CN116448798B - Positron annihilation life two-dimensional distribution measurement system - Google Patents
Positron annihilation life two-dimensional distribution measurement system Download PDFInfo
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- CN116448798B CN116448798B CN202310285340.2A CN202310285340A CN116448798B CN 116448798 B CN116448798 B CN 116448798B CN 202310285340 A CN202310285340 A CN 202310285340A CN 116448798 B CN116448798 B CN 116448798B
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- 238000009826 distribution Methods 0.000 title claims abstract description 29
- 238000005259 measurement Methods 0.000 title claims abstract description 23
- 238000001514 detection method Methods 0.000 claims abstract description 29
- 230000005855 radiation Effects 0.000 claims abstract description 19
- 238000012545 processing Methods 0.000 claims abstract description 17
- 238000006073 displacement reaction Methods 0.000 claims abstract description 10
- 230000007246 mechanism Effects 0.000 claims description 38
- 238000001228 spectrum Methods 0.000 claims description 25
- 230000002285 radioactive effect Effects 0.000 claims description 20
- 238000013519 translation Methods 0.000 claims description 15
- 230000007547 defect Effects 0.000 abstract description 10
- 238000010586 diagram Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 3
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229920003223 poly(pyromellitimide-1,4-diphenyl ether) Polymers 0.000 description 2
- 229910002601 GaN Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 230000002391 anti-complement effect Effects 0.000 description 1
- 108010008730 anticomplement Proteins 0.000 description 1
- 229910001632 barium fluoride Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention relates to the technical field of positron annihilation life, in particular to a positron annihilation life two-dimensional distribution measurement system. The invention discloses a positron annihilation life two-dimensional distribution measurement system which comprises an anti-coincidence module, a first detection module, a second detection module, a displacement module, a data acquisition module and a data processing module, wherein the anti-coincidence module is used for detecting the annihilation life of a positron annihilation source; the anti-coincidence module can make the size of a region of the positron which is beaten on the sample to be measured consistent with the size of an orifice of the radiation blind hole, can accurately obtain the service life information of the region of the sample to be measured, and further analyze the defect information of the region of the sample to be measured.
Description
Technical Field
The invention relates to the technical field of positron annihilation life, in particular to a positron annihilation life two-dimensional distribution measurement system.
Background
In all the microscopic defect characterization means of the material, a positron annihilation life spectrometer stands out by a unique high-precision time detection method. The method utilizes a positron injection material to detect gamma photons generated by positron annihilation, and can analyze life information of the positron annihilation so as to obtain related information of material defects.
Positron annihilation lifetime measurement is generally performed by 22 Na is used as a positive electron source and is used as a negative electron source, 22 na decays almost simultaneously to produce gamma photons with energy of 1.275 MeV and positrons with energy of 0-0.545 MeV, the former acts as a starting signal, the latter annihilates with electrons in the material to produce a pair of gamma photons with energy of 0.511 MeV as an ending signal, and then the time difference of the two signals is counted to obtain positron annihilation lifetime spectrum.
A conventional positron annihilation lifetime spectrometer is composed of a scintillator detector and various NIM standard electronics modules (including constant ratio timing discriminators, time-to-amplitude converters, amplifiers and multi-channel analyzers). The two scintillator detectors are used as a start detector and a stop detector for measuring a start signal and a stop signal respectively.
The two paths of signals respectively pass through constant ratio timing discriminators with different threshold ranges, output two paths of pulses with time information, then are converted into pulses with amplitude associated with time through a time-amplitude converter, and finally pass through a multi-channel analyzer to obtain positron annihilation life spectrums. The positron annihilation lifetime spectrum can analyze the information of the size, concentration and the like of the internal defects of the material.
In the traditional positron annihilation life spectrometer measurement process, a sandwich structure of a sample to be measured, a radioactive source and the sample to be measured is generally adopted, and the radioactive source is generally wrapped by a Kapton film 22 In the Na radioactive source, since positrons also enter a Kapton film in the process of measuring the positron annihilation lifetime spectrum of a sample to be measured, the lifetime of the portion is called as a source component, in order to remove the source component, a sandwich structure of a standard sample, the radioactive source and the standard sample is generally adopted to measure the source component, and the lifetime of the standard sample is known (yttrium doped zirconia or gallium nitride monocrystal is generally adopted). Therefore, the traditional positron annihilation life spectrometer can only obtain the defect information of the whole sample to be detected, and cannot obtain the two-dimensional distribution of the defect information of the sample to be detected.
