Miniature He-3 tube neutron pre-amplification circuit

Abstract

The invention relates to a micro He-3 tube neutron pre-amplification circuit, which comprises a charge sensitive pre-amplification circuit, a main amplification circuit and a power supply circuit, the charge sensitive pre-amplification circuit is connected with the main amplification circuit, the power supply circuit is used for supplying power to the charge sensitive pre-amplification circuit and the main amplification circuit, and the main amplification circuit is connected with the charge sensitive pre-amplification circuit. The charge sensitive pre-amplification circuit is connected with a signal output end of the He-3 tube and is used for providing working bias voltage and signal acquisition of the He-3 tube, the main amplification circuit is used for further amplification and discrimination of signals, pulse width adjustment and logic and operation, and the micro He-3 tube neutron pre-amplification circuit can be used for measurement in a relatively high gamma radiation field. By manually adjusting the screening threshold, noise and signals generated by gamma rays are filtered out, and the optimal working bias voltage can be conveniently set when the micro He-3 tube neutron pre-amplification circuit module is singly used or used in a cascade connection mode.

Description

Technical Field

[0001] The invention belongs to the technical field of neutron measurement for nuclear material inspection, and in particular relates to a miniature He-3 tube neutron preamplifier circuit and a connection method. Background Art

[0002] When using He-3 neutron counting tubes for neutron counting detection, particles passing through the detector cause the detector to undergo ionization, excitation or photoelectric conversion processes. Since the signal output by the counter tube is relatively small (usually only a few mV), it is generally amplified by an amplifier before measurement. The preamplifier is an important component of the entire circuit, and the signal amplification effect is directly related to the performance of the entire detector.

[0003] The existing preamplifier composed of integrated circuit boards is expensive and cannot achieve simple series operation between multiple modules. When multiple neutron tubes are measured, the circuits must be assembled and welded in advance and then the entire range must be adjusted. Most preamplifiers cannot be disassembled after assembly.

[0004] Therefore, a miniature He-3 tube neutron preamplifier circuit is needed to identify, amplify and shape the weak signal generated by the He-3 proportional counter tube, and output an effective signal that meets the monitoring and measurement requirements. In addition, by further integrating the preamplifier circuit and the wiring module, the preamplifier can be quickly disassembled and assembled when multiple neutron tube detectors are used in series, making the device portable, miniaturized and flexible to operate. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a miniature He-3 tube neutron preamplifier circuit, which can collect the weak electrical signal generated by the He-3 proportional counter tube, and output a TTL level pulse signal that meets the measurement requirements through signal shaping, amplification and screening.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a miniature He-3 tube neutron preamplifier circuit, including: a charge-sensitive preamplifier circuit, a main amplifier circuit and a power supply circuit, the charge-sensitive preamplifier circuit is connected to the main amplifier circuit, wherein the power supply circuit is used to supply power to the charge-sensitive preamplifier circuit and the main amplifier circuit, the charge-sensitive preamplifier circuit is connected to the signal output end of the He-3 tube, and is used to provide the He-3 tube working bias and signal acquisition, and the main amplifier circuit is used for further amplification, identification, pulse width adjustment and logical AND operation of the signal.

[0007] Furthermore, the charge-sensitive preamplifier circuit includes a high-voltage filtering and signal shaping circuit, a voltage amplification and current following circuit, and a signal matching circuit. The high-voltage filtering and signal shaping circuit is connected to the output end of the He-3 tube to provide a working bias and signal shaping for the He-3 tube; the voltage amplification and current following circuit is connected to the high-voltage filtering and signal shaping circuit to amplify the formed weak voltage signal; the signal matching circuit is connected to the voltage amplification and circuit following circuit to provide high input and low output of circuit resistance.

[0008] Further, the high voltage filtering and signal shaping circuit includes a filter capacitor C3, a filter capacitor C7, a resistor R8, a resistor R12, a DC blocking capacitor C8, a resistor R19 and a matching resistor R14;

[0009] Among them, one end of the filter capacitor C3 is connected to the resistor R8, and the other end is grounded; a section of the filter capacitor C7 is connected to the resistor R8, and the other end is grounded; one end of the resistor R8 is connected to the input working bias voltage J1 and the filter capacitor C3, and the other end is connected to the resistor R12; one end of the resistor R12 is connected to the resistor R8 and the filter capacitor C7, and the other end is connected to the He-3 tube anode J2 and the DC blocking capacitor C8; one end of the DC blocking capacitor C8 is connected to the He-3 tube anode J2 and the resistor R12, and the other end is connected to the resistor R19 and the resistor R14; one end of the resistor R19 is connected to the DC blocking capacitor C8 and the matching resistor R14, and the other end is grounded; one end of the matching resistor R14 is connected to the DC blocking capacitor C8 and the resistor R19, and the other end is connected to the voltage amplification and current following circuit.

