46 results about "Neutron measurement" patented technology

The invention discloses a fast thermal neutron and gamma ray multi-mode detector, and relates to the technical field of nuclear radiation detection, and the detector comprises a detector housing, and the interior of the detector housing is connected with a fast neutron detection unit, a thermal neutron detection unit and a gamma ray detection unit. The gamma ray detection unit is located between the fast neutron detection unit and the thermal neutron detection unit; and an insulating separation unit is connected between two adjacent detection units. The detector can detect fast neutrons, thermal neutrons and gamma rays in the same equipment at the same time, structures such as a cadmium thermal neutron shielding layer and a fast neutron moderation layer do not need to be added, the size of the detector can be greatly reduced, and the detector has the advantages of being compact in structure, stable in performance, wide in energy measurement range, wide in fluence rate measurement range and the like. The ultrahigh-energy high-flux neutron measurement with the neutron energy at least covering # imgabs0 # and the neutron fluence rate at least covering # imgabs1 # can be realized.

The invention provides a joint optimization method for a stacking sequence and a grabbing posture of a neutron measurement system, and relates to the field of data processing. According to the method, multi-source monitoring data of a neutron measurement system are collected, shadow voxels are constructed in combination with a three-dimensional space model, a neutron resonance shadow domain is formed through clustering superposition, and a dangerous concentration cloud cluster and a safe rarefied area are marked; mapping candidate stacking positions and postures according to sample mass distribution, geometric dimensions, centroid positions and irradiation sensitive characteristics, generating a stacking mode and determining a stacking sequence; performing path risk assessment on the grabbing postures, and selecting the grabbing postures of which the crossing risk meets a threshold value; superposing micro-random jitter on the path to suppress resonance phase locking; and abnormal events are monitored in real time during operation, and a risk domain is updated to execute hierarchical unloading control, so that the instantaneous impact and damage risk is reduced. According to the technical scheme, the probability of instantaneous impact risks caused by stacking overall micro-drift and grabbing track overlapping can be effectively reduced, and therefore the safety of the system is guaranteed.

The invention provides a joint space smooth motion trail generation method of a multi-ball neutron spectrometer ball changing device, and relates to the field of data processing. According to the method, a topological framework is constructed by extracting key static postures of a ball changing process, and a plurality of operation fibers are sampled and verified in a joint space channel to form a weaving domain; acquiring short-time sequence characteristics such as irradiation temperature, sphere temperature rise, contact force and structural vibration in real time, and compressing the short-time sequence characteristics into thermal disturbance fingerprints; screening target operation fibers meeting safety margin and vibration constraint according to the mapping relation, and dynamically modulating the weights of the operation fibers through thermal disturbance fingerprints; and dividing a micro-cycle weaving window to limit a weight change rate in combination with a neutron measurement rhythm, and realizing smooth and safe trajectory output under thermal deformation interference. By implementing the technical scheme provided by the invention, the safety of the ball changing device of the multi-ball neutron spectrometer in the ball changing process is improved.

To provide a neutron measurement device, a neutron measurement system, a neutron measurement method, and a neutron detector for easily measuring energy distribution of fast neutrons.SOLUTION: A neutron measurement system 1 performs: calculating a response function for each of a plurality of predetermined thresholds in accordance with a specification of a detector 3 capable of detecting neutrons and the predetermined thresholds, which are different from each other; calculating a discrete value for each threshold using a measurement result by the detector 3; and deriving neutron energy distribution in accordance with the response function and discrete value.SELECTED DRAWING: Figure 3

The present application belongs to the field of neutron background technology, and specifically relates to a device and method for measuring the neutron background of metal products. The device includes: a grabbing assembly, a supporting steel frame and a moving assembly; the moving assembly is fixed on the supporting steel frame, one end of the grabbing assembly is connected to the moving assembly, and moves under the drive of the moving assembly; the other end of the grabbing assembly is provided with a clamping claw for grabbing a standard source or a metal product to be measured. The device can realize fixed-point grabbing of a certain metal product, and transport it to the center of the neutron measurement device for measurement through a grabbing motion unit. After application, the neutron background of metal products can be measured in batches in an automated factory, protecting the health of operators, reducing the labor intensity of operators, improving work efficiency, and being easy to promote and apply.

