CN-121978741-A - Single-sphere neutron spectrometer electronic system

CN121978741ACN 121978741 ACN121978741 ACN 121978741ACN-121978741-A

Abstract

Compared with the prior art, the invention realizes synchronization, parallel acquisition and reliable counting of multichannel signals through a plurality of independent signal processing channels respectively and correspondingly arranged on a detector 1 and a detector 2, wherein each channel of signals is sequentially converted and amplified by a charge sensitive preamplifier, waveform is corrected by a zero cancellation circuit, standard pulse is output by a pulse conditioning module, the standard pulse is respectively sent to a counting module channel 1 and a counting module channel 2 in an FPGA, the counting module channel n is subjected to parallel counting, a counting result is written into an n-channel data RAM buffer memory, and is stably operated under the configuration guarantee of a clock and a Flash, and finally the data is transmitted to an upper computer through an Ethernet module according to TCP/IP, meanwhile, a low ripple power module supplies power for each link to reduce noise interference, and the integrity and the stability of the counting data acquisition of the multiple detectors are ensured on a structure and a data flow path.

Inventors

SUN BOWEN
XIA SANQIANG
WANG XIAOLONG
LI YINGGUO
LI ZHIGANG
HUANG ZHENGLIN
ZHANG TINGTING
FANG DENGFU
WEI YINGJING
TANG ZHIHUI

Assignees

中国辐射防护研究院

Dates

Publication Date: 20260505
Application Date: 20260109

Claims (10)

1. The electronic system of the single-sphere neutron spectrometer comprises a detection system, an electronic system and a spectrum decomposition system, and is characterized in that the detection system comprises a single moderating body and a plurality of thermal neutron detectors embedded in different positions in the moderating body, and the thermal neutron detectors are used for converting neutron radiation of a neutron field to be detected into pulse signals which can be identified by the electronic system; the electronic system comprises a plurality of front-end signal conversion circuits, a plurality of pulse conditioning circuits, an FPGA module, a communication interface module and a low-ripple power supply module; Each front-end signal conversion circuit corresponds to one thermal neutron detector and comprises a charge sensitive preamplifier and a zero cancellation circuit, and the front-end signal conversion circuits are used for converting weak charge signals output by the thermal neutron detector into voltage signals and carrying out preliminary amplification, and meanwhile compensating and correcting distortion generated in the detector and the preamplifier; the pulse conditioning circuit is connected with the output end of the front-end signal conversion circuit and is used for carrying out waveform shaping and filtering processing on the corrected pulse signals, conditioning the pulse signals into standard pulses meeting the subsequent counting requirement, and each path of detector signals corresponds to an independent pulse conditioning circuit so as to ensure independent parallel processing of the multichannel signals; The FPGA module is connected to the output ends of all the pulse conditioning circuits and is used for carrying out parallel counting and data processing on the multi-channel pulse signals, a plurality of pulse counting modules corresponding to all the channels, a data memory for temporarily storing multi-channel counting data and an energy spectrum acquisition module for acquiring pulse energy spectrum information are integrated in the FPGA module, and a clock and configuration storage unit is arranged, so that the acquisition and temporary storage of the pulse count values of all the channels and the synchronous acquisition of the pulse energy spectrum data are realized, and the operation of all the functional modules of the FPGA according to a preset logic time sequence is ensured; the communication interface module is connected with the FPGA module, converts the counting data and the energy spectrum data processed by the FPGA module into network signals, and transmits the network signals to the upper computer through a TCP/IP protocol so as to realize high-speed remote transmission and interaction of the data; the low-ripple power supply module provides a stable low-noise direct current power supply for each module of the electronic system, and avoids interference of power supply ripple on signal processing; the spectrum resolving system is spectrum resolving software running on the upper computer and is used for calculating neutron energy spectrum according to the multi-channel counting data.
2. The single sphere neutron spectrometer electronic system according to claim 1, wherein the thermal neutron detectors are SiC semiconductor thermal neutron detectors coated with 6 LiF material.
3. The electronic system of claim 1, wherein the output signal of each of the thermal neutron detectors is processed sequentially by a corresponding charge sensitive preamplifier and a zero cancellation circuit, wherein the charge sensitive preamplifier converts the output weak charge signal into a voltage signal and amplifies the voltage signal, and the zero cancellation circuit compensates for undershoot distortion generated by a preceding stage and shortens the pulse width to reduce pulse pile-up effects at a high count rate.
4. The electronic system of single-sphere neutron spectrometer according to claim 3, wherein the pulse conditioning circuit performs waveform shaping and filtering on the pulse signal corrected by the pole zero cancellation circuit, adjusts the amplitude and width of the pulse to a predetermined range, outputs a standard pulse signal meeting the counting requirement, and ensures independent parallel processing of each channel signal.
5. The electronic system of single-sphere neutron spectrometer according to claim 1, wherein the pulse counting modules in the FPGA module count the pulse signals of the channels respectively, and count the number of pulses in a unit time to obtain the pulse counting rate of the corresponding channel.
6. The electronic system of single-sphere neutron spectrometer according to claim 1, wherein the data storage is used for temporarily storing the count data output by the pulse counting modules, and the count data is used as a data buffer unit to coordinate the data transmission and processing rhythm in the system so as to ensure the orderly circulation of the multi-channel count data in the system and provide temporary storage space for the subsequent data transmission or further processing.
7. The electronic system of single-sphere neutron spectrometer according to claim 1, wherein the energy spectrum acquisition module works in parallel with the plurality of pulse counting modules, and performs acquisition processing of energy spectrum related information on the pulse signal to obtain energy distribution data of the pulse signal, so as to assist in judging signal characteristics and discriminating signal types.
8. The electronic system of the single-ball neutron spectrometer according to claim 1, wherein the electronic system is provided with a clock circuit and an FPGA configuration memory, the clock circuit provides synchronous time sequence signals for all functional modules in the FPGA to ensure that the functional modules work stably according to set time sequences, and the FPGA configuration memory is used for storing configuration programs of the FPGA and loading the configuration programs to the FPGA to initialize logic of all the functional modules when the system is powered on.
9. The single sphere neutron spectrometer electronic system according to claim 1, wherein the communication interface module is an ethernet communication module, the ethernet communication module converts the count data and the energy spectrum data processed by the FPGA module into network signals, and transmits the network signals to the upper computer according to a TCP/IP protocol, so that high-speed remote transmission of data between the device and the upper computer is realized.
10. The electronic system of any one of claims 1-9, wherein the low ripple power module provides a stable low noise dc power supply to the charge sensitive preamplifier, the zero cancellation circuit, the pulse conditioning circuit, the FPGA module, and the like, and can provide power outputs of different voltage specifications according to the needs of different modules, respectively, so as to ensure normal operation of the modules and avoid interference of power noise on signal processing.

