阅读说明：本技术 一种具有透镜组的掺铊碘化铯闪烁晶体辐射探测器 (Thallium-doped cesium iodide scintillation crystal radiation detector with lens group ) 是由 魏海清 于 2019-11-30 设计创作，主要内容包括：本发明涉及一种具有透镜组的闪烁晶体辐射探测器,构建了相匹配的广角度和大景深透镜组,增加了光传感器对闪烁光的收集效率并提高了能量分辨率,其具体的参数设计考虑了与闪烁晶体本身的出射波段的匹配,能够增加对闪烁光进行聚焦收集后入射光传感器,提高了能量分辨率,相应提高了测量效率和测量精度,尤其是在研制高性能探测器时能够进一步提高探测性能。(The invention relates to a scintillation crystal radiation detector with a lens group, which constructs the lens group with wide angle and large depth of field which are matched, increases the collection efficiency of a light sensor to scintillation light and improves energy resolution, takes the matching of the specific parameter design into consideration with the emergent wave band of a scintillation crystal, can increase an incident light sensor for focusing and collecting the scintillation light, improves the energy resolution, correspondingly improves the measurement efficiency and the measurement precision, and can further improve the detection performance particularly when a high-performance detector is developed.)

1. The utility model provides a scintillation crystal radiation detector with lens group, includes scintillation crystal, photosensor, preamplification circuit and multichannel analysis appearance, and the scintillation crystal surface is provided with reflector layer and antireflection layer, and the reflector layer sets up on the surface except scintillation light emergent face, and the antireflection layer sets up at scintillation light emergent face, the scintillation crystal is thallium-doped cesium iodide crystal, and scintillation crystal and photosensor setting are provided with multichannel analysis appearance, its characterized in that outside the casing: and a lens group matched with the wave band of the scintillation light of the thallium-doped cesium iodide crystal is arranged between the scintillation light emergent surface and the optical sensor.

2. The radiation detector of claim 1, wherein: the optical axis of the lens group coincides with the central axis of the light receiving surface of the optical sensor, the lens group sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens along the emergent direction of the scintillation light, the surfaces of two sides of each lens are aspheric surfaces, and the following aspheric surface equation is satisfied:

y＝(x²/R)/（1+（1－(k+1) (x²/R²)）^1/2+A4x⁴+A6x⁶+A8x⁸+A10x¹⁰+A12x¹²+A14x¹⁴+A16x¹⁶，

wherein R is a radius of curvature (length in mm in absolute value) on the central axis, k is a conic coefficient, A4, A6, A8, A10, A12, A14, A16 are aspherical coefficients,

the values are as follows:

lens surface R k A4 A6 A8 A10 A12 A14 A16 1-R 1.20 1.56E+00 5.22E-02 4.54E-02 -2.40E-01 5.92E-01 -8.05E-01 4.85E-01 -1.02E-01 1-L 7.30 4.53E+01 -9.21E-02 2.48E-02 1.80E-01 -4.11E-01 1.83E-01 1.59E-01 -1.03E-01 2-R 26.20 7.61E+01 -1.38E-01 2.87E-01 -1.59E-01 -5.42E-02 -1.20E-01 4.41E-01 -2.13E-01 2-L 3.66 -2.53E+00 -8.93E-02 2.56E-01 -1.46E-01 -1.27E-01 2.45E-01 -2.27E-02 -4.73E-02 3-R 6.72 -3.60E+01 -6.94E-02 1.33E-03 -8.58E-02 9.99E-02 2.59E-02 -9.67E-02 2.73E-02 3-L -8.27 1.92E+01 -3.33E-02 -5.54E-02 -1.16E-01 1.60E-01 -1.19E-01 4.80E-03 5.81E-03 4-R -1.42 -1.18E+01 -4.75E-02 8.44E-02 -4.30E-01 4.76E-01 -4.80E-01 3.60E-01 -2.33E-01 4-L -2.03 1.79E+00 -1.80E-02 -3.17E-02 5.86E-02 -9.50E-02 6.66E-02 -4.49E-02 1.93E-02 5-R 3.72 -1.42E+01 -2.65E-01 2.91E-02 -6.39E-03 -8.37E-03 6.81E-03 7.89E-03 -4.39E-03 5-L -3.24 -6.69E+01 -2.67E-02 -3.26E-02 1.89E-02 -3.66E-03 1.74E-03 -6.04E-04 -7.50E-06 6-R -1.42 -2.74E+00 3.66E-02 -1.81E+02 6.89E-03 -6.90E-04 -1.40E-04 -1.34E-05 7.58E-06 6-L 5.20 -8.59E+01 -2.86E-02 -9.44E-03 5.54E-03 -1.30E-03 2.07E-04 -3.04E-05 2.31E-06

