The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC cryst...The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.展开更多
Zirconium oxide(ZrO2) and boron carbide(B4C) were added to Zr B2 raw powders to prepare Zr B2 porous ceramics by reactive spark plasma sintering(RSPS). The reactions between Zr O2 and B4 C which produce Zr B2 and gas(...Zirconium oxide(ZrO2) and boron carbide(B4C) were added to Zr B2 raw powders to prepare Zr B2 porous ceramics by reactive spark plasma sintering(RSPS). The reactions between Zr O2 and B4 C which produce Zr B2 and gas(such as CO and B2O3) result in pore formation. X-Ray Diffraction results indicated that the products phase was Zr B2 and the reaction was completed after the RSPS process. The porosity could be controlled by changing the ratio of synthesized Zr B2 to raw Zr B2 powders. The porosity of porous ceramics with 20 wt% and 40 wt% synthsized ZrB2 are 0.185 and 0.222, respectivly. And dense Zr B2-Si C ceramic with a porosity of 0.057 was prepared under the same conditions for comparison. The pores were homogeneously distributed within the microstructure of the porous ceramics. The results indicate a promising method for preparing porous Zr B2-based ceramics.展开更多
Whereas the light yield of PWO crystal can be significantly improved by doping with either of F- and Sb3+, effects of heavily co-doping with by F-+Sb3+, F-+Ca2+, and F-+Ca2++Sb3+, respectively, on the properties of PW...Whereas the light yield of PWO crystal can be significantly improved by doping with either of F- and Sb3+, effects of heavily co-doping with by F-+Sb3+, F-+Ca2+, and F-+Ca2++Sb3+, respectively, on the properties of PWO scintillation crystals, including optical transmission, luminescence and light yield were studied. The result indicates that co-doping with three dopants, F-+Ca2++Sb3+, is a more effective measure than doping with single dopant F- for the improvement of scintillation properties of PWO crystals, including light yield.展开更多
Loss of light yield of doped lead tungstate crystals after irradiation with a low dose rate has been observed.The La,Pr,and Y doping may improve radiation hardness,whereas Bi or Mo doping is harmful.
The effect of Y and Sb co-doping on the luminescence property of PbWO 4 crystals has been investigated. Compared with undoped PbWO4, the transmittance and emission peak intensity of Y∶Sb∶PbWO 4 crystals were obvious...The effect of Y and Sb co-doping on the luminescence property of PbWO 4 crystals has been investigated. Compared with undoped PbWO4, the transmittance and emission peak intensity of Y∶Sb∶PbWO 4 crystals were obviously improved. In addition, its transmittance cutoff wavelength and emission peak shifted to the shorter one. The mechanism of effect of Y and Sb on the transmittance spectra was briefly discussed. The light yield of Y∶Sb∶PbWO 4 crystals was 25p.e./MeV, which was two times of that of undoped PbWO 4. Our experiments showed that Y and Sb co-doping was a selectable method to improve the luminescence property of PbWO 4.展开更多
Introduction The main physical objective of the GECAM satellite is to detect gamma-ray bursts,which is related to gravitational waves of double compact object mergers.The GECAM satellite also detects and investigates ...Introduction The main physical objective of the GECAM satellite is to detect gamma-ray bursts,which is related to gravitational waves of double compact object mergers.The GECAM satellite also detects and investigates various bursts of high-energy celestial bodies.Purposes and methods In this study,we designed,developed and calibrated the payload and launched it into orbit with GECAM satellite.The payload consists of the gamma ray detector(GRD,for detecting 4 keV–4 MeV X/γray),the charged particle detector(CPD,for detecting 150 keV–5 MeV charged particle),and the electronic box(EBOX).The all-sky field coverage is achieved via two 229-degree large-area satellites positioned 180 degrees apart and are on opposite sides of the geo-center.Each satellite is equipped with 25 GRDs and 8 CPDs;thus,the satellite can identify charged particle bursts in space.Gamma-ray detectors adopt lanthanum bromide crystal technology combined with silicon photomultipliers.This is the first time that this technology was used massively in space detectors.Conclusions The GECAM satellite can quickly determine the direction of gamma-ray bursts(positioning)via indexing and fitting method,while the transmit variability,energy spectrum and direction of the gamma-ray bursts guide subsequent observations through the Beidou-3 RDSS in quasi-real time.It will play an important role in the study of high energy celestial bursts.展开更多
We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of...We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.展开更多
基金supported by the National Natural Science Foundation of China(No.11575145)
文摘The first domestic inorganic scintillator, Cs_2LiYCl_6:Ce^(3+)(CLYC), was grown at Beijing Glass Research Institute using the vertical Bridgman method. In this work, we evaluated the performance of this new CLYC crystal in terms of its gamma-ray energy resolution and pulse shape discrimination(PSD) capability between neutrons and gamma rays. The decay times associated with different scintillation mechanisms were obtained by fitting decay functions to the neutron and gamma-ray waveform structures. We found an energy resolution of * 4.5% for 662-ke V gamma rays and efficient neutron/gamma PSD with a figure of merit of * 2.6. Under gamma-ray excitation, there is an ultrafast scintillation mechanism in CLYC with a decay time of approximately 2 ns, whereas there is no evidence of ultrafast decay under thermal neutron excitation. This work contributes to the promotion of domestic development of CLYC.
