Space neutron detection energy identification device and method

Abstract

The invention provides a space neutron detection energy identification device and method, and belongs to the technical field of neutron detection. The system comprises a plastic scintillator, a photomultiplier, a first charge measurement chip, a second charge measurement chip, a first operational amplifier and analog-to-digital conversion chip, a second operational amplifier and analog-to-digital conversion chip and an FPGA chip. The plastic scintillator interacts with incident neutrons, and generated middle-bullet scattered fluorescence and neutron capture fluorescence are amplified and converted by the photomultiplier to form neutron signals; the first charge measuring chip and the second charge measuring chip are used for collecting neutron signals, and the collected neutron signals are transmitted to the FPGA chip after being processed by the first operational amplifier and analog-to-digital conversion chip and the second operational amplifier and analog-to-digital conversion chip respectively. The method reduces the overall power consumption and quality, is simple in process, is safe and reliable, is high in environment adaptability, and is very suitable for deep space exploration tasks with limited quality and functions.

Description

Technical Field

[0001] The present invention belongs to the technical field of neutron detection, and in particular relates to a space neutron detection energy identification device and method. Background Art

[0002] Neutron detection technology in space environments is of great significance for space radiation protection and the search for water resources on planetary surfaces. Existing space neutron detection technologies often rely on helium-3 proportional counters or complex readout electronics, placing high demands on detector weight, power consumption, and manufacturing processes, making them unsuitable for deep space exploration applications, which have significant technical limitations. Summary of the Invention

[0003] The present invention addresses the shortcomings of existing technologies and provides a space neutron detection energy identification device and method. By using a boron-doped plastic scintillator and a photomultiplier tube as the detection unit, coupled with two charge measurement chips, an operational amplifier, and an analog-to-digital conversion chip, along with parallel data acquisition and pulse interval measurement methods, the device achieves neutron detection and energy measurement in space environments.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a space neutron detection energy identification device, comprising: a plastic scintillator, a photomultiplier tube, a first charge measurement chip, a second charge measurement chip, a first operational amplifier and analog-to-digital conversion chip, a second operational amplifier and analog-to-digital conversion chip, and an FPGA chip; the plastic scintillator interacts with incident neutrons, and the generated neutron scattering fluorescence and neutron capture fluorescence are amplified and converted by the photomultiplier tube to form a neutron signal; the first charge measurement chip and the second charge measurement chip are used to collect neutron signals, and the collected neutron signals are processed by the first operational amplifier and analog-to-digital conversion chip and the second operational amplifier and analog-to-digital conversion chip respectively and then transmitted to the FPGA chip.

[0006] Optionally, the plastic scintillator is a boron-doped plastic scintillator of model EJ254.

[0007] Optionally, the photomultiplier tube is a phototube of model R3886A.

[0008] Optionally, the first charge measurement chip and the second charge measurement chip are IDE3381 chips.

[0009] Optionally, a high-voltage power supply module is further included, and the FPGA chip provides voltage to the photomultiplier tube by controlling the high-voltage power supply module.

[0010] In a second aspect, the present invention provides a method for identifying energy of space neutron detection, using the space neutron detection energy identification device as described in the first aspect, comprising the following steps:

[0011] The first charge measurement chip receives the neutron signal and generates a trigger. The FPGA chip receives the trigger signal from the first charge measurement chip and controls the second charge measurement chip to detect subsequent neutron signals.

[0012] If the second charge measurement chip receives a neutron signal within the set time t1, it is considered that the neutron signal is indistinguishable from the neutron signal received by the first charge measurement chip, and the acquisition operation of the two charge measurement chips is terminated. The two charge measurement chips are reset to the initial state and wait for the neutron signal again;

[0013] If the second charge measurement chip does not receive a neutron signal within the set time t1, the amplitude of the neutron signal received by the first charge measurement chip is detected as follows:

[0014] ① If the amplitude exceeds the preset threshold, the neutron signal received by the first charge measurement chip is considered to be incorrect, the acquisition operation of the two charge measurement chips is terminated, and the two charge measurement chips are reset to the initial state and wait for the neutron signal again;

[0015] ② If the amplitude does not exceed the preset threshold, and within the set time t2, the second charge measurement chip receives the neutron signal and generates a trigger, then the dual-pulse acquisition process is entered, and the FPGA chip controls the first op amp and analog-to-digital conversion chip corresponding to the first charge measurement chip to collect the neutron dispersion signal, and controls the second op amp and analog-to-digital conversion chip corresponding to the second charge measurement chip to collect the neutron capture signal; if within the set time t2, the second charge measurement chip does not receive the neutron signal, then the single-pulse acquisition process is entered, and the FPGA chip only controls the first op amp and analog-to-digital conversion chip corresponding to the first charge measurement chip to collect the neutron capture signal.

