Method for Increasing Luminescence Uniformity and Reducing Afterglow of Ce-Doped Gadolinium-Aluminum-Gallium Garnet Structure Scintillation Crystal, Crystal Material and Detector

Abstract

The present disclosure provides a method for increasing luminescence uniformity and reducing afterglow of a Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal, a crystal material and a detector. Sc ions are doped into the crystal material, and the Sc ions occupy at least an octahedral site. The effective segregation coefficient of active Ce ions is increased by a radius compensation effect of Sc—Ce ions and adjustment of lattice parameters, thereby the luminescence uniformity of the crystal is increased and the energy resolution is optimized; and at the same time, the potential barrier for Gd ions entering the octahedral site is increased, thereby the probability of the Gd ions entering the octahedral site is reduced, the density of point defects in the crystal is decreased, and the afterglow intensity is reduced. A general formula of the Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal is {Gd.sub.1-x-y-pSc.sub.xCe.sub.yMe.sub.p}.sub.3[Al.sub.1-q].sub.5O.sub.12, 0<x≤0.1, 0<y<0.02, 0≤p≤0.02, 0.4≤q≤0.7.

Claims

1. A method for increasing luminescence uniformity and reducing afterglow of a Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal, comprising: doping Sc ions with a ionic radius between Gd ion and Ga ion into the Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal, so that the Sc ions occupy octahedral site and dodecahedral site at the same time, a chemical composition general formula of the obtained garnet structure scintillation crystal is {Gd.sub.1-x-y-pSc.sub.xCe.sub.yMe.sub.p}.sub.3[Al.sub.1-q].sub.5O.sub.12, wherein the Sc ions occupying the dodecahedral site substitute Gd ions with a ionic radius between Ce ions and Sc ions, after the Sc enters the dodecahedron lattice, it makes the Ce ions enter the dodecahedron lattice more easily depending on the radius compensation effect, increasing the effective segregation coefficient of the Ce ions. the Sc ions occupying the octahedral site substitute the Ga ions with a ionic radius smaller than Sc ions, after entering the octahedral sites, the Sc ions increase lattice parameters, thereby facilitating the Ce ions to enter the dodecahedral sites with a larger space, and further increasing the effective segregation coefficient of the Ce ions; and the effective segregation coefficient of active Ce ions is increased by means of a radius compensation effect of Sc—Ce ions and adjustment of lattice parameters, thereby the luminescence uniformity of the scintillation crystal is increased and the energy resolution is optimized; and at the same time, the potential barrier for Gd ions entering the octahedral site is increased by Sc ion doping, thereby the probability of the Gd ions entering the octahedral site is reduced, the density of point defects in the scintillation crystal is decreased, and the afterglow intensity is reduced.

2. (canceled)

3. The method for increasing luminescence uniformity and reducing afterglow of the Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal according to claim 1, wherein the Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal is doped with a Me ion, and the Me ion is selected from one or more of a group consisting of Mg, Ca and Li.

4. A Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal, wherein a chemical composition general formula is {Gd.sub.1-x-y-pSc.sub.xCe.sub.yMe.sub.p}.sub.3[Al.sub.1-q].sub.5O.sub.12, and in the general formula, Me is selected from one or more of a group consisting of Mg, Ca and Li. wherein: 0<x≤0.1, 0<y≤0.02, 0≤p≤0.02, 0.4≤q≤≤0.07.

5. The Ce-doped gadolinium-aluminum-gallium garnet structure scintillation crystal according to claim 4, wherein 0.01≤x≤0.05, 0.002≤y≤0.01, 0≤p≤0.003, 0.5≤q≤0.6.

6. A scintillation crystal detector, comprising a scintillation crystal and a photoelectric device, wherein the scintillation crystal is connected with the photoelectric device by an optical medium, the scintillation crystal is the Cr-doped gadolinium-aluminum-gallium garnet structure scintillation crystal according to claims 4, and a reflective material is arranged on the surface of the scintillation crystal.

