Design method and detection method of low-energy proton detection probe based on cadmium zinc telluride

Abstract

The application discloses a kind of based on tellurium zinc cadmium's low-energy proton detection probe design and detection method, high-energy particles can be energy attenuation by energy shielding material, realize the detection of low-energy particles by tellurium zinc cadmium detector, belong to space particle measurement technical field.The method steps are as follows: (1) the selection of static shielding material of tellurium zinc cadmium probe;(2) the selection and size calculation of energy shielding layer are carried out by TRIM module in SRIM software package of Monte Carlo algorithm;(3) the electrode structure and size of tellurium zinc cadmium detector are simulated and calculated by the AC / DC static module in finite element software Comsol Multiphysics;(4) the detection of low-energy proton.The method can realize the detection of low-energy proton, and energy resolution is high, measurement result is accurate, method is feasible, and can serve space exploration activities.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of space particle measurement, and particularly relates to a design method and a detection method of a low-energy proton detection probe based on cadmium zinc telluride. BACKGROUND

[0002] Space particle detection is the guarantee for human space activities, and is also the primary condition for human to understand and study space and march into the universe. However, the deposited energy formed by ionization of low-energy protons is enough to cause single event effect of the detector, which has a very serious impact on the high-integration circuit of the detector. With the improvement of technology, more and more miniature electronic components will be used in space missions, and the protection of these electronic components which are extremely sensitive to radiation damage is a severe test of the technology and ability of particle radiation protection. Therefore, monitoring low-energy particles in the space environment has important significance for exploring the universe.

[0003] The detection of low-energy charged particles puts forward requirements for the detection system, such as fast energy spectrum readout speed, high energy resolution, and high reliability.

[0004] In the literature "S.M, Vincent, et al. In-beam performance of CdZnTe detectors for proton and alpha-particle measurement [J]. Nuclear Instruments & Methods in Physics Research, 2002.", cadmium zinc telluride is used to detect 13Mev proton beam and 2Mev alpha beam, and a simple simulation of the incident depth is carried out, which realizes the detection of particles and distinguishes the types of particle beams. However, the energy range of the detectable protons and alpha particles is quite limited, and the energy spectrum readout speed is slow, which means that it is not feasible to identify different charged particle species by a complete energy spectrum shape. SUMMARY

[0005] In order to solve the problems of slow energy spectrum readout speed, unstable work and poor energy resolution, the present application provides a design method and a detection method of a low-energy proton detection probe based on cadmium zinc telluride, which is particularly related to a detection method of protons with an energy of 1-40Mev. The method can realize the detection of low-energy protons, has high energy resolution, accurate measurement results, and is practical and feasible, and can serve space detection activities.

[0006] The technical scheme of the present application is: a design method of a low-energy proton detection probe based on cadmium zinc telluride, the probe comprising a plastic shell 3, a metal shell 4, a base 6, a preamplifier circuit 7, a detection unit 8, an electrostatic shielding layer 9 and an energy attenuation layer 10; the plastic shell 3 is coaxially sleeved in the metal shell 4, the electrostatic shielding layer 9 is placed above the plastic shell 3, the base 6 is connected below the plastic shell 3, and the detection unit 8 and the preamplifier circuit 7 are arranged in the plastic shell 3; the energy attenuation layer 10 is located above the electrostatic shielding layer 9 and is clamped through a port of the metal shell 4.

[0007] The design method comprises the following steps:

[0008] Step 1: selection of the material and thickness of the energy shielding layer; the thickness is designed to enable incident protons to fall in the detection unit;

[0009] Step 2: selection of the material of the electrostatic shielding layer; the electrostatic material has a surface resistivity less than 1×10 4 Ω / m 2 or a volume resistivity not more than 1×10 3 Ω·cm;

[0010] Step 3: design of the detection unit, comprising the following sub-steps:

[0011] Step 3.1: the detection unit is a cadmium zinc telluride detector, and Cd:Zn:Te is 0.9:0.1:1;

[0012] Step 3.2: design of the semiconductor electrode structure of the cadmium zinc telluride detector.

[0013] A further technical scheme of the present application is: in step 3, the detection unit is a cadmium zinc telluride detector, the base is a cadmium zinc telluride conductor, and Cd:Zn:Te is 0.9:0.1:1.

