CN115032678A

CN115032678A - Ray type identification and activity online measurement system

Info

Publication number: CN115032678A
Application number: CN202210457386.3A
Authority: CN
Inventors: 董春辉; 彭伟欣; 左晶鑫; 魏凌峰; 廖开勇; 王明; 张庆贤; 谷懿; 李飞; 程锋; 张牧昊; 黄起昌; 黎刚; 李伟兰
Original assignee: Sichuan University; Southwestern Institute of Physics; Chengdu Univeristy of Technology
Current assignee: Sichuan University; Southwestern Institute of Physics; Chengdu Univeristy of Technology
Priority date: 2022-04-28
Filing date: 2022-04-28
Publication date: 2022-09-09

Abstract

The invention discloses a ray type identification and activity online measurement system, which at least comprises a detector and an electronics processing unit; the detector is of a double-cavity structure consisting of a first measuring cavity and a second measuring cavity, the first measuring cavity is of a columnar structure and wraps the inner side of the second measuring cavity, and the first measuring cavity and the second measuring cavity are separated by a first shell; the material to be measured is led into one end of the first measuring cavity through the inlet and is led out through the outlet arranged at the other end, the first measuring cavity collects and identifies signals of n (neutrons), alpha (alpha particles), beta (beta particles), gamma (gamma rays) and heavy particles in the material to be measured, the second measuring cavity collects and identifies signals of n and gamma rays of the material to be measured, and the electronic processing unit detects scintillation light signals based on the detector to complete ray type identification and activity online measurement.

Description

Ray type identification and activity online measurement system

Technical Field

The invention belongs to the field of radiation detection, and particularly relates to a ray type identification and activity online measurement system.

Background

The traditional measurement mode is that the radioactivity in the liquid is measured by using a liquid flash method, the influence of interference rays is removed by using a chemical method at first, then a single ray solution to be measured is prepared, the ray activity measurement is carried out by using the liquid flash method, if the ray activity is very low, the single ray solution to be measured is required to be concentrated, meanwhile, the measurement time required by the liquid flash method is long, the three-day time required by one-time measurement flow is usually finished, and the real-time online measurement of the rays cannot be realized. That is, in the conventional measurement process, the measurement process is complex and the measurement efficiency is low.

Disclosure of Invention

The invention aims to provide a ray type identification and activity online measurement system for overcoming the defects of the prior art.

The purpose of the invention is realized by the following technical scheme:

a ray type identification and activity online measurement system at least comprises a detector and an electronics processing unit;

the detector is of a double-cavity structure consisting of a first measuring cavity and a second measuring cavity, the first measuring cavity is of a columnar structure and wraps the inner side of the second measuring cavity, and the first measuring cavity and the second measuring cavity are separated by a first shell;

a plurality of first PSD plastic flash fibers are arranged in the first measuring cavity along the axis direction of the cavity, a first photomultiplier and a second photomultiplier are respectively arranged at two ends of the first measuring cavity, two ends of each first PSD plastic flash fiber are respectively connected with the first photomultiplier and the second photomultiplier, and when the first photomultiplier and the second photomultiplier receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition;

a plurality of second PSD plastic flash fibers are arranged in the second measuring cavity along the axis direction of the cavity, a third photomultiplier and a fourth photomultiplier are respectively arranged at two ends of the second measuring cavity, two ends of each second PSD plastic flash fiber are respectively connected with the third photomultiplier and the fourth photomultiplier, and when the third photomultiplier and the fourth photomultiplier receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition;

the material to be measured is led into one end of the first measuring cavity through the inlet and led out through the outlet arranged at the other end, the first measuring cavity is used for collecting and identifying n, alpha, beta, gamma and heavy particle signals in the material to be measured, the second measuring cavity is used for collecting and identifying n and gamma ray signals in the material to be measured, and the electronic processing unit is used for completing ray type identification and activity online measurement based on scintillation light signals measured by the detector.

According to a preferred embodiment, the first housing is made of an aluminum material.