基金Funded by the National Natural Science Foundation of China(No.51272190)the 111 Project(No.B13035)
文摘Zirconium oxide(ZrO2) and boron carbide(B4C) were added to Zr B2 raw powders to prepare Zr B2 porous ceramics by reactive spark plasma sintering(RSPS). The reactions between Zr O2 and B4 C which produce Zr B2 and gas(such as CO and B2O3) result in pore formation. X-Ray Diffraction results indicated that the products phase was Zr B2 and the reaction was completed after the RSPS process. The porosity could be controlled by changing the ratio of synthesized Zr B2 to raw Zr B2 powders. The porosity of porous ceramics with 20 wt% and 40 wt% synthsized ZrB2 are 0.185 and 0.222, respectivly. And dense Zr B2-Si C ceramic with a porosity of 0.057 was prepared under the same conditions for comparison. The pores were homogeneously distributed within the microstructure of the porous ceramics. The results indicate a promising method for preparing porous Zr B2-based ceramics.
文摘Whereas the light yield of PWO crystal can be significantly improved by doping with either of F- and Sb3+, effects of heavily co-doping with by F-+Sb3+, F-+Ca2+, and F-+Ca2++Sb3+, respectively, on the properties of PWO scintillation crystals, including optical transmission, luminescence and light yield were studied. The result indicates that co-doping with three dopants, F-+Ca2++Sb3+, is a more effective measure than doping with single dopant F- for the improvement of scintillation properties of PWO crystals, including light yield.
基金Supported by the Chinese Academy of Sciences under Grant No.006.
文摘Loss of light yield of doped lead tungstate crystals after irradiation with a low dose rate has been observed.The La,Pr,and Y doping may improve radiation hardness,whereas Bi or Mo doping is harmful.
文摘The effect of Y and Sb co-doping on the luminescence property of PbWO 4 crystals has been investigated. Compared with undoped PbWO4, the transmittance and emission peak intensity of Y∶Sb∶PbWO 4 crystals were obviously improved. In addition, its transmittance cutoff wavelength and emission peak shifted to the shorter one. The mechanism of effect of Y and Sb on the transmittance spectra was briefly discussed. The light yield of Y∶Sb∶PbWO 4 crystals was 25p.e./MeV, which was two times of that of undoped PbWO 4. Our experiments showed that Y and Sb co-doping was a selectable method to improve the luminescence property of PbWO 4.
基金This project is supported by National Natural Science Foundation of China(12173038)the strategic leading science and technology program(XDA 15360100,XDA 15360102)of the Chinese Academy of Sciences.
文摘Introduction The main physical objective of the GECAM satellite is to detect gamma-ray bursts,which is related to gravitational waves of double compact object mergers.The GECAM satellite also detects and investigates various bursts of high-energy celestial bodies.Purposes and methods In this study,we designed,developed and calibrated the payload and launched it into orbit with GECAM satellite.The payload consists of the gamma ray detector(GRD,for detecting 4 keV–4 MeV X/γray),the charged particle detector(CPD,for detecting 150 keV–5 MeV charged particle),and the electronic box(EBOX).The all-sky field coverage is achieved via two 229-degree large-area satellites positioned 180 degrees apart and are on opposite sides of the geo-center.Each satellite is equipped with 25 GRDs and 8 CPDs;thus,the satellite can identify charged particle bursts in space.Gamma-ray detectors adopt lanthanum bromide crystal technology combined with silicon photomultipliers.This is the first time that this technology was used massively in space detectors.Conclusions The GECAM satellite can quickly determine the direction of gamma-ray bursts(positioning)via indexing and fitting method,while the transmit variability,energy spectrum and direction of the gamma-ray bursts guide subsequent observations through the Beidou-3 RDSS in quasi-real time.It will play an important role in the study of high energy celestial bursts.
文摘We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.