[0014] A further technical scheme of the present application is: the design of the semiconductor electrode structure of the cadmium zinc telluride detector comprises the following steps:

[0015] Step 3.1: a working surface is added at the electrode of the cadmium zinc telluride, the working surface is regarded as an electrode, a voltage is applied to the anode and the cathode respectively, the grid division mode adopts automatic division for special refinement; data of the electric field distribution and the potential distribution of the middle cross section are extracted and outputted;

[0016] Step 3.2: the data of the electric field distribution and the potential distribution of the middle cross section obtained in step 3.1 are used to determine a suitable electrode structure.

[0017] A further technical scheme of the present application is: in step 3.1, the cathode surface is connected to 0V, and the anode surface is connected to high voltage.

[0018] The further technical scheme of the present application is: in step 3.2, from the potential distribution, since the change of the potential corresponds to the change of the weight potential field, the more rapid the change of the weight potential near the anode is, the more the structure and size of the electrode meet the requirements; from the electric field distribution, the stronger the electric field near the anode is, the more beneficial it is to make the electrons drifted to the anode near the anode be collected rapidly, and the holes generated near the anode be drifted to the region with slow weight potential near the cathode, and the more the structure and size of the electrode meet the requirements.

[0019] The further technical scheme of the present application is: the energy shielding layer material in step 1 is selected from lead or tungsten.

[0020] The further technical scheme of the present application is: the detection method of the low-energy proton detection probe based on tellurium-zinc-cadmium includes the following steps:

[0021] Step 1: the protons are incident to the energy attenuation layer of the probe to attenuate the energy, shield the high-energy protons, and leave the low-energy protons;

[0022] Step 2: the low-energy protons pass through the electrostatic shielding layer and enter the tellurium-zinc-cadmium detector base, and electron-hole pairs are generated in the detector; the electrons and holes move to the corresponding electrodes to generate a pulse charge signal, which is sent to the input end of the pre-processing circuit board through the signal cable and enters the pre-amplifier;

[0023] Step 3: the pre-amplifier performs primary amplification on the pulse charge signal and outputs it to the main amplifier;

[0024] Step 4: the main amplifier performs shaping and secondary amplification on the pulse charge signal from the pre-amplifier and outputs it to the multichannel, and finally inputs into the computer to obtain the full energy spectrum.

[0025] Inventive effects

[0026] The technical effect of the present application is:

[0027] 1. The present application proposes a design method and a detection method of a low-energy proton detection probe based on tellurium-zinc-cadmium, which uses an energy attenuation shielding layer to shield high-energy protons and leave low-energy protons, realizes the detection of low-energy protons by the tellurium-zinc-cadmium detector, can obtain a higher count rate and a high energy resolution, and has a fast energy spectrum reading speed.

[0028] 2. The low-energy proton detection probe based on tellurium-zinc-cadmium developed by using the method can detect 1-40Mev protons in space, and can provide data for space detection activities. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 (a) is a track distribution diagram of 100Mev protons incident to the probe with a lead shielding layer in the horizontal direction

[0030] Figure 1 (b) is a plot of the radial distribution of 100 MeV protons incident into a probe with a lead shield in the vertical direction

[0031] Figure 1 (c) is a plot of the energy deposition distribution of 100 MeV protons incident into a probe with a lead shield

[0032] Figure 1 (d) is a plot of the range distribution of 100 MeV protons incident into a probe with a lead shield

[0033] Figure 2 (a) is a plot of the radial distribution of 33 MeV protons incident into a probe without a lead shield in the horizontal direction

[0034] Figure 2 (b) is a plot of the range distribution of 33 MeV protons incident into a probe without a lead shield

[0035] Figure 3 (a) is a plot of the radial distribution of 100 MeV protons incident into a probe with a tungsten shield in the horizontal direction

[0036] Figure 3 (b) is a plot of the radial distribution of 100 MeV protons incident into a probe with a tungsten shield in the vertical direction

[0037] Figure 3 (c) is a plot of the energy deposition distribution of 100 MeV protons incident into a probe with a tungsten shield