According to a preferred embodiment, the first housing is made of an aluminum material, and the thickness of the first housing is 0.2 cm.

According to a preferred embodiment, the housing of the second measurement chamber is a second casing made of radiation shielding metal.

According to a preferred embodiment, the second housing is made of a lead material.

According to a preferred embodiment, the second shell is further wrapped by a third shell, and the third shell is made of a plastic material.

According to a preferred embodiment, the electronic processing unit comprises an ADC analog-to-digital conversion circuit, an FPGA operational circuit and four amplifiers; each photomultiplier is respectively connected with an ADC analog-to-digital conversion circuit through an amplifier, and the ADC analog-to-digital conversion circuit is connected with an FPGA arithmetic circuit; the FPGA arithmetic circuit is used for finishing the identification of n, alpha, beta, gamma and heavy particle rays in the material and the on-line measurement of corresponding activity based on the output signal of the photomultiplier.

According to a preferred embodiment, the FPGA arithmetic circuit obtains a waveform when receiving radiation irradiation based on each second PSD plastic-flash optical fiber in the second measurement cavity, and completes γ -ray identification and online measurement of corresponding activity.

According to a preferred embodiment, the FPGA arithmetic circuit obtains a waveform when receiving radiation irradiation based on each first PSD plastic flash fiber in the first measurement cavity, and completes the identification of α, n and heavy particle rays and the online measurement of corresponding activity.

According to a preferred embodiment, the FPGA arithmetic circuit obtains a β/γ -ray waveform when receiving radiation based on each first PSD plastic-flash optical fiber in the first measurement cavity, and obtains a γ -ray waveform when receiving radiation based on each second PSD plastic-flash optical fiber in the second measurement cavity, thereby completing the identification of β -particles and the online measurement of corresponding activities.

The aforementioned main aspects of the invention and their respective further alternatives can be freely combined to form a plurality of aspects, all of which are aspects that can be adopted and claimed by the present invention. The skilled person in the art can understand that there are many combinations, which are all the technical solutions to be protected by the present invention, according to the prior art and the common general knowledge after understanding the scheme of the present invention, and the technical solutions are not exhaustive herein.

The invention has the beneficial effects that:

1. the structure of the measuring system is extremely simple. The PSD plastic scintillation fiber is used for building, the plastic scintillation fiber is stable in property, moisture-resistant and corrosion-resistant, and a harsh measurement environment (such as liquid nitrogen cooling for high-purity germanium) is not needed.

2. The online real-time measurement of the ray activity can be realized. The measurement range of the ray activity is extremely large, the lower limit of the activity detection is extremely small, and the upper limit of the activity detection is extremely high.

Due to the fact that the PSD plastic flashing array is used, the contact area of the liquid to be detected and the PSD plastic flashing is large enough, the number of rays entering the PSD plastic flashing in unit time is enough, the radioactive liquid with low activity can ensure that enough rays enter a detector in unit time, and therefore the lower detection limit of the system is extremely low.

Secondly, the traditional measurement mode is to use a liquid flash method to measure the radioactivity in the liquid, firstly, a chemical method is used to remove the influence of interference rays, then, a single ray solution to be measured is prepared, then, the online measurement of the ray activity is carried out through the liquid flash method, then, the ray activity is very low, the single ray solution to be measured also needs to be concentrated, meanwhile, the measurement time required by the liquid flash method is long, and the real-time online measurement of the rays cannot be realized usually after the measurement process is finished for three days. In the system, when the ray is incident to the PSD plastic flash, energy is deposited to generate flash light, the flash light propagates in the optical fiber and reaches PMTs (photomultiplier tubes) at two ends, the PMTs at the two ends can capture a corresponding number of flash photons at the same time, and the number of the flash photons captured by the PMTs at the two ends is related to the position of the energy deposited by the ray in the optical fiber. When the incident position is close to a certain PMT, the PMT captures a larger number of scintillation photons. The reason why the two PMTs are used for coincidence measurement is that the PMTs themselves have dark current outputs, and the influence of randomly generated dark current noise can be effectively eliminated by coincidence measurement. The PMT converts an optical signal into an electric signal, then the electric signal is amplified and formed and then input into the four-channel high-speed ADC, the ADC converts an analog signal into a digital signal and then transmits the digital signal to the FPGA at the rear end, and ray type identification and activity online measurement are realized in the FPGA.

