Neutron dose rate measuring device based on gamma energy spectrum

Abstract

The utility model belongs to the technical field of neutron measurement, and particularly relates to a neutron dose rate measuring device based on a gamma energy spectrum. Comprising a shell, a high-voltage power supply, a photomultiplier, a protective cover and a lanthanum bromide crystal, the lanthanum bromide crystal and the photomultiplier are coupled and packaged in the protective cover, the photomultiplier is connected with the high-voltage power supply, and the protective cover and the high-voltage power supply are installed in the shell. The neutron dose rate measuring device has the advantages that the neutron dose rate can be directly measured, and the gamma dose rate can be measured at the same time. The system has the advantages of quick response, light weight, simplicity in operation, high applicability and the like, has the capability of measuring a conventional radiation environment and a nuclear accident emergency scene, can provide support for homemade autonomous controllability of radiation monitoring equipment, and provides a guidance basis for nuclear safety supervision and nuclear emergency actions of nuclear instruments.

Description

Technical Field

[0001] The utility model belongs to the technical field of neutron measurement, and in particular relates to a neutron dose rate measuring device based on a gamma energy spectrum. Background Art

[0002] Neutrons themselves are not charged, and their electromagnetic interactions with atomic nuclei and extranuclear electrons are weak. They can only be detected indirectly by generating secondary particles through strong interactions with atomic nuclei. Therefore, from the perspective that neutrons are easy to react with detection media, and the reaction products are measurable and easy to measure, many neutron detection methods have been developed based on the types of interactions between neutrons and atomic nuclei. The basic detection methods include: nuclear reaction method, nuclear recoil method, nuclear fission method and nuclear activation method.

[0003] The detection of neutrons by semiconductor detectors is mainly to load a thin film layer containing neutron sensitive media onto a semiconductor diode, and to detect neutrons through the interaction between neutrons and sensitive media. Representative detectors include 6LiF sandwich semiconductor detectors, 4H-SiC detectors, and high-purity germanium detectors. This type of semiconductor-based neutron detector has the advantages of high amplitude resolution and wide linear range, and is widely used in precision physics experiments and large nuclear physics devices, but it is susceptible to radiation damage, and the use or storage of some detectors is limited by temperature, which has limitations in portability. Commonly used portable instruments for neutron ambient dose equivalent measurement are mostly based on 3H proportional counters or BF3 counters. This type of detector mostly uses the pulse amplitude method for neutron / γ discrimination, and the discrimination effect is better. Neutron radiation is always accompanied by γ emission. The development of neutron detection methods and measuring instruments has always been inseparable from how to eliminate or suppress the influence of γ rays. When γ rays are present, a higher γ count rate may cause signal accumulation and produce a larger amplitude γ signal, which has a greater impact on the neutron pulse signal, and then leads to deviations in neutron measurement results. Based on shielding, eliminating, avoiding and reducing the interference of gamma rays on neutron detection, a variety of neutron / gamma identification methods have been developed, including pulse amplitude identification method, pulse waveform identification method and time-of-flight method. The basic principle of the time-of-flight method is to use the different flying speeds of photons and neutrons, and the difference in the time required to fly the same distance, so as to achieve the identification of the two. The time-of-flight method directly uses the basic characteristics of neutrons and photons, and the identification results obtained are highly accurate. However, since the implementation of the method requires a dedicated time analysis system to accurately measure the take-off and arrival times of neutrons and photons, this cannot be achieved in actual radiation environment monitoring. Therefore, the time-of-flight method is mostly used for neutron / gamma identification in precision nuclear physics experiments, and is rarely used in actual radiation field measurements.

[0004] Therefore, a device suitable for directly measuring the neutron energy spectrum and neutron dose rate without suppressing gamma rays is established, so as to realize the function of directly measuring neutrons and measuring the gamma dose rate at the same time, provide technical means for the accurate and rapid measurement of neutron radiation fields under normal and emergency situations, and provide strong technical support for improving the radiation monitoring and nuclear emergency disposal equipment system.

[0005] The existing detection devices currently have the following problems:

[0006] 1. During the neutron measurement process, a gamma-ray environment with high energy and high counting rate may produce a large-amplitude gamma signal, which in turn affects the neutron pulse signal.

[0007] 2. Currently, neutron dose rate measurement is mainly carried out by calculating the counting rate and dose conversion coefficient, but it is mainly carried out by averaging or presetting the neutron dose conversion coefficient. This method lacks consideration of the different biological effects caused by different energy rays, resulting in poor measurement accuracy. Utility Model Content

[0008] The utility model aims to provide a neutron dose rate measuring device based on gamma energy spectrum, which can be applied to the accurate and rapid measurement of neutron radiation field in normal and emergency situations, while taking into account the measurement of gamma rays.

[0009] The technical solution of the utility model is as follows: a neutron dose rate measuring device based on gamma energy spectrum, comprising a shell, a high-voltage power supply, a photomultiplier tube, a protective cover and a lanthanum bromide crystal, the lanthanum bromide crystal is coupled with the photomultiplier tube and packaged in the protective cover, the photomultiplier tube is connected to the high-voltage power supply, and the protective cover and the high-voltage power supply are installed in the shell.

[0010] The coupled lanthanum bromide crystal is connected to the photomultiplier tube and the voltage divider circuit, the voltage divider circuit is connected to multiple channels respectively, the multiple channels are connected to the control board through RS485 serial port communication, the control board is connected to the terminal circuit and the PC through the RS485 serial port, the high-voltage power supply provides PMT high-voltage power supply to the voltage divider circuit, the high-voltage power supply provides 12V power supply to the multiple channels, the control board, and the terminal circuit respectively, and the terminal circuit is also powered by two 12V batteries.