Therefore, the existing sample positron annihilation life two-dimensional distribution measurement system adopts a sandwich structure of a standard sample, a radioactive source and a sample to be measured. Because positrons generated by decay of a radioactive source are emitted in a 4 pi solid angle, the size of a region where positrons are injected into a sample to be detected cannot be accurately controlled by the conventional system, the position resolution of two-dimensional distribution of positron annihilation life is not controlled, and meanwhile, the positron annihilation life spectrum of a standard sample is required to be removed for obtaining the positron annihilation life spectrum of the sample to be detected, so that a certain interference is generated on a measured result.
Disclosure of Invention
In order to solve the problems, the invention provides a positron annihilation life two-dimensional distribution measuring system which is used for accurately measuring positron annihilation lives of different areas of a two-dimensional plane of a sample to be measured.
The specific technical scheme of the invention is as follows: the positron annihilation life two-dimensional distribution measurement system comprises an anti-coincidence module, a first detection module, a second detection module, a displacement module, a data acquisition module and a data processing module;
the anti-coincidence module comprises a first detector 1, wherein the lower end of the first detector 1 is connected with a first lead 11, the upper end of the first detector 1 is coupled with a thin plastic scintillator 12, the middle part of the thin plastic scintillator 12 is provided with a radiation blind hole 13 for placing a radiation source, and the anti-coincidence module is used for detecting positron signals generated by decay of the radiation source;
the first detection module comprises a second detector 2, the upper end of the second detector 2 is connected with a second lead 21, the lower end of the second detector 2 is coupled with a first scintillator 22, and the first detection module is used for detecting an initial gamma photon signal generated by decay of a radioactive source;
the second detection module comprises a third detector 3, the upper end of the third detector 3 is connected with a third conducting wire 31, the lower end of the third detector 3 is coupled with a second scintillator 32, and the second detection module is used for detecting a termination gamma photon signal generated by positron annihilation;
the first lead 11, the second lead 21 and the third lead 31 are respectively connected with the input end of the data acquisition module, and the output end of the data acquisition module is connected with the data processing module;
the displacement module comprises a plane moving mechanism, a clamping and fixing mechanism and a square bottom plate 5, wherein the plane moving mechanism and the clamping and fixing mechanism are respectively fixed at two ends of the square bottom plate 5, and the plane moving mechanism is used for adjusting the translation of the sample 4 to be measured in the x and y directions of a plane so that the radioactive source can be sequentially covered on the whole area of the sample 4 to be measured;
the clamping mechanism is used for clamping and fixing the first detector 1, the second detector 2 and the third detector 3;
when the anti-coincidence module does not detect positron signals generated by decay of the radioactive source, namely the annihilation of the positrons in the sample 4 to be detected is indicated, the first detection module detects initial gamma photon signals generated by decay of the radioactive source, the second detection module detects end gamma photon signals generated by the annihilation of the positrons, the data acquisition module acquires time difference signals of the initial gamma photon signals and the end gamma photon signals to obtain positron annihilation life spectrums of measurement areas of the sample 4 to be detected, the positron annihilation life spectrums of all areas of the sample 4 to be detected are sequentially obtained through the displacement module, and the two-dimensional distribution of the positron annihilation life and the intensity of the positron annihilation life spectrums of the sample 4 to be detected is obtained through the resolution of the data processing module.
Further, the data acquisition module comprises a data acquisition card, and the data processing module comprises a computer.
Further, the planar movement mechanism includes a first translation mechanism, a second translation mechanism, and a connecting rod 56;
the first translation mechanism comprises a pair of opposite plates 51, a pair of first guide rods 52, a first screw 53, a first stepping motor 54 and a first sliding block 55;
a pair of opposite plates 51 are arranged on the square bottom plate 5 at intervals in parallel, a pair of first guide rods 52 and a first screw rod 53 are horizontally and fixedly arranged between the pair of opposite plates 51, the first screw rod 53 is positioned between the pair of opposite plates 51, one end of the first screw rod 53 is connected with a motor shaft of a first stepping motor 54, and the pair of first guide rods 52 and the first screw rod 53 horizontally penetrate through a first sliding block 55 so that the first sliding block 55 translates along the arrangement direction of the first guide rods;
the second translation mechanism comprises a second guide rod 57, a second screw rod 58, a second stepping motor 59 and a second sliding block 510, wherein one end of the second guide rod 57 is fixedly connected with the first sliding block 55, so that the second guide rod 57 is horizontally arranged perpendicular to the first guide rod, the second screw rod 58 penetrates through the second sliding block 510, one end of the second screw rod 58 is connected with a motor shaft of the second stepping motor 59, and the second guide rod 57 and the second screw rod 58 horizontally penetrate through the second sliding block 510, so that the second sliding block 510 translates along the arrangement direction of the second guide rod 57;
one end of the connecting rod 56 is fixed on the second slider 510, and is horizontally arranged parallel to the first guide rod, and the other end of the connecting rod 56 clamps and fixes the sample 4 to be measured through the clamp 41.