[0038] Figure 3 (d) is a plot of the range distribution of 100 MeV protons incident into a probe with a tungsten shield

[0039] Figure 4 (a) is a plot of the radial distribution of 37 MeV protons incident into a probe without a tungsten shield in the horizontal direction

[0040] Figure 4 (b) is a plot of the range distribution of 37 MeV protons incident into a probe without a tungsten shield

[0041] Figure 5 (a) is a plot of the electric potential distribution inside a quasi-hemispherical CdZnTe detector

[0042] Figure 5 (b) is a plot of the electric field distribution inside a quasi-hemispherical CdZnTe detector

[0043] Figure 6 is a schematic of a low-energy proton detection

[0044] Figure 7 is a two-dimensional schematic of a CdZnTe-based low-energy proton detection probe

[0045] Figure 8 is a schematic diagram of an energy attenuation shielding layer structure

[0046] BRIEF DESCRIPTION OF DRAWINGS: 1 - probe unit support frame; 2 - plastic groove; 3 - plastic shell; 4 - copper shell; 5 - BNC interface; 6 - base; 7 - preamplifier circuit; 8 - probe unit; 9 - electrostatic shielding layer; 10 - energy attenuation layer DETAILED DESCRIPTION

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0048] Referring to Figures 1-8 , the present application is directed to 63-102Mev protons, when 63-102Mev protons are incident into the probe, the energy of the protons is attenuated by the energy attenuation shielding layer, so that when the 63-102Mev protons pass through the energy attenuation shielding layer and the electrostatic shielding layer into the cadmium zinc telluride sensitive detector, the energy of the protons is attenuated to 1-40Mev, at this time the anode is positively biased and the cathode is connected to the signal processing circuit. When 1-40Mev protons enter the cadmium zinc telluride detector layer, the protons cause the cadmium zinc telluride matrix particles (atoms or molecules) to ionize, forming hole-electron pairs, which move towards the anode under the action of the built-in electric field, and the holes move towards the cathode, generating an output signal.

[0049] Based on the above principle, the present application provides a design method and a detection method for a low-energy proton detection probe based on cadmium zinc telluride,

[0050] The low-energy proton detection probe based on cadmium zinc telluride comprises a metal shell 4, a BNC interface 5, a base 6, a preamplifier circuit 7, a probe unit 8, an electrostatic shielding layer 9 and an energy attenuation layer 10.

[0051] The plastic shell 3 and the metal shell 4 are coaxially placed from the inside to the outside without contact, and the energy attenuation layer 10 is placed between one side of the plastic shell 3 and the metal shell 4, and the three are not in contact with each other.

[0052] The electrostatic shielding layer 9 is located on the plastic shell 3 and between the probe unit 8 and the energy attenuation layer 10.

[0053] The plastic shell 3 is provided with a groove near one end of the energy attenuation layer 10 for placing the detection unit 8, and the other end is the base 6 which is connected with the Lemo interface 5;

[0054] The preamplifier circuit 7 is located inside the plastic shell 3 and does not contact the detection unit 8 and the base 6.

[0055] Further, the plastic shell 3 is provided with a groove at one end for placing the detection unit 8, and the detection unit 8 is fixed in the groove through the detection unit support frame 1.

[0056] Further, the detection unit is a cadmium zinc telluride detector, the base is a cadmium zinc telluride semiconductor, and the outer side is plated with a gold electrode, wherein one side near the electrostatic shielding layer 9 is an anode, and the other side is a cathode.

[0057] Further, the pins on the PCB board of the cadmium zinc telluride detector are connected with the preamplifier circuit 7 through a cable.

[0058] Further, the energy attenuation layer is a cylindrical member with one end open and the other end closed, which is inverted on the plastic shell 3, and the bottom of the cylindrical member and the side wall of the cylindrical member do not contact the plastic shell 3 and the metal shell 4.

[0059] Further, the energy attenuation layer is tungsten.

[0060] Further, the metal shell 4 is provided with a ring-shaped protrusion radially inward at one end for positioning the energy attenuation layer 10, and the other end is provided with an internal thread.

[0061] Further, the plastic shell 3 is open at both ends, and the electrostatic shielding layer 9 is placed on one end of the plastic shell 3 and connected therewith.

