A temperature automatic correction system and method for online measurement of neutron flux

Abstract

The present invention specifically relates to a system and method for automatic temperature correction of online neutron fluence measurement, which solves the current problem of large errors in directly measuring neutron fluence in a temperature-varying environment. The present invention provides an automatic temperature correction system for online neutron fluence measurement, comprising a processing computer, a power supply module, a constant current source module, a current measurement module, and a detector module; the power supply module is connected to the detector module and the current measurement module, respectively; the detector module is connected to the constant current source module; the current measurement module is connected to the detector module, and the processing computer loads a neutron fluence measurement program and a temperature correction program; the detector module includes a connected temperature detector and a neutron fluence detector, the neutron fluence detector being a semiconductor detector, and the temperature detector being installed adjacent to the neutron fluence detector. The present invention also provides a method for automatic temperature correction of online neutron fluence measurement.

Description

Technical Field

[0001] The invention relates to temperature measurement in a radiation detection process, and relates to a temperature automatic correction system and method for online neutron flux measurement. Background Art

[0002] Neutron fluence measurement is one of the key parameter measurement projects in important research fields such as radiophysical diagnosis, device damage assessment, and material modification measurement. How to accurately obtain neutron fluence data has become a hot topic in neutron detection research. At present, the semiconductor detection method has been widely used in neutron fluence measurement due to its advantages such as real-time and simple measurement. In the semiconductor detection method, the displacement damage caused by neutron irradiation in the semiconductor material significantly reduces the minority carrier lifetime of the material, which in turn causes the current gain of the semiconductor detector to change. The neutron fluence (1MeV equivalent fluence) can be measured using the mathematical relationship between the current gain change and the neutron fluence. During the measurement process, if the detector working current is fixed, the input current and the neutron fluence are proportional to each other. The relationship between them is: in, is the neutron flux, C is a constant, △I in is the input current change value, I C is the working current.

[0003] However, semiconductor material performance parameters are closely related to temperature. Neutron fluence measured by semiconductor detectors varies at different temperatures. Generally, within a small temperature range (less than 10 degrees Celsius), the measurement error due to temperature is no more than 5%. However, as the temperature range increases, the measurement error increases, and in a superlinear manner. Therefore, to accurately obtain neutron fluence measurements in a variable temperature environment, the influence of temperature must be considered.

[0004] The influence of temperature on semiconductor materials is reflected in multiple parameters, such as the built-in potential barrier of the PN junction, carrier concentration, bandgap width, etc. However, these underlying parameters are difficult to measure, and it is very difficult to use these underlying parameters to directly correct the measurement errors caused by temperature changes. Summary of the Invention

[0005] The present invention provides a temperature automatic correction system and method for online neutron fluence measurement, which is used to automatically correct neutron fluence measurement errors caused by temperature drift through a small number of parameter measurements, solving the current problem of large errors in directly measuring neutron fluence in a temperature-varying environment.

[0006] Research has found that as temperature rises, heavily doped semiconductor regions produce more intrinsic carriers due to the narrowing bandgap effect, increasing the electron emission efficiency and, in turn, increasing the current gain of the semiconductor detector. If the operating current remains unchanged, the input current will decrease. Therefore, as long as the relationship between the input current and temperature is obtained, the error caused by temperature can be corrected by measuring the input current. Analysis has found the following relationship between input current and temperature:

[0007]

[0008] Among them I in , I in0 are the input currents at temperatures T and T0 respectively, and m is a constant. C In this case, by measuring I in , I in0 You can calculate m, get the expression of input current and temperature, and then get the neutron injection Relationship with temperature: Where C is a constant. Based on the above inference, a temperature automatic correction system for online neutron fluence measurement is designed.

[0009] To achieve the above object, the technical solution of the present invention is as follows:

[0010] A temperature automatic correction system for online neutron fluence measurement is characterized in that it comprises a processing computer, a power supply module, a constant current source module, a current measurement module, and a detector module; the detector module comprises a temperature detector and a neutron fluence detector connected in sequence, the neutron fluence detector being a semiconductor detector, and the temperature detector being arranged adjacent to the neutron fluence detector;

[0011] The power supply module is connected to the neutron flux detector, the temperature detector and the current measurement module respectively, and provides a positive working voltage and a control voltage for the neutron flux detector and the temperature detector, and provides a positive and negative bidirectional bias voltage for the current measurement module;

[0012] The neutron flux detector is connected to the constant current source module to obtain a constant working current;

[0013] The current measurement module is connected to the neutron flux detector and the temperature detector respectively. The current measurement module is used to sample the input current signals of the neutron flux detector and the temperature detector, and transmit the input current signals to a processing computer. The processing computer is loaded with a neutron flux measurement program and a temperature correction program, and is used to process the input current signal to obtain the corresponding neutron flux and temperature, and correct the neutron flux according to the temperature.