7. The scintillation crystal detector according to claim 6, wherein the surface roughness Ra of the crystal is R.sub.a≤200 Å, the reflective material is an enhanced specular reflector (ESR) film, a mixture of TiO.sub.2 powder and epoxy resin, a mixture of BaSO.sub.4 powder and epoxy resin, or a mixture of MgO powder and epoxy resin, or a mixture of any two or three of TiO.sub.2 powder, BaSO.sub.4 powder and MgO powder and epoxy resin, and the particle size R of TiO.sub.2 powder. BaSO.sub.4 powder and MgO powder is: 5 mm<R<100 μm.

8. The scintillation crystal detector according to claim 7, wherein the particle size R of TiO.sub.2 powder, BaSO.sub.4 powder and MgO powder is: 100 mm<R<10 μm.

9. The scintillation crystal detector according to claim 6, wherein the photoelectric device is a silicon photomultiplier, a photomuitplier, a photodiode or an avalanche photodiode.

10. The scintillation crystal detector according to claim 6, wherein the optical medium is silicone oil or epoxy optical adhesive, and a refractive index n of the optical medium is >4.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a structure schematic diagram of a scintillation crystal detector based on a scintillation crystal provided by the present disclosure.

[0024] In FIG. 1, 1 denotes a scintillation crystal; 2 denotes a optical medium; 3 denotes a photoelectric device; and 4 denotes a reflective material.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present disclosure provides a garnet structure scintillation crystal composed of Gd, Al, Ga and O as main elements, Which is co-doped with Ce/Sc ions. By doping Sc ions with the ionic radius between Gd ion and Ga ion into the Ce:GAGG or Ce:GGAG crystal, and depending on a radius compensation effect of Sc—Ce ions and adjustment of lattice parameters mainly, the effective segregation coefficient of active ions (Ce ions) is increased, and the density of point defects caused by the non-equilibrium replacement of Gd ions is reduced, thereby the luminescence uniformity of the crystal is increased, the energy resolution is optimized and the afterglow intensity is reduced.

[0026] A chemical composition general formula of the scintillation crystal provided by the present disclosure is: {Gd.sub.1-x-y-pSc.sub.xCe.sub.yMe.sub.p}.sub.3[Al.sub.1-qGa.sub.q].sub.5O.sub.12, where 0<x≤0.1, 0<y≤0.02, 0≤p≤0.02, 0.4≤q≤0.7. In the general formula, Me is selected from one or more of a group consisting of Mg, Ca and Li or it is undoped, namely p is 0.

[0027] In order to guarantee that the comprehensive performance indexes of the crystal such as light output. decay time, energy resolution and luminescence uniformity arc good, and it is easy to prepare a high-quality single crystal by a melt method, the preferred range of x is: 0.01≤x0.05; the preferred range of y is: 0.002≤y≤0.01; the preferred range of p is: 0≤p≤003: and the preferred range of q is: 0.5≤q≤0.6.

[0028] l In the general formula, the doping of Me ions may shorten the decay time of the crystal and reduce the afterglow intensity, while the doping of Se ions may further enhance this effect and improve the luminescence uniformity of the crystal. It is important to note that the doping of Me ions has a lower optical yield and poorer energy resolution than those without doping, and the energy resolution is also worse. Therefore, whether to dope the Me ions depends on the actual application scenario. For example, in the measurement of an energy spectrum, the energy resolution of the crystal is the first indicator of its concern, and at this time, it is not suitable to dope the Me ions, namely p=0; and in the application of time-of-flight positron emission tomography (PET), the coincidence time resolution of the system is the first indicator of its concern, and at this time, it is necessary to dope an appropriate amount of the Me ions to shorten the decay time of the crystal, namely p>0. However, whether to dope the Me ions or not, the doping of Se ions may further optimize the luminescence uniformity. energy resolution and afterglow intensity of the crystal.

[0029] In the general formula. Sc ions with the content of x do not only occupy the dodecahedral site.