[0062] Further, the electrostatic shielding layer is beryllium.

[0063] Further, the detection unit support frame, the plastic groove, the plastic shell, the copper shell, the Lemo interface, the base, the preamplifier circuit, the detection unit, the electrostatic shielding layer and the energy attenuation layer are coaxially arranged.

[0064] The design method of the application comprises the following steps:

[0065] (1) Selection of electrostatic shielding material

[0066] According to the principle of electrostatic shielding, the surface resistivity of the material is less than 1×10 4 Ω / m 2 or the volume resistivity is not more than 1×10 3Ω·cm, the Faraday shield made of this material can prevent electrostatic sensitive devices from being affected by static electricity. And because it is to be applied to aerospace structural devices, it must have superior nuclear performance and physical performance. According to these principles, an electrostatic shielding material is obtained. The metal beryllium has a small density, a high tensile strength and good electrical conductivity, making it an ideal EMI shielding material for use in a wide frequency band, so the metal beryllium is selected as the electrostatic shielding material, and the thickness is selected to be 200 μm, and the density is 1.85 g / cm 3 .

[0067] (2) Selection and size design of energy shielding material

[0068] According to the principle of the interaction between protons and matter, that is, in the process of the interaction between protons and matter, the energy loss is mainly caused by non-elastic collision of the electrons outside the nucleus of the medium atom, ionization or excitation of the electrons, or reaction with the nucleus of the medium atom and elastic collision. The greater the mass density of the medium atom, the more energy is lost when the protons and the medium atom have elastic collision. Therefore, a substance with a high atomic number and a large mass density is generally selected as an energy shielding material.

[0069] Common shielding materials are lead and tungsten. The atomic number of lead is 82, and the density is 11.35 g / cm 3 . Lead has the advantages of low melting point, high corrosion resistance, X-ray and gamma-ray, good plasticity and the like, and is the earliest application in radiation protection materials. The atomic number of tungsten is 74, and the density is 18.1 g / cm 3 . Tungsten has high hardness, high melting point, is not affected by air at room temperature, and has stable chemical properties. The present application selects lead and tungsten as energy shielding materials.

[0070] Because a too thick tellurium zinc cadmium semiconductor increases the probability of carrier capture by defects, thereby reducing the collection efficiency of the carrier, the thickness of the tellurium zinc cadmium detector designed by the present application is 2-5 mm.

[0071] Further, the TRIM module in the SRIM software package based on the Monte Carlo algorithm is used for calculation, the first layer is input with a certain thickness of energy shielding material, and the thickness is determined by the standard that 63-102 MeV protons finally fall in the last layer of semiconductor tellurium zinc cadmium detection material.

[0072] Further, the second layer is input with a thickness of 200 μm of electrostatic shielding material and the third layer is input with a thickness of 2-5 mm of tellurium zinc cadmium semiconductor, wherein the density of the tellurium zinc cadmium semiconductor is 5.8 g / cm 3, and Cd:Zn:Te is 0.9:0.1:1, pre-simulation is carried out to calculate the track of 63-102Mev protons in the structure, at this time the energy of the protons incident to the tellurium-zinc-cadmium semiconductor is low-energy protons, and the ionization energy loss and the depth of incidence of 63-102Mev protons in the structure are calculated.

[0073] Further, the Bragg curve formed by the ionization energy loss, i.e. the specific ionization curve, is used to select the energy shielding material in the structure probe, and the specific ionization gradually increases as the residual range decreases, and reaches a maximum value, i.e. the Bragg peak, at the end of the residual range. If the Bragg peak formed by the protons in the energy shielding material is high, it indicates that the energy absorption effect of the energy shielding material is good and meets the requirements.

[0074] Further, since the thickness of the electrostatic shielding layer is 200μm, and the thickness of the energy shielding layer is determined by making the 63-102Mev protons finally fall into the last layer of the semiconductor tellurium-zinc-cadmium detection material, the distance finally incident to the tellurium-zinc-cadmium detector is obtained according to the depth of incidence of 63-102Mev protons in the structure.