Wherein N-R in the lens surface column represents an object side surface of the Nth lens and N-L represents an image side surface of the Nth lens.

3. The radiation detector of claim 1, wherein: the light sensor is a silicon photomultiplier.

4. The radiation detector of claim 1, wherein: the focal lengths of the first lens, the second lens, the third lens and the fourth lens are respectively 2.68mm, -6.80mm, 7.16mm, -8.68mm, 3.37mm and-2.14 mm.

5. The radiation detector of claim 1, wherein: the thicknesses of the first lens, the second lens, the third lens and the fourth lens are respectively 0.53mm, 0.21mm, 0.33mm, 0.21mm, 0.29mm and 0.33 mm.

Technical Field

The present invention relates to the measurement of nuclear or X-ray radiation, and in particular to the measurement of X-ray radiation, gamma-ray radiation, corpuscular radiation or cosmic radiation, and in particular to scintillation detectors in which the scintillator is a crystal in the measurement of the intensity of the radiation.

Background

Radiation measurement has played an important role in many fields, such as nuclear power plant and thermal power plant radiation measurement, continuous measurement of radiation dose at a measurement site; the radiation measurement is widely applied to radioactive places such as radioactivity monitoring, industrial nondestructive inspection, hospital treatment and diagnosis, isotope application, waste recovery and the like, the radiation measurement monitors radiation to prevent radiation from generating harm on one hand, and plays a role in monitoring and calculating diagnosis and treatment on the other hand.

Radiation detection is the most fundamental research field of radiation measurement, the basic principle of radiation detectors is that radiation detection is performed by using an ionization excitation effect or other physical or chemical changes caused by radiation in gas, liquid or solid, the known types of detectors include gas detectors, scintillation detectors and semiconductor detectors, the gas detectors are complex in structure and the semiconductor detectors are not ideal in detection efficiency, the scintillation detectors are the most commonly used detectors at present, the scintillation detectors are strictly classified into liquid scintillation detectors and solid scintillation detectors, the liquid scintillation detectors are much less portable than the solid scintillation detectors, and the liquid scintillation detectors are basically used for laboratory research, and the solid detectors for measuring radiation by using scintillation crystals are the most researched detector types in the field.

A typical structure of a conventional scintillation crystal radiation measuring apparatus is shown in fig. 1, in which a scintillation crystal is used as a detection crystal, a reflective layer is disposed on a surface facing an emission source and around the surface, and the remaining surface is an excited light emitting surface, and the excited light emitting surface is connected to a photosensor (typically, a photomultiplier tube, for example) through an optical coupling structure, and the photosensor photomultiplier tube is respectively connected to a high voltage divider and a preamplifier; the input high voltage is loaded on the photomultiplier through the high voltage divider, and the output signal is processed by the preamplifier, the linear amplifier and the multi-channel analyzer in sequence to form the final output signal. Such detectors using scintillation crystals have also been well studied by those skilled in the art because of their ease of use and simplicity of construction to provide the most widely used detectors.

At present, how to further improve the energy resolution and the time resolution of the detector is a technical bottleneck for developing a high-performance detector.

