CN108051847B - Utilize the method and neutron dose rate instrument of lanthanum bromide detector measurement neutron dose rate - Google Patents

Abstract

The invention discloses a method for measuring the neutron dose rate by using a lanthanum bromide detector and a neutron dose rate meter, wherein the method for measuring the neutron dose rate utilizes the neutron characteristic gamma energy generated by the neutron in the lanthanum bromide detector There is a deterministic functional relationship between the net count rate of the peak and the neutron dose rate caused by the neutron at that point, and the neutron dose is calculated and obtained by measuring the gamma energy spectrum and using the deterministic functional relationship Rate. Therefore, using the method for measuring neutron dose rate in the embodiment of the present invention can obtain neutron dose rate more conveniently, quickly and accurately.

Description

Method for Measuring Neutron Dose Rate Using Lanthanum Bromide Detector and Neutron Dose Rate Instrument

technical field

The invention belongs to the technical field of radiation detection and environmental monitoring equipment. Specifically, the invention relates to a method for measuring neutron dose rate using a lanthanum bromide detector and a neutron dose rate meter.

Background technique

A neutron dose rate meter is a radiation monitoring device used to measure and evaluate the surrounding dose equivalent rate produced by neutron radiation. At present, the basic components of common neutron dose rate meters for radiation protection include moderators, neutron energy compensation materials, thermal neutron sensitive counters and electronic circuits. Its structural feature is that the thermal neutron sensitive counter is wrapped in the center with a spherical or cylindrical moderator; in the moderator body, a neutron absorption sieve with slow neutron penetration holes is set at a certain distance from the central detector. Or use the absorption layer of boron-containing material, the incident neutrons are moderated (or thermal neutron diffusion) after entering the moderator, and part of the slow (thermal) neutrons are absorbed when passing through the absorption sieve (or absorption layer). A proportion of neutrons pass through, and some neutrons that pass through the absorbing sieve continue to be slowed down or diffused, and finally some neutrons that reach the central detector are detected and recorded.

Existing neutron dose rate meters can be roughly divided into three categories according to different structural designs: one is the single-counter type. This type of dose rate meter uses a single spherical or cylindrical polyethylene as the moderator, and a single counter is placed in the center of the sphere. Proportional counters (such as BF ₃ , ³ He) or ⁶ Li glass scintillators, with some specially designed neutron energy compensation materials such as boroplastic or cadmium materials in the middle of the sphere. The second is the multi-counter type. The moderator of this type of dose rate meter is a single-sphere or multi-sphere design. The probe uses multiple proportional counters (such as ³ He), which are respectively placed on the center or spherical surface of the moderator. Neutron energy compensating materials. The third is the spectrometer type. This type of dose rate meter wraps thermal neutron detectors in moderator spherical shells with different diameters, and uses the different moderating capabilities of moderator spheres of different sizes to obtain neutron responses of different energies. The measured moderated neutron energy spectrum is solved to obtain the actual energy spectrum of the neutron radiation field, and then the neutron dose rate of the radiation field is calculated.

Lanthanum bromide detector is a new type of inorganic scintillator detector, which has excellent time resolution (hundreds of picoseconds), high energy resolution (<3%, for 662keV gamma rays) and high detection efficiency, and is widely used Measured by gamma spectroscopy. As an inorganic scintillator detector, the lanthanum bromide detector is mainly composed of lanthanum bromide crystals, and the constituent elements mainly include La and Br. Considering the natural isotope abundance, it is mainly ¹³⁹ La, ⁷⁹ Br and ⁸¹ Br, three nuclides All are stable nuclides. However, when neutrons are incident on the lanthanum bromide crystal material, the neutrons will undergo a nuclear reaction with the target nuclide. The main reaction types include elastic scattering, inelastic scattering and radiation capture. Among them, if the neutron kinetic energy is enough to excite the target nucleus, inelastic scattering A(n,n′γ)A′ occurs, then the incident neutron will transfer part of the initial kinetic energy to the nucleus, so that the target nucleus is excited to an excited state, and the target nucleus Gamma rays are emitted during de-excitation, such as ⁷⁹ Br(n, n′γ) ^79m Br, ^79m Br de-excitation will emit γ-rays with an energy of 217keV; if the radiation capture reaction A(n, γ)B occurs, the target nucleus captures Neutrons generate new target nuclei. The new nuclei are usually in an unstable excited state. The excitation energy depends on the binding energy and kinetic energy of the neutrons. The excited nuclei will transition back to the ground state by emitting one or several γ quanta, and will Emit subsequent radioactive decay, such as ¹³⁹ La(n,γ) ¹⁴⁰ La, ¹⁴⁰ La decays to ¹⁴⁰ Ce ⁱⁿ the form of β-; ⁷⁹ Br(n,γ) ⁸⁰ Br, ⁸⁰ Br in the form of β- ^and orbital electron capture Decays to ⁸⁰ Kr; ⁸¹ Br(n,γ) ⁸² Br, ⁸² Br decays to ⁸² Kr in a β ^- way. Gamma rays of different energies produced by nuclear reactions can be detected and resolved by lanthanum bromide detectors.