[0075] Further, the TRIM module in the SRIM software package based on the Monte Carlo algorithm is used for calculation, the first layer is the electrostatic shielding layer with a thickness of 200μm, and the second layer is the tellurium-zinc-cadmium semiconductor with a thickness of the distance finally incident to the tellurium-zinc-cadmium detector obtained in the previous step and a density of 5.8g / cm 3 , and Cd:Zn:Te is 0.9:0.1:1, and the energy of the protons that are just completely deposited in the structure is calculated, which is the energy after the attenuation of the energy shielding layer, so the absorption effect of the energy shielding layer can be obtained.

[0076] (3) Design of electrode structure and size of the tellurium-zinc-cadmium detector

[0077] The electrode structure is simulated by using the AC / DC electrostatic module in the finite element software Comsol Multiphysics, and since there is no tellurium-zinc-cadmium in the material library, cadmium telluride close to tellurium-zinc-cadmium is selected, and the dielectric constant is set to 10.6. In the calculation, it is assumed that the electrode and the tellurium-zinc-cadmium are ohmic contact, and since the thickness of the electrode is only 100nm, it is ignored in the modeling and grid division to avoid grid division being too dense or error due to the small thickness. The electrode is processed as follows: a working surface is added at the electrode of the tellurium-zinc-cadmium, the working surface is regarded as the electrode, a voltage is applied to the working surface, the anode is applied with a voltage of 800V, and the cathode is applied with a voltage of 0V, and the grid division mode in the calculation adopts automatic division to special refinement. The data of the electric field distribution and the potential distribution of the cross section are extracted and output, and the output format adopts full-precision format.

[0078] According to the electric field distribution and the potential distribution of the middle section, the suitable electrode structure is determined.

[0079] The detection method of the application is:

[0080] 63-102Mev protons are attenuated in energy when entering the first layer of energy shielding layer of the probe, high-energy protons are shielded, and low-energy protons are left, then pass through the electrostatic shielding layer, enter the effective detection area of the cadmium zinc telluride detector, i.e., the cadmium zinc telluride matrix, and ionize to produce electron-hole pairs in the detector. Under the action of the built-in electric field in the detector, the electrons and holes move towards the corresponding electrodes. At this time, a pulse charge signal is generated on the detector. The pulse charge signal generated by the detector is sent to the input end of the pre-processing circuit board through the signal cable and enters the preamplifier. The preamplifier performs primary amplification on the pulse charge signal from the detector and outputs it to the main amplifier. The main amplifier performs shaping and secondary amplification on the pulse charge signal from the preamplifier and outputs it to the multichannel. Finally, it is transmitted into a computer to obtain a full energy spectrum.

[0081] Example 1:

[0082] Since a too thick cadmium zinc telluride semiconductor increases the probability of carrier capture by defects, thereby reducing the collection efficiency of the carrier, the thickness of the cadmium zinc telluride detector designed by the application is 5mm.

[0083] The TRIM module in the SRIM software package based on the Monte Carlo algorithm is used for calculation. The first layer is named Pb, the thickness of the metal lead is 12mm, the density is 11.35g / cm 3 The thickness determination standard is to make the incident protons finally fall in the last layer of semiconductor cadmium zinc telluride detection material.

[0084] The second layer is named Be, the thickness of the metal beryllium is 200μm, the density is 1.85g / cm 3 The third layer is named CZT, the thickness of the cadmium zinc telluride semiconductor is 5mm, and the density is 5.8g / cm 3Cd:Zn:Te is 0.9:0.1:1, the specific energy used in the simulation of the application is 100Mev proton, the track of 100Mev proton in the structure is calculated, at this time the energy of the proton incident on the tellurium zinc cadmium semiconductor is low-energy proton, and the ionization energy loss and the depth of incidence of 100Mev proton in the structure are calculated.

[0085] As shown in Figure 1 (a) and (b) are the track distribution of 100Mev proton in the structure of the probe along the horizontal direction and the vertical incident direction, because the mass of the proton is relatively light, the track of the proton is more similar to a straight line relative to the track of the heavy ion scattering, as can be seen from the figure, the track distribution of the proton in the structure of the probe is horn-shaped, and there is a large scattering in the incident process, which is because the target atomic mass of the tellurium zinc cadmium crystal is large, so that when the proton and the target atom have an elastic collision, the scattering angle is large. Through TRIM calculation, the longitudinal dispersion of 100Mev proton in the probe is 990μm, and the transverse dispersion is 1.35mm.