In order to further improve the performance of the detector, the applicant's technical team develops an external light guide idea in a creative way, the conventional technical idea usually does not aim at the light path between the scintillation light emitting surface of the crystal and the light sensor, and usually focuses on how to avoid the damage of rays to the light sensor, and the light path needs to be changed, or when the light is connected by using an optical fiber, a corresponding lens is arranged for transmitting light to the optical fiber so as to perform light guiding and focusing, and a corresponding lens unit is arranged when imaging is needed. As is well known, the design of a lens assembly with multiple lens combinations is very complex, and a technical bias lies in that, in general, a person skilled in the art considers that designing a lens assembly for improving the corresponding efficiency of a detector in a limited space is irrevocable, even if the lens assembly is improved and arranged in a few existing technologies, only a simple description is provided, and no practical lens assembly design parameters are given, so that the applicant team can find several groups of lens assembly design schemes (planning multiple groups of patent layouts on research results) which break through the conventional effect and are applicable to a detector system in a large amount of irregular experimental data and form a detection system on the basis of the lens assembly design schemes, wherein the scheme is a detection system based on one of the design schemes, and other schemes are filed for another application.

It should be noted that, after more than three years of research in this field, the technical team of the applicant has arrived at a plurality of technical achievements, and in order to avoid the prior art that may become the later application or the conflicting application, the technical achievements are purposely proposed to be applied on the same day and combined with different techniques to form a patent layout, the prior art mentioned in the corresponding background art is not necessarily the one that has been disclosed to the public, and some of the prior art that is not disclosed when the technical team of the applicant researches the corresponding technique, so neither the prior art mentioned in the background art nor the claimed prior art can be taken as the evidence that the related art has been known to the public, and can not be the evidence of common knowledge.

Disclosure of Invention

In view of the problems and bottlenecks of the prior art, the invention provides a scintillation crystal radiation detector with a lens set, and mainly aims to provide a structure capable of further improving the light collection rate when a high-performance radiation detector is developed so as to improve the detection efficiency and precision.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the utility model provides a scintillation crystal radiation detector with lens group, includes scintillation crystal, photosensor, preamplification circuit and multichannel analysis appearance, and the scintillation crystal surface is provided with reflector layer and antireflection layer, and the reflector layer sets up on the surface except scintillation light emergent face, and the antireflection layer sets up at scintillation light emergent face, the scintillation crystal is thallium-doped cesium iodide crystal, and scintillation crystal and photosensor setting are provided with multichannel analysis appearance, its characterized in that outside the casing: a lens group matched with the wave band of the scintillation light of the thallium-doped cesium iodide crystal is arranged between the scintillation light emergent surface and the optical sensor;

further, the optical axis of the lens group coincides with the central axis of the light receiving surface of the optical sensor, the lens group sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens along the scintillation light emergence direction, the two side surfaces of each lens are aspheric surfaces, and the following aspheric surface equation is satisfied:

y＝(x²/R)/（1+（1－(k+1) (x²/R²)）^1/2+A4x⁴+A6x⁶+A8x⁸+A10x¹⁰+A12x¹²+A14x¹⁴+A16x¹⁶，

wherein R is a radius of curvature (length in mm in absolute value) on the central axis, k is a conic coefficient, A4, A6, A8, A10, A12, A14, A16 are aspherical coefficients,

the values are as follows:

lens surface

R

k

A4

A6

A8

A10

A12

A14

A16

1-R

1.20

1.56E+00

5.22E-02

4.54E-02

-2.40E-01

5.92E-01

-8.05E-01

4.85E-01

-1.02E-01

1-L

7.30

4.53E+01

-9.21E-02

2.48E-02

1.80E-01

-4.11E-01

1.83E-01

1.59E-01

-1.03E-01

2-R

26.20

7.61E+01

-1.38E-01

2.87E-01

-1.59E-01

-5.42E-02

-1.20E-01

4.41E-01

-2.13E-01

2-L

3.66

-2.53E+00

-8.93E-02

2.56E-01

-1.46E-01

-1.27E-01

2.45E-01

-2.27E-02

-4.73E-02

3-R

6.72

-3.60E+01

-6.94E-02

1.33E-03

-8.58E-02

9.99E-02

2.59E-02

-9.67E-02

2.73E-02

3-L

-8.27

1.92E+01

-3.33E-02

-5.54E-02

-1.16E-01

1.60E-01

-1.19E-01

4.80E-03

5.81E-03

4-R

-1.42

-1.18E+01

-4.75E-02

8.44E-02

-4.30E-01

4.76E-01

-4.80E-01

3.60E-01

-2.33E-01

4-L

-2.03

1.79E+00

-1.80E-02

-3.17E-02

5.86E-02

-9.50E-02

6.66E-02

-4.49E-02

1.93E-02

5-R

3.72

-1.42E+01

-2.65E-01

2.91E-02

-6.39E-03

-8.37E-03

6.81E-03

7.89E-03

-4.39E-03

5-L

-3.24

-6.69E+01

-2.67E-02

-3.26E-02

1.89E-02

-3.66E-03

1.74E-03

-6.04E-04

-7.50E-06

6-R

-1.42

-2.74E+00

3.66E-02

-1.81E+02

6.89E-03

-6.90E-04

-1.40E-04

-1.34E-05

7.58E-06

6-L

5.20

-8.59E+01

-2.86E-02

-9.44E-03

5.54E-03

-1.30E-03

2.07E-04

-3.04E-05

2.31E-06

Wherein N-R columns in the lens surface columns represent the object side surface of the Nth lens, and N-L represents the image side surface of the Nth lens;

further, the light sensor is a silicon photomultiplier;

further, the focal lengths of the first to sixth lenses are respectively 2.68mm, -6.80mm, 7.16mm, -8.68mm, 3.37mm and-2.14 mm;

further, the thicknesses of the first to sixth lenses are respectively: 0.53mm, 0.21mm, 0.33mm, 0.21mm, 0.29mm, 0.33 mm.

Compared with the prior art, the invention has the advantages that:

the invention breaks through the traditional technical thought, overcomes the inherent defects that the data volume is overlarge and difficult to select and optimize when the lens group is designed aiming at the main emergent wave band of the scintillation crystal, constructs the matched wide-angle and large-depth-of-field lens group, increases the collection efficiency of the optical sensor to the scintillation light and improves the energy resolution, and the specific parameter design considers the matching with the emergent wave band of the scintillation crystal, can increase the incident light sensor after focusing and collecting the scintillation light, improves the energy resolution, correspondingly improves the measurement efficiency and the measurement precision, and particularly can further improve the detection performance when developing a high-performance detector.

Drawings

FIG. 1 is a schematic diagram of a prior art radiation detector;

FIG. 2 is a schematic view of a radiation detector of the present invention;

FIG. 3 is a schematic view of a lens stack geometry of the present invention;

in the figure: r: a radioactive source L: lens group S1: scintillation crystal light exit surface S2: scintillation crystal light reflection surface S3: light-receiving surface 1 of photomultiplier: scintillation crystal 2: the optical sensor 3: internal circuit 4: the detector packaging shell 5: external power supply and circuit, L1-L6: first to sixth lenses.

Detailed Description

The present invention is further explained with reference to the accompanying drawings, as shown in fig. 2, a scintillation crystal radiation detector with a lens set includes a scintillation crystal 1, a photosensor 2, a preamplifier circuit and multi-channel analyzers 3 and 5, wherein a light reflecting layer and an anti-reflection layer are disposed on the surface of the scintillation crystal S2 except for a scintillation light exit surface, the anti-reflection layer is disposed on the scintillation light exit surface S1, the scintillation crystal is a thallium-doped cesium iodide crystal, the scintillation crystal 1 and the photosensor 3 are disposed in a package case 4, the multi-channel analyzer is disposed outside the case, and a lens set L matching with a waveband of scintillation light of the thallium-doped cesium iodide crystal is disposed between the scintillation light exit surface S2 and the photosensor 3.

