Copper-based scintillator nanocrystals and preparation method and application thereof

Abstract

The present invention discloses a copper-based scintillator nanocrystal and its preparation method and application. The preparation method of the copper-based scintillator nanocrystal includes: preparing a copper-based scintillator precursor solution; atomizing and quenching the copper-based scintillator precursor solution to prepare copper-based scintillator nanocrystals. The present invention utilizes alkali metal halide and cuprous halide as reactants, dissolving them in an aqueous solution of hydrohalic acid, adding a reducing protective agent, and heating to obtain a copper-based scintillator precursor solution; then, utilizing atomization and quenching technology, atomizing the precursor solution and passing it into the pores of solid carbon dioxide, rapidly cooling to precipitate scintillator nanocrystals. The copper-based scintillator prepared by the method of the present invention has high physical purity, good crystallinity, and excellent optical properties, and can realize the particle size control of the scintillator nanocrystals. In addition, the atomization and quenching method is simple in process and low in production cost.

Description

Technical Field

[0001] The present disclosure relates to the technical field of scintillator materials, and more specifically, to a copper-based scintillator nanocrystal and a preparation method and application thereof. Background Art

[0002] Medical imaging equipment is indispensable in the screening and diagnosis of pneumonia. How to design medical X-ray detection technology with higher resolution, lower X-ray dosage and lower cost has become a research hotspot and urgent goal in this field. X-ray imaging detectors can be divided into direct and indirect imaging detectors according to the different photoelectric conversion processes. Direct imaging detectors directly convert X-rays into electrical signals through photoelectric conversion for imaging. However, due to the high energy of X-ray photons and the low range of X-ray energy that photoelectric conversion materials can withstand, direct detectors are inefficient and have a short lifespan. Most of the X-ray detectors currently in use are indirect imaging detectors, which use scintillators to convert X-rays into fluorescent signals, and then convert the fluorescent signals into electrical signals through photodiodes. Therefore, the scintillator is the core photosensitive element of the indirect X-ray detector, and its performance directly affects the resolution of the final image.

[0003] At present, the common scintillators are terbium-doped gadolinium oxysulfide (Gd2O2S: Tb, GOS), cerium-doped lutetium yttrium orthosilicate (Lu 1.8 Y 0.2 The main scintillator materials are SiO5:Ce, LYSO:Ce) and thallium-doped cesium iodide (Csi:Tl). These traditional scintillators are complex to prepare, especially oxide scintillators, which require temperatures exceeding 1700°C. CsI:Tl crystals require a high vacuum environment for growth, resulting in a low growth rate and high cost. Furthermore, they have untunable emission wavelengths and limited X-ray conversion efficiency.

[0004] In recent years, perovskite materials, as a novel material, have attracted widespread attention in fields such as photocatalysis, solar cells, and light-emitting diodes due to their excellent properties, including simple preparation, low production cost, high fluorescence quantum yield, tunable wavelength, and high photoluminescence conversion efficiency. Due to their high effective atomic number, perovskite materials exhibit high X-ray absorption coefficients. Furthermore, their suitable and easily tunable band gap and high photoluminescence quantum yield make them promising scintillators for use in X-ray detectors. In 2018, the lead-based halide perovskite CsPbBr3 was first reported as a scintillator. Subsequent studies have shown that the average photoluminescence lifetime of CsPbBr3 perovskite nanocrystal scintillators is approximately 5.6 times faster than that of commercial gadolinium oxide (GOS)-based scintillators, and their emission intensity is even higher. Despite the promising prospects of lead-based perovskite scintillators, their application remains limited. Light yield, one of the most important quality indicators of scintillators, determines X-ray conversion efficiency and detection contrast. The small Stokes shift and self-absorption of lead-based perovskite CsPbBr3 scintillators severely limit the light extraction efficiency of thin films and crystals, resulting in a low light yield of only 21,000 photons / MeV, far lower than commercial scintillators LYSO (33,000 photons / MeV), CsI:Tl (54,000 photons / MeV), and GOS (60,000 photons / MeV). Furthermore, the toxicity of lead also severely restricts the application of lead-based halide perovskite materials. The ionic properties and water-soluble lead content of lead-based perovskites can pose serious risks to human health and the environment. Summary of the Invention