In recent years, with the deepening of research, foreign researchers have found through experimental research that using the physical mechanism of the above-mentioned nuclear reaction to generate γ-rays and using the time-of-flight method, the detection of neutrons by lanthanum bromide detectors can be realized. For example, for 700keV For neutrons, the detection efficiency of 2in×2in lanthanum bromide detector can reach 5%. From the perspective of the detector itself, the detection efficiency is better than other types of neutron detectors. However, the above-mentioned detection method is based on the time-of-flight method and is not suitable for the field of radiation protection. Because the time-of-flight method is based on the fact that neutrons with different energies (flight speeds) fly over a certain distance, the time required to fly over a certain distance is different, and the measurement of neutron energy is converted into the measurement of the time required for the neutron to fly over a selected distance. time distribution to determine the neutron energy distribution. This method needs to record the start time and end time of the neutron flight distance very accurately, which is obviously impossible to achieve in the field of radiation protection.

Therefore, the present invention proposes a neutron dose rate meter based on a lanthanum bromide detector, which is used for neutron dose rate measurement in the field of radiation protection.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. For this reason, an object of the present invention is to propose the method for measuring neutron dose rate and neutron dose rate instrument, adopt the method for measuring neutron dose rate proposed by the present invention, this method utilizes lanthanum bromide detector to be able to communicate with incident neutron The reaction occurs to produce characteristic gamma energy peaks of different energies, which are detected and resolved by lanthanum bromide detectors, and then the deterministic functional relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peaks can be used to obtain neutron dose rate.

The inventors have found that the detection of neutrons by lanthanum bromide detectors can be realized by using the time-of-flight method, but determining the energy distribution of neutrons by accurately recording the starting time and ending time of neutrons on a selected flight distance is not feasible in the field of radiation protection. Unrealizable, the time-of-flight method is not applicable in the field of radiation protection. The inventor unexpectedly found that the change of the net count rate of the characteristic gamma energy peak of different energies produced by the reaction of neutrons and lanthanum bromide crystal materials is consistent with the change trend of the neutron dose rate, and the neutron dose rate and the characteristic gamma The deterministic functional relationship between the net count rates of the energy peaks can be measured by combining the net count rates of one or several neutron characteristic gamma energy peaks and calculating the spectrum to realize the measurement of the neutron dose rate in the radiation field.

To this end, according to a first aspect of the present invention, the present invention proposes a method for measuring neutron dose rate, according to a specific embodiment of the present invention, the method utilizes neutrons generated in a lanthanum bromide detector There is a deterministic functional relationship between the net count rate of the sub-feature gamma energy peak and the neutron dose rate caused by the neutron at this point, by measuring the gamma energy spectrum, and using the deterministic functional relationship, calculate and Obtain neutron dose rate.

The method for measuring the neutron dose rate proposed by the present invention is actually based on the fact that the inventors have found that the net count rate of the neutron characteristic gamma energy peak produced by neutrons in the lanthanum bromide detector is related to the neutrons in the lanthanum bromide detector. There is a deterministic functional relationship between the neutron dose rate caused by the point. Furthermore, a neutron dose rate meter based on a lanthanum bromide detector can be used to measure the combination of characteristic gamma energy peaks produced by one or several incident neutrons, and the relationship between the neutron dose rate and the net count rate of neutron characteristic gamma energy peaks can be used. A deterministic functional relationship yields the neutron dose rate.