[0014] Furthermore, the power supply module includes an LDO voltage conversion circuit, the output end of which is connected to the neutron flux detector and the temperature detector respectively, and provides a forward working voltage and a control voltage for the neutron flux detector and the temperature detector;

[0015] The LDO voltage conversion circuit is also connected to the current measurement module.

[0016] Furthermore, the constant current source module includes an adaptation resistor and a constant current transistor connected in sequence, the constant current transistor is connected to the neutron flux detector through the adaptation resistor in series, and the common end of the constant current transistor is grounded.

[0017] Furthermore, the current measurement module includes a sampling resistor, an AD converter, a communication chip and a USB data interface connected in sequence. The sampling resistor is installed between the temperature detector and the neutron detector or between the LDO voltage conversion circuit and the temperature detector. The AD converter converts the voltage across the sampling resistor into a digital signal and transmits it to a processing computer through the communication chip and the USB data interface. The processing computer includes a USB interface, and the USB interface is connected to the USB data interface.

[0018] A method for automatic temperature correction of online neutron fluence measurement is based on the above-mentioned automatic temperature correction system for online neutron fluence measurement. The method comprises the following steps:

[0019] Step 1: Turn on the power module and constant current source module. The constant current source module clamps the working current of the neutron flux detector at I C ;

[0020] Step 2: The current measurement module collects the input current of the neutron flux detector and the operating current of the temperature detector and converts them into differential digital signals and transmits them to the processing computer;

[0021] Step 3: The processing computer processes the differential digital signal transmitted by the current measurement module to obtain the input current of the neutron flux detector and the temperature of the temperature detector;

[0022] By changing the temperature of the neutron flux detector, the processing computer obtains at least two groups of neutron flux detector input currents and the corresponding temperature detector temperatures, namely (T0, I in0 ) and (T, I in ), and according to the formula Calculate the value of parameter m;

[0023] Step 4: Place the neutron flux detector and temperature detector in the neutron radiation environment, and obtain the temperature value Tz of the temperature controller and the input current value I of the neutron flux detector in real time. inz, the processing computer according to the formula Calculate the reference temperature T C Neutron Fluence Correction

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) In the correction method of the present invention, the current measurement module only measures two parameters: the input current value of the neutron flux detector and the temperature value of the temperature detector. This can measure the neutron flux and eliminate the measurement error caused by temperature changes. The processing computer automatically processes and calculates the measured data, greatly improving the measurement efficiency and operational convenience. The correction method is based on the temperature dependence of semiconductor materials and has a strong theoretical basis. At the same time, only two current parameters are required to eliminate the measurement error caused by temperature changes. The steps are simple and clear, easy to implement, and significantly improve the measurement accuracy of neutron flux in temperature-varying environments.

[0026] (2) The calibration system of the present invention includes a processing computer, a power supply module, a constant current source module, a current measurement module, and a detector module. After power is applied, the parameters of the power supply module, the constant current source module, and the detector module are automatically configured, which improves the test speed, reduces labor costs, and significantly improves the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the neutron fluence online measurement temperature correction system in an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of the connection relationship of the constant current source modules in an embodiment of the present invention;

[0029] Figure 3 This is a schematic structural diagram of a current measurement module according to an embodiment of the present invention;

[0030] Figure 4 Inputting a current-temperature correction curve for the neutron fluence detector in an embodiment of the present invention;

[0031] Figure 5 This is a temperature correction curve for neutron fluence measurement in an embodiment of the present invention.

[0032] The accompanying drawings are numerals as follows:

[0033] 1. Power supply module, 2. Detector module, 21. Temperature detector, 22. Neutron detector, 3. Constant current source module, 31. Adapter resistor, 32. Constant current source transistor, 4. Processing computer, 5. Current measurement module, 51. Sampling resistor, 52. AD converter, 53. Communication chip, 54. USB data interface. DETAILED DESCRIPTION

[0034] The present invention will be further described with reference to the accompanying drawings and specific embodiments.

[0035] A temperature automatic correction system for online measurement of neutron flux, such as Figure 1 As shown, it includes the following five parts: a processing computer 4, a power supply module 1, a constant current source module 3, a current measurement module 5 and a detector module 2.