[0005] (1) Technical issues to be solved

[0006] In view of this, the main purpose of the present disclosure is to provide a copper-based scintillator nanocrystal and its preparation method and application, so as to simplify the preparation process, reduce production costs, improve the performance of copper-based scintillator nanocrystals, and improve the safety of the process.

[0007] (2) Technical solution

[0008] According to one aspect of the present disclosure, a method for preparing copper-based scintillator nanocrystals is provided, comprising: preparing a copper-based scintillator precursor solution; and atomizing and rapidly cooling the copper-based scintillator precursor solution to prepare the copper-based scintillator nanocrystals.

[0009] In the above scheme, the preparation of the copper-based scintillator precursor solution includes: dissolving an alkali metal halide in deionized water to form a solution A, and dissolving cuprous halide in hydrohalic acid to form a solution B; uniformly mixing solution A and solution B in a molar ratio of 2:1, and then adding a reducing protective agent to prevent oxidation of cuprous ions; heating the reaction solution to a specific temperature and then keeping it warm for a period of time to obtain the copper-based scintillator precursor solution.

[0010] In the above scheme, the alkali metal halide is RbBr, the cuprous halide is CuBr, and the hydrohalic acid is HBr.

[0011] In the above solution, the reducing protective agent is hypophosphorous acid or hypochlorous acid, and the added amount is 2%-6% of the volume of the mixed liquid.

[0012] In the above scheme, in the step of heating the reaction solution to a specific temperature and then keeping it warm for a period of time, the specific temperature is 100-150° C., and the keeping time is 2-6 hours.

[0013] In the above scheme, the copper-based scintillator precursor liquid is subjected to atomization and rapid cooling to prepare copper-based scintillator nanocrystals, including: using atomization and rapid cooling technology to atomize the copper-based scintillator precursor liquid, passing the atomized copper-based scintillator precursor liquid into the pores of solid carbon dioxide, and precipitating scintillator nanocrystals after rapid cooling.

[0014] In the above scheme, the copper-based scintillator precursor liquid is atomized by ultrasonic atomization or compressed air atomization, wherein the atomized particle size after ultrasonic atomization is 10 μm, and the atomized particle size after compressed air atomization is 3 μm.

[0015] In the above scheme, the parameters of the ultrasonic atomization are: ultrasonic frequency 1.7 MHz, power 50 W.

[0016] In the above solution, the copper-based scintillator precursor liquid is atomized, and the particle size of the droplets after atomization is 10 μm, 5 μm or 2 μm.

[0017] In the above solution, after the scintillator nanocrystals are precipitated, the method further comprises: washing the nanocrystals with an organic solvent, and then centrifuging and drying to obtain copper-based scintillator nanocrystal powder.

[0018] In the above scheme, the organic solvent is isopropanol or ethanol.

[0019] In the above scheme, during the centrifugation and drying process, the centrifugal speed is 2000-5000 rpm, the vacuum drying temperature is 20-40° C., the vacuum drying time is 20-60 minutes, and the vacuum degree is -0.05--0.1 MPa.

[0020] According to another aspect of the present disclosure, a copper-based scintillator nanocrystal is provided, which is prepared using the method for preparing the copper-based scintillator nanocrystal.

[0021] According to another aspect of the present disclosure, provided is the application of the copper-based scintillator nanocrystals prepared by the preparation method of the copper-based scintillator nanocrystals in the fields of X-ray detectors and gamma-ray detectors.