The invention relates to a neutron measuring device (1). The device (1) comprises a housing (90), a high-density polyethylene block (10) in the housing (90), a shell made of neutron-absorbing material (20) integrated into the block (10), a first scintillation neutron detector (30) located inside the shell (20) and capable of emitting a signal proportional to the number of neutrons detected per unit of time, and a module (40) capable of converting the signal into a neutron count rate.

The invention relates to the technical field of neutron measurement, and particularly discloses a multi-activation foil and method for measuring a neutron energy spectrum. The multi-activation foil comprises a shell and an activation sheet placed in the shell, and the activation sheet sequentially comprises Ni, Sc, Au, W, Cu, Pt, In, Zn and Fe from top to bottom. The activated foil can realize high-resolution measurement of a neutron spectrum in a very small space, has the characteristics of size miniaturization, wide energy response range, wide neutron fluence rate application range, controllable manufacturing tolerance, optimized material ratio and the like, and is suitable for neutron spectrum and neutron dose measurement of a small-scale region of a nuclear facility and neutron dose measurement of a small-scale region of a nuclear facility. The method can also be popularized and applied to fine dose field distribution measurement of a large-scale area of a nuclear facility, and provides accurate data support for safe operation, shielding verification and radiation protection of the nuclear facility.

The invention relates to the technical field of nuclear, in particular to a device for detecting selenium content in fruits, which comprises a D-D neutron generator and a measuring chamber, the D-D neutron generator generates neutrons, the neutrons in the measuring chamber enter a sample to generate nuclear reaction with atomic nucleuses in the sample in the measuring chamber, and the neutrons in the measuring chamber are generated; after the atomic nucleus of the measuring chamber is activated, instant gamma rays and delayed gamma rays are released; the high-purity germanium detector in the measuring chamber receives delayed gamma rays of all elements in the sample in the measuring chamber and converts each gamma photon into an electric pulse signal; the multichannel analyzer is used for converting the electric pulse signals of the measuring chamber into digital signals, dividing channel addresses according to the size of the digital signals, counting the pulse number and forming a gamma ray energy spectrum; and the computer in the measuring chamber calculates the selenium content in the sample in the measuring chamber through the gamma ray energy spectrum in the measuring chamber. The method has the advantages of low detection limit, small error and high measurement result precision, and can quickly realize the detection of the selenium content in the fruits.

The invention relates to the technical field of neutron measurement, and particularly discloses a thermoluminescence field dosimeter for measuring neutron energy spectrum.The thermoluminescence field dosimeter comprises a thermoluminescence field dosimeter body, and the thermoluminescence field dosimeter body comprises a front-end assembly, a rear-end assembly and a center assembly located between the front-end assembly and the rear-end assembly; the center assembly and the rear end assembly are detachably connected with the front end assembly. Wherein the distance between the front surface of the central assembly and the front surface of the front end assembly is 1mm, the distance between the front surface of the rear end assembly and the front surface of the front end assembly is 7mm, and the front surface of the central assembly and the front surface of the rear end assembly are respectively provided with a 6LiF thermoluminescence dosage piece and a 7LiF thermoluminescence dosage piece. The thermoluminescence field dosimeter is wide in neutron energy response range, covers 0.0253 eV-20 MeV, can be suitable for neutron energy spectrum measurement of nuclear facilities such as fission reactors, fusion reactors and medical accelerators, and is particularly suitable for measurement in measurement occasions with narrow spaces and large neutron field gradients.

The invention provides a GM counting tube suitable for alpha / beta / gamma ray and neutron measurement and a manufacturing method thereof. The GM counting tube comprises a cathode shell; a first detection window and a second detection window; the boron neutron sensitive layer is coated on one part of the outer surface of the first detection window and / or one part of the outer surface of the second detection window; an insulating seat; a first anode wire; a hole is formed in the middle of the second anode wire, the first end of the second anode wire is communicated with the middle of the first anode wire, and the second end of the second anode wire penetrates through the insulating base and is led out of the cathode shell. According to the GM counting tube, the function of detecting alpha, beta and gamma rays and neutrons at the same time is achieved, the boron neutron sensitive layer is arranged on the outer surface of the detection window, and daily maintenance and repair are facilitated.