And thirdly, because the pulse width of the PSD flash output signal is the minimum of all nuclear detectors and is only a few to tens of nanoseconds, the probability of overlapping between pulses in unit time is the minimum, and the detection ray activity range of the detection system is extremely large.

Drawings

FIG. 1 is a schematic diagram of the structure of a probe of the on-line measuring system of the present invention;

FIG. 2 is a schematic cross-sectional view of a probe of the electronic processing unit of the present invention;

FIG. 3 is a schematic block diagram of the electronics processing unit of the on-line measurement system of the present invention;

FIG. 4 is a waveform diagram obtained during a radiation measurement of a PSD plastic flash fiber;

101-inlet, 102-first measuring cavity, 103-second measuring cavity, 104-first PSD plastic flash fiber, 105-second PSD plastic flash fiber, 106-first shell, 107-second shell, 108-third shell, and 109-outlet.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the features in the following embodiments and examples may be combined with each other without conflict. It should be noted that, in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations and positional relationships that are conventionally used in the products of the present invention, and are used merely for convenience in describing the present invention and for simplicity in description, but do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1:

referring to fig. 1 to 3, the invention discloses a ray type identification and activity online measurement system, which at least comprises a detector and an electronic processing unit. The electronic processing unit completes identification of various ray types emitted in the material to be measured and online measurement of corresponding activity based on signals measured by the detector.

Preferably, the probe is a double-cavity structure formed by a first measurement cavity 102 and a second measurement cavity 103, the first measurement cavity 102 is a cylindrical structure and is wrapped inside the second measurement cavity 103, and the first measurement cavity 102 and the second measurement cavity 103 are separated by a first shell 106.

Preferably, a plurality of first PSD plastic flash fibers 104 are arranged in the first measurement cavity 102 along the axis direction of the cavity, a first photomultiplier tube PMT1-1 and a second photomultiplier tube PMT1-2 are respectively arranged at two ends of the first measurement cavity 102, two ends of each first PSD plastic flash fiber 104 are respectively connected with the first photomultiplier tube PMT1-1 and the second photomultiplier tube PMT1-2, and when the first photomultiplier tube PMT1-1 and the second photomultiplier tube PMT1-2 receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition.

Preferably, a plurality of second PSD plastic flash fibers 105 are arranged in the second measurement cavity 103 along the axis direction of the cavity, a third photomultiplier tube PMT2-1 and a fourth photomultiplier tube PMT2-2 are respectively arranged at two ends of the second measurement cavity 103, two ends of each second PSD plastic flash fiber 105 are respectively connected with the third photomultiplier tube PMT2-1 and the fourth photomultiplier tube PMT2-2, and when the third photomultiplier tube PMT2-1 and the fourth photomultiplier tube PMT2-2 receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition.

The material to be measured is introduced into one end of the first measuring chamber 102 via the inlet 101 and is discharged via the outlet 109 arranged at the other end. The first measurement cavity 102 is used for collecting and identifying signals of n, alpha, beta, gamma and heavy particles in the material to be measured, the second measurement cavity 103 is used for collecting and identifying signals of n and gamma rays in the material to be measured, and the electronic processing unit is used for identifying and measuring activity on line based on scintillation light signals measured by a detector.

Preferably, the first housing 106 is made of an aluminum material. Further, the first housing 106 is made of an aluminum material, and the thickness of the first housing 106 is 0.2 cm.