In some embodiments of the present invention, the method for measuring neutron dose rate includes:

Use lanthanum bromide detectors to detect neutrons in order to obtain the characteristic gamma energy peak;

Based on the characteristic gamma energy peak, the neutron dose rate is calculated and obtained, wherein the neutron dose rate and the net count rate of the characteristic gamma energy peak are in a deterministic functional relationship, and the functional relationship can be expressed as:

D _i =f(N _i )

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic γ energy peak generated by the nuclear reaction between the incident neutron and the lanthanum bromide crystal material, the unit is cps.

In some embodiments of the present invention, in the deterministic functional relationship, the range of the net count rate is: N _i >0.

In some embodiments of the present invention, in the deterministic functional relationship, the measurement range of the neutron dose rate is: D _i >0.

In some embodiments of the invention, the neutrons are generated by a californium source. As a result, neutrons of different energies can be generated and react with lanthanum bromide crystals to generate characteristic γ energy peaks of different energies, and then the functional relationship between the neutron dose rate and the net count rate of the peak position can be used to obtain neutron dose rate.

In some embodiments of the present invention, the characteristic gamma energy peak includes at least one selected from the following: 22.34±5keV, 54.64±5keV, 83.05±5keV, 101.1±5keV, 119.2±5keV, 166.5±5keV, 207.1±5keV , 217.5±5keV, 243.3±5keV, 276.7±5keV, 294.9±5keV, 307.2±5keV, 335±5keV, 344±5keV, 387.9±5keV, 536.9±10keV, 606.9±10keV, 650.5±5keV, 725.1±10keV, 766.8 ±10keV842.7±10keV, 872.4±10keV, 962.8±10keV, 1002±10keV, 1043±10keV, 1084±10keV, 1115±10keV, 1268±10keV. Therefore, the accuracy of measuring the neutron dose rate can be further improved.

In some embodiments of the present invention, the deterministic functional relationship is a logarithmic functional relationship, and the logarithmic functional relationship is expressed as:

D _i =alnNi+b

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons with the lanthanum bromide crystal material, the unit is cps; a, b are constants , and a>0.

In some embodiments of the present invention, the deterministic functional relationship is a linear fitting function, and the linear fitting function is expressed as:

D _i =kN _i +c

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons with the lanthanum bromide crystal material, the unit is cps; k, c are constants , and k>0.

According to another aspect of the present invention, the present invention also proposes a neutron dose rate meter having a lanthanum bromide detector adapted to react with incident neutrons The characteristic gamma energy peak is generated, and the energy spectrum of the characteristic gamma full energy peak is detected.

According to the neutron dose rate meter proposed by the present invention, by using the lanthanum bromide detector in the neutron dose rate meter, the incident neutrons can react with the lanthanum bromide crystal material to produce characteristic gamma energy peaks of different energies, and utilize The lanthanum bromide detector detects the characteristic gamma energy peak generated. Thus, adopting the neutron dose rate meter proposed by the present invention can measure the combination of one or several neutron characteristic gamma energy peaks, and utilize the deterministic function between the neutron dose rate and the net count rate of the characteristic gamma energy peaks relationship, to achieve the measurement of radiation field neutron dose rate.

Description of drawings

Fig. 1 is a background spectrum measured by a neutron dose rate meter according to an embodiment of the present invention and a measurement spectrum obtained by measuring a ²⁵² Cf source.

Fig. 2 is a measurement spectrum obtained by using a neutron dose rate meter according to an embodiment of the present invention measured in a radiation field with different neutron dose rates.

Fig. 3 is a graph showing the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak according to an embodiment of the present invention.

Fig. 4 is a graph showing the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak according to one embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak according to one embodiment of the present invention.

Fig. 6 is a graph showing the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak according to one embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

According to one aspect of the present invention, the present invention proposes a method for measuring the neutron dose rate. According to a specific embodiment of the present invention, the method utilizes the neutron characteristic gamma energy peak generated by the neutron in the lanthanum bromide detector There is a deterministic functional relationship between the net count rate of the neutron and the neutron dose rate caused by the neutron at this point, by measuring the gamma energy spectrum, and using the deterministic functional relationship, the neutron dose rate is calculated and obtained .