[0030] In fact. the Se ions occupy the octahedral site preferentially. Only while, the number of the Sc ions in the octahedral site reaches a certain characteristic value (x≥0.01), it may enter the dodecahedral site. Under normal conditions, the Sc ions occupy both the octahedral site and the dodecahedral site, it means that the Sc ions exist at both sites. The Sc ions occupying the dodecahedral site are replaced by Gd ions, and the radius of the Gd ion is between Ce ion and. Sc ion (R.sub.Ce>R.sub.Gd>R.sub.Sc). Therefore, after Sc enters the dodecahedral site, it is easier for Ce ions to enter the dodecahedral site by the radius compensation effect, namely it may increase the effective segregation coefficient of the Ce ions; and the Sc ions occupying the octahedral site are replaced by Ga ions, and because the Ga ionic radius is smaller than the Sc ionic radius, after the Sc ions enter the octahedral site, it may increase the lattice parameters, and also facilitate the Ce ions entering the dodecahedral site with the larger space, namely the effective segregation coefficient of the Ce ions is further increased.

[0031] In the general formula. Gd ions with the content of 1-x-y-p do not all occupy the dodecahedral site, and a small number of the Gd ions still enter the octahedral site, namely non-equilibrium replacement, an antisite defect is formed. The doping of Sc ions may reduce the probability of Gd ions entering the octahedral site, this is because the doping of the Sc ions increases the potential barrier of the Gd ions entering the octahedral site. Therefore, the doping of the Se ions may reduce the density of point defects in the crystal and weaken the afterglow.

[0032] The preparation method for the scintillation crystal provided by the present disclosure is mainly a melt method, including but not limited to Czochralski method (Cz), Bridgman method (Bridgman), horizontal directional crystallization method (HDC), edge-defined film-fed growth method (EFG) and the like. In order to obtain a high-quality single crystal with a large size, the preferred preparation method is the Czochralski method.

[0033] The use form of the scintillation crystal provided by the present disclosure may be a crystal column, a crystal sheet, a crystal block or a crystal, array, and it is connected with a photoelectric device 3 by an optical medium 2. A reflective material 4 s arranged on the surface of the scintillation crystal 1, to form a scintillation crystal detector, and its structure is shown in FIG. 1.

[0034] The surface roughness Ra of the crystal is Ra≤200 Å, the reflective material may be an ESR film, a mixture of TiO.sub.2 powder and epoxy resin, a mixture of BaSO.sub.4 powder and epoxy resin, or a mixture of MgO powder and epoxy resin, or a mixture of any two or three of TiO.sub.2 powder, BaSO.sub.4 powder and MgO powder and epoxy resin, and the particle size R of TiO.sub.2 powder, BaSO.sub.4 powder and MgO powder is: 5 nm<R<100 μm; and in order to obtain the higher reflectivity, the preferred range of the particle size is: 100 nm<R<10 μm. The above three types of powder may be mixed in any ratios, the volume ratio of the powder to the epoxy resin is controlled between 100:1 to 1:2, and the most preferred range is between 30:1 to 2:1.

[0035] The photoelectric device 3 is a silicon photomultiplier (SiPM), a photomultiplier (PMT), a photodiode (PD), an avalanche photodiode (APD) and the like. In order to obtain the better energy resolution, it is best to choose SiPM.

[0036] The optical medium 2 connected with the scintillation crystal 1 and the photoelectric device 3 is silicone oil epoxy optical adhesive and the like, and its refractive index n is >1.4.

[0037] The scintillation crystal provided by the present disclosure may be used for detection of X-rays, γ-rays, electrons, neutrons, u-ions and other charged ions. The specific application fields contain: PET, SPECT, petroleum logging, security inspection, industrial CT, high-energy physics, nuclear physics and the like.