[0010] Further, the voltage amplification and current following circuit includes a protection diode D2, a protection diode D3, a resistor R20, a resistor R21, a capacitor C11, a junction field effect transistor D1, a transistor Q3, a resistor R6, a resistor R10, a capacitor C6, a resistor R4 and a DC blocking capacitor C2;

[0011] Among them, after the protection diode D2 and the protection diode D3 are connected in parallel, one end is connected to the matching resistor R14 and the gate of the junction field effect transistor D1, and the other end is grounded; the source of the junction field effect transistor D1 is connected to the emitter of the transistor Q3, and the other end is connected to the resistor R20; one end of the resistor R20 is connected to the drain of the junction field effect transistor D1, and the other end is connected to the resistor R21 and the capacitor C11; after the resistor R21 and the capacitor C11 are connected in parallel, one end is connected to the resistor R20, and the other end is grounded; one end of the resistor R6 is connected to the 2.5V reference voltage source, and the other end is connected to the resistor R10 , capacitor C6 and the base of transistor Q3 are connected; after capacitor C6 and resistor R10 are connected in parallel, one end is connected to resistor R6 and the base of transistor Q3, and the other end is grounded; the base of transistor Q3 is connected to resistor R6, resistor R10 and capacitor C6, the collector is connected to resistor R4 and DC-blocking capacitor C2, and the emitter is connected to the source of junction field effect transistor D1; one end of resistor R4 is connected to a 5V power supply, and the other end is connected to the collector of the transistor and the DC-blocking capacitor C2; one end of the DC-blocking capacitor C3 is connected to the collector of the transistor and resistor R4, and the other end is connected to the signal matching circuit.

[0012] Further, the signal matching circuit includes a capacitor C1, a resistor R1, a resistor R2, a resistor R5, a resistor R3, a resistor R9, a resistor R11, a transistor Q1, a transistor Q2 and a DC blocking capacitor C4;

[0013] Among them, after the capacitor C1 is connected in parallel with the resistor R1, one end is grounded, and the other end is connected to the resistor R2 and the resistor R5; after the resistor R2 and the resistor R5 are connected in series, one end of the resistor R2 is connected to the 5V power supply, and the other end of the resistor R5 is connected to the DC blocking capacitor C2 and the base of the transistor Q1; the base of the transistor Q1 is connected to the resistor R5 and the DC blocking capacitor C2, and the emitter is connected to the resistor R9 and the base of the transistor Q2; one end of the resistor R9 is connected to the emitter of the transistor Q1 and the base of Q2, and the other end is grounded ; One end of the resistor R3 is connected to the 5V power supply, and the other end is connected to the collector of the transistor Q1; the collector of the transistor Q2 is connected to the 5V power supply, the base is connected to the emitter of the transistor Q1 and the resistor R9, and the emitter is connected to the resistor R11 and the DC blocking capacitor C4; one end of the resistor R11 is connected to the emitter of the transistor Q2 and the DC blocking capacitor C4, and the other end is grounded; one end of the DC blocking capacitor is connected to the emitter of the transistor Q2 and the resistor R11, and the other end is connected to the main amplifier circuit and the processing circuit.

[0014] Furthermore, the main amplifier circuit includes a signal amplification circuit, a threshold discrimination circuit, a pulse width modulation circuit and a logic AND operation circuit. The signal amplification circuit is connected to the threshold discrimination circuit for amplifying the voltage pulse signal; the threshold discrimination circuit is connected to the pulse width modulation circuit for signal discrimination; the pulse width modulation circuit is connected to the logic AND operation circuit for adjusting the signal to a fixed pulse width and outputting a variable pulse signal; the logic AND operation circuit is used to realize the logic AND operation of the signal when multiple modules are used in series.

[0015] Further, the signal amplification circuit includes a resistor R7, a resistor R15, a linear amplifier U1, a linear amplifier U2, a resistor R15, a feedback resistor R13, a feedback capacitor C9, a resistor R18, a feedback resistor R16, a potentiometer R17, and a feedback capacitor C10;

[0016] Among them, the resistor R7 is connected to the positive input terminal of the linear amplifier U1 and the DC blocking capacitor C4, and the other end is grounded; the resistor R15 is connected to the negative input terminal of the linear amplifier U1, the feedback resistor R13 and the feedback capacitor C9, and the other end is grounded; after the feedback resistor R13 and the feedback capacitor C9 are connected in parallel, one end is connected to the resistor R15 and the negative input terminal of the linear amplifier U1, and the other end is connected to the output terminal of the linear amplifier U1 and the DC blocking capacitor C5; the positive input terminal of the linear amplifier U1 is connected to the resistor R7 and the DC blocking capacitor C4, and the negative input terminal is connected to the resistor R15, the feedback resistor R13, and the feedback capacitor C9; the output terminal is connected to the DC blocking capacitor C5, the feedback resistor R13, and the feedback capacitor C9; one end of the DC blocking capacitor is connected to the linear The output end of the amplifier U1 is connected to the feedback resistor R13 and the feedback capacitor C9, and the other end is connected to the positive input end of the linear amplifier U2; one end of the resistor R18 is connected to the negative input end of the linear amplifier U2, the feedback resistor R16 and the feedback capacitor C10, and the other end is grounded; the feedback capacitor R16 is connected in series with the potentiometer R17 and then connected in parallel with C10, one end is connected to the resistor R18 and the negative input end of the linear amplifier U2, and the other end is connected to the output end of the linear amplifier U2; the positive input end of the linear amplifier U2 is connected to the DC blocking capacitor C5, the negative input end is connected to the resistor R18, the feedback resistor R16 and the feedback capacitor C10, and the output end is connected to the potentiometer R17, the feedback capacitor C10, and the threshold discrimination circuit.

[0017] Further, the threshold discrimination circuit includes a resistor R22, a resistor R23, a resistor R26, a potentiometer R24, and a comparator U4;

[0018] Among them, one end of resistor R22 is connected to the signal amplification circuit, and the other end is connected to the comparator input terminal a; one end of resistor R23 is connected to the comparator input terminal b, and the other end is connected to potentiometer R24 ​​and resistor R26; one end of potentiometer R24 ​​is connected to a 5V power supply, and the other end is connected to resistor R23 and resistor R26; one end of resistor R26 is connected to potentiometer R24 ​​and resistor R23, and the other end is grounded; input terminal a of comparator U4 is connected to resistor R22, input terminal b is connected to resistor R23, and the output end is connected to the pulse width modulation circuit.