[0022] (3) Beneficial effects

[0023] It can be seen from the above technical solutions that the copper-based scintillator nanocrystals and their preparation methods and applications provided by the present disclosure have at least the following beneficial effects:

[0024] 1. Compared with traditional oxide scintillators, the preparation method of copper-based scintillator nanocrystals provided by the present disclosure adopts an atomization rapid cooling method with a simple process, simple and controllable process, and a maximum temperature of only 100°C, which simplifies the preparation process and greatly reduces the production cost of copper-based scintillator nanocrystals.

[0025] 2. Compared with traditional lead-based perovskite materials, the copper-based scintillator prepared in the present invention does not have the problem of lead toxicity, improves the safety of the process, and is biofriendly.

[0026] 3. The preparation method of copper-based scintillator nanocrystals provided in the present disclosure adopts an atomization and rapid cooling method to prepare copper-based scintillator nanocrystals. The atomization and rapid cooling method has a simple process and low production cost. The particle size of the copper-based scintillator nanocrystals is controllable, which can realize the particle size control of the scintillator nanocrystals and is conducive to the subsequent preparation of scintillator films.

[0027] 4. The preparation method of copper-based scintillator nanocrystals provided by the present disclosure has a larger Stokes shift, which also indicates that the scintillator produces vibration relaxation and internal conversion after absorbing excitation energy, which can be more efficiently converted into fluorescent emission energy, thereby improving the performance of copper-based scintillator nanocrystals.

[0028] 5. The present disclosure provides a method for preparing copper-based scintillator nanocrystals. The copper-based scintillator material prepared by this method has high phase purity, good crystallinity, and excellent optical properties, and can be widely used in the fields of X-ray detectors and gamma-ray detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings. When considered in conjunction with the accompanying drawings, the present disclosure can be more completely and better understood, and many of the accompanying advantages thereof can be easily appreciated by referring to the following detailed description. However, the drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure. In the drawings:

[0030] Figure 1 A flow chart of the method for preparing copper-based scintillator nanocrystals provided in the present disclosure.

[0031] Figure 2 is an X-ray diffraction pattern of the copper-based scintillator nanocrystal prepared according to Example 1 of the present disclosure;

[0032] Figure 3 This is a luminescence image of the copper-based scintillator nanocrystal prepared according to Example 1 of the present disclosure under 254nm light source;

[0033] Figure 4 is a fluorescence spectrum of the copper-based scintillator nanocrystal prepared according to Example 1 of the present disclosure;

[0034] Figure 5 is a scanning electron microscope image of the copper-based scintillator nanocrystal prepared according to Example 1 of the present disclosure;

[0035] Figure 6 3 is a scanning electron microscope image of the copper-based scintillator powder prepared according to Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0037] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0038] Furthermore, the shapes and sizes of the components in the figures do not reflect the actual sizes and proportions, but are merely illustrative of the contents of the embodiments of the present disclosure. In addition, in the claims, any reference signs placed between brackets should not be construed as limiting the claims.

[0039] Furthermore, the word "comprise" or "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0040] In order to simplify the preparation process, reduce production costs, improve the performance of copper-based scintillator nanocrystals, and improve the safety of the process, the present disclosure provides a preparation method of copper-based scintillator nanocrystals, such as Figure 1 As shown, Figure 1 The present invention provides a flow chart of a method for preparing copper-based scintillator nanocrystals, which comprises the following steps:

[0041] Step S1: preparing a copper-based scintillator precursor solution, specifically comprising:

[0042] Dissolve an alkali metal halide in deionized water to form a solution A, and dissolve cuprous halide in a hydrohalic acid to form a solution B; optionally, the alkali metal halide is RbBr, the cuprous halide is CuBr, and the hydrohalic acid is HBr;

[0043] Solution A and solution B are uniformly mixed in a molar ratio of 2:1, and then a reducing protective agent is added to prevent oxidation of cuprous ions; optionally, the reducing protective agent is hypophosphorous acid or hypochlorous acid, and the amount added is 2%-6% of the volume of the mixed liquid;

[0044] The reaction solution is heated to a specific temperature and then kept warm for a period of time to obtain a copper-based scintillator precursor solution; optionally, the specific temperature is 100-150° C., and the holding time is 2-6 hours.