[0086] As shown in Figure 1 (c) is the Bragg curve formed by 100Mev proton in the probe, it can be seen that the Bragg peak is formed in the metal lead layer and the tellurium zinc cadmium detection layer respectively, which shows that the structure meets the requirements.

[0087] As shown in Figure 1 (d) is the depth of incidence of 100Mev proton in the stacked tellurium zinc cadmium structure, the depth of incidence is 15.7mm. Since the thickness of the metal lead is 12mm and the thickness of the metal beryllium is 200μm, the distance of the tellurium zinc cadmium is 3.5mm.

[0088] Through the TRIM module in the SRIM software package based on the Monte Carlo algorithm, as shown in Figure 2 (a) and (b) are the track distribution and the depth of incidence of 33Mev proton in the metal beryllium and the tellurium zinc cadmium semiconductor along the horizontal direction, wherein the first layer is metal beryllium with a thickness of 200μm and a density of 1.85g / cm 3 , and the second layer is tellurium zinc cadmium semiconductor with a thickness of 3.5mm and a density of 5.8g / cm 3 .

[0089] Example 2:

[0090] Since the probability of carrier being captured by defects increases and the collection efficiency of carrier decreases when the thickness of CdZnTe semiconductor is too thick, the thickness of the CdZnTe detector designed in the application is 5mm.

[0091] The TRIM module in the SRIM software package based on the Monte Carlo algorithm is used for calculation, the first layer is named W, the input thickness of tungsten metal is 7mm, and the density is 18.1g / cm 3 The thickness is determined according to the standard that the incident protons finally fall into the last layer of semiconductor CdZnTe detection material.

[0092] The second layer is named Be, the input thickness of beryllium metal is 200μm, and the density is 1.85g / cm 3 The third layer is named CZT, the input thickness of CdZnTe semiconductor is 5mm, and the density is 5.8g / cm 3 Cd:Zn:Te is 0.9:0.1:1, and the specific energy used in the simulation of the application is 100Mev protons, the track of 100Mev protons in the structure is calculated, at this time the energy of the protons incident on the CdZnTe semiconductor is low-energy protons, and the ionization energy loss and incident depth of 100Mev protons in the structure are calculated.

[0093] As shown in Figure 3 (a) and (b) are the track distribution of 100Mev protons in the structure of the probe along the horizontal direction and the vertical incident direction, since the mass of the protons is relatively light, the track of the protons is more similar to a straight line relative to the track of heavy ion scattering, as can be seen from the figure, the track distribution of the protons in the structure of the probe is horn-shaped, and there is a large scattering in the incident process, which is due to the large target atomic mass of the CdZnTe crystal, so that when the protons and the target atoms are elastically collided, the scattering angle is large. Through TRIM calculation, the longitudinal dispersion of 100Mev protons in the probe is 833μm, and the transverse dispersion is 1.05mm.

[0094] As shown in Figure 3 (c) is the Bragg curve formed by 100Mev protons in the probe, it can be seen that the Bragg peak is formed in the tungsten layer and the CdZnTe detection layer respectively, which shows that the structure meets the requirements.

[0095] As shown in Figure 3 (d) is the incident depth of 100Mev protons in the structure, and the incident depth is 11.4mm. Since the thickness of tungsten metal is 7mm and the thickness of beryllium metal is 200μm, the distance of the incident on the CdZnTe is 4.2mm.

[0096] Through the TRIM module in the SRIM software package based on the Monte Carlo algorithm, as shown in Figure 4(a), (b) are the horizontal direction track distribution and the depth of incidence of 37Mev protons in metal beryllium and tellurium zinc cadmium semiconductor, wherein the first layer is metal beryllium with a thickness of 200μm and a density of 1.85g / cm 3 , the second layer is tellurium zinc cadmium semiconductor with a thickness of 4.2mm and a density of 5.8g / cm 3 , wherein Cd:Zn:Te is 0.9:0.1:1, and it is calculated that 37Mev protons are just completely deposited in the structure, so that 7mm of metal lead can attenuate 100Mev protons to 37Mev protons, so that the tellurium zinc cadmium detector can detect the energy of 37Mev protons.