[0036] The power module 1 is an LDO voltage conversion circuit with various voltage output standards. It is connected to the detector module 2 and the current measurement module 5. The power module 1 provides a forward operating voltage and a control voltage to the detector module 2, and a positive and negative bidirectional bias voltage to the current measurement module 5. The detector module 2 is connected to the constant current source module 3, ensuring a constant operating current for the detector module 2. The current measurement module 5 is also connected to the detector module 2 and samples the input current of the detector module 2 and transmits it to the processing computer 4, which is loaded with an automatic neutron fluence and temperature correction program.

[0037] The detector module 2 includes a temperature detector 21 and a neutron fluence detector 22, which are connected in sequence. The neutron fluence detector 22 is a semiconductor detector, and the temperature detector 21 is a metal detector. This ensures that the temperature detector 22 is not affected by changes in the implantation fluence during the experiment. The neutron fluence detector 22 is welded to the irradiation plate, and the temperature detector 21 is welded adjacent to the neutron fluence detector to ensure that the temperature is the same as that of the neutron fluence detector 22. An LDO voltage conversion circuit is connected to the temperature detector 21 to provide input current to the temperature detector 21 and the neutron fluence detector 22. The temperature detector 21 and the neutron fluence detector 22 are both connected to the current measurement module 5. The neutron fluence detector 22 is also connected to the constant current source module 3 to maintain a constant current in the neutron fluence detector 22.

[0038] like Figure 2 As shown, the constant current source module 3 includes an adaptation resistor 31 and a constant current transistor 32. The rated value of the constant current transistor 32 is preferably selected from 100μA to 1mA, and the adaptation resistor 31 is preferably selected from 1kΩ to 10kΩ. The source end of the constant current transistor 32 is connected to the neutron flux detector 22 through the series adaptation resistor 31, and the common end of the constant current transistor 32 is grounded. The constant current transistor 32 provides a constant operating current for the neutron flux detector 22. The constant current source transistor 32 is specifically a constant current diode.

[0039] like Figure 3As shown, the current measurement module 5 includes an AD converter 52, a communication chip 53, and a USB data interface 54 connected in sequence. A sampling resistor 51 is connected in series between the power module 1 and the temperature detector 21 or between the temperature detector 21 and the fluence detector 22. The AD converter 52 converts the voltage across the sampling resistor 51 into a digital signal, which is transmitted to the processing computer 4 via the communication chip 53 and the USB data interface 54. The processing computer 4 loads the neutron fluence measurement program and the temperature correction program, connects to the USB data interface 54 in the current measurement module 5 via the USB interface to achieve communication, and calculates and processes the input voltage value of the neutron fluence detector 22 and the voltage value of the temperature detector 21 measured by the current measurement module 5 to obtain the temperature-corrected neutron fluence measurement value.

[0040] The steps of the automatic temperature correction method for online neutron fluence measurement based on the automatic temperature correction system for online neutron fluence measurement are as follows:

[0041] Step 1: Before neutron irradiation, the power module 1 is turned on to power on the temperature automatic correction system for neutron fluence online measurement, and the constant current source module 3 clamps the operating current of the neutron fluence detector 22 at I C Since the current and voltage in the constant current source module 3 do not change, the working current of the neutron flux detector is constant at I C It will not change and will be a fixed value.

[0042] Step 2: The input current of the neutron flux detector and the operating current of the temperature detector are converted into differential digital signals by the current measurement module and transmitted to the processing computer.

[0043] Step 3: The processing computer 4 processes the differential digital signal transmitted by the current measurement module 5 to obtain the input current of the neutron flux detector 22 and the temperature of the temperature detector 21 respectively.

[0044] By changing the temperature of the neutron flux detector 22, the processing computer 4 obtains at least two sets of neutron flux detector 22 input currents and corresponding temperature detector temperatures, namely (T0, I in0 ) and (T, I in ), and according to the formula Calculate the value of parameter m.

[0045] Step 4: Place the neutron flux detector 22 and the temperature detector 21 in the neutron radiation environment, and obtain the temperature value Tz of the temperature controller 21 and the input current value I of the neutron flux detector 22 in real time. inz , processing computer 4 according to the formula in is the neutron flux, and the final calculation is obtained at the reference temperature T CCorrection value at reference temperature T C It is a manually set value, such as setting the reference temperature T C The reference temperature is 300K. Substituting 300K into the above formula, the calculated result is the neutron flux after correction for the reference temperature of 300K.