[0045] Step S2: atomizing and rapidly cooling the copper-based scintillator precursor liquid to prepare copper-based scintillator nanocrystals, specifically comprising: atomizing the copper-based scintillator precursor liquid using atomization and rapid cooling technology, passing the atomized copper-based scintillator precursor liquid into the pores of solid carbon dioxide, and rapidly cooling the scintillator nanocrystals.

[0046] In this step, the copper-based scintillator precursor liquid is atomized by ultrasonic atomization or compressed air atomization, wherein the atomized particle size after ultrasonic atomization is 10 μm, and the atomized particle size after compressed air atomization is 3 μm.

[0047] Optionally, the parameters of the ultrasonic atomization are: ultrasonic frequency 1.7 MHz, power 50 W.

[0048] Optionally, the copper-based scintillator precursor liquid is atomized, and the particle size of the droplets after atomization is 10 μm, 5 μm or 2 μm.

[0049] In this step, after the scintillator nanocrystals are precipitated, the process further includes: washing the nanocrystals with an organic solvent, and then centrifuging and drying to obtain copper-based scintillator nanocrystal powder.

[0050] Optionally, the organic solvent is isopropanol or ethanol.

[0051] Optionally, during the centrifugation and drying process, the centrifugal speed is 2000-5000 rpm, the vacuum drying temperature is 20-40° C., the vacuum drying time is 20-60 minutes, and the vacuum degree is -0.05--0.1 MPa.

[0052] Furthermore, the copper-based scintillator nanocrystals prepared according to the preparation method of the copper-based scintillator nanocrystals provided in the present disclosure have a large Stokes shift, produce vibration relaxation and internal conversion after absorbing excitation energy, and can be more efficiently converted into fluorescent emission energy, thereby improving the performance of the copper-based scintillator nanocrystals, having high phase purity, good crystallinity, and excellent optical properties, and can be widely used in the fields of X-ray detectors and gamma-ray detectors.

[0053] Example 1: In this example, atomization and rapid cooling treatment is performed

[0054] A method for preparing copper-based scintillator nanocrystals comprises the following steps:

[0055] Step 1: Preparation of copper-based scintillator precursor solution:

[0056] 10 mmol of RbBr was dissolved in 1.7 ml of deionized water, and 5 mmol of CuBr was dissolved in 3.4 ml of HBr. The two solutions were then mixed to obtain a molar ratio of RbBr to CuBr of 2:1.

[0057] 100 μL of hypophosphorous acid was added as a reducing protective agent to prevent oxidation of cuprous ions;

[0058] The reaction solution was heated to 100° C. and kept warm for 2 hours to obtain a copper-based scintillator precursor solution.

[0059] Step 2: Preparation of copper-based scintillator nanocrystals by atomization and rapid cooling:

[0060] The copper-based scintillator precursor liquid is subjected to ultrasonic atomization treatment, and the typical droplet size after ultrasonic atomization is 10 μm;

[0061] The atomized scintillator precursor liquid is passed into the pores of solid carbon dioxide for rapid cooling;

[0062] adding isopropyl alcohol to clean the precipitated scintillator nanocrystals;

[0063] Then, the copper-based scintillator nanocrystalline powder is obtained by centrifugation and drying;

[0064] The centrifugal speed was 3000 rpm, the vacuum drying temperature was 25°C, the vacuum drying time was 30 minutes, and the vacuum degree was -0.08 MPa;