[0011] The high-voltage power supply provides high-voltage input for the detector, including a boost chip, an LDO circuit, a high-voltage module, a high-voltage acquisition circuit and a high-voltage control circuit. The boost chip outputs a 13V voltage to the LDO circuit, and the LDO circuit outputs an 11.8V voltage to the high-voltage module. The high-voltage module is connected to the main control module through the high-voltage acquisition circuit. The main control module controls the high-voltage module through the high-voltage control circuit, and the high-voltage module outputs voltage to the voltage divider circuit.

[0012] The high voltage module adopts CC228P-01Y power module.

[0013] The beneficial effect of the utility model is that the device can directly measure the neutron dose rate and can also measure the gamma dose rate. It has the advantages of fast response, light weight, simple operation, strong applicability, etc. It has the ability to measure conventional radiation environments and nuclear accident emergency scenarios, and can provide support for the domestic independent control of radiation monitoring equipment, and provide guidance for nuclear safety supervision and nuclear emergency actions of our nuclear instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic diagram of a neutron dose rate measuring device based on gamma energy spectrum provided by the utility model;

[0015] Figure 2 This is a structural diagram of a neutron dose rate measurement device based on gamma energy spectrum provided by the utility model;

[0016] Figure 3 Schematic diagram of high voltage power supply.

[0017] In the figure: 1 housing, 2 high voltage power supply, 3 photomultiplier tube, 4 protective cover, 5 lanthanum bromide crystal. DETAILED DESCRIPTION

[0018] The utility model is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, a neutron dose rate measuring device based on gamma energy spectrum includes a shell 1, a high-voltage power supply 2, a photomultiplier tube 3, a protective cover 4 and a lanthanum bromide crystal 5. The lanthanum bromide crystal 5 is coupled with the photomultiplier tube 3 and packaged in the protective cover 4. The photomultiplier tube 3 is connected to the high-voltage power supply 2. The protective cover 4 and the high-voltage power supply 2 are installed in the shell 1.

[0020] As shown in Figure 2, the coupled lanthanum bromide crystal is connected to the photomultiplier tube and the voltage divider circuit, the voltage divider circuit is connected to the multi-channel respectively, the multi-channel is connected to the control board via RS485 serial port communication, the control board is connected to the terminal circuit and the PC via RS485 serial port, the high-voltage power supply provides PMT high-voltage power supply to the voltage divider circuit, the high-voltage power supply provides 12V power supply to the multi-channel, the control board, and the terminal circuit respectively, and the terminal circuit is also powered by two 12V batteries.

[0021] like Figure 3As shown, the high-voltage power supply provides high-voltage input for the detector, including a boost chip, an LDO circuit, a high-voltage module, a high-voltage acquisition circuit and a high-voltage control circuit. The boost chip outputs a 13V voltage to the LDO circuit, and the LDO circuit outputs a 11.8V voltage to the high-voltage module. The high-voltage module is connected to the main control module through the high-voltage acquisition circuit. The main control module controls the high-voltage module through the high-voltage control circuit, and the high-voltage module outputs the voltage to the voltage divider circuit. The high-voltage module uses the CC228P-01Y power module. The main control module can collect the output voltage of the high-voltage module through the high-voltage acquisition circuit, and then control the output voltage of the high-voltage module through the high-voltage control circuit, thereby realizing closed-loop control and greatly improving the accuracy of the high-voltage output.

[0022] The power supply voltage required by the high-voltage module is 11.5-12.5V. To improve the reliability of the system, the battery voltage is first increased to 13V through a boost circuit, and then the voltage is stabilized at 11.8V through an LDO circuit to power the high-voltage module. Powering the high-voltage module through LDO can reduce the output ripple of the high-voltage module, thereby reducing the noise of the detector's signal output.

Claims

1. A neutron dose rate measuring device based on gamma energy spectrum, characterized in that: The invention comprises a shell, a high-voltage power supply, a photomultiplier tube, a protective cover and a lanthanum bromide crystal. The lanthanum bromide crystal is coupled with the photomultiplier tube and packaged in the protective cover. The photomultiplier tube is connected with the high-voltage power supply. The protective cover and the high-voltage power supply are installed in the shell.

2. A neutron dose rate measuring device based on gamma energy spectrum as claimed in claim 1, characterized in that: The coupled lanthanum bromide crystal is connected to the photomultiplier tube and the voltage divider circuit, the voltage divider circuit is connected to multiple channels respectively, the multiple channels are connected to the control board through RS485 serial port communication, the control board is connected to the terminal circuit and the PC through the RS485 serial port, the high-voltage power supply provides PMT high-voltage power supply to the voltage divider circuit, the high-voltage power supply provides 12V power supply to the multiple channels, the control board, and the terminal circuit respectively, and the terminal circuit is also powered by two 12V batteries.

3. The neutron dose rate measuring device based on gamma energy spectrum according to claim 1, characterized in that: The high-voltage power supply provides high-voltage input for the detector, including a boost chip, an LDO circuit, a high-voltage module, a high-voltage acquisition circuit and a high-voltage control circuit. The boost chip outputs a 13V voltage to the LDO circuit, and the LDO circuit outputs an 11.8V voltage to the high-voltage module. The high-voltage module is connected to the main control module through the high-voltage acquisition circuit. The main control module controls the high-voltage module through the high-voltage control circuit, and the high-voltage module outputs voltage to the voltage divider circuit.

4. A neutron dose rate measuring device based on gamma spectrum as claimed in claim 3, characterized in that: The high voltage module adopts CC228P-01Y power module.

Images