remote detection of beta and gamma radiation. Remote detection is facilitated by the development of an efficient data management system utilising MySQL database storage for recording periodic spectra data for wireless access over a private Wi-Fi network. A trapezoidal peak shaping algorithm has been implemented on an FPGA for the continuous conversation of pulses from the SiPM, signifying the detection of a radiological particle, into spectra. This system has been designed to fit within a 46 mm cylindrical diameter for in situ characterization, and can be attached to one or more SiPMs used in conjunction with a range of scintillators. LED blink tests have been used to optimise the trapezoidal shaper coefficients to maximise the resolution of the recorded spectra. Experiments with an array of SiPMs integrated with a NaI(Tl) scintillator exposed to sealed sources of Co-60, Cs-137, Na-22 and Am-241 have shown that the detector achieves a peak efficiency of 27.09 ± 0.13% for a gamma peak at 59.54 keV produced by Am-241, and a minimum energy resolution (Delta E/E) of 4.27 ± 1.16% for the 1332.5 keV gamma peak from Co-60.