[0019] Further, the pulse width modulation circuit includes a monostable multivibrator U5, a monostable multivibrator U6, a resistor R27, a capacitor C12, a potentiometer R29, a resistor R28, a capacitor C13, and a resistor R25;

[0020] Among them, the input terminal A of the monostable multivibrator U5 is connected to the threshold discrimination circuit, the input terminal B is grounded, the R terminal is connected to the resistor R27 and the capacitor C12, the C terminal is connected to the capacitor C12, and the output terminal is connected to the logic and operation circuit; one end of the capacitor C12 is connected to the C terminal of the monostable multivibrator U5, and the other end is connected to the R terminal of the monostable multivibrator U5 and the resistor R27; one end of the resistor R27 is connected to the R terminal of the monostable multivibrator U5 and the capacitor C12, and the other end is connected to the 5V power supply; the input terminal A of the monostable multivibrator U6 is connected to the logic and operation circuit, and the input terminal B is grounded, the output end is connected to resistor R25, the R end is connected to capacitor C13 and resistor R28, and the C end is connected to capacitor C13; one end of resistor R25 is connected to the output end of monostable multivibrator U6, and the other end is grounded; one end of capacitor C13 is connected to the C end of monostable multivibrator U6, and the other end is connected to the R end of monostable multivibrator U6 and resistor R28; one end of resistor R28 is connected to the R end of monostable multivibrator U6 and capacitor C13, and the other end is connected to potentiometer R29; one end of potentiometer R29 is connected to resistor R28, and the other end is connected to a 5V power supply.

[0021] Furthermore, the logic and operation circuit includes a logic device U3, an input terminal A of the logic device U3 is connected to an output terminal of another module, an input terminal B is connected to an output terminal of a monostable multivibrator U5, and an output terminal is connected to an input terminal A of a monostable multivibrator U6.

[0022] Further, the power supply circuit includes a 2.5V reference voltage P2, a capacitor C16, a capacitor C17, a 5V power supply P1, a capacitor C15, a capacitor C14, a resistor R30, and a resistor R31;

[0023] Among them, the 2nd pin of the 2.5V reference voltage P2 is grounded, the 3rd pin is connected to the 5V power supply and capacitor C16, and the 4th pin is connected to the resistor R6 and capacitor C17; one end of the capacitor C16 is connected to the 3rd pin of the 2.5V reference voltage P2, and the other end is grounded; one end of the capacitor C17 is connected to the 4th pin of the 2.5V reference voltage P2 and the resistor R6, and the other end is grounded; the 1st, 2nd and 3rd pins of the 5V power supply P1 are connected to the external power supply and capacitor C15, the 5th, 6th and 7th pins are connected to the resistor R31, capacitor C14 and the 5V power supply, and the 7th pin is connected to the resistor R30, capacitor C14 and the 5V power supply. Resistor R31 is connected, and pins 9 and 10 are grounded; one end of capacitor C15 is connected to the external power supply and pins 1, 2, and 3 of the 5V power supply P1, and the other end is grounded; one end of capacitor C14 is connected to pins 5, 6, and 7 of the 5V power supply P1, resistor R31, and the 5V power supply, and the other end is grounded; one end of resistor R31 is connected to pins 5, 6, and 7 of the 5V power supply P1, capacitor C14, and the 5V power supply, and the other end is connected to pin 8 of the 5V power supply P1 and resistor R30; one end of resistor R30 is connected to resistor R31 and pin 8 of the 5V power supply P1, and the other end is grounded.

[0024] The invention has the following effects: it has a threshold adjustment function, and when used for measurement under a relatively high gamma radiation field, the noise and the signal generated by the gamma ray can be filtered out by manually adjusting the discrimination threshold. The working power supply of the He-3 tube is uniformly provided by an external high voltage, which is convenient for setting the optimal working bias voltage when the micro He-3 tube neutron preamplifier circuit module is used alone or in cascade. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a circuit structure diagram of a charge sensitive preamplifier circuit and a signal amplifier circuit in a main amplifier circuit;

[0026] Figure 2 It is a schematic diagram of the circuit structure of the main amplifier circuit except the signal amplifier circuit;

[0027] Figure 3 It is a circuit structure diagram of a voltage amplifier and current follower circuit;

[0028] Figure 4 It is a circuit structure diagram of a pulse width modulation circuit and a logic and operation circuit;

[0029] Figure 5 It is a circuit structure diagram of the power supply circuit. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0031] like Figure 1-5As shown, the present invention provides a miniature He-3 tube neutron preamplifier circuit, which includes: a charge-sensitive preamplifier circuit, a main amplifier circuit and a power supply circuit. The charge-sensitive preamplifier circuit is connected to the main amplifier circuit, wherein the power supply circuit is used to supply power to the charge-sensitive preamplifier circuit and the main amplifier circuit. The charge-sensitive preamplifier circuit is connected to the signal output end of the He-3 tube to provide the He-3 tube working bias and signal collection. The main amplifier circuit is used for further amplification, identification, pulse width adjustment and logical AND operation of the signal.

[0032] In this embodiment, the charge-sensitive preamplifier circuit is located closest to the He-3 tube, with a high-voltage pin, and the circuit board and the high-voltage pin are insulated with plastic and then shielded by a metal shell. The charge-sensitive preamplifier circuit and the main amplifier circuit are connected using a 4P pin header, which are: 5VDC, 2.5VDC, preamplifier signal output, GND.