Thallium-doped cesium iodide is one of conventional scintillation crystals known in the prior art, low-energy visible photons generated inside the crystal are distributed isotropically, when the visible photons generated inside the crystal reach the end scintillation light exit surface S1, the exit angle range is large, the energy resolution of the detector is affected, in order to improve the collection rate of large-angle photons of the detector and improve the energy resolution of the detector, a lens group design of a large amount of data is performed around the wavelength of thallium-doped cesium iodide scintillation light, and after practical tests and performance comparison, an aspheric lens group as shown in fig. 3 is obtained, of course, fig. 3 is also a schematic diagram, and actual parameters satisfy the following relationships:

the optical axis of the lens group coincides with the central axis of the light receiving surface of the photosensor, the lens group sequentially comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6 along the emergent direction of scintillation light, the two side surfaces of each lens are aspheric surfaces, and the following aspheric surface equations are satisfied:

y＝(x²/R)/（1+（1－(k+1) (x²/R²)）^1/2+A4x⁴+A6x⁶+A8x⁸+A10x¹⁰+A12x¹²+A14x¹⁴+A16x¹⁶，

wherein R is a radius of curvature (length in mm in absolute value) on the central axis, k is a conic coefficient, A4, A6, A8, A10, A12, A14, A16 are aspherical coefficients,

the values are as follows:

lens surface

R

k

A4

A6

A8

A10

A12

A14

A16

1-R

1.20

1.56E+00

5.22E-02

4.54E-02

-2.40E-01

5.92E-01

-8.05E-01

4.85E-01

-1.02E-01

1-L

7.30

4.53E+01

-9.21E-02

2.48E-02

1.80E-01

-4.11E-01

1.83E-01

1.59E-01

-1.03E-01

2-R

26.20

7.61E+01

-1.38E-01

2.87E-01

-1.59E-01

-5.42E-02

-1.20E-01

4.41E-01

-2.13E-01

2-L

3.66

-2.53E+00

-8.93E-02

2.56E-01

-1.46E-01

-1.27E-01

2.45E-01

-2.27E-02

-4.73E-02

3-R

6.72

-3.60E+01

-6.94E-02

1.33E-03

-8.58E-02

9.99E-02

2.59E-02

-9.67E-02

2.73E-02

3-L

-8.27

1.92E+01

-3.33E-02

-5.54E-02

-1.16E-01

1.60E-01

-1.19E-01

4.80E-03

5.81E-03

4-R

-1.42

-1.18E+01

-4.75E-02

8.44E-02

-4.30E-01

4.76E-01

-4.80E-01

3.60E-01

-2.33E-01

4-L

-2.03

1.79E+00

-1.80E-02

-3.17E-02

5.86E-02

-9.50E-02

6.66E-02

-4.49E-02

1.93E-02

5-R

3.72

-1.42E+01

-2.65E-01

2.91E-02

-6.39E-03

-8.37E-03

6.81E-03

7.89E-03

-4.39E-03

5-L

-3.24

-6.69E+01

-2.67E-02

-3.26E-02

1.89E-02

-3.66E-03

1.74E-03

-6.04E-04

-7.50E-06

6-R

-1.42

-2.74E+00

3.66E-02

-1.81E+02

6.89E-03

-6.90E-04

-1.40E-04

-1.34E-05

7.58E-06

6-L

5.20

-8.59E+01

-2.86E-02

-9.44E-03

5.54E-03

-1.30E-03

2.07E-04

-3.04E-05

2.31E-06

Wherein N-R columns in the lens surface columns represent the object side surface of the Nth lens, and N-L represents the image side surface of the Nth lens;

the focal lengths of the first lens, the second lens, the third lens and the fourth lens are respectively 2.68mm, -6.80mm, 7.16mm, -8.68mm, 3.37mm and-2.14 mm, and the thicknesses are respectively: 0.53mm, 0.21mm, 0.33mm, 0.21mm, 0.29mm, 0.33 mm.

The light sensor used in this experiment was a photomultiplier tube, but other light sensors known to those skilled in the art may be used.

It should be noted that, the aspheric formula is a known formula for lens design, and the difficulty lies in specific aspheric parameter design, after the parameters of the aspheric formula are disclosed, the conventional manufacturing technology in the prior art can easily implement the aspheric processing, and the specific processing manner is not described again.

Through comparison of a large amount of experimental data, average data of design comparison experiments of the invention are as follows, when other conditions are the same, the design of the lens group is not adopted, the detected number of the coincident events is reduced by more than 8%, and the arrangement of the visible lens group can effectively improve the energy resolution of the system.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.