Further, the clamp 41 is in an inverted U shape, the bottom plate of the U shape is fixedly connected with the overhanging end of the connecting rod 56, a screwing bolt is inserted on the lower side plate of the U shape, and one side of the sample 4 to be tested is located between the opening bars of the U shape and is clamped and fixed through the screwing bolt.
Further, the clamping and fixing mechanism comprises 3 fixing rods 61 vertically fixed at the upper end of the square bottom plate 5, each fixing rod 61 is provided with a hoop 62, and the first detector 1, the second detector 2 and the third detector 3 are all cylindrical and are fixed on the corresponding fixing rod 61 through the hoops 62; such that the first scintillator 22 and the second scintillator 32 are located correspondingly above the sample 4 to be measured, and the thin plastic scintillator 12 is located correspondingly below the sample 4 to be measured.
Further, the radioactive source is 22 Na radiation source, and the intensity is below 1 mCi.
Further, the depth of the radiation blind holes 13 in the thin plastic scintillator 12 is 1-4 mm.
The beneficial technical effects of the invention are as follows:
(1) The two-dimensional distribution measuring system for positron annihilation life comprises an anticomplement module, a first detection module, a second detection module, a displacement module, a data acquisition module and a data processing module;
the anti-coincidence module can make the size of the positron striking the region of the sample to be detected consistent with the size of the orifice of the radiation blind hole, so that the positron annihilation life spectrum of the region of the sample to be detected can be accurately obtained;
then, a plane moving mechanism is used for controlling the sample to be measured to move once on a two-dimensional plane at intervals (for example, the time for measuring the positron annihilation lifetime spectrum of a region is 4 hours); according to the size of the sample to be detected and the size of the radiation blind hole, moving for a plurality of times to obtain positron annihilation life spectrums of all regions of the sample to be detected, carrying out spectrum decomposition on the positron annihilation life spectrums of different regions to obtain two-dimensional distribution of positron annihilation life and intensity of the positron annihilation life spectrums of different regions of the sample to be detected;
meanwhile, the size of the emission blind hole in the thin plastic scintillator can be changed to control the size of the area where positrons are emitted into a sample to be detected, so that the two-dimensional distribution of positron annihilation life and intensity under different position resolutions is obtained.
(2) According to the invention, the structure of the sample to be detected, the radioactive source and the thin plastic scintillator is adopted, and when the anti-coincidence module does not detect positron signals generated by decay of the radioactive source, the positron annihilation in the sample to be detected is indicated, so that annihilation signals of the positron in the thin plastic scintillator can be removed, and the finally obtained positron annihilation life spectrum only contains life information of the sample to be detected and has no life information interference of a standard sample.
Drawings
Fig. 1 is a system block diagram of a positron annihilation lifetime two-dimensional distribution measurement system of the present invention.
Fig. 2 is a schematic structural diagram of a positron annihilation lifetime two-dimensional distribution measurement system according to the present invention.
Fig. 3 is a schematic structural diagram of the anti-coincidence module of the present invention.
FIG. 4 is a schematic view of the structure of the sample holder, the connection and the second slider according to the present invention.
Fig. 5 is a schematic structural diagram of the initial state of the positron annihilation lifetime two-dimensional distribution measurement system of the present invention.
Fig. 6 is a schematic diagram showing the structure of the end state of the positron annihilation lifetime two-dimensional distribution measurement system according to the present invention.
Fig. 7 is a positron annihilation lifetime spectrum measured by a positron annihilation lifetime two-dimensional distribution measurement system of the present invention.
Wherein: the first detector 1, the first lead 11, the thin plastic scintillator 12, the radiation blind hole 13, the second detector 2, the second lead 21, the first scintillator 22, the third detector 3, the third lead 31, the second scintillator 32, the square bottom plate 5, the sample 4 to be measured, the connecting rod 56, the pair of plates 51, the pair of first guide rods 52, the first screw 53, the first stepping motor 54, the first slider 55, the second guide rod 57, the second screw 58, the second stepping motor 59, the second slider 510, the clamp 41, the fixing rod 61, and the anchor ear 62.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the detailed description is presented by way of example only and is not intended to limit the invention.