[0046] The units corresponding to the temperatures obtained from the above measurements are all Kelvin.

[0047] When not irradiated by neutrons, the temperature correction effect of the neutron flux input current measured in the temperature range of 281K to 305K is as follows: Figure 4 As shown in Figure 2, it can be seen that this method reduces the measurement error caused by temperature drift from 11% to less than 2%. Figure 5 As shown in the figure, the neutron flux correction effect is obvious when the temperature changes from 281K to 305K.

Claims

1. A temperature automatic correction system for online neutron fluence measurement, characterized by: The invention comprises a processing computer (4), a power supply module (1), a constant current source module (3), a current measurement module (5) and a detector module (2); the detector module (2) comprises a temperature detector (21) and a neutron flux detector (22) connected in sequence, the neutron flux detector (22) is a semiconductor detector, and the temperature detector (21) is arranged adjacent to the neutron flux detector (22); The power supply module (1) is connected to the neutron flux detector (22), the temperature detector (21) and the current measurement module (5) respectively, and the power supply module (1) provides a positive working voltage and a control voltage for the neutron flux detector (22) and the temperature detector (21), and provides a positive and negative bidirectional bias voltage for the current measurement module (5); The neutron flux detector (22) is connected to the constant current source module (3) to obtain a constant operating current; The current measurement module (5) is connected to the neutron fluence detector (22) and the temperature detector (21) respectively. The current measurement module (5) is used to sample the input current signals of the neutron fluence detector (22) and the temperature detector (21), and transmit the input current signals to a processing computer (4). The processing computer (4) is loaded with a neutron fluence measurement program and a temperature correction program, and is used to process the input current signal to obtain corresponding neutron fluence and temperature, and correct the neutron fluence according to the temperature.

2. The automatic temperature correction system for online neutron fluence measurement according to claim 1, characterized in that: The power supply module (1) comprises an LDO voltage conversion circuit, wherein the output end of the LDO voltage conversion circuit is connected to a neutron flux detector (22) and a temperature detector (21) respectively, and provides a forward working voltage and a control voltage for the neutron flux detector and the temperature detector; The LDO voltage conversion circuit is also connected to a current measurement module (5).

3. The automatic temperature correction system for online neutron fluence measurement according to claim 2, characterized in that: The constant current source module (3) comprises an adaptive resistor (31) and a constant current transistor (32) connected in sequence, the constant current transistor (32) is connected to the neutron flux detector (22) via the series adaptive resistor (31), and the common end of the constant current transistor (32) is grounded.

4. The automatic temperature correction system for online neutron fluence measurement according to claim 3, characterized in that: The current measurement module (5) comprises a sampling resistor (51), an AD converter (52), a communication chip (53) and a USB data interface (54) connected in sequence. The sampling resistor (51) is installed between the temperature detector (21) and the neutron flux detector (22) or between the LDO voltage conversion circuit and the temperature detector (21). The AD converter (52) converts the voltage across the sampling resistor (51) into a digital signal and transmits it to a processing computer (4) through the communication chip (53) and the USB data interface (54). The processing computer (4) is provided with a USB interface, and the USB interface is connected to the USB data interface (54).

5. A method for automatic temperature correction of neutron fluence online measurement, based on the automatic temperature correction system for neutron fluence online measurement according to any one of claims 1 to 4, characterized in that: Here are the steps: Step 1: Turn on the power supply module (1) and the constant current source module (3). The constant current source module (3) clamps the operating current of the neutron flux detector (22) at I C ; Step 2: The current measurement module (5) collects the input current of the neutron flux detector (22) and the operating current of the temperature detector (21) and converts them into differential digital signals and transmits them to the processing computer (4); Step 3: The processing computer (4) processes the differential digital signal transmitted by the current measurement module (5) to obtain the input current of the neutron flux detector (22) and the temperature of the temperature detector (21); By changing the temperature of the neutron flux detector (22), the processing computer (4) obtains at least two groups of input currents of the neutron flux detector (22) and the temperatures of the corresponding temperature detectors (21), namely (T0, I in0 ) and (T, I in ), and according to the formula Calculate the value of parameter m; Step 4: Place the neutron flux detector (22) and the temperature detector (21) in a neutron radiation environment, and obtain the temperature value Tz of the temperature detector (21) and the input current value I of the neutron flux detector in real time. inz , processing computer (4) according to the formula Calculate the reference temperature T C Neutron Fluence Correction

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