The method for measuring the neutron dose rate proposed by the present invention is actually based on the fact that the inventors have found that the net count rate of the neutron characteristic gamma energy peak produced by neutrons in the lanthanum bromide detector is related to the neutrons in the lanthanum bromide detector. There is a deterministic functional relationship between the neutron dose rate caused by the point. Furthermore, a neutron dose rate meter based on a lanthanum bromide detector can be used to measure the combination of characteristic gamma energy peaks produced by one or several incident neutrons, and the relationship between the neutron dose rate and the net count rate of neutron characteristic gamma energy peaks can be used. A deterministic functional relationship yields the neutron dose rate.

According to the specific implementation of the present invention, the method for measuring the neutron dose rate in the above embodiment includes: using a lanthanum bromide detector to detect neutrons so as to obtain the characteristic gamma energy peak; based on the characteristic gamma energy peak, calculate and obtain the neutron Sub-dose rate, wherein, the neutron dose rate and the net count rate of the characteristic gamma energy peak are in a deterministic functional relationship, and the functional relationship can be expressed as:

D _i =f(N _i )

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic γ energy peak generated by the nuclear reaction between the incident neutron and the lanthanum bromide crystal material, the unit is cps.

According to the method for measuring neutron dose rate in the above-mentioned embodiments of the present invention, a neutron dose rate meter can be used to measure one or several characteristic gamma energy peaks produced by incident neutrons and use the net count of neutron dose rate and characteristic gamma energy peaks The deterministic functional relationship between the neutron dose rates at the measured point is obtained.

According to a specific embodiment of the present invention, N _i >0 and D _i >0 in the above deterministic functional relationship. Therefore, the method has a wider scope of application.

According to a specific embodiment of the present invention, the measured neutrons are generated by a californium source ( ²⁵² Cf). Therefore, the californium source ( ²⁵² Cf ) can be used to generate neutrons with different energies and react with lanthanum bromide crystals to produce characteristic gamma energy peaks with different energies, and then the net difference between neutron dose rate and peak position can be used The functional relationship between the count rates yields the neutron dose rate.

According to a specific embodiment of the present invention, the characteristic gamma energy peak may include but not limited to one selected from the following: 22.34±5keV, 54.64±5keV, 83.05±5keV, 101.1±5keV, 119.2±5keV, 166.5±5keV, 207.1± 5keV, 217.5±5keV, 243.3±5keV, 262±5keV, 276.7±5keV, 294.9±5keV, 307.2±5keV, 335±5keV, 344±5keV, 387.9±5keV, 536.9±10keV, 606.9±10keV, 650.5±5keV, 725.1±10keV, 766.8±10keV, 842.7±10keV, 872.4±10keV, 962.8±10keV, 1002±10keV, 1043±10keV, 1084±10keV, 1115±10keV, 1268±10keV.

According to a specific embodiment of the present invention, the deterministic functional relationship is a logarithmic functional relationship, and the logarithmic functional relationship is expressed as:

D _i =alnNi+b

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons with the lanthanum bromide crystal material, the unit is cps; a, b are constants , and a>0. Therefore, through the above functional relational formula, the net count rate N _i of the characteristic gamma energy peak is obtained according to the detection of neutrons by the lanthanum bromide detector, and then the neutron dose rate D _i is effectively calculated. Therefore, the method for measuring neutron dose rate in the above embodiments of the present invention can measure neutron dose rate more conveniently and quickly.

According to a specific embodiment of the present invention, the deterministic functional relationship may be expressed as a linear fitting function. The specific form of the function can be expressed as:

D _i =kN _i +c

Among them, D _i is the neutron dose rate, μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons and lanthanum bromide crystal materials, the unit is cps; k, c are constants, and k>0. Therefore, through the above functional relational formula, the net count rate N _i of the characteristic gamma energy peak is obtained according to the detection of neutrons by the lanthanum bromide detector, and then the neutron dose rate D _i is effectively calculated. Therefore, the method for measuring neutron dose rate in the above embodiments of the present invention can measure neutron dose rate more conveniently and quickly.

According to one aspect of the present invention, the present invention proposes a neutron dose rate meter, the neutron dose rate meter has a lanthanum bromide detector, and the lanthanum bromide detector is suitable for reacting with incident neutrons to generate a characteristic gamma energy peak, And detect the energy spectrum of the characteristic γ all-energy peak.