Examples
Referring to fig. 1 and 2, a positron annihilation lifetime two-dimensional distribution measurement system includes an anti-coincidence module, a first detection module, a second detection module, a displacement module, a data acquisition module and a data processing module;
referring to fig. 3, the anti-coincidence module is used for detecting positron signals and comprises a first detector 1, the lower end of the first detector 1 is connected with a first lead 11, the upper end of the first detector 1 is coupled with a thin plastic scintillator 12, and the middle part of the thin plastic scintillator 12 is provided with a radiation blind hole 13 for placing a radiation source; the radioactive source is 22 Na radiation source, the intensity is below 1 mCi, and the depth of the radiation blind hole 13 on the thin plastic scintillator 12 is 1-4 mm.
The sample 4 to be measured is closely attached to the thin plastic scintillator 12, and when positrons generated by decay of the radioactive source enter the thin plastic scintillator 12, signals are generated, and whether positrons are annihilated in the sample 4 to be measured can be distinguished by the signals of the thin plastic scintillator 12 (i.e. if annihilated in the sample 4 to be measured, the thin plastic scintillator 12 has no signals).
The diameter of the first detector 1 is 20 mm-50 mm, the diameter of the thin plastic scintillator 12 is 20 mm-50 mm, and the thickness is 5 mm.
The first detection module comprises a second detector 2, the upper end of the second detector 2 is connected with a second conducting wire 21, the lower end of the second detector 2 is coupled with a first scintillator 22, and gamma photons of 1.275 MeV generated by annihilation of positrons in a sample 4 to be detected are detected.
The second detection module comprises a third detector 3, the upper end of the third detector 3 is connected with a third wire 31, and the lower end of the third detector 3 is coupled with a second scintillator 32; gamma photons of 0.511 MeV generated by annihilation of positrons in the sample 4 to be measured are detected.
The displacement module comprises a plane moving mechanism, a clamping and fixing mechanism and a square bottom plate 5, wherein the plane moving mechanism and the clamping and fixing mechanism are respectively fixed at two ends of the square bottom plate 5, the plane moving mechanism is used for adjusting translation of a sample 4 to be measured in the x and y directions of a plane, the clamping mechanism is used for clamping and fixing a first detector 1, a second detector 2 and a third detector 3, so that positrons generated by radioactive source decay are emitted to the sample 4 to be measured, the first detection module detects an initial gamma photon signal, the second detection module detects a termination gamma photon signal on the premise that the reflection coincidence module does not detect a positrons signal, the data acquisition module acquires signal data and processes the signal data through the data processing module, positron annihilation life spectrums of all areas of the sample 4 to be measured are obtained firstly, and defect distribution of different areas of the sample 4 to be measured is obtained through analysis of the data processing module.
The data acquisition module comprises a data acquisition card, and the data processing module comprises a computer.
Referring to fig. 2, 5 and 6, the planar movement mechanism includes a first translation mechanism, a second translation mechanism and a connecting rod 56;
the first translation mechanism comprises a pair of opposite plates 51, a pair of first guide rods 52, a first screw rod 53, a first stepping motor 54 and a first sliding block 55, wherein the opposite plates 51 are arranged on the square bottom plate 5 at intervals in parallel, the pair of first guide rods 52 and the first screw rod 53 are horizontally and fixedly arranged between the pair of opposite plates 51, the first screw rod 53 is positioned between the pair of opposite plates 51, one end of the first screw rod 53 is connected with a motor shaft of the first stepping motor 54, and the pair of first guide rods 52 and the first screw rod 53 horizontally penetrate through the first sliding block 55 so that the first sliding block 55 translates along the arrangement direction of the first guide rods;
the second translation mechanism comprises a second guide rod 57, a second screw rod 58, a second stepping motor 59 and a second sliding block 510, wherein one end of the second guide rod 57 is fixedly connected with the first sliding block 55, so that the second guide rod 57 is horizontally arranged perpendicular to the first guide rod, the second screw rod 58 penetrates through the second sliding block 510, one end of the second screw rod 58 is connected with a motor shaft of the second stepping motor 59, and the second guide rod 57 and the second screw rod 58 horizontally penetrate through the second sliding block 510, so that the second sliding block 510 translates along the arrangement direction of the second guide rod 57;
one end of the connecting rod 56 is fixed on the second slider 510, and is horizontally arranged parallel to the first guide rod, and the other end of the connecting rod 56 clamps and fixes the sample 4 to be measured through the clamp 41.