[0033] In this embodiment, the main amplifier circuit further amplifies the signal, discriminates the signal, performs logic and operation, and adjusts the pulse width, and finally outputs a TTL signal with the pulse width required by the user. The main amplifier and processing circuit has a 2.5V reference voltage source, which provides a 2.5VDC working power supply for the charge sensitive preamplifier circuit, and has three potentiometers, which are used to adjust the amplification factor, the discrimination threshold, and the output signal pulse width. The main amplifier and processing circuit and the power supply circuit are directly connected using 4P pin headers, and the 4P pin headers are: 5VDC, LED control signal, GND, GND.

[0034] In this embodiment, the power supply circuit is a 5V wide input power supply, which provides the module with working power, has an LED drive circuit for pulse signal indication, and the power supply circuit is shielded by a metal shell.

[0035] The charge-sensitive preamplifier circuit includes a high-voltage filtering and signal shaping circuit, a voltage amplification and current following circuit, and a signal matching circuit. The high-voltage filtering and signal shaping circuit is connected to the output end of the He-3 tube to provide the working bias and signal shaping of the He-3 tube; the voltage amplification and current following circuit is connected to the high-voltage filtering and signal shaping circuit to amplify the formed weak voltage signal; the signal matching circuit is connected to the voltage amplification and circuit following circuit to be used for high input and low output of circuit resistance.

[0036] Furthermore, the high voltage filtering and signal shaping circuit includes a filter capacitor C3, a filter capacitor C7, a resistor R8, a resistor R12, a DC blocking capacitor C8, a resistor R19 and a matching resistor R14.

[0037] Among them, one end of the filter capacitor C3 is connected to the resistor R8, and the other end is grounded; a section of the filter capacitor C7 is connected to the resistor R8, and the other end is grounded; one end of the resistor R8 is connected to the input working bias voltage J1 and the filter capacitor C3, and the other end is connected to the resistor R12; one end of the resistor R12 is connected to the resistor R8 and the filter capacitor C7, and the other end is connected to the He-3 tube anode J2 and the DC blocking capacitor C8; one end of the DC blocking capacitor C8 is connected to the He-3 tube anode J2 and the resistor R12, and the other end is connected to the resistor R19 and the resistor R14; one end of the resistor R19 is connected to the DC blocking capacitor C8 and the matching resistor R14, and the other end is grounded; one end of the matching resistor R14 is connected to the DC blocking capacitor C8 and the resistor R19, and the other end is connected to the voltage amplifier and current follower circuit.

[0038] Furthermore, the voltage amplifier and current follower circuit includes a protection diode D2, a protection diode D3, a resistor R20, a resistor R21, a capacitor C11, a junction field effect transistor D1, a transistor Q3, a resistor R6, a resistor R10, a capacitor C6, a resistor R4 and a DC blocking capacitor C2.

[0039] Among them, after the protection diode D2 and the protection diode D3 are connected in parallel, one end is connected to the matching resistor R14 and the gate of the junction field effect transistor D1, and the other end is grounded; the source of the junction field effect transistor D1 is connected to the emitter of the transistor Q3, and the other end is connected to the resistor R20; one end of the resistor R20 is connected to the drain of the junction field effect transistor D1, and the other end is connected to the resistor R21 and the capacitor C11; after the resistor R21 and the capacitor C11 are connected in parallel, one end is connected to the resistor R20, and the other end is grounded; one end of the resistor R6 is connected to the 2.5V reference voltage source, and the other end is connected to the resistor R10 , capacitor C6 and the base of transistor Q3 are connected; after capacitor C6 and resistor R10 are connected in parallel, one end is connected to resistor R6 and the base of transistor Q3, and the other end is grounded; the base of transistor Q3 is connected to resistor R6, resistor R10 and capacitor C6, the collector is connected to resistor R4 and DC-blocking capacitor C2, and the emitter is connected to the source of junction field effect transistor D1; one end of resistor R4 is connected to a 5V power supply, and the other end is connected to the collector of the transistor and the DC-blocking capacitor C2; one end of the DC-blocking capacitor C3 is connected to the collector of the transistor and resistor R4, and the other end is connected to the signal matching circuit.

[0040] Furthermore, the signal matching circuit includes a capacitor C1 , a resistor R1 , a resistor R2 , a resistor R5 , a resistor R3 , a resistor R9 , a resistor R11 , a transistor Q1 , a transistor Q2 and a DC blocking capacitor C4 .

[0041] Among them, after the capacitor C1 is connected in parallel with the resistor R1, one end is grounded, and the other end is connected to the resistor R2 and the resistor R5; after the resistor R2 and the resistor R5 are connected in series, one end of the resistor R2 is connected to the 5V power supply, and the other end of the resistor R5 is connected to the DC blocking capacitor C2 and the base of the transistor Q1; the base of the transistor Q1 is connected to the resistor R5 and the DC blocking capacitor C2, and the emitter is connected to the resistor R9 and the base of the transistor Q2; one end of the resistor R9 is connected to the emitter of the transistor Q1 and the base of Q2, and the other end is connected ground; one end of the resistor R3 is connected to the 5V power supply, and the other end is connected to the collector of the transistor Q1; the collector of the transistor Q2 is connected to the 5V power supply, the base is connected to the emitter of the transistor Q1 and the resistor R9, and the emitter is connected to the resistor R11 and the DC blocking capacitor C4; one end of the resistor R11 is connected to the emitter of the transistor Q2 and the DC blocking capacitor C4, and the other end is grounded; one end of the DC blocking capacitor is connected to the emitter of the transistor Q2 and the resistor R11, and the other end is connected to the main amplifier circuit and the processing circuit.