According to the neutron dose rate meter of the above-mentioned embodiment of the present invention, by using the lanthanum bromide detector in the neutron dose rate meter, incident neutrons can react with the lanthanum bromide crystal material to produce characteristic gamma energy peaks of different energies, The characteristic gamma energy peak generated is detected by a lanthanum bromide detector. Thus, using the neutron dose rate meter of the above-mentioned embodiment of the present invention, the combination of one or several neutron characteristic gamma energy peaks can be measured, and the difference between the neutron dose rate and the net count rate of the characteristic gamma energy peak can be determined The functional relationship of nature can realize the measurement of neutron dose rate in radiation field.

According to a specific embodiment of the present invention, the working principle of the neutron dose rate meter is: incident neutrons react with the lanthanum bromide crystal material to produce characteristic gamma energy peaks of different energies, and the net count rate of the characteristic gamma energy peaks is related to the radiation field There is a deterministic functional relationship between neutron dose rates, which is:

D _i =f(N _i )

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic γ energy peak generated by the nuclear reaction between the incident neutron and the lanthanum bromide crystal material, the unit is cps. The change of the net count rate of the characteristic gamma energy peaks of different energies is consistent with the change trend of the neutron dose rate. By measuring the net count rate combination of any one or several neutron characteristic gamma energy peaks and corresponding solution spectrum calculation, The neutron dose rate of the measured radiation field can be obtained.

Example 1

The neutron dose rate is measured by a neutron dose rate meter. Among them, the neutron dose rate meter has a lanthanum bromide detector, and the lanthanum bromide detector adopts a 3in×3in lanthanum bromide detector (LaBr ₃ :Ce). The californium source (Cf-252 source) was selected as the neutron source to be tested.

The characteristic gamma energy peaks generated by the reaction between ²⁵² Cf source and lanthanum bromide crystal include but not limited to the energy values listed in Table 1; The net count rate and neutron dose rate of the characteristic gamma energy peak, the characteristic gamma energy peak includes but not limited to the five energies listed in Table 2.

The background spectrum measured by the neutron dose rate meter and the measured spectrum obtained by measuring the ²⁵² Cf source are shown in Fig. 1; Fig. 2 is the gamma energy spectrum detected by the neutron dose rate meter when measuring different neutron dose rates, The neutron dose rate includes but is not limited to the seven dose rate levels listed in Figure 2; Figure 3 shows the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak, and the neutron dose rate includes but is not limited to 3 The 7 dose rate levels mentioned above, the characteristic γ energy peaks include but not limited to the 5 energies listed in Figure 3. Figure 4 shows the relationship between the neutron dose rate and the characteristic gamma energy peak net count rate after normalization processing according to the maximum value of the net count rate of each energy peak. The neutron dose rate includes but is not limited to that described in Figure 4 There are 7 dose rate levels, and the characteristic gamma energy peaks include but are not limited to the 4 energies listed in Figure 4. Figure 5 shows the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak when the characteristic gamma peak is at 119.2keV. For the above seven dose rate levels, the characteristic gamma energy peaks include but are not limited to the energies listed in Figure 5. Figure 6 shows the relationship between the neutron dose rate and the net count rate of the characteristic gamma energy peak when the characteristic gamma peak is at 119.2keV. The characteristic gamma energy peaks of the seven dose rate levels include but are not limited to the energies listed in Figure 6 .

Table 1 The characteristic γ-energy peaks produced by the reaction between ²⁵² Cf source and lanthanum bromide crystal

Table 2 Energy of neutron characteristic gamma energy peak, net count rate of characteristic gamma energy peak and neutron dose rate

According to the measured results in Figures 3 and 4, it can be seen that the deterministic functional relationship between the net count rate of the characteristic gamma energy peak generated by the reaction of neutrons and lanthanum bromide crystals and the neutron dose rate can be expressed as a logarithmic function . The specific form of the function can be expressed as:

D _i =alnNi+b

Among them, D _i is the neutron dose rate, the unit is μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons with the lanthanum bromide crystal material, the unit is cps; a, b are constants , and a>0. For example, Figure 5 shows that when the characteristic gamma peak is at 119.2keV, the neutron dose rate and the net count rate of the characteristic gamma energy peak have a logarithmic function relationship. The change of the net count rate of the characteristic gamma energy peaks of different energies is consistent with the change trend of the neutron dose rate, that is, by measuring the net count rate combination of any one or several neutron characteristic gamma energy peaks, the measured The neutron dose rate of the radiation field.