Referring to fig. 3, the clamp 41 is in an inverted U shape, the bottom plate of the U shape is fixedly connected with the overhanging end of the connecting rod 56, a tightening bolt is inserted on the lower side plate of the U shape, and one side of the sample 4 to be tested is located between the opening bars of the U shape and is clamped and fixed by the tightening bolt.
The clamping and fixing mechanism comprises 3 fixing rods 61 vertically fixed at the upper end of the square bottom plate 5, each fixing rod 61 is provided with a hoop 62, and the first detector 1, the second detector 2 and the third detector 3 are all cylindrical and are fixed on the corresponding fixing rod 61 through the hoops 62; such that the first scintillator 22 and the second scintillator 32 are located correspondingly above the sample 4 to be measured, and the thin plastic scintillator 12 is located correspondingly below the sample 4 to be measured.
The first scintillator 22 and the second scintillator 32 may be selected from a crystal such as BaF2, laBr3, or LYSO, and the first detector 1, the second detector 2, and the third detector 3 may be selected from a photomultiplier tube, a silicon photomultiplier tube, or the like.
Referring to fig. 1, the first conductive wire 11, the second conductive wire 21 and the third conductive wire 31 are respectively connected with the input end of the data acquisition module, and the output end of the data acquisition module is connected with the data processing module;
and in a certain coincidence time window (100 ns), when the anti-coincidence module does not detect the positron signals and the first detection module and the second detection module detect the initial gamma photon signals and the termination gamma photon signals respectively, indicating a valid coincidence event, wherein the event is recorded by the data processing module according to a preset data format.
The time difference between the starting gamma photon signal and the ending gamma photon signal is determined by the effective coincidence event through a constant ratio timing method, and the positron annihilation life spectrum of the measurement area of the sample 4 to be measured can be obtained by counting the time difference of a large number of effective coincidence events, as shown in fig. 7.
As shown in fig. 5 and 6, the sample 4 to be measured is controlled to move once on the two-dimensional plane at intervals (for example, the time for measuring a positron annihilation lifetime spectrum of a region is 4 hours) by a plane moving mechanism; and (3) moving for a plurality of times according to the size of the sample 4 to be detected and the size of the radiation blind hole 13 to obtain the positron annihilation life spectrum of the whole area of the sample 4 to be detected.
The positron annihilation lifetime spectrum shown in fig. 7 is resolved (completed in a data processing module), and software such as lifetime9, patfit88, melt and the like can be used for resolving the positron annihilation lifetime spectrum to obtain two-dimensional distributions of positron annihilation lifetimes and intensities of the positron annihilation lifetimes in different areas of the sample 4 to be detected, defect distributions in different areas of the sample 4 to be detected can be obtained through further analysis, the size of the positron annihilation lifetime can generally reflect size information of defects of the sample 4 to be detected, and the size of the positron annihilation lifetime intensity can generally reflect concentration information of the defects of the sample 4 to be detected.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (5)
1. A positron annihilation life two-dimensional distribution measurement system is characterized in that: the device comprises an anti-coincidence module, a first detection module, a second detection module, a displacement module, a data acquisition module and a data processing module;
the anti-coincidence module comprises a first detector (1), wherein the lower end of the first detector (1) is connected with a first lead (11), the upper end of the first detector (1) is coupled with a thin plastic scintillator (12), the middle part of the thin plastic scintillator (12) is provided with a radiation blind hole (13) for placing a radiation source, and the anti-coincidence module is used for detecting positron signals generated by decay of the radiation source;
the first detection module comprises a second detector (2), the upper end of the second detector (2) is connected with a second wire (21), the lower end of the second detector (2) is coupled with a first scintillator (22), and the first detection module is used for detecting an initial gamma photon signal generated by decay of a radioactive source;
the second detection module comprises a third detector (3), the upper end of the third detector (3) is connected with a third conducting wire (31), the lower end of the third detector (3) is coupled with a second scintillator (32), and the second detection module is used for detecting a termination gamma photon signal generated by positron annihilation;
the first lead (11), the second lead (21) and the third lead (31) are respectively connected with the input end of the data acquisition module, and the output end of the data acquisition module is connected with the data processing module;
