Rockburst problems induced by high in-situ stresses were prominent during construction of the headrace tunnels of Jinping II hydropower station. The rockbursts occurred in various forms, and it is necessary to take pe...Rockburst problems induced by high in-situ stresses were prominent during construction of the headrace tunnels of Jinping II hydropower station. The rockbursts occurred in various forms, and it is necessary to take pertinent measures for integrated prevention and control of rockbursts. In view of the rockburst characteristics during tunnel construction of Jinping II hydropower station, the engineering geological conditions were presented, and the features, mechanisms and forms of rockbursts observed during construction were analyzed in detail. A large number of scientific researches, experiments and applications were conducted. Multiple measures were adopted to prevent and control rockbursts, including the prediction and early warning measures, stress relief by blasting in advance, optimized blasting design and optimized tunnel support in the tunnel sections prone to strong rockbursts. The effectiveness of these prevention and control measures was evaluated. Experiences have been accumulated through a great number of helpful explorations and practices for rockburst prevention and control. A comprehensive rockburst prevention and control system has been gradually established.展开更多
We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been instal...We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.展开更多
The CDEX-10 experiment searches for light weakly interacting massive particles, a form of dark matter, at the China Jinping Underground Laboratory, where approximately 10 kg of germanium detectors are arranged in an a...The CDEX-10 experiment searches for light weakly interacting massive particles, a form of dark matter, at the China Jinping Underground Laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher rise-time resolution of the CDEX-10 prototype detector as compared with CDEX-1 B, we identified the origin of an observed category of extremely fast events. For data analysis of the CDEX-10 prototype detector, we introduced and applied an improved bulk/surface event discrimination method. The results of the new method were compared to those of the CDEX-1 B spectrum. Both sets of results showed good consistency in the 0-12 ke Vee energy range, except for the 8.0 keV K-shell X-ray peak from the external copper.展开更多
In this work, Er-doped aluminum nitride(AlN), Pr-doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. ...In this work, Er-doped aluminum nitride(AlN), Pr-doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. Some new and interesting phenomena were observed. The peak at 480 nm was observed only for Er-doped AlN. However, for Er, Pr co-doped AlN, it disappeared. At the same time, a new peak at 494 nm was observed,although it was not observed for Er-doped AlN or Pr-doped AlN before. Therefore, the energy transfer mechanism between Er^3+and Pr^3+in AlN thin films was investigated in detail. Through optimizing the dose ratio of Er^3+with respect to Pr^3+, white light emission with an International Commission on Illumination chromaticity coordinate(0.332, 0.332) was obtained. This work may provide a new strategy for realizing white light emission based on nitride semiconductors.展开更多
文摘Rockburst problems induced by high in-situ stresses were prominent during construction of the headrace tunnels of Jinping II hydropower station. The rockbursts occurred in various forms, and it is necessary to take pertinent measures for integrated prevention and control of rockbursts. In view of the rockburst characteristics during tunnel construction of Jinping II hydropower station, the engineering geological conditions were presented, and the features, mechanisms and forms of rockbursts observed during construction were analyzed in detail. A large number of scientific researches, experiments and applications were conducted. Multiple measures were adopted to prevent and control rockbursts, including the prediction and early warning measures, stress relief by blasting in advance, optimized blasting design and optimized tunnel support in the tunnel sections prone to strong rockbursts. The effectiveness of these prevention and control measures was evaluated. Experiences have been accumulated through a great number of helpful explorations and practices for rockburst prevention and control. A comprehensive rockburst prevention and control system has been gradually established.
基金supported by the National Natural Science Foundation of China(Grant Nos.11275107,11475117,11475099,and 11675088)the National Key Basic Research Program of China(Grant No.2010CB833006)
文摘We report the first results on 76Ge neutrinoless double beta decay from stage one of the China dark-matter experiment （CDEX）. A p-type point-contact high-purity germanium detector with a mass of 994g has been installed to detect neutrinoless double beta decay events, as well as to directly detect dark matter particles. An exposure of 304kgd has been analyzed over a wide spectral band from 500keV to 3MeV. The average event rate obtained was about 0.012 counts per keV per kg per day over the 2.039MeV energy range. The half-life of76Ge neutrinoless double beta decay derived based on this result is 70v2〉6.4× 1022 yr （90%C.L.）. An upper limit on the effective Majorana-neutrino mass of 5.0eV has been achieved.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0402201)the National Natural Science Foundation of China(Grant Nos.11475092,11475099,11675088,and 11725522)
文摘The CDEX-10 experiment searches for light weakly interacting massive particles, a form of dark matter, at the China Jinping Underground Laboratory, where approximately 10 kg of germanium detectors are arranged in an array and immersed in liquid nitrogen. Herein, we report on the experimental apparatus, detector characterization, and spectrum analysis of one prototype detector. Owing to the higher rise-time resolution of the CDEX-10 prototype detector as compared with CDEX-1 B, we identified the origin of an observed category of extremely fast events. For data analysis of the CDEX-10 prototype detector, we introduced and applied an improved bulk/surface event discrimination method. The results of the new method were compared to those of the CDEX-1 B spectrum. Both sets of results showed good consistency in the 0-12 ke Vee energy range, except for the 8.0 keV K-shell X-ray peak from the external copper.
基金supported by the National Natural Science Foundation of China(Nos.61306004 and51002179)the Program of Suzhou Key Laboratory for Low Dimensional Optoelectronic Materials and Devices(No.SZS201611)+1 种基金the Jiangsu Key Disciplines of 13th Five-Year Plan(No.20168765)the Graduate Research and Practice Innovation Project of USTS(Nos.SKCX18_Y11 and SKCX17_034)
文摘In this work, Er-doped aluminum nitride(AlN), Pr-doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. Some new and interesting phenomena were observed. The peak at 480 nm was observed only for Er-doped AlN. However, for Er, Pr co-doped AlN, it disappeared. At the same time, a new peak at 494 nm was observed,although it was not observed for Er-doped AlN or Pr-doped AlN before. Therefore, the energy transfer mechanism between Er^3+and Pr^3+in AlN thin films was investigated in detail. Through optimizing the dose ratio of Er^3+with respect to Pr^3+, white light emission with an International Commission on Illumination chromaticity coordinate(0.332, 0.332) was obtained. This work may provide a new strategy for realizing white light emission based on nitride semiconductors.