[0065] Furthermore, the copper-based scintillator nanocrystalline powder prepared in Example 1 was subjected to X-ray diffraction analysis. The X-ray diffraction pattern of the copper-based scintillator nanocrystalline powder was as follows: Figure 2 As shown, by comparison with the standard PDF card (01-072-9847), it was confirmed that the synthesized product was Rb2CuBr3 crystal, and no other impurity phases were produced. Figure 3 It shows that copper-based scintillator nanocrystals produce obvious fluorescence under 254nm light source. Figure 4 The fluorescence spectrum shown shows that the excitation peak of this copper-based scintillator is at 270nm, the emission peak is at 386.6nm, and the Stokes shift is 116.2nm. The large Stokes shift indicates that this scintillator produces vibration relaxation and internal conversion after absorbing excitation energy, which can be efficiently converted into fluorescence emission energy. Figure 5 The scanning electron microscope images shown indicate that the lateral size of the copper-based scintillator nanosheets prepared by atomization quenching is less than 10 μm.

[0066] Comparative Example 1: No atomization treatment was performed in this comparative example

[0067] A method for preparing copper-based scintillator nanocrystals, wherein no atomization treatment is performed during the preparation process, comprises the following steps:

[0068] Step 1: Preparation of copper-based scintillator precursor solution:

[0069] Dissolve 10 mmol of RbBr in 1.7 ml of deionized water and 5 mmol of CuBr in 3.4 ml of HBr. Then mix the two solutions to obtain a molar ratio of RbBr to CuBr of 2:1.

[0070] 100 μL of hypophosphorous acid was added as a reducing protective agent to prevent oxidation of cuprous ions;

[0071] The reaction solution was heated to 100° C. and kept at this temperature for 2 hours to obtain a copper-based scintillator precursor solution;

[0072] Step 2: Preparation of copper-based scintillator nanocrystals by atomization and rapid cooling:

[0073] Dropping the scintillator precursor into the pores of solid carbon dioxide for rapid cooling;

[0074] adding isopropyl alcohol to clean the precipitated scintillator nanocrystals;

[0075] Then, the copper-based scintillator nanocrystalline powder is obtained by centrifugation and drying;

[0076] The centrifugal speed was 3000 rpm, the vacuum drying temperature was 25° C., the vacuum drying time was 30 minutes, and the vacuum degree was -0.08 MPa.

[0077] Furthermore, the copper-based scintillator nanocrystalline powder prepared in Comparative Example 1 was subjected to scanning electron microscopy analysis. The scanning electron microscopy image of the copper-based scintillator nanocrystalline powder is as follows: Figure 6 Compared with the copper-based scintillator nanocrystals subjected to atomization treatment in Example 1, the non-atomized copper-based scintillator nanocrystal powder of Comparative Example 1 is needle-shaped, and due to the sufficient supply of precursors during the crystallization process, its length can reach up to 500 μm.

[0078] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the various specific structures, shapes, or methods described in the embodiments, and can be easily modified or replaced by those skilled in the art.

[0079] In summary, the copper-based scintillator nanocrystals and their preparation methods and applications provided by the embodiments of the present disclosure are simple and controllable in comparison with traditional oxide scintillators. The maximum temperature is only 100°C, which simplifies the preparation process and greatly reduces the production cost of copper-based scintillator nanocrystals. Compared with traditional lead-based perovskite materials, the copper-based scintillator prepared by the present disclosure does not have the problem of lead toxicity, improves the safety of the process, and is bio-friendly. The copper-based scintillator nanocrystals are prepared by atomization and rapid cooling. The atomization and rapid cooling method is simple in process and has low production cost. The particle size of the copper-based scintillator nanocrystals is controllable, which can achieve particle size control of the scintillator nanocrystals and is conducive to the subsequent preparation of scintillator films. The larger Stokes shift also indicates that the scintillator produces vibration relaxation and internal conversion after absorbing excitation energy, which can be more efficiently converted into fluorescence emission energy, thereby improving the performance of the copper-based scintillator nanocrystals. The copper-based scintillator material prepared by this method has high phase purity, good crystallinity, and excellent optical properties.