Specifically, the thickness of the first housing 106 aluminum material is calculated as:

the relationship between the maximum range R (g/cm2) of beta rays in aluminum and the maximum energy E beta max (mev) can be expressed by empirical calculation. (formula references-Huole, Liujiali, Mayong and eds. radiation dose and protection [ M ]. Beijing: electronics industry Press, 2015)

When E is _βmax <At a value of 0.2MeV,

when 0.15MeV<E _βmax <At a value of 0.8MeV,

when 0.8MeV<E _βmax <At the time of 3MeV, the glass fiber is,

when E is _βmax <2.5MeV, the unified formula can be used:

in the above empirical formula, if the maximum energy of the β -ray is located in the overlap region of different empirical calculation formulas, which formula is used may be used, and the error of the calculation result is less than 10%.

The calculated ranges of beta rays with different energies in the aluminum layer are as follows:

table 1

Note: in Table 1, the range values outside the range numbers are mass thickness, g/cm 2; the range value in brackets is the line thickness, cm.

The intensity attenuation of gamma rays in the aluminum layer can also be calculated by the formula. Assuming a thickness d of the aluminum layer and a density p, the intensity of gamma rays before passing through the aluminum layer is N ₀ The intensity of the gamma ray after passing through the aluminum layer is N and the intensity of the attenuation of the interaction generated within the thickness dx of the aluminum layer is dN, the fraction dN/N of the interaction generated will be proportional to the thickness dx of the thin layer, i.e., the fraction dN/N of the interaction generated will be proportional to the thickness dx of the thin layer

In the formula, the proportionality coefficient μ is referred to as a linear attenuation coefficient of gamma rays in a substance, and assuming that the absorbing substance component is uniform, the formula (1) is integrated and initial conditions are used (when d is 0, N is N ═ N ₀ ) The following results were obtained:

N＝N ₀ e ^-μd (2)

the density rho of the aluminum is 2.702g/cm ³ The linear attenuation coefficient mu is 0.1832cm ² And/g, calculating to obtain the condition of the radiation intensity loss after passing through the gamma rays with different energies of the aluminum layers with different thicknesses in the following table. (N) ₀ Intensity before ray penetration)

In summary, the aluminum layer with the thickness of 0.2cm is selected to block all beta rays with energy less than or equal to 1.6MeV, and can meet the basic detection requirement. Gamma rays with a minimum energy of 100KeV do not attenuate by more than ten percent in intensity when they pass through the aluminum layer to the outer detector layers, and the attenuation decreases with increasing energy.

Preferably, the outer shell of the second measurement cavity 103 is a second shell 107, and the second shell 107 is made of radiation shielding metal. Further, the second housing 107 is made of lead material.

Preferably, the outer side of the second casing 107 is further wrapped with a third casing 108, and the third casing 108 is made of a plastic material.

The detector is divided into an inner layer and an outer layer, wherein the inner layer (namely the first measuring cavity 102) is a plurality of PSD plastic scintillating fibers (the outer parts of the fibers are not provided with cladding layers) which are uniformly distributed, the outer layer (namely the second measuring cavity 103) is a PSD plastic scintillating fiber array which is uniformly distributed around the inner layer, and the middle part of the PSD plastic scintillating fiber array is separated by an aluminum layer. The liquid (gas) to be detected only flows in the inner layer pipeline, so the PSD plastic scintillation optical fiber in the inner layer pipeline can detect n, alpha, beta, gamma and heavy particles in the liquid, and because the outer wall of the inner layer pipeline is an aluminum pipe, the beta, alpha and heavy particles cannot penetrate through the aluminum pipe and are detected by the outer layer PSD plastic scintillation optical fiber. Only gamma and n can penetrate through the aluminum layer to be detected by the outer layer optical fiber. And the outermost lead shell and the outermost plastic shell are used for preventing external rays from influencing the detection system.

Preferably, the electronic processing unit comprises an ADC analog-to-digital conversion circuit, an FPGA operational circuit and four amplifiers. Each photomultiplier is respectively connected with an ADC analog-to-digital conversion circuit through an amplifier, and the ADC analog-to-digital conversion circuit is connected with an FPGA operation circuit. The FPGA arithmetic circuit is used for finishing the identification of n, alpha, beta, gamma and heavy particle rays in the material and the on-line measurement of corresponding activity based on the output signal of the photomultiplier.