[0097] Comparative examples 1, 2:

[0098] Through comparative examples 1 and 2, it can be found that lead and tungsten are both materials that can be used as energy shielding materials, but by observing the energy loss diagrams of the two examples, it can be found that the energy absorption effect of tungsten is better than that of lead, and for protons of the same energy, the thickness of tungsten required is smaller. Moreover, by observing the track diagrams in the horizontal direction and the vertical direction of the two examples, it can be found that the longitudinal and transverse divergence of protons in the probe with a tungsten shielding layer is smaller, so that metal tungsten is more suitable as an energy shielding material of the present application.

[0099] (3) Electrode structure and size design of the laminated tellurium zinc cadmium detector

[0100] The electrode structure is simulated by using the AC / DC static electricity module in the finite element software Comsol Multiphysics, and a quasi-hemispherical electrode structure is adopted, and the size of the detector is 10×10×5mm 3 Since there is no tellurium zinc cadmium in the material library, cadmium telluride close to tellurium zinc cadmium is selected, and the dielectric constant is set to 10.6. During calculation, it is assumed that the electrode and the tellurium zinc cadmium are ohmic contact, and since the thickness of the electrode is only 100nm, it is ignored during meshing to avoid too dense meshing or error due to too small thickness. The electrode is processed as follows: a working surface is added to the top surface with a diameter of 1.6mm, and the working surface is regarded as the electrode, and a voltage is applied to the working surface. Since the top surface is an anode with a diameter of 1.6mm, and the side surface and the bottom surface are cathodes, the voltage applied to the top surface is 800V, and the voltage applied to the side surface and the bottom surface is 0V. The meshing method in the calculation is automatic meshing with special refinement. The two-dimensional data in the cross section are extracted for output, and the output format is full-precision format.

[0101] As Figure 5 (a), (b) are the potential distribution and electric field distribution of the derived quasi-hemispherical tellurium zinc cadmium detector inside the middle cross section, Figure 5(a) The change of the middle potential corresponds to the change of the weight potential field. It is known that the structure has obvious optimization effect on the weight potential field. The weight potential changes slowly near the cathode, and the induced charge produced by the hole drift to the cathode is less. The weight potential changes rapidly near the anode, and the induced charge produced by the electron drift to the anode is more. Figure 5 (b) is the distribution of the electric field in the cadmium zinc telluride crystal under 800V. The electric field intensity is weak near the cathode, and the electric field intensity increases sharply near the anode. The electric field intensity is very large at the contact between the cadmium zinc telluride crystal and the electrode due to the potential mutation. The strong electric field near the anode is beneficial to the rapid collection of the electrons drifting to the anode, and the holes produced near the anode drift to the region with slow weight potential near the cathode. Therefore, the electrode structure and size are very effective for realizing single electron collection.

[0102] (4) Low-energy proton detection

[0103] As shown in Figure 6 The low-energy proton detection schematic diagram is shown. The signal processing system includes a preamplifier, a main amplifier, a multichannel, and a computer.