Description

Single-sphere neutron spectrometer electronic system Technical Field The invention relates to the field of neutron energy spectrum measurement, in particular to a single-sphere neutron spectrometer electronic system. Background Neutrons are widely found in nuclear power, medical radiation protection, accelerator devices, nuclear facility monitoring, and other scenarios. Because the interaction mechanism of neutrons and substances is complex, and the neutron dose is closely related to neutron energy, accurate acquisition of neutron energy spectrum is an important basis for carrying out neutron dose measurement and risk assessment in radiation protection and dose assessment. The conventional on-site neutron dose measuring device is represented by a moderating type Ram instrument, a multi-sphere neutron spectrometer and the like, wherein the moderating type Ram instrument is generally composed of a moderating material wrapped on a thermal neutron detector, the energy response of the moderating type Ram instrument is difficult to further improve in design and is easy to cause insufficient accuracy of a dose result although the moderating type Ram instrument is relatively simple in structure, and the multi-sphere neutron spectrometer can solve energy spectrums reversely through different responses of moderating spheres with different radiuses to neutrons with different energies, so that the energy spectrum measuring accuracy is relatively better, but obvious using and realizing bottlenecks still exist in engineering application. The multi-sphere neutron spectrometer comprises a plurality of slowing-down spheres, the whole volume of the equipment is large, carrying and arrangement are inconvenient, and during measurement, the plurality of neutron spheres are usually required to be placed at a measuring point one by one to collect counting data in sequence, so that an energy spectrum result can be given in subsequent calculation, and the measuring steps are complicated and the measuring period is long. More importantly, the time-sharing measurement mode of replacing the slowing ball for multiple times is difficult to ensure that the neutron field is kept stable and consistent in the whole measurement process, and under the condition that the neutron field fluctuates, non-simultaneous measurement can introduce a non-negligible system error, so that the reliability of the energy spectrum inversion result is affected. In order to simplify the operation flow, a single-sphere neutron spectrometer configuration with a plurality of thermal neutron detectors embedded in a single moderating body is recently developed, count information of the plurality of detectors is obtained simultaneously through one-time measurement to support energy spectrum inversion, moderating sphere replacement can be reduced in device form, and measurement efficiency is improved, however, the engineering realization key of the single-sphere multi-detector spectrometer is that an electronic system can realize stable, synchronous and parallel pulse processing and counting on output signals of a plurality of detectors, otherwise, the online measurement target of 'acquiring full data through single measurement' is still difficult to meet. In terms of the electronic implementation of single sphere multi-detector spectrometers, there are several problems that remain unsolved by the prior art. Firstly, the electric signal output by the thermal neutron detector is very weak, belongs to low-charge/low-current magnitude signals, has current amplitude of about pA magnitude and is easy to be interfered by noise, and if the low-noise front end conversion and amplification capability aiming at weak charge pulses is lacking, the effective pulse amplitude is insufficient, the signal to noise ratio is reduced, and further the counting is unstable, and the lost counting and the false counting are increased. In the scene of higher neutron flux, the nuclear pulse amplified at the front end is easy to generate the phenomena of pulse accumulation, baseline lifting and the like, the effective rising edge is difficult to accurately extract by a follow-up screening and counting circuit due to pulse waveform distortion, so that counting is lost or false triggering is caused, and if a correction mechanism aiming at pulse distortion and undershoot and an effective compression means for pulse width are not provided, the passing rate and accuracy of the system under the condition of high counting rate are difficult to ensure. And thirdly, the single-sphere neutron spectrometer often needs to process multiple paths of signals output by multiple detectors at the same time, if the electronic system still adopts a structure of channel multiplexing, time-sharing scanning or lack of independent processing among channels, the problems of inconsistent time sequence among channels, unsynchronized data, insufficient multi-channel data throughput and the like are easily caused, and fina