[0016] Optionally, after all acquisition processes are completed, the FPGA chip controls the two charge measurement chips to wait for a set time t3 and then re-enter the observation mode to wait for a new neutron signal.

[0017] Optionally, after all acquisition processes are completed, the acquired data are recorded in an internal memory according to time information, and the acquired data are summarized into an energy spectrum according to numerical information.

[0018] Optionally, the set time t1 is 400 ns, t2 is 5 us, and t3 is at least 25.6 us.

[0019] Optionally, the preset threshold is 2.5 MeV.

[0020] The beneficial effects of the present invention are as follows: the present invention utilizes the different ratios of elastic scattering and nuclear reactions between neutrons of different energies and the detector material, creatively uses multiple charge measurement chips to collect the photoelectric signals output by different reactions in parallel, and uses the differences in signal spacing and amplitude to achieve neutron energy identification. The advantages of the present invention are: 1. It avoids the use of complex detector materials and only uses boron-doped plastic scintillators. This material can adapt to the application environment of space detectors and avoid complex shockproofing and thermal control requirements; 2. It avoids the use of complex electronic readout systems for signal waveform identification, reducing system power consumption and weight, and improving system reliability; 3. By comparing signals in different time periods, it can effectively screen out accidental coincidences during energy spectrum accumulation, improving neutron identification accuracy. To meet the scientific needs of space neutron detection, the present invention realizes up to 8 channels of neutron signal measurement function, which can realize independent detection and correlation detection of 8 channels to meet scientific research needs. Compared with traditional neutron measurement solutions, the overall power consumption and weight of the device of the present invention are lower, the process is simple, safe and reliable, and the environmental adaptability is strong, making it very suitable for deep space exploration missions with limited quality and function. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural diagram of a space neutron detection energy identification device.

[0022] Figure 2 This is the working timing diagram of the charge measurement chip.

[0023] Figure 3 Control system workflow diagram. DETAILED DESCRIPTION

[0024] The present invention will now be described in further detail with reference to the accompanying drawings.

[0025] Example 1

[0026] This embodiment proposes a space neutron detection energy identification device, the structure of which is shown in the attached Figure 1 , including: plastic scintillator, photomultiplier tube, two charge measurement chips and corresponding operational amplifier and analog-to-digital conversion chips, FPGA chip (acquisition control system) and data transmission circuit, a total of four parts, each part has the following functions:

[0027] The plastic scintillator is EJ254 produced by EJ Company of the United States. The boron doping ratio of the plastic scintillator is 5% by mass. 10 The content of B isotope is 1% of the crystal mass, and the operating temperature range is -60℃ to +60℃. 10The B isotope undergoes a capture reaction, depositing the full 2.34 MeV of energy. Fast neutrons are moderated by the plastic scintillator and undergo a capture reaction after an average of approximately 2.7 microseconds. In this device, for 2.5 MeV fast neutrons, the plastic scintillator volume should be no smaller than a 50mm*50mm*50mm cube; otherwise, the fast neutron moderation efficiency will be significantly reduced.

[0028] The photomultiplier tube is a 1.5-inch R3886A tube manufactured by Hamamatsu Corporation of Japan. It operates at a voltage of 1250V and a temperature range of -30°C to +50°C. It can withstand a shock of 100g and a random vibration of 20g. This photomultiplier tube converts the fluorescence photons emitted by the plastic scintillator into an electronic signal, which is then read out and collected by the subsequent charge measurement chip and peripheral circuitry. The photomultiplier tube has a sensitive wavelength of 420nm, matching the wavelength of the selected plastic scintillator, the EJ454. The photomultiplier tube should be no smaller than half the length of the plastic scintillator's light-emitting surface, otherwise significant light reception loss will occur.