[0104] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of designing a low-energy proton detection probe based on cadmium zinc telluride, characterized in that, The probe comprises a plastic shell (3), a metal shell (4), a Luer interface (5), a base (6), a preamplifier circuit (7), a detection unit (8), an electrostatic shielding layer (9) and an energy attenuation layer (10); the plastic shell (3) and the metal shell (4) are coaxially arranged from inside to outside and are not in contact, and the energy attenuation layer (10) is arranged between one side of the plastic shell (3) and the metal shell (4), and the three are not in contact with each other; the electrostatic shielding layer (9) is located on the plastic shell (3) and is between the detection unit (8) and the energy attenuation layer (10); the plastic shell (3) is provided with a groove at one end close to the energy attenuation layer (10) for placing the detection unit (8), and the other end is the base (6) connected with the Luer interface (5); the preamplifier circuit (7) is located inside the plastic shell (3) and does not contact the detection unit (8) and the base (6); The detection unit is a cadmium zinc telluride detector, the base is a cadmium zinc telluride semiconductor, and the outer side is plated with a gold electrode, wherein one side close to the electrostatic shielding layer (9) is an anode, and the other side is a cathode; the pins on the PCB board of the cadmium zinc telluride detector are connected with the preamplifier circuit (7) through a cable; the energy attenuation layer is a cylindrical piece with one end open and the other end closed, which is invertedly buckled on the plastic shell (3), and the bottom of the cylindrical piece and the side wall of the cylindrical piece do not contact the plastic shell (3) and the metal shell (4); The design method comprises the following contents: (1) selecting an electrostatic shielding layer material; The metal is selected as the electrostatic shielding material, the surface resistivity is less than 1 x 10 4 Ω / m 2 , or the volume resistivity is not more than 1 x 10 3 Ω.cm, the thickness is selected as 200 μm, and the density is 1.85 g / cm 3 ; (2) selecting an energy shielding layer and designing the size of the energy shielding layer: lead or tungsten is selected as the energy shielding material; the size design process of the energy shielding layer is: The TRIM module in the SRIM software package based on the Monte Carlo algorithm is used for calculation: a first layer is inputted with energy shielding material with a certain thickness, a second layer is inputted with electrostatic shielding material with a thickness of 200 μm, and a third layer is inputted with a cadmium zinc telluride semiconductor with a thickness of 2-5 mm, wherein the cadmium zinc telluride semiconductor has a density of 5.8 g / cm 3 , and Cd:Zn:Te is 0.9:0.1:1, a pre-simulation is performed to calculate the ionization energy loss and the incident depth of 63-102 MeV protons in the structure; the Bragg curve formed by the ionization energy loss is used to determine the thickness of the energy shielding layer so that the 63-102 MeV protons finally fall into the last layer of semiconductor cadmium zinc telluride detection material. (3) designing the structure size of the cadmium zinc telluride detector: the electrode structure is simulated by using the AC / DC electrostatic module in the finite element software Comsol Multiphysics; in the calculation, it is assumed that the electrode and the cadmium zinc telluride are ohmic contacts, the electrode thickness is ignored in the modeling grid division, the electrode is processed in the following manner, a working surface is added at the electrode of the cadmium zinc telluride, the working surface is regarded as the electrode, a voltage is added on the working surface, the anode is applied with a voltage of 800V, the cathode is applied with a voltage of 0V, the grid division mode in the calculation adopts automatic division for special refinement; the data of the electric field distribution and the potential distribution of the middle section are extracted and output, and the output format adopts full-precision format.

2. The design method of a low-energy proton detection probe based on cadmium zinc telluride as claimed in claim 1, characterized by, The semiconductor electrode structure design of the cadmium zinc telluride detector comprises the following steps: according to the data of the electric field distribution and the potential distribution of the middle section, the suitable electrode structure is determined.

3. The design method of a low-energy proton detection probe based on cadmium zinc telluride as claimed in claim 1, characterized in that, From the potential distribution, since the change of the potential corresponds to the change of the weight potential field, the faster the weight potential changes near the anode, the more the structure and size of the electrode meet the requirements; From the electric field distribution, the stronger the electric field near the anode, the more conducive to collecting the electrons drifting to the anode, and the slower the holes generated near the anode drift to the area with slow weight potential of the cathode, and the more the structure and size of the electrode meet the requirements.

4. A detection method of a CdZnTe-based low-energy proton detection probe using the design method of claim 1, characterized in that, The method comprises the following steps: Step 1: protons are incident on the energy attenuation layer of the probe to attenuate the energy, shield high-energy protons, and leave low-energy protons; Step 2: When low-energy protons pass through the static shielding layer and enter the CdZnTe detector substrate, electron-hole pairs are generated by ionization inside the detector; the electrons and holes move towards the corresponding electrodes to generate a pulse charge signal, which is sent to the input end of the pre-processing circuit board through the signal cable and enters the pre-amplifier; Step 3: The pre-amplifier performs primary amplification on the pulse charge signal and outputs it to the main amplifier; Step 4: The main amplifier performs shaping and secondary amplification on the pulse charge signal from the pre-amplifier and outputs it to the multichannel, and finally to the computer to obtain the full energy spectrum.

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