the displacement module comprises a plane moving mechanism, a clamping and fixing mechanism and a square bottom plate (5), wherein the plane moving mechanism and the clamping and fixing mechanism are respectively fixed at two ends of the square bottom plate (5), and the plane moving mechanism is used for adjusting the translation of a sample (4) to be measured in the x and y directions of a plane so that a radiation source can be sequentially covered on the whole area of the sample (4) to be measured;
the clamping mechanism is used for clamping and fixing the first detector (1), the second detector (2) and the third detector (3);
when the anti-coincidence module does not detect positron signals generated by decay of a radioactive source, namely, the annihilation of positrons in a sample (4) to be detected is indicated, on the basis, a first detection module detects initial gamma photon signals generated by decay of the radioactive source, a second detection module detects end gamma photon signals generated by the annihilation of positrons, a data acquisition module acquires time difference signals of the initial gamma photon signals and the end gamma photon signals, so that positron annihilation life spectrums of measurement areas of the sample (4) to be detected are obtained, positron annihilation life spectrums of all areas of the sample (4) to be detected are sequentially obtained through a displacement module, and two-dimensional distribution of positron annihilation life and intensity of the sample (4) to be detected is obtained through the resolution of a data processing module;
the clamping and fixing mechanism comprises 3 fixing rods (61) vertically fixed at the upper end of the square bottom plate (5), each fixing rod (61) is provided with a hoop (62), and the first detector (1), the second detector (2) and the third detector (3) are all cylindrical and are fixed on the corresponding fixing rod (61) through the hoops (62); so that the first scintillator (22) and the second scintillator (32) are correspondingly positioned above the sample (4) to be tested, and the thin plastic scintillator (12) is correspondingly positioned below the sample (4) to be tested;
the planar movement mechanism comprises a first translation mechanism, a second translation mechanism and a connecting rod (56);
the first translation mechanism comprises a pair of plates (51), a pair of first guide rods (52), a first screw (53), a first stepping motor (54) and a first sliding block (55),
the pair of opposite plates (51) are arranged on the square bottom plate (5) at intervals in parallel, a pair of first guide rods (52) and first screw rods (53) are horizontally and fixedly arranged between the pair of opposite plates (51), the first screw rods (53) are positioned between the pair of opposite plates (51), one ends of the first screw rods (53) are connected with a motor shaft of a first stepping motor (54), and the pair of first guide rods (52) and the first screw rods (53) horizontally penetrate through a first sliding block (55) so that the first sliding block (55) can translate along the arrangement direction of the first guide rods;
the second translation mechanism comprises a second guide rod (57), a second screw rod (58), a second stepping motor (59) and a second sliding block (510), one end of the second guide rod (57) is fixedly connected with the first sliding block (55) so that the second guide rod (57) is horizontally arranged perpendicular to the first guide rod, the second screw rod (58) penetrates through the second sliding block (510), one end of the second screw rod is connected with a motor shaft of the second stepping motor (59), the second guide rod (57) and the second screw rod (58) horizontally penetrate through the second sliding block (510), and the second sliding block (510) can translate along the arrangement direction of the second guide rod (57);
one end of the connecting rod (56) is fixed on the second sliding block (510) and is horizontally arranged parallel to the first guide rod, and the other end of the connecting rod (56) is clamped and fixed with the sample (4) to be measured through the clamp (41).
2. The positron annihilation lifetime two-dimensional distribution measurement system of claim 1, wherein: the data acquisition module comprises a data acquisition card, and the data processing module comprises a computer.
3. The positron annihilation lifetime two-dimensional distribution measurement system of claim 1, wherein: the fixture (41) is of an inverted U shape, the bottom plate of the U shape is fixedly connected with the overhanging end of the connecting rod (56), a screwing bolt is inserted on the lower side plate of the U shape, one side of the sample (4) to be tested is positioned between the opening of the U shape, and the sample is clamped and fixed through the screwing bolt.
4. The positron annihilation lifetime two-dimensional distribution measurement system of claim 1, wherein: the radioactive source is 22 Na radiation source, and the intensity is below 1 mCi.
5. The positron annihilation lifetime two-dimensional distribution measurement system of claim 1, wherein: the depth of the radial blind holes (13) on the thin plastic scintillator (12) is 1-4 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310285340.2A CN116448798B (en) | 2023-03-22 | 2023-03-22 | Positron annihilation life two-dimensional distribution measurement system |
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