[0038] The difference between the present disclosure and Ce: GAGG or Ce: GGAG crystal reported in the existing documents or patents is that: the Sc ions occupy at least the octahedral site, and the best choice is that the Sc ions occupy both the octahedral site and the dodecahedral site. After the Sc ions enter the crystal site, on the one hand, it may increase the effective segregation coefficient of the Ce ions, and on the other hand, it may effectively inhibit the formation of Gd—Al antisite defects. By increasing the effective segregation coefficient of the Ce ions, the non-uniformity of Ce ion distribution in the crystal may be improved under the same crystallization ratio, and then the luminescence uniformity of the crystal is increased, and finally the energy resolution of the crystal is improved. This is essentially different from other methods to improve the luminescence uniformity and energy resolution of the crystal.

[0039] In addition, it is important to noted that: in the present disclosure, both of Sc and Ga two elements must exist in the crystal at the same time, and the Sc ions should occupy not only the octahedral site, but also the dodecahedral site, in order to obtain the excellent energy resolution and luminescence uniformity; the concentration range of Sc ion doping in the present disclosure shall satisfy: 0≤x≤0.1. After the Se ions enter the crystal site, on the one hand, it may increase the effective segregation coefficient of the Ce ions, and on the other hand, it may effectively inhibit the formation of Gd—Al antisite defects. If x>0.1, it may cause the conduction band bottom of the crystal to move up, then reduce the light output of the crystal, so the good energy resolution may not be obtained; and the present disclosure proposes that in order to obtain the good energy resolution and luminescence uniformity, it is necessary to guarantee that the effective segregation coefficient K.sub.eff of the Ce ions is ≥0.28. The present disclosure proposes that in order to further reduce the afterglow, intensity, it is better to doping the Me ion, and the Me ion is selected from one or more of a group consisting of Mg, Ca and Li; and in addition, the present disclosure may not contain Lu element, because β decay produced by .sup.138Lu may cause the crystal to produce radioactive background.

[0040] The technical schemes and effects of the present disclosure are further described below in combination with embodiments and contrast examples.

[0041] Embodiment 1: Gd.sub.0.98Sc.sub.0.01Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Scintillation Crystal and Performance

[0042] According to the raw material compositions specified in the chemical formula Gd.sub.0.98Sc.sub.0.01Ce.sub.0.07A;.sub.2Ga.sub.3O.sub.12, Gd.sub.2O.sub.3, Sc.sub.2O.sub.3, CeO.sub.2, Al.sub.2O.sub.3 and Ga.sub.2O.sub.3 powder raw materials were weighed according to the stoichiometric ratio. The purity was 99.999%, and the total mass was 4.0 kg. A crystal with a diameter of 40 mm was grown by Czochralski method. In the growth process, a mixed gas of 98% of N.sub.2 and 2% of O.sub.2 was fed as a protective atmosphere. The pulling speed was 1 mm/h, the revolution speed was 15 rpm, the cooling time was 20 hours, and the crystallization ratio of the crystal was 43%. In order to compare the effects of doping the Sc ion on the effective segregation coefficient, luminescence uniformity, energy resolution and afterglow intensity of the crystal, the same size crystal with the Gd.sub.0.99Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 composition was grown by the same method and process parameters. About 10 g of a sample was respectively taken from heads of two crystals close to a seed crystal in order to test concentration of Ce ions, and the effective segregation coefficient was calculated; a sample of 5 mm×5 mm×5 mm was respectively taken from the head (crystallization ratio g≈2%) and tail (crystallization ratio g≈40%) of two crystals in order to test light output, decay time and afterglow, and the uniformity of crystal light output was calculated; and a columnar crystal of Dia.25 mm×25 mm was respectively cut from equal-diameter parts of two crystals in order to test the energy resolution. The samples for comparison were taken from the same part of different crystals, and it was guaranteed that all test conditions were consistent. Since the light output and energy resolution were related to the test conditions, and the effective segregation coefficient was related to the growth conditions and environment, all test results had only its relative significance. Its test results were shown in Table 1:

TABLE-US-00001 TABLE 1 Performance parameters of Gd.sub.0.98Sc.sub.0.01Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 crystal Crystal composition Gd.sub.0.99Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Gd.sub.0.98Sc.sub.0.01Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Effective segregation coefficient 0.21 0.29 Head light output (photons/MeV) 48500 48000 Tail light output (photons/MeV) 45000 46500 Decay time (ns) 138 140 Afterglow intensity (@100 ms) 0.6% 0.4% 1-inch sample energy resolution (@662 keV) 8.1% 6.3%