Preferably, the FPGA arithmetic circuit obtains a waveform when receiving radiation irradiation based on each second PSD plastic flash fiber 105 in the second measurement cavity 103, and completes γ -ray identification and online measurement of corresponding activity.

Preferably, the FPGA arithmetic circuit obtains a waveform when receiving radiation irradiation based on each first PSD plastic flash fiber 104 in the first measurement cavity 102, and completes the identification of α, n and heavy particle radiation and the corresponding activity online measurement.

Preferably, the FPGA arithmetic circuit obtains a β/γ -ray waveform when receiving radiation based on each first PSD plastic flash fiber 104 in the first measurement cavity 102, and obtains a γ -ray waveform when receiving radiation based on each second PSD plastic flash fiber 105 in the second measurement cavity 103, so as to complete the identification and corresponding activity online measurement of β particles.

The on-line measuring system of the invention can quickly identify alpha rays, beta rays, gamma rays, neutrons (n) and heavy particles in the liquid (gas) to be measured:

the working principle is as follows: when alpha, beta, gamma, n and heavy particle rays exist in the liquid at the same time, all the rays can be detected by the PSD plastic scintillator in the inner part (the first measurement cavity 102) at the same time, and alpha particles, neutrons, heavy particles and beta/gamma rays can be identified according to different waveforms by combining with an electronic processing unit at the rear end. Although the waveforms of the beta rays and the gamma rays are different from those of the three rays, the waveforms of the beta rays and the gamma rays are the same, namely, the internal PSD plastic flash array can detect the gamma rays and the beta rays, and only can not distinguish which are the beta rays and which are the gamma rays. The penetrating power of gamma rays is far higher than that of beta rays with the same energy, the gamma rays can easily penetrate through an aluminum pipe and can be captured by an external PSD plastic flash array, the external PSD plastic flash array (the second measurement cavity 103) can identify gamma rays and neutrons penetrating through the aluminum pipe according to different waveforms, neutron signals are extracted according to the waveforms, and the count of the gamma rays is extracted. The inner PSD captures the total count of gamma rays and beta rays, the outer PSD only captures the count of the gamma rays, the respective counts of the beta rays and the gamma rays can be obtained according to the inner count and the outer count, and then the beta rays and the gamma rays are identified.

The on-line measuring system of the invention can detect the activity of different rays in real time:

in summary, the activity of α rays, neutron rays, heavy particle rays, beta and γ rays can be obtained by the inner PSD plastic flash according to the waveform count, and the activity of γ rays can be obtained by the outer PSD plastic flash. Thus, the ray type is also identified.

The working principle of the PSD plastic flash optical fiber of the on-line measuring system is as follows:

when different types of radiation are incident on a PSD (pulse shape discrimination) plastic scintillator, the resulting waveforms are shown in fig. 4. So that different incident rays can be identified by the different trailing edges of the waveform.

The principle that the PSD plastic scintillator can perform waveform discrimination is as follows: according to a generally accepted mechanism ([1 ]]J.B.Birks,The Theory and Practice of Scintillation Counting,Pergamon Press,London,1964；[2]F.D.Brooks,Nucl.Instr.and Meth.162(1979)477. [3]Nyibule,S.a；Henry,E.b；