The invention discloses a neutron-gamma mixed radiation screening method based on a radiation response signal. The neutron-gamma mixed radiation screening method depends on a nano-coating CMOS sensor neutron measurement system. The neutron measurement system of the nano-coating CMOS sensor comprises a detector, the detector comprises a CMOS sensor; a LiF thin film is attached to the light-sensitive surface of the CMOS sensor; the method comprises the following steps that a part of neutrons enable the CMOS sensor to generate a radiation response signal A; the other part of neutrons and 6Li are subjected to nuclear reaction to generate alpha rays and tritium ions, so that the CMOS sensor respectively generates a radiation response signal B and a radiation response signal C; the gamma ray enables the CMOS sensor to generate a radiation response signal D; and according to the difference of the four radiation response signals in morphology and / or gray values, discriminating the neutron-gamma mixed radiation field. The detector formed by combining the LiF film and the CMOS sensor is used for discriminating a neutron-gamma mixed radiation field and can be used for monitoring nuclear leakage of a reactor.

The present application relates to the technical field of data processing and remote maintenance of oil logging instrument, and particularly relates to a remote data calibration method and system for a neutron measurement system. The method comprises the following steps: collecting multi-dimensional time sequence data of downhole instrument, and identifying the current temperature change state; based on the principle of non-steady-state heat conduction, the thermal hysteresis index is calculated by using the temperature change rate and the material thermal saturation limit constant; the real temperature of the crystal is reconstructed by using the thermal hysteresis index to inversely correct the measured temperature of the sensor; and based on the equivalent lattice temperature, the original energy spectrum characteristics are dynamically gain calibrated by using a preset quadratic polynomial multiplication compensation model. By reconstructing the real temperature of the crystal, the present application eliminates the gain hysteresis loop in the up-measuring and down-measuring processes, and significantly improves the interpretation accuracy and consistency of the logging data in a complex variable temperature environment.

The invention discloses a wide-range neutron measurement method, and belongs to the technical field of neutron detection and measurement, and the method comprises the steps: selecting a wide bandgap semiconductor material, an electrode metal material, a neutron conversion material and a neutron conversion material coating method, obtaining a wide bandgap semiconductor radiation detector coated with the neutron conversion material, and taking the wide bandgap semiconductor radiation detector as a neutron detector; a neutron detector is connected with a pre-amplifier, the pre-amplifier is connected with a rear-end digital sampling circuit, the rear-end digital sampling circuit processes pulse waveforms output by the pre-amplifier, and digital pulse signals are output; processing the digital pulse signal by using a pulse counting method and a Campbell method in upper computer software to obtain a pulse counting rate value and a Campbell value, and calculating neutron fluence rates obtained by the two methods; and obtaining the neutron fluence rate as an output result by adopting different methods according to the size of the neutron fluence rate. According to the invention, a neutron fluence rate measurement system with a small size, high temperature resistance, radiation resistance and a wide range can be obtained, and real-time accurate measurement under the condition of large-range change of the neutron fluence rate is realized.

The invention discloses a method and system for measuring and controlling the neutron fluence rate of a reactor core, and relates to the technical field of neutron measurement. The method comprises the following steps: acquiring a neutron fluence rate analog signal acquired by a detector and a position signal fed back by electromechanical equipment corresponding to the detector; performing analog-to-digital conversion on the neutron fluence rate analog signal to obtain a corresponding neutron fluence rate digital signal; analyzing the neutron fluence rate digital signal to obtain a corresponding neutron fluence rate, and analyzing the position signal to obtain a corresponding reactor core position; and matching the neutron fluence rate with the reactor core position to generate a measurement data table. In the invention, the neutron fluence rate analog signal is converted into the neutron fluence rate digital signal, the influence of noise interference is avoided to a certain extent, and the digital signal has stronger anti-interference capability and can be kept stable in a complex reactor environment, so that the signal processing precision is improved; the accuracy of measuring the neutron fluence rate of the reactor core is improved.

The invention relates to the technical field of data processing and remote maintenance of petroleum logging instruments, in particular to a remote data calibration method and system for a neutron measurement system. The method comprises the following steps: collecting multi-dimensional time sequence data of an underground instrument, and identifying a current temperature change state; calculating a thermal hysteresis index by using a temperature change rate and a material thermal saturation limit constant based on an unsteady state heat conduction principle; performing reverse correction on the actually measured temperature of the sensor by using the thermal hysteresis index, and reconstructing the equivalent lattice temperature in the crystal; and based on the equivalent lattice temperature, performing dynamic gain calibration on the original energy spectrum characteristics by using a preset quadratic polynomial multiplication compensation model. According to the invention, by reconstructing the real temperature of the crystal, a gain lag loop in the upper measurement and lower measurement processes is eliminated, and the interpretation precision and consistency of logging data in a complex variable-temperature environment are remarkably improved.