According to the measured results in Figures 3 and 4, it can be seen that the deterministic functional relationship between the net count rate of the characteristic gamma energy peak generated by the reaction of neutrons and lanthanum bromide crystals and the neutron dose rate can be expressed as a linear fitting function. The specific form of the function can be expressed as:

D _i =kN _i +c

Among them, D _i is the neutron dose rate, μSv/h; N _i is the net count rate of the characteristic gamma energy peak produced by the reaction of incident neutrons and lanthanum bromide crystal materials, the unit is cps; k, c are constants, and k>0. For example, Figure 6 shows that when the characteristic gamma peak is at 119.2keV, the neutron dose rate and the net count rate of the characteristic gamma energy peak have a linear fitting function relationship. The change of the net count rate of the characteristic gamma energy peaks of different energies is consistent with the change trend of the neutron dose rate, that is, by measuring the net count rate combination of any one or several neutron characteristic gamma energy peaks, the measured The neutron dose rate of the radiation field.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (7)

1. a kind of method for measuring neutron dose rate, which is characterized in that the method is produced in lanthanum bromide detector using neutron There are deterministic between the neutron dose rate caused by the point for the net counting rate and the neutron at raw middle subcharacter γ energy peak Functional relation by measuring gamma spectrum, and utilizes the deterministic functional relation, calculates and obtain neutron dose rate,

Wherein, the deterministic functional relation is logarithmic function relationship or linear fit function:

The logarithmic function relationship is expressed as: D_i=alnNi+b, wherein D_iFor neutron dose rate, unit is μ Sv/h；N_iTo enter Hit son and lanthanum bromide crystalline material react generation feature γ can peak net counting rate, unit cps；A, b are constant, And a > 0；

The linear fit function representation are as follows: D_i=kN_i+ c, wherein D_iFor neutron dose rate, unit is μ Sv/h；N_iTo enter to hit Son and lanthanum bromide crystalline material react generation feature γ can peak net counting rate, unit cps；K, c are constant, and k > 0。

2. the method according to claim 1, wherein including:

Neutron is detected using lanthanum bromide detector, it can peak to obtain feature γ；

Net counting rate and the deterministic functional relation based on feature γ energy peak, calculate and obtain neutron dose rate.

3. according to the method described in claim 2, it is characterized in that, in the deterministic functional relation, the net counting rate Range are as follows: N_i>0。

4. according to the method described in claim 2, it is characterized in that, in the deterministic functional relation, the neutron dose The measurement range of rate are as follows: D_i>0。

5. the method according to claim 1, wherein the neutron is generated by californium source.

6. method according to claim 1 or 5, which is characterized in that the feature γ can peak include selected from it is following at least it One: 22.34 ± 5keV, 54.64 ± 5keV, 83.05 ± 5keV, 101.1 ± 5keV, 119.2 ± 5keV, 173.5 ± 5keV, 207.1±5keV、217.5±5keV、243.3±5keV、262±5keV、276.7±5keV、294.9±5keV、307.2± 5keV、335±5keV、344±5keV、387.9±5keV、536.9±10keV、606.9±10keV、650.5±10keV、 725.1±10keV、766.8±10keV 842.7±10keV、872.4±10keV、962.8±10keV、1002±10keV、 1043±10keV、1084±10keV、1115±10keV、1268±10keV。

7. a kind of neutron dose rate instrument, which is characterized in that the neutron dose rate instrument has lanthanum bromide detector, the lanthanum bromide Detector, which is suitable for reacting with incident neutron, generates feature γ energy peak, and detects and obtain the power spectrum of feature γ full energy peak,

Wherein, the working principle of the neutron dose rate instrument are as follows: incident neutron reacts with lanthanum bromide crystalline material, generates not Co-energy feature γ energy peak, feature γ can there are claim 1- between the net counting rate at peak and the neutron dose rate of radiation field Deterministic functional relation described in any one of 6, the variation and neutron agent of the net counting rate at the feature γ energy peak of different-energy The variation tendency of dose rate is consistent, and passes through any one of measurement or the net counting rate combination and phase at several middle subcharacter γ energy peaks The spectrum unscrambling answered calculates, and can obtain the neutron dose rate of tested radiation field.