W.U.a,b；

J.b；Acosta,L. c,g；Auditore,L.d；Cardella,G.e；De Filippo,E.e；Francalanza,L.c,f；Gìani, S.f；Minniti,T.d；Morgana,E.d；Pagano,E.V.c,f；Pirrone,S.e；Politi,G. e,f；Quattrocchi,L.d；Rizzo,F.f；Russotto,P.e；Trifirò,A.d；Trimarchi,M. d.Radioluminescent characteristics of the EJ 299-33plastic scintillator(Article)[J]The excitation of ionizing radiation in benzene molecules in PSD scintillators to produce scintillation light, which contains both short (prompt) and long (delayed) decay light components. The transient component is generated by direct de-excitation of the excited singlet state (S1) to the ground state (S0). The slow component is determined by the interaction between the triplet states (T1). The kinetics of the diffusion process of triplet excitons affect the probability of the interaction between triplet states, and organic scintillators with higher triplet exciton concentrations or faster diffusion rates have a higher probability of exciting slow component light. Because the PSD plastic scintillator hardly generates photoelectric effect because of relatively low atomic mass, the light excited by gamma ray is mainly indirectly excited by Compton scattered electrons generated by the interaction between the gamma ray and the plastic scintillator, the ionization capacity of the scattered electrons and beta rays in the organic scintillator is the same, the density of the deposited energy is the same, the occurrence probability of the interaction between triplet states is the same, and the generated interaction between triplet states is the sameThe fast/slow component ratios of the signals are the same, and the pulse shapes are the same. Compared with the relatively long range of electrons in the plastic scintillator, the proton with shorter range in the plastic scintillator and the recoil proton generated by the collision of the high-energy neutron to the PSD plastic scintillator rich in H element can generate triplet excitons with higher concentration than the electrons in the energy deposition process in the organic scintillator, and the emission ratio of delayed light is improved. Therefore, because of the higher proportion of delay components, the scintillation pulse generated by the proton or the neutron has the signal decay time slower than that generated by the electron or the gamma photon, and has a longer and slower tail, and through the difference of the pulse shapes, the ray signals with different ionization capacities can be distinguished. Similarly, α particles having a shorter range in a plastic scintillator and heavily charged particles having a shorter range than the α particles generate triplet excitons of correspondingly higher concentration, and the emission ratio of delayed light is further increased. Therefore, the decay speed of the pulse signal is ordered from slow to fast as: heavy charged particles > alpha particles > protons and fast neutrons > gamma rays and beta rays.

The on-line measuring system has the advantages that:

2. The on-line real-time measurement of the ray activity can be realized. The measurement range of the ray activity is extremely large, the lower limit of the activity detection is extremely small, and the upper limit of the activity detection is extremely high.

Firstly, due to the fact that the PSD plastic flashing array is used, the contact area of the liquid to be detected and the PSD plastic flashing is large enough, the number of rays entering the PSD plastic flashing in unit time is enough, and the radioactive liquid with low activity can ensure that enough rays enter a detector in unit time, so that the detection lower limit of the system is extremely low.

Secondly, the traditional measurement mode is to use a liquid flash method to measure the radioactivity in the liquid, firstly, a chemical method is used to remove the influence of interference rays, then, a single ray solution to be measured is prepared, then, the online measurement of the ray activity is carried out through the liquid flash method, then, the ray activity is very low, the single ray solution to be measured also needs to be concentrated, meanwhile, the measurement time required by the liquid flash method is long, and the real-time online measurement of the rays cannot be realized usually after the three days required by one measurement process. In the system, when rays are incident to the PSD plastic flashes, energy is deposited to generate scintillation light, the scintillation light propagates in the optical fiber and reaches the PMTs at two ends, the PMTs at the two ends can capture a corresponding number of scintillation photons at the same time, and the number of the scintillation photons captured by the PMTs at the two ends is related to the position of the energy deposited by the rays in the optical fiber. When the incident position is close to a certain PMT, the PMT captures a larger number of scintillation photons. The reason why the two PMTs are used for coincidence measurement is that the PMTs themselves have randomly generated dark current outputs, and the influence of dark current noise can be effectively eliminated by coincidence measurement. The PMT converts an optical signal into an electric signal, then the electric signal is amplified and formed and then input into the four-channel high-speed ADC, the ADC converts an analog signal into a digital signal and then transmits the digital signal to the FPGA at the rear end, and ray type identification and activity online measurement are realized in the FPGA.