A method for determining the quantity of plutonium in a radioactive sample in the presence of curium, comprising the steps of: Measuring (301) a train of electrical pulses using a radiation detection system, Determining (302), respectively in a first and a second time window, a first and a second number of second-order pulse coincidences between the electrical pulses supplied by the detectors, The second time window being formed by the union of the first time window and a third time window, The first and third time windows being chosen such that the number of second-order pulse coincidences related to plutonium is greater than that related to curium in one of the two windows between the first and third time windows and less than that related to curium in the other window,Determine (304) the quantity of plutonium by applying a nonlinear regression model taking as parameters: the total number of measured pulses, the first number of second-order pulse coincidences, and the second number of second-order pulse coincidences, the model having been previously trained on a set of values ​​simulated from a numerical model. Figure 3,

The application discloses a kind of metal halogen perovskite-based neutron multiplicity measuring device and method, the device includes: shell, the shell is used to install and protect other components of the measuring device;Radiation detection module is arranged in the shell, and the radiation detection module is mainly composed of perovskite material and photomultiplier tube etc.;Shielding unit is arranged in the shell and located at the side and bottom of the perovskite scintillator, for reducing gamma-ray background;And, readout electronics module is arranged in the shell, and the readout electronics module is used to read the electrical signal generated by the photomultiplier tube and convert it into digital signal output.The application can realize the effective discrimination of neutron and gamma, so as to accurately deduct the influence of gamma-ray background, improve the sensitivity of fast neutron measurement.

The invention discloses an imaging device based on a hexagonal boron nitride neutron imaging plate and a preparation method thereof, and the device comprises a neutron source, a collimator, a neutron imaging plate, a first reflector and an imaging device, and also comprises an excitation source which is used for emitting laser; the neutron imaging plate is an h-BN imaging plate and comprises a substrate and an h-BN film covering the substrate. The imaging device is a CCD (Charge Coupled Device) fluorescence imaging device; thermal neutrons emitted by the neutron source irradiate a to-be-detected sample, part of the thermal neutrons penetrate through the to-be-detected sample and then irradiate the h-BN imaging plate, thermal neutron irradiation damage defects occur, photoluminescence is generated under excitation of laser emitted by the laser source, and the photoluminescence is reflected to the CCD fluorescence imaging device through the first reflector to complete imaging of the to-be-detected sample. According to the invention, neutron current detection can be realized according to the boron vacancy defect of h-10BN and by utilizing the photoluminescence characteristic of h-10BN, the gamma sensitivity is low, the device process is simple, and the neutron measurement cost is reduced.

The invention relates to a method for determining the amount of plutonium in a radioactive sample in the presence of curium, comprising the following steps: measuring (301) an electrical pulse train by means of a radiation detection system, determining (302) a first number and a second number of second order pulse coincidence between the electrical pulses delivered by the detector, respectively,-the second time window consisting of a union of the first time window and a third time window, the first time window and the third time window are selected such that the number of second order pulses associated with plutonium is higher in one of the first time window and the third time window than the number of second order pulses associated with curium and lower in the other window than the number of second order pulses associated with curium; -determining (304) the amount of plutonium by applying a non-linear regression model having as parameters: the total number of measured pulses, a first number of second order pulse coincidence and a second number of second order pulse coincidence, said model being pre-trained on a set of simulated values obtained using a numerical model.

A method for determining the quantity of plutonium in a radioactive sample in the presence of curium, comprising the steps of: Measuring (301) a train of electrical pulses using a radiation detection system, Determining (302), respectively in a first and a second time window, a first and a second number of second-order pulse coincidences between the electrical pulses supplied by the detectors, The second time window being formed by the union of the first time window and a third time window, The first and third time windows being chosen such that the number of second-order pulse coincidences related to plutonium is greater than that related to curium in one of the two windows between the first and third time windows and less than that related to curium in the other window,Determine (304) the quantity of plutonium by applying a nonlinear regression model taking as parameters: the total number of measured pulses, the first number of second-order pulse coincidences, and the second number of second-order pulse coincidences, the model having been previously trained on a set of values ​​simulated from a numerical model. Figure 3,