[0029] The charge measurement chip uses the IDE3381 chip produced by the Norwegian IDEAS company. This chip has 16-channel photoelectric tube or photodiode input and independent processing functions, with a minimum signal triggering of 50ns and a signal shaping capability of 50ns. This chip can input positive charge signals or negative charge signals, and can adapt to the working mode of the front-end photoelectric tube using anode capacitor distribution dual output or anode dynode dual output. Figure 2 As shown, when operating in parallel, since the neutron dispersion signal appears first and the neutron capture signal appears within 0 to 5 μs, the first charge measurement chip responsible for neutron dispersion signal processing should directly convert the first input signal and provide a trigger signal to the control system. The second charge measurement chip responsible for neutron capture signal processing does not process the first input signal until the control system receives the trigger of the neutron dispersion signal and notifies the second charge measurement chip responsible for capture signal conversion to begin waiting for the neutron capture signal. After this, any subsequent neutron signals are treated as neutron capture signals and converted by the second charge measurement chip responsible for neutron capture signal processing. If no neutron capture signal is received within 5 μs, it is assumed that the first charge measurement chip responsible for neutron dispersion signal processing has acquired the neutron capture signal. This embodiment, by using two chips in parallel, achieves the functions of simultaneously processing and acquiring neutron dispersion and neutron capture signals.

[0030] The operational amplifier and analog-to-digital conversion chip are responsible for amplifying the signal output by the charge measurement chip and converting it into a digital signal for subsequent data storage and transmission. The operational amplifier and analog-to-digital conversion chip are directly controlled by the acquisition system, and the corresponding charge measurement chip triggers the circuit to start acquisition. When the acquisition system receives a trigger signal from the first charge measurement chip, it controls the corresponding operational amplifier and analog-to-digital conversion chip to perform signal conversion; similarly, when the acquisition system receives a trigger signal from the second charge measurement chip, it controls the corresponding operational amplifier and analog-to-digital conversion chip to perform signal conversion. According to the attached Figure 2 The working time of the analog-to-digital conversion circuit is about 4us. During this period, the corresponding charge measurement chip cannot work and process new neutron signals.

[0031] The field-programmable logic chip (FPGA) is responsible for controlling various parts of the entire system, such as the high-voltage power supply, charge measurement chip, analog-to-digital conversion chip, etc., and is responsible for the external interface of the entire system.

[0032] When a neutron enters the plastic scintillator of the detector, it interacts with the scintillator to produce neutron scattering or neutron capture fluorescence; after the fluorescence is generated, it is amplified and converted by the phototube multiplier tube to form an electrical signal, which enters the charge measurement chip; the two charge measurement chips respectively process the neutron scattering signal and neutron capture signal to identify the energy of the incident neutron; subsequent operational amplifiers, analog-to-digital conversion chips and FPGA chips realize signal acquisition, storage and transmission to actual users.

[0033] Example 2

[0034] Based on the space neutron detection energy identification device proposed in the embodiment, this embodiment further proposes a space neutron detection energy identification method. The FPGA chip responsible for acquisition control needs to be based on the attached Figure 3 The control logic is performed:

[0035] 1. When the acquisition system receives a trigger signal from the first charge measurement chip, the control system starts to control the second charge measurement chip to detect subsequent neutron signals.

[0036] 2. If the second charge measurement chip receives a neutron signal and generates a trigger within 400ns, it is considered that the signal cannot be distinguished from the first signal. At this time, all processing and acquisition operations should be terminated, the invalid data counter is increased by 1, and both charge measurement chips are recharged to the initial state, and the neutron signal is waited for again.

[0037] 3. If the second charge measurement chip does not receive a neutron signal and generate a trigger within 400ns, it will start to detect the signal amplitude of the first charge measurement chip. If the amplitude exceeds the threshold of 2.5MeV, it is considered that the first signal is not a neutron signal. At this time, all processing and acquisition operations should be terminated, the large signal counter is increased by 1, and both charge measurement chips are recharged to the initial state, and the neutron signal is waited for again.

[0038] 4. If the signal from the first chip does not exceed the limit, and the second charge measurement chip receives a neutron signal and generates a trigger within 5µs, the dual-pulse acquisition process begins. The op amp and analog-to-digital converter chip corresponding to the first charge measurement chip collects the neutron dispersion signal, while the op amp and analog-to-digital converter chip corresponding to the second charge measurement chip collects the neutron capture signal.

[0039] 5. If the second charge measurement chip does not receive a neutron signal trigger within 5µs, the single pulse acquisition process begins. The acquisition system only controls the op amp and analog-to-digital converter chip corresponding to the first charge measurement chip to collect the neutron capture signal.

[0040] 6. Regardless of which acquisition process is completed, the acquisition control system should control the two charge measurement chips to wait for 25.6us and then enter the observation mode again to wait for new neutron signals.

[0041] After the acquisition and control system completes the above process, it can record the acquired data in internal memory according to time information and summarize the acquired data into an energy spectrum according to numerical information. When an external data request is sent, the recorded case information and energy spectrum data are sent to the external user.