And thirdly, because the pulse width of the PSD flash output signal is the minimum of all nuclear detectors and is only a few to tens of nanoseconds, the probability of overlapping between pulses in unit time is the minimum, and the activity range of the detected rays of the detection system is extremely large.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. The system is characterized by at least comprising a detector and an electronics processing unit;

the probe is of a double-cavity structure consisting of a first measuring cavity (102) and a second measuring cavity (103), the first measuring cavity (102) is of a columnar structure and is wrapped on the inner side of the second measuring cavity (103), and the first measuring cavity (102) and the second measuring cavity (103) are separated by a first shell (106);

a plurality of first PSD plastic flash fibers (104) are arranged in the first measurement cavity (102) along the axis direction of the cavity, a first photomultiplier and a second photomultiplier are respectively arranged at two ends of the first measurement cavity (102), two ends of each first PSD plastic flash fiber (104) are respectively connected with the first photomultiplier and the second photomultiplier, and when the first photomultiplier and the second photomultiplier receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition;

a plurality of second PSD plastic flash fibers (105) are arranged in the second measurement cavity (103) along the axis direction of the cavity, a third photomultiplier and a fourth photomultiplier are respectively arranged at two ends of the second measurement cavity (103), two ends of each second PSD plastic flash fiber (105) are respectively connected with the third photomultiplier and the fourth photomultiplier, and when the third photomultiplier and the fourth photomultiplier receive scintillation photons simultaneously, the electronic processing unit finishes primary signal acquisition;

the material to be measured is led into one end of the first measuring cavity (102) through the inlet (101) and led out through the outlet (109) arranged at the other end, the first measuring cavity (102) collects and identifies n, alpha, beta, gamma and heavy particle signals in the material to be measured, the second measuring cavity (103) collects and identifies n and gamma ray signals in the material to be measured, and the electronic processing unit collects scintillation light signals based on the detector to complete ray type identification and activity online measurement.

2. The on-line measuring system of claim 1, wherein the first housing (106) is made of an aluminum material.

3. The on-line measuring system of claim 2, characterized in that the first housing (106) is made of aluminum material, the first housing (106) having a thickness of 0.2 cm.

4. The on-line measuring system of claim 1, characterized in that the housing of the second measuring chamber (103) is a second housing (107), the second housing (107) being made of radiation shielding metal.

5. The on-line measuring system of claim 4, characterized in that the second housing (107) is made of lead material.

6. The on-line measuring system of claim 4, wherein a third housing (108) is further wrapped around the second housing (107), and the third housing (108) is made of plastic.

7. The on-line measurement system of claim 1, wherein the electronics processing unit comprises an ADC analog-to-digital conversion circuit, an FPGA operational circuit, and four amplifiers;

each photomultiplier is respectively connected with an ADC analog-to-digital conversion circuit through an amplifier, and the ADC analog-to-digital conversion circuit is connected with an FPGA arithmetic circuit;

the FPGA arithmetic circuit is used for finishing the identification of n, alpha, beta, gamma and heavy particle rays in the material and the on-line measurement of corresponding activity based on the output signal of the photomultiplier.

8. The on-line measuring system of claim 7, wherein the FPGA arithmetic circuit is used for performing gamma ray identification and corresponding activity on-line measurement based on the waveform obtained by each second PSD plastic flash fiber (105) in the second measuring cavity (103) when receiving radiation.

9. The on-line measuring system of claim 7, wherein the FPGA arithmetic circuit is used for completing the identification of alpha, n and heavy particle rays and the corresponding activity on-line measurement based on the waveform obtained by each first PSD plastic flash optical fiber (104) in the first measuring cavity (102) when the first PSD plastic flash optical fiber receives the irradiation of the rays.

10. The on-line measuring system of claim 8, wherein the FPGA arithmetic circuit is used for obtaining a beta/gamma ray waveform when receiving radiation based on each first PSD plastic flash fiber (104) in the first measuring cavity (102) and obtaining a gamma ray waveform when receiving radiation based on each second PSD plastic flash fiber (105) in the second measuring cavity (103), thereby completing the identification of beta particles and the corresponding activity on-line measurement.