The present invention provides a high-temperature and high-pressure aspiration system for preventing titanium film oxidation, which relates to the technical field of application of compact deuterium-deuterium accelerator neutron source in neutron measurement and irradiation. A high vacuum pumping unit is used to vacuum the film preparation chamber and the film aspiration chamber, so as to achieve a 10 ‑5 Pa-level high vacuum is achieved; a micron-level high-purity titanium film is then prepared in a film preparation chamber using magnetron sputtering technology. After the titanium film is prepared, a magnetic rod transmission device is used to transport the titanium film sample into a film aspiration chamber in a high vacuum environment, where it is heated and raised in the high vacuum environment. A gate valve isolation device is then used to isolate the film aspiration chamber from the film preparation chamber, and high-purity, high-pressure gas is filled into the film aspiration chamber, ultimately achieving high-temperature, high-pressure gas adsorption on the titanium film under oxidation-free conditions. This method reduces the impact of the oxide layer on the metal film surface on gas adsorption.

The present invention relates to a method for installing a temporary neutron measurement system (TNMS) mounted on a core of an integrated nuclear reactor, comprising the steps of: (S10) arranging, inside a reactor core, a measurement assembly capable of measuring neutrons discharged from the reactor core; and (S20) connecting, to the measurement assembly, a connection assembly for supplying power to the measurement assembly and receiving a measurement signal.

The application provides a GM counting tube suitable for alpha / beta / gamma ray and neutron measurement and a manufacturing method thereof. The GM counting tube comprises a cathode shell, a first detection window and a second detection window, a boron neutron sensitive layer coated on a part of the outer surface of the first detection window and / or a part of the outer surface of the second detection window, an insulating seat, a first anode wire and a second anode wire with a hole in the middle, wherein the first end of the second anode wire is communicated with the middle part of the first anode wire, and the second end of the second anode wire penetrates through the insulating seat and is led out to the outside of the cathode shell. The GM counting tube realizes the function of simultaneously detecting alpha, beta, gamma ray and neutron, and the boron neutron sensitive layer is on the outer surface of the detection window, so that daily maintenance and repair are facilitated.

The neutron measurement system with the combination of the dual-CMOS sensor and the conversion material comprises a detector; the detector comprises two CMOS sensors and a neutron conversion material, wherein the light-sensitive surfaces of the two CMOS sensors are oppositely arranged, and the neutron conversion material is arranged between the light-sensitive surfaces of the two CMOS sensors. The neutron conversion material is used for carrying out nuclear reaction with neutrons and generating alpha rays. The neutron detection device has the advantages that the neutron conversion material is arranged between the two CMOS sensors of which the light-sensitive surfaces are oppositely arranged, neutron detection is converted into sensitive alpha particle detection of the CMOS sensors, the detection efficiency of neutrons (especially thermal neutrons) is improved, and a wide-area neutron measurement angle almost covering the whole spherical space is realized.

The present invention discloses a method for inverting neutron flux distribution based on the PGNAA technology. This method utilizes the characteristics of the in-situ radioactivity and high penetrability of neutron-induced gamma rays in the PGNAA technology. Intervals are divided according to the neutron field distribution to be analyzed, and a gamma-ray detector array is set around the neutron field. Gamma-ray volume sources are set in each interval based on Monte Carlo simulation. The response factors between each gamma-ray volume source and the detector array are obtained through simulation calculation, that is, the response function of the detector to the gamma-ray volume sources in each interval, and a response matrix is established. The gamma-ray detector array is used to collect the neutron-induced gamma rays in the materials within the neutron field, and inversion calculation is carried out in combination with the response matrix obtained through simulation calculation to obtain the neutron flux in each interval of the neutron field, and thus the neutron flux distribution of the neutron field can be obtained. The present invention effectively reduces the interference effects of gamma-ray background and strong radiation field on neutron measurement in the traditional method, and the measurement of neutron flux distribution inversion is simple and has high accuracy.

The invention provides a neutron diffraction stress measurement device and method based on space coordinate measurement. The neutron diffraction stress measurement device comprises an autonomous navigation trolley, an attitude adjustment system, a space measurement sensor, a neutron detector, a sample table and a main controller, the attitude adjusting system is fixedly mounted on the autonomous navigation trolley, the neutron detector is detachably mounted on the attitude adjusting system, and the autonomous navigation trolley is used for carrying the neutron detector and the attitude adjusting system to move to a position near a specified position in a measurement space; the space measurement sensor is used for measuring the actual position posture of the neutron detector in a measurement space and sending measurement data to the main controller; the main controller is used for sending a motion instruction, receiving measurement data, executing coordinate transformation operation and kinematics inverse solution operation and outputting a control signal. Through combination of the autonomous navigation trolley, the attitude adjustment system and the space measurement system, accurate positioning of the neutron detector in a neutron measurement space is realized, and a neutron diffraction stress measurement task is completed.