[0080] The use of ordinal numbers in the specification and claims, such as "step S1" and "step S2", to modify corresponding elements, does not in itself mean that the elements have any ordinal numbers, nor does it represent the order of one element relative to another, or the order of the manufacturing method. The use of such ordinal numbers is only used to clearly distinguish one element with a certain name from another element with the same name.

[0081] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present disclosure, various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed approach should not be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as reflected in the claims below, the disclosed aspects consist of fewer than all the features of the individual embodiments disclosed above. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present disclosure.

[0082] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for preparing copper-based scintillator nanocrystals, characterized in that: include: preparing a copper-based scintillator precursor solution; as well as The copper-based scintillator precursor liquid is atomized and rapidly cooled to prepare copper-based scintillator nanocrystals; The method for preparing a copper-based scintillator precursor solution comprises: dissolving an alkali metal halide RbBr in deionized water to form a solution A, and dissolving a cuprous halide CuBr in a hydrohalic acid HBr to form a solution B; uniformly mixing the solution A and the solution B in a molar ratio of 2:1, and then adding a reducing protective agent to prevent oxidation of the cuprous ions; heating the reaction solution to 100-150° C. and then keeping the temperature for a period of time to obtain the copper-based scintillator precursor solution; The method of preparing copper-based scintillator nanocrystals by atomizing and rapidly cooling the copper-based scintillator precursor liquid comprises: atomizing the copper-based scintillator precursor liquid by using atomizing and rapidly cooling technology, passing the atomized copper-based scintillator precursor liquid into the pores of solid carbon dioxide, and precipitating the scintillator nanocrystals after rapid cooling.

2. The method for preparing copper-based scintillator nanocrystals according to claim 1, characterized in that: The reducing protective agent is hypophosphorous acid or hypochlorous acid, and the added amount is 2%-6% of the volume of the mixed liquid.

3. The method for preparing copper-based scintillator nanocrystals according to claim 1, characterized in that: In the step of heating the reaction solution to 100-150° C. and then keeping the temperature for a period of time, the holding time is 2-6 hours.

4. The method for preparing copper-based scintillator nanocrystals according to claim 1, wherein: The copper-based scintillator precursor liquid is atomized by ultrasonic atomization or compressed air atomization, wherein the atomized particle size after ultrasonic atomization is 10 μm, and the atomized particle size after compressed air atomization is 3 μm.

5. The method for preparing copper-based scintillator nanocrystals according to claim 4, characterized in that: The parameters of the ultrasonic atomization are: ultrasonic frequency 1.7 MHz, power 50 W.

6. The method for preparing copper-based scintillator nanocrystals according to claim 1, characterized in that: The copper-based scintillator precursor liquid is atomized, and the particle size of the atomized droplets is 10 μm, 5 μm or 2 μm.

7. The method for preparing copper-based scintillator nanocrystals according to claim 1, characterized in that: After the scintillator nanocrystals are precipitated, the method further comprises: The nanocrystals are washed with an organic solvent, and then centrifuged and dried to obtain copper-based scintillator nanocrystal powder.

8. The method for preparing copper-based scintillator nanocrystals according to claim 7, characterized in that: The organic solvent is isopropanol or ethanol.

9. The method for preparing copper-based scintillator nanocrystals according to claim 7, characterized in that: During the centrifugation and drying process, the centrifugal speed is 2000-5000 rpm, the vacuum drying temperature is 20-40° C., the vacuum drying time is 20-60 minutes, and the vacuum degree is -0.05-0.1 MPa.

10. A copper-based scintillator nanocrystal, characterized in that: The copper-based scintillator nanocrystal is prepared by the preparation method of any one of claims 1 to 9.

11. Application of the copper-based scintillator nanocrystals prepared by the method for preparing the copper-based scintillator nanocrystals according to any one of claims 1 to 9 in the fields of X-ray detectors and gamma-ray detectors.

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