[0042] In this embodiment, the high-voltage filtering and signal shaping circuit 11 uses filter capacitor C3, filter capacitor C7, and resistor R8 high-voltage components for high-voltage filtering. After the resistor R12 limits the current, it provides the He-3 tube working bias. The signal generated by the He-3 tube is shaped by the DC isolation capacitor C8 and the resistor R19. The shaped signal enters the voltage amplification and current following circuit, passes through the protection diode D2 and the protection diode D3 protection circuit, and is then subjected to the amplification circuit composed of the junction field effect transistor D1 and the transistor Q3. The junction field effect transistor D1 is used for low-noise voltage amplification of the signal, and the transistor Q3 is a low-noise transistor for circuit following to eliminate the Miller effect. The amplified signal passes through the transistor Q1 and transistor Q2 combination circuit, and the impedance is adjusted to output the preamplified signal for further processing by the main amplifier circuit.

[0043] It should be noted that the charge-sensitive preamplifier circuit plays a role in resisting vibration interference of the signal in the process of providing the working bias voltage of the He-3 tube and collecting the signal.

[0044] The main amplifier circuit includes a signal amplifier circuit, a threshold discrimination circuit, a pulse width adjustment circuit and a logic and operation circuit. The signal amplifier circuit is connected to the threshold discrimination circuit for amplifying the voltage pulse signal; the threshold discrimination circuit is connected to the pulse width adjustment circuit for signal discrimination; the pulse width adjustment circuit is connected to the logic and operation circuit for adjusting the signal to a fixed pulse width and outputting a variable pulse signal; the logic and operation circuit is used to realize the logic and operation of the signal when multiple modules are used in series.

[0045] Furthermore, the signal amplification circuit includes a resistor R7, a resistor R15, a linear amplifier U1, a linear amplifier U2, a resistor R15, a feedback resistor R13, a feedback capacitor C9, a resistor R18, a feedback resistor R16, a potentiometer R17, and a feedback capacitor C10.

[0046] Among them, the resistor R7 is connected to the positive input terminal of the linear amplifier U1 and the DC blocking capacitor C4, and the other end is grounded; the resistor R15 is connected to the negative input terminal of the linear amplifier U1, the feedback resistor R13 and the feedback capacitor C9, and the other end is grounded; after the feedback resistor R13 and the feedback capacitor C9 are connected in parallel, one end is connected to the resistor R15 and the negative input terminal of the linear amplifier U1, and the other end is connected to the output terminal of the linear amplifier U1 and the DC blocking capacitor C5; the positive input terminal of the linear amplifier U1 is connected to the resistor R7 and the DC blocking capacitor C4, and the negative input terminal is connected to the resistor R15, the feedback resistor R13, and the feedback capacitor C9; the output terminal is connected to the DC blocking capacitor C5, the feedback resistor R13, and the feedback capacitor C9; one end of the DC blocking capacitor is connected to the linear The output end of the amplifier U1 is connected to the feedback resistor R13 and the feedback capacitor C9, and the other end is connected to the positive input end of the linear amplifier U2; one end of the resistor R18 is connected to the negative input end of the linear amplifier U2, the feedback resistor R16 and the feedback capacitor C10, and the other end is grounded; the feedback capacitor R16 is connected in series with the potentiometer R17 and then connected in parallel with C10, one end is connected to the resistor R18 and the negative input end of the linear amplifier U2, and the other end is connected to the output end of the linear amplifier U2; the positive input end of the linear amplifier U2 is connected to the DC blocking capacitor C5, the negative input end is connected to the resistor R18, the feedback resistor R16 and the feedback capacitor C10, and the output end is connected to the potentiometer R17, the feedback capacitor C10, and the threshold discrimination circuit.

[0047] Furthermore, the threshold discrimination circuit includes a resistor R22, a resistor R23, a resistor R26, a potentiometer R24, and a comparator U4.

[0048] Among them, one end of resistor R22 is connected to the signal amplification circuit, and the other end is connected to the comparator input terminal a; one end of resistor R23 is connected to the comparator input terminal b, and the other end is connected to potentiometer R24 ​​and resistor R26; one end of potentiometer R24 ​​is connected to a 5V power supply, and the other end is connected to resistor R23 and resistor R26; one end of resistor R26 is connected to potentiometer R24 ​​and resistor R23, and the other end is grounded; input terminal a of comparator U4 is connected to resistor R22, input terminal b is connected to resistor R23, and the output end is connected to the pulse width modulation circuit.

[0049] Furthermore, the pulse width modulation circuit includes a monostable multivibrator U5, a monostable multivibrator U6, a resistor R27, a capacitor C12, a potentiometer R29, a resistor R28, a capacitor C13, and a resistor R25.