A neutron measurement system and method based on a nano-coated pixel sensor, relating to the field of neutron measurement technology. The neutron measurement system based on a nano-coated pixel sensor includes a detector; the detector includes an active pixel sensor; the photosensitive surface of the active pixel sensor is not encapsulated in glass, and the photosensitive surface of the active pixel sensor has a layered neutron conversion material. A neutron measurement method is applied to the neutron measurement system based on a nano-coated pixel sensor; the method is as follows: a neutron undergoes a nuclear reaction with a target element, and the generated alpha rays are incident on the photosensitive surface of the active pixel sensor, causing the active pixel sensor to generate a radiation response signal; the indirect measurement of neutrons is achieved by statistically analyzing the radiation response signal. The advantage of this invention is that by combining a specific neutron conversion material with an active pixel sensor, neutron detection is transformed into alpha particle detection, which is the strength of the active pixel sensor, significantly improving the detection efficiency of neutrons (especially thermal neutrons).

The invention relates to an epithermal neutron measurement system for boron neutron capture therapy, and belongs to the technical field of epithermal neutron measurement, and the system comprises a collimation shielding body which is used for shielding and collimating an incident neutron beam to be measured; the thermal neutron absorber is used for absorbing thermal neutron components of the neutron beam passing through the collimation shielding body; the epithermal neutron regulation and control body is used for regulating and controlling the proportion and energy distribution of epithermal neutron beams passing through the thermal neutron absorber; the alpha particle shielding body is used for shielding alpha particles of the detector or the surrounding environment; the detector is used for detecting the total number of alpha particles generated by nuclear reaction between the target epithermal neutron beam passing through the epithermal neutron regulation and control body and elements in a detector material based on the set detection efficiency; and the data acquisition system is used for acquiring the measurement signal information, and calculating the number of epithermal neutrons of the neutron beam to be measured based on the measurement signal information, the detector counting rule and the detection efficiency. According to the invention, accurate and real-time monitoring of the number of epithermal neutrons is realized.

The application discloses a digital visualized reactivity measurement method, device, system and equipment, and the method comprises the following steps: obtaining a digital neutron measurement signal by using a front-end digitization-based signal measurement method; establishing a three-dimensional physical analysis model by using a three-dimensional digital coordinate positioning-based digital modeling method; correcting the three-dimensional physical analysis model by using a three-dimensional calculation model optimization method based on a measured critical rod position to obtain a corrected calculation model; obtaining a correction factor based on the corrected calculation model, correcting the digital neutron measurement signal to obtain a corrected neutron detection signal; performing reactivity measurement based on the corrected neutron detection signal; and establishing a three-dimensional core visualized model based on the corrected calculation model, and displaying the reactivity measurement result in a numerical form on the three-dimensional core visualized model. The application realizes accurate and reliable digital visualized reactivity measurement, and provides a theoretical basis for efficient and accurate measurement of core reactivity physical parameters.

The invention discloses a gamma-ray compensation type recoil proton proportional counter for fast neutron detection, and belongs to the technical field of neutron detection, the gamma-ray compensation type recoil proton proportional counter comprises a cylindrical shell, an insulator is arranged in the cylindrical shell along the cross section direction of the cylindrical shell, and the insulator divides the interior of the cylindrical shell into a neutron measurement cavity and a gamma-ray measurement cavity; cathode tubes and anodes are arranged in the neutron measurement cavity and the gamma-ray measurement cavity, field tubes are installed at the two ends of each cathode tube, the anodes in the neutron measurement cavity are electrically connected with the electronics system, and the cathode tubes and the field tubes of the neutron measurement cavity and the gamma-ray measurement cavity are connected through wires penetrating through the insulator. Hydrogen-containing gas is arranged in the neutron measurement cavity, and equivalent gas is arranged in the gamma ray measurement cavity. The influence of gamma rays during measurement of fast neutrons in a low-energy region is suppressed or reduced through the gamma ray compensation system, the energy measurement lower limit of the recoil proton proportional counter is expanded, and absolute measurement of the single-energy neutron fluence rate in the 10-100 keV energy region can be achieved.