[0042] To improve fast neutron identification and reduce the rate of accidental coincidence events, the acquisition and control system not only collects dual-signal events between 400ns and 5us, but also collects dual-signal events between 20us and 25.6us. By deducting dual-signal events between 20us and 25.6us from the dual-signal events between 400ns and 5us when aggregating them into energy spectrum events, fast neutron identification is effectively improved.

[0043] This embodiment uses a boron-doped plastic scintillator, coupled with the dual-pulse recognition and acquisition function of subsequent electronics, effectively realizing the identification function of different neutron energies, avoiding the use of complex processes in space environments. 3 He proportional counter or 6The Li-glass detector also avoids the use of complex, high-power electronics chips for waveform identification. It can achieve neutron detection and energy identification with eight detectors while keeping the total detector mass below 10kg and total power consumption below 5W. Through simulation and actual calibration testing, the identification capability for 700keV fast neutrons exceeds 81%.

[0044] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A space neutron detection energy identification device, characterized in that: include: A plastic scintillator, a photomultiplier tube, a first charge measurement chip, a second charge measurement chip, a first operational amplifier and analog-to-digital conversion chip, a second operational amplifier and analog-to-digital conversion chip, and an FPGA chip; the plastic scintillator interacts with incident neutrons, and the generated neutron scattering fluorescence and neutron capture fluorescence are amplified and converted by the photomultiplier tube to form a neutron signal; the first charge measurement chip and the second charge measurement chip are used to collect neutron signals, and the collected neutron signals are processed by the first operational amplifier and analog-to-digital conversion chip and the second operational amplifier and analog-to-digital conversion chip respectively, and then transmitted to the FPGA chip.

2. The space neutron detection energy identification device according to claim 1, characterized in that: The plastic scintillator adopts a boron-doped plastic scintillator of model EJ254.

3. The space neutron detection energy identification device according to claim 1, characterized in that: The photomultiplier tube is a phototube of model R3886A.

4. The space neutron detection energy identification device according to claim 1, characterized in that: The first charge measurement chip and the second charge measurement chip are IDE3381 chips.

5. The space neutron detection energy identification device according to claim 1, characterized in that: It also includes a high-voltage power supply module, and the FPGA chip provides voltage to the photomultiplier tube by controlling the high-voltage power supply module.

6. A space neutron detection energy identification method, using the space neutron detection energy identification device according to any one of claims 1 to 5, characterized in that: The steps include: The first charge measurement chip receives the neutron signal and generates a trigger. The FPGA chip receives the trigger signal from the first charge measurement chip and controls the second charge measurement chip to detect subsequent neutron signals. If the second charge measurement chip receives a neutron signal within the set time t1, it is considered that the neutron signal is indistinguishable from the neutron signal received by the first charge measurement chip, and the acquisition operation of the two charge measurement chips is terminated. The two charge measurement chips are reset to the initial state and wait for the neutron signal again; If the second charge measurement chip does not receive a neutron signal within the set time t1, the amplitude of the neutron signal received by the first charge measurement chip is detected as follows: ① If the amplitude exceeds the preset threshold, the neutron signal received by the first charge measurement chip is considered to be incorrect, the acquisition operation of the two charge measurement chips is terminated, and the two charge measurement chips are reset to the initial state and wait for the neutron signal again; ② If the amplitude does not exceed the preset threshold, and within the set time t2, the second charge measurement chip receives the neutron signal and generates a trigger, then the dual-pulse acquisition process begins. The FPGA chip controls the first operational amplifier and analog-to-digital conversion chip corresponding to the first charge measurement chip to collect the neutron dispersion signal, and controls the second operational amplifier and analog-to-digital conversion chip corresponding to the second charge measurement chip to collect the neutron capture signal. If the second charge measurement chip does not receive the neutron signal within the set time t2, the single pulse acquisition process is entered, and the FPGA chip only controls the first operational amplifier and analog-to-digital conversion chip corresponding to the first charge measurement chip to collect the neutron capture signal.

7. A space neutron detection energy identification method according to claim 6, characterized in that: After all acquisition processes are completed, the FPGA chip controls the two charge measurement chips to wait for the set time t3 and then enter the observation mode again to wait for new neutron signals.

8. The method for identifying space neutron detection energy according to claim 6, wherein: After all acquisition processes are completed, the acquired data are recorded in the internal memory according to the time information, and the acquired data are summarized into an energy spectrum according to the numerical information.

9. The method for identifying space neutron detection energy according to claim 6, wherein: The set time t1 is 400 ns, t2 is 5 us, and t3 is at least 25.6 us.

10. The space neutron detection energy identification method according to claim 6, characterized in that: The preset threshold is 2.5 MeV.

Images