[0050] Among them, the input terminal A of the monostable multivibrator U5 is connected to the threshold discrimination circuit, the input terminal B is grounded, the R terminal is connected to the resistor R27 and the capacitor C12, the C terminal is connected to the capacitor C12, and the output terminal is connected to the logic and operation circuit; one end of the capacitor C12 is connected to the C terminal of the monostable multivibrator U5, and the other end is connected to the R terminal of the monostable multivibrator U5 and the resistor R27; one end of the resistor R27 is connected to the R terminal of the monostable multivibrator U5 and the capacitor C12, and the other end is connected to the 5V power supply; the input terminal A of the monostable multivibrator U6 is connected to the logic and operation circuit, and the input terminal B is grounded, the output end is connected to resistor R25, the R end is connected to capacitor C13 and resistor R28, and the C end is connected to capacitor C13; one end of resistor R25 is connected to the output end of monostable multivibrator U6, and the other end is grounded; one end of capacitor C13 is connected to the C end of monostable multivibrator U6, and the other end is connected to the R end of monostable multivibrator U6 and resistor R28; one end of resistor R28 is connected to the R end of monostable multivibrator U6 and capacitor C13, and the other end is connected to potentiometer R29; one end of potentiometer R29 is connected to resistor R28, and the other end is connected to a 5V power supply.

[0051] It should be noted that the pulse width modulation circuit achieves the effect of reducing the signal compliance when multiple modules are used in series through signal pulse modulation.

[0052] Furthermore, the logic and operation circuit includes a logic device U3, an input terminal A of the logic device U3 is connected to an output terminal of another module, an input terminal B is connected to an output terminal of a monostable multivibrator U5, and an output terminal is connected to an input terminal A of a monostable multivibrator U6.

[0053] It should be noted that, through the logic and operation circuit, multiple modules can be used in series to increase the detection efficiency.

[0054] In this embodiment, the signal amplification circuit is composed of linear amplifier U1 and linear amplifier U2 to achieve signal amplification, and the amplification factor is adjusted by potentiometer R17. The threshold discrimination circuit is composed of comparator U4, and the discrimination threshold is adjusted by potentiometer R24. The pulse width adjustment circuit is composed of monostable multivibrator U6, and the output signal pulse width is adjusted by potentiometer R29. The logic and operation circuit is composed of logic device U3 to achieve the logic and operation of the external input signal for cascading and the signal of this module.

[0055] The power supply circuit includes a 2.5V reference voltage P2, a capacitor C16, a capacitor C17, a 5V power supply P1, a capacitor C15, a capacitor C14, a resistor R30, and a resistor R31.

[0056] Among them, the 2nd pin of the 2.5V reference voltage P2 is grounded, the 3rd pin is connected to the 5V power supply and capacitor C16, and the 4th pin is connected to the resistor R6 and capacitor C17; one end of the capacitor C16 is connected to the 3rd pin of the 2.5V reference voltage P2, and the other end is grounded; one end of the capacitor C17 is connected to the 4th pin of the 2.5V reference voltage P2 and the resistor R6, and the other end is grounded; the 1st, 2nd and 3rd pins of the 5V power supply P1 are connected to the external power supply and capacitor C15, the 5th, 6th and 7th pins are connected to the resistor R31, capacitor C14 and the 5V power supply, and the 7th pin is connected to the resistor R30, capacitor C14 and the 5V power supply. Resistor R31 is connected, and pins 9 and 10 are grounded; one end of capacitor C15 is connected to the external power supply and pins 1, 2, and 3 of the 5V power supply P1, and the other end is grounded; one end of capacitor C14 is connected to pins 5, 6, and 7 of the 5V power supply P1, resistor R31, and the 5V power supply, and the other end is grounded; one end of resistor R31 is connected to pins 5, 6, and 7 of the 5V power supply P1, capacitor C14, and the 5V power supply, and the other end is connected to pin 8 of the 5V power supply P1 and resistor R30; one end of resistor R30 is connected to resistor R31 and pin 8 of the 5V power supply P1, and the other end is grounded.

[0057] In this embodiment, the power supply circuit is composed of a wide-range 5V power supply chip and has an LED drive circuit, and the LED drive signal is provided by U6.

[0058] It can be seen from the above embodiments that the micro He-3 tube neutron preamplifier circuit provided by the present invention has a threshold adjustment function, which is used for measuring under a higher gamma radiation field, and the noise and the signal generated by the gamma ray can be filtered out by manually adjusting the discrimination threshold. The working power supply of the He-3 tube is uniformly provided by an external high voltage, which is convenient for setting the optimal working bias voltage when the micro He-3 tube neutron preamplifier circuit module is used alone or in cascade.

[0059] The present invention is not limited to the embodiments described in the specific implementation manner. Those skilled in the art may derive other implementation manners based on the technical solution of the present invention, which also fall within the technical innovation scope of the present invention.

Claims

1. A miniature He-3 tube neutron preamplifier circuit, characterized in that: include: A charge-sensitive preamplifier circuit, a main amplifier circuit and a power supply circuit. The charge-sensitive preamplifier circuit is connected to the main amplifier circuit, wherein the power supply circuit is used to supply power to the charge-sensitive preamplifier circuit and the main amplifier circuit. The charge-sensitive preamplifier circuit is connected to the signal output end of the He-3 tube to provide the He-3 tube with a working bias voltage and signal acquisition. The main amplifier circuit is used for further amplification, identification, pulse width adjustment and logic AND operation of the signal.

2. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 1, characterized in that: The charge-sensitive preamplifier circuit includes a high-voltage filtering and signal shaping circuit, a voltage amplification and current following circuit, and a signal matching circuit. The high-voltage filtering and signal shaping circuit is connected to the output end of the He-3 tube to provide the working bias and signal shaping of the He-3 tube; the voltage amplification and current following circuit is connected to the high-voltage filtering and signal shaping circuit to amplify the formed weak voltage signal; the signal matching circuit is connected to the voltage amplification and circuit following circuit to provide high input and low output of circuit resistance.

3. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 2, characterized in that: The high voltage filtering and signal shaping circuit includes a filter capacitor C3, a filter capacitor C7, a resistor R8, a resistor R12, a DC blocking capacitor C8, a resistor R19 and a matching resistor R14; Among them, one end of the filter capacitor C3 is connected to the resistor R8, and the other end is grounded; one end of the filter capacitor C7 is connected to the resistor R8, and the other end is grounded; one end of the resistor R8 is connected to the input working bias voltage J1 and the filter capacitor C3, and the other end is connected to the resistor R12; one end of the resistor R12 is connected to the resistor R8 and the filter capacitor C7, and the other end is connected to the He-3 tube anode J2 and the DC blocking capacitor C8; one end of the DC blocking capacitor C8 is connected to the He-3 tube anode J2 and the resistor R12, and the other end is connected to the resistor R19 and the resistor R14; one end of the resistor R19 is connected to the DC blocking capacitor C8 and the matching resistor R14, and the other end is grounded; one end of the matching resistor R14 is connected to the DC blocking capacitor C8 and the resistor R19, and the other end is connected to the voltage amplification and current following circuit.

4. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 2, characterized in that: The voltage amplification and current following circuit includes a protection diode D2, a protection diode D3, a resistor R20, a resistor R21, a capacitor C11, a junction field effect transistor D1, a transistor Q3, a resistor R6, a resistor R10, a capacitor C6, a resistor R4 and a DC blocking capacitor C2; Among them, after the protection diode D2 and the protection diode D3 are connected in parallel, one end is connected to the matching resistor R14 and the gate of the junction field effect transistor D1, and the other end is grounded; the source of the junction field effect transistor D1 is connected to the emitter of the transistor Q3, and the other end is connected to the resistor R20; one end of the resistor R20 is connected to the drain of the junction field effect transistor D1, and the other end is connected to the resistor R21 and the capacitor C11; after the resistor R21 and the capacitor C11 are connected in parallel, one end is connected to the resistor R20, and the other end is grounded; one end of the resistor R6 is connected to the 2.5V reference voltage source, and the other end is connected to the resistor R10 , capacitor C6 and the base of transistor Q3 are connected; after capacitor C6 and resistor R10 are connected in parallel, one end is connected to resistor R6 and the base of transistor Q3, and the other end is grounded; the base of transistor Q3 is connected to resistor R6, resistor R10 and capacitor C6, the collector is connected to resistor R4 and DC-blocking capacitor C2, and the emitter is connected to the source of junction field effect transistor D1; one end of resistor R4 is connected to a 5V power supply, and the other end is connected to the collector of the transistor and the DC-blocking capacitor C2; one end of the DC-blocking capacitor C3 is connected to the collector of the transistor and resistor R4, and the other end is connected to the signal matching circuit.

5. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 2, characterized in that: The signal matching circuit includes a capacitor C1, a resistor R1, a resistor R2, a resistor R5, a resistor R3, a resistor R9, a resistor R11, a transistor Q1, a transistor Q2 and a DC blocking capacitor C4; Among them, after the capacitor C1 is connected in parallel with the resistor R1, one end is grounded, and the other end is connected to the resistor R2 and the resistor R5; after the resistor R2 and the resistor R5 are connected in series, one end of the resistor R2 is connected to the 5V power supply, and the other end of the resistor R5 is connected to the DC blocking capacitor C2 and the base of the transistor Q1; the base of the transistor Q1 is connected to the resistor R5 and the DC blocking capacitor C2, and the emitter is connected to the resistor R9 and the base of the transistor Q2; one end of the resistor R9 is connected to the emitter of the transistor Q1 and the base of Q2, and the other end is grounded ; One end of the resistor R3 is connected to the 5V power supply, and the other end is connected to the collector of the transistor Q1; the collector of the transistor Q2 is connected to the 5V power supply, the base is connected to the emitter of the transistor Q1 and the resistor R9, and the emitter is connected to the resistor R11 and the DC blocking capacitor C4; one end of the resistor R11 is connected to the emitter of the transistor Q2 and the DC blocking capacitor C4, and the other end is grounded; one end of the DC blocking capacitor is connected to the emitter of the transistor Q2 and the resistor R11, and the other end is connected to the main amplifier circuit and the processing circuit.

6. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 1, characterized in that: The main amplifier circuit includes a signal amplifier circuit, a threshold discrimination circuit, a pulse width modulation circuit and a logic and operation circuit. The signal amplifier circuit is connected to the threshold discrimination circuit for amplifying the voltage pulse signal; the threshold discrimination circuit is connected to the pulse width modulation circuit for signal discrimination; the pulse width modulation circuit is connected to the logic and operation circuit for adjusting the signal to a fixed pulse width and outputting a variable pulse signal; the logic and operation circuit is used to realize the logic and operation of the signal when multiple modules are used in series.

7. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 6, characterized in that: The signal amplification circuit includes a resistor R7, a linear amplifier U1, a linear amplifier U2, a resistor R15, a feedback resistor R13, a feedback capacitor C9, a resistor R18, a feedback resistor R16, a potentiometer R17, and a feedback capacitor C10; Among them, the resistor R7 is connected to the positive input terminal of the linear amplifier U1 and the DC blocking capacitor C4, and the other end is grounded; the resistor R15 is connected to the negative input terminal of the linear amplifier U1, the feedback resistor R13 and the feedback capacitor C9, and the other end is grounded; after the feedback resistor R13 and the feedback capacitor C9 are connected in parallel, one end is connected to the resistor R15 and the negative input terminal of the linear amplifier U1, and the other end is connected to the output terminal of the linear amplifier U1 and the DC blocking capacitor C5; the positive input terminal of the linear amplifier U1 is connected to the resistor R7 and the DC blocking capacitor C4, and the negative input terminal is connected to the resistor R15, the feedback resistor R13, and the feedback capacitor C9; the output terminal is connected to the DC blocking capacitor C5, the feedback resistor R13, and the feedback capacitor C9; one end of the DC blocking capacitor is connected to the linear The output end of the amplifier U1 is connected to the feedback resistor R13 and the feedback capacitor C9, and the other end is connected to the positive input end of the linear amplifier U2; one end of the resistor R18 is connected to the negative input end of the linear amplifier U2, the feedback resistor R16 and the feedback capacitor C10, and the other end is grounded; the feedback capacitor R16 is connected in series with the potentiometer R17 and then connected in parallel with C10, one end is connected to the resistor R18 and the negative input end of the linear amplifier U2, and the other end is connected to the output end of the linear amplifier U2; the positive input end of the linear amplifier U2 is connected to the DC blocking capacitor C5, the negative input end is connected to the resistor R18, the feedback resistor R16 and the feedback capacitor C10, and the output end is connected to the potentiometer R17, the feedback capacitor C10, and the threshold discrimination circuit.

8. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 6, characterized in that: The threshold discrimination circuit includes a resistor R22, a resistor R23, a resistor R26, a potentiometer R24, and a comparator U4; Among them, one end of resistor R22 is connected to the signal amplification circuit, and the other end is connected to the comparator input terminal a; one end of resistor R23 is connected to the comparator input terminal b, and the other end is connected to potentiometer R24 ​​and resistor R26; one end of potentiometer R24 ​​is connected to a 5V power supply, and the other end is connected to resistor R23 and resistor R26; one end of resistor R26 is connected to potentiometer R24 ​​and resistor R23, and the other end is grounded; input terminal a of comparator U4 is connected to resistor R22, input terminal b is connected to resistor R23, and the output end is connected to the pulse width modulation circuit.

9. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 6, characterized in that: The pulse width modulation circuit includes a monostable multivibrator U5, a monostable multivibrator U6, a resistor R27, a capacitor C12, a potentiometer R29, a resistor R28, a capacitor C13, and a resistor R25; Among them, the input terminal A of the monostable multivibrator U5 is connected to the threshold discrimination circuit, the input terminal B is grounded, the R terminal is connected to the resistor R27 and the capacitor C12, the C terminal is connected to the capacitor C12, and the output terminal is connected to the logic and operation circuit; one end of the capacitor C12 is connected to the C terminal of the monostable multivibrator U5, and the other end is connected to the R terminal of the monostable multivibrator U5 and the resistor R27; one end of the resistor R27 is connected to the R terminal of the monostable multivibrator U5 and the capacitor C12, and the other end is connected to the 5V power supply; the input terminal A of the monostable multivibrator U6 is connected to the logic and operation circuit, and the input terminal B is grounded, the output end is connected to resistor R25, the R end is connected to capacitor C13 and resistor R28, and the C end is connected to capacitor C13; one end of resistor R25 is connected to the output end of monostable multivibrator U6, and the other end is grounded; one end of capacitor C13 is connected to the C end of monostable multivibrator U6, and the other end is connected to the R end of monostable multivibrator U6 and resistor R28; one end of resistor R28 is connected to the R end of monostable multivibrator U6 and capacitor C13, and the other end is connected to potentiometer R29; one end of potentiometer R29 is connected to resistor R28, and the other end is connected to a 5V power supply.

10. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 6, characterized in that: The logic and operation circuit includes a logic device U3, an input terminal A of the logic device U3 is connected to the output terminal of another module, an input terminal B is connected to the output terminal of the monostable multivibrator U5, and an output terminal is connected to the input terminal A of the monostable multivibrator U6.

11. A miniature He-3 tube neutron preamplifier circuit as claimed in claim 1, characterized in that: The power supply circuit includes a 2.5V reference voltage P2, a capacitor C16, a capacitor C17, a 5V power supply P1, a capacitor C15, a capacitor C14, a resistor R30, and a resistor R31; Among them, the 2nd pin of the 2.5V reference voltage P2 is grounded, the 3rd pin is connected to the 5V power supply and capacitor C16, and the 4th pin is connected to the resistor R6 and capacitor C17; one end of the capacitor C16 is connected to the 3rd pin of the 2.5V reference voltage P2, and the other end is grounded; one end of the capacitor C17 is connected to the 4th pin of the 2.5V reference voltage P2 and the resistor R6, and the other end is grounded; the 1st, 2nd and 3rd pins of the 5V power supply P1 are connected to the external power supply and capacitor C15, the 5th, 6th and 7th pins are connected to the resistor R31, capacitor C14 and the 5V power supply, and the 7th pin is connected to the resistor R30, capacitor C14 and the 5V power supply. Resistor R31 is connected, and pins 9 and 10 are grounded; one end of capacitor C15 is connected to the external power supply and pins 1, 2, and 3 of the 5V power supply P1, and the other end is grounded; one end of capacitor C14 is connected to pins 5, 6, and 7 of the 5V power supply P1, resistor R31, and the 5V power supply, and the other end is grounded; one end of resistor R31 is connected to pins 5, 6, and 7 of the 5V power supply P1, capacitor C14, and the 5V power supply, and the other end is connected to pin 8 of the 5V power supply P1 and resistor R30; one end of resistor R30 is connected to resistor R31 and pin 8 of the 5V power supply P1, and the other end is grounded.

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