[0043] Embodiment 2: Gd.sub.0.95 SC.sub.0.04Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Scintillation Crystal and Performance

[0044] According to the raw material compositions specified in, the chemical formula Gd.sub.0.95Sc.sub.0.04Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12, Gd.sub.2O.sub.3, Sc.sub.2O.sub.3, Sc.sub.2O.sub.3, CeO.sub.2, Al.sub.2O.sub.3 powder raw materials were weighed according to the stoichiometric ratio. The purity was 99.999%, and the total mass was 4.0 kg. A crystal with a diameter of 40 mm was grown by Czochralski method. In the growth process, a mixed gas of 98% of N.sub.2 and 2% of O.sub.2 was fed as a protective atmosphere. The pulling speed was 1 mm/h, the revolution speed was 15 rpm, the cooling time was 20 hours, and the crystallization ratio of the crystal was 43%. In order to compare the effects of doping the Sc ion on the effective segregation coefficient, luminescence uniformity, energy resolution and afterglow intensity of the crystal, the same size crystal with the Gd.sub.0.99Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 composition was grown by the same method and process parameters. About 10 g of a sample was respectively taken from heads of two crystals close to a seed crystal in order to test the concentration of Ce ions, and the effective segregation coefficient was calculated; a sample of 5 mm×5 mm×5 mm was respectively taken from the head (crystallization ratio g≈2%) and tail (crystallization ratio g≈40%) of two crystals in order to test the light output, decay time and afterglow. and the uniformity of crystal light output was calculated; and a columnar crystal of Dia.25 mm×25 mm was respectively cut from equal-diameter parts of two crystals in order to test the energy resolution. The samples for comparison were taken from the same part of different crystals, and it was guaranteed that all test conditions were consistent, Since the light output and energy resolution were related to the test conditions, and the effective segregation coefficient was related to the growth conditions and environment, all test results had only its relative significance. Its test results were shown in Table 2.

TABLE-US-00002 TABLE 2 Performance parameters of Gd.sub.0.95Sc.sub.0.04Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 crystal Crystal composition Gd.sub.0.99Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Gd.sub.0.95Sc.sub.0.04Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Effective segregation coefficient 0.21 0.38 Head light output (photons/MeV) 48500 47500 Tail light output (photons/MeV) 45000 46500 Decay time (ns) 138 142 Afterglow intensity (@100 ms) 0.6% 0.3% 1-inch sample energy resolution (@662 keV) 8.1% 6.0%

[0045] Embodiment 3: Gd.sub.0.978Sc.sub.0.01Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Scintillation Crystal and Performance

[0046] According to the raw material compositions specified in the chemical formula Gd.sub.0.979Sc.sub.0.01Mg.sub.0.001Ce.sub.0.001Al.sub.2Ga.sub.3O.sub.12, Gd.sub.2O.sub.3, Sc.sub.2O.sub.3, CeO.sub.2, Al.sub.2O.sub.3, Ga.sub.2O.sub.3 and MgCO.sub.3 powder raw materials were weighed according to the stoichiometric ratio. The purity was 99.999%, and the total mass was 4.0 kg. A crystal with a diameter of 40 mm was grown by Czochralski method. In the growth process, a mixed gas of 98% of N.sub.2 and 2% of O.sub.2 was fed as a protective atmosphere. The pulling speed was 1 mm/h, the revolution speed was 15 rpm, the cooling time was 20 hours, and the crystallization ratio of the crystal was 43%. In order to compare the effects of doping the Sc ion on the effective segregation coefficient, luminescence uniformity, energy resolution and afterglow intensity of the crystal, the same size crystal with the Gd.sub.0.989Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 composition was grown by the same method and process parameters. About 10 g of a sample was respectively taken from heads of two crystals close to a seed crystal in order to test the concentration of Ce ions and the effective segregation coefficient was calculated; a sample of 5 mm×5 mm×5 mm was respectively taken from the head (crystallization ratio g≈2%) and tail (crystallization ratio g≈40%) of two crystals in order to test the light output, decay time and afterglow. and the uniformity of crystal light output was calculated; and a columnar crystal of Dia.25 mmx×25 mm was respectively cut from equal-diameter parts of two crystals in order to test the energy resolution. The samples for comparison were taken from the same part of different crystals, and it was guaranteed that all test conditions were consistent. Since the light output and energy resolution were related to the test conditions, and the effective segregation coefficient was related to the growth conditions and environment, all test results had only its relative significance. Its test results were shown in Table 3:

TABLE-US-00003 TABLE 3 Performance parameters of Gd.sub.0.979Sc.sub.0.01Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 crystal Crystal composition Gd.sub.0.989Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Gd.sub.0.979Sc.sub.0.01Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Effective segregation coefficient 0.22 0.40 Head light output (photons/MeV) 42000 42000 Tail light output (photons/MeV) 38000 41000 Decay time (ns) 72 72 Afterglow intensity (@100 ms) 0.03% 0.02% 1-inch sample energy resolution  9.0%  7.6% (@662 keV)

[0047] Embodiment 4: Gd.sub.0.949Sc.sub.0.04Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Scintillation Crystal and Performance

[0048] According to the raw material compositions specified in the chemical formula Gd.sub.0.949Sc.sub.0.04Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12, Gd.sub.2O.sub.3, Sc.sub.2O.sub.3, CeO.sub.2, Al.sub.2O.sub.3, Ga.sub.2O.sub.3 and MgCO.sub.3 powder raw materials were weighed according to the stoichiometric ratio. The purity was 99.999%, and the total mass was 4.0 kg. A crystal with a diameter of 40mm was grown by Czochralski method. In the growth process, a mixed gas of 98% of N.sub.2 and 2% of P.sub.2 was fed as a protective atmosphere. The pulling speed was 1 mm/h, the revolution speed was 15 rpm, the cooling time was 20 hours, and the crystallization ratio of the crystal was 43%. In order to compare the effects of Se ion doping on the effective segregation coefficient, luminescence uniformity, energy resolution and afterglow intensity of the crystal, the same size crystal with the Gd.sub.0.989Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 composition was grown by using the same method and process parameters. About 10 g of a sample was respectively taken from heads of two crystals close to a seed crystal in order to test the concentration of Ce ions, and the effective segregation coefficient was calculated: a sample of 5 mm×5 mm≈40%) of two crystals in order to test the light output, decay time and afterglow, and the uniformity of crystal light output was calculated; and a columnar crystal of Dia.25 mm×25 mm was respectively cut from equal-diameter parts of two crystals in order to test the energy resolution. The samples for comparison were taken from the same part of different crystals, and it was guaranteed that all test conditions were consistent. Since the light output and energy resolution were related to the test conditions, and the effective segregation coefficient was related to the growth conditions and environment, all test results had only its relative significance. Its test results were shown in Table 3:

TABLE-US-00004 TABLE 4 Performance parameters of Gd.sub.0.949Sc.sub.0.04Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 crystal Crystal composition Gd.sub.0.989Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Gd.sub.0.949Sc.sub.0.04Mg.sub.0.001Ce.sub.0.01Al.sub.2Ga.sub.3O.sub.12 Effective segregation coefficient 0.22 0.46 Head light output (photons/MeV) 42000 41000 Tail light output (photons/MeV) 38000 40500 Decay time (ns) 72 74 Afterglow intensity (@100 ms) 0.03% 0.01% 1-inch sample energy resolution  9.0%  7.8% (@662 keV)

[0049] The above embodiments of the present disclosure are only examples listed to describe the present disclosure, not to limit implementation modes of the present disclosure. For those of ordinary skill in the art, other changes and variations in different forms may be made on the basis of the above descriptions. It is impossible to enumerate all the implementation modes here. All apparent changes or variations derived from the technical schemes of the present disclosure ate still within a scope of protection of the present disclosure.