In order to push the grating-based phase contrast imaging system to be used in hospitM and laboratories, this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating,...In order to push the grating-based phase contrast imaging system to be used in hospitM and laboratories, this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating, which has been proposed for grating-based x-ray differential phase contrast imaging. According to this design, the scintillator should have a periodical structure in one dimension with the pitch equaling the period of self-image of the phase grating at the Talbot distance, where one half of the pitch is pixellated and is made of x-ray sensitive fluorescent material, such as CsI（T1）, and the remaining part of the pitch is made of x-ray insensitive material, such as silicon. To realize the design, a deep pore array with a high aspect ratio and specially designed grating pattern are successfully manufactured on 5 inch silicon wafer by the photo-assisted electrochemical etching method. The related other problems, such as oxidation-caused geometrical distortion, the filling of CsI（T1） into deep pores and the removal of inside bubbles, have been overcome. Its pixel size, depth and grating pitch are 3 p.m^7.5 ~m, 150 p^m and 3 Ixm, respectively. The microstructure of the scintillator has been examined microscopically and macroscopically by scanning electron microscope and x-ray resolution chart testing, respectively. The preliminary measurements have shown that the proposed scintillator, also functioning as an analyser grating, has been successfully designed and developed.展开更多
CDEX(China Dark matter EXperiment)合作组将在中国锦屏极深地下实验室(CJPL China Jin-Ping deep underground Laboratory)利用极低能阈高纯锗(ULE-HPGe)探测器进行暗物质的直接探测。在地下实验之前,对CsI(Tl)晶体反符合探测器进行...CDEX(China Dark matter EXperiment)合作组将在中国锦屏极深地下实验室(CJPL China Jin-Ping deep underground Laboratory)利用极低能阈高纯锗(ULE-HPGe)探测器进行暗物质的直接探测。在地下实验之前,对CsI(Tl)晶体反符合探测器进行了地面的实验研究。主要包括光导的选择,光反射层的选择,CsI(Tl)晶体的高度一致性测试,不同侧面非均匀性的测试,以及所有晶体的测试结果。通过地面实验的前期工作,我们对反符合探测器有了一定认识,为地下实验做了准备。展开更多
In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, se...In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to electromagnetic signal transmission from a NaI（TI） radiation detector is presented. The innovative device takes advantage mainly of the optical fibers large passband, small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches.展开更多
The inorganic CsI（Tl） crystal scintillator is a candidate anti-compton detector for the China Dark matter Experiment. Studying the intrinsic radiopurity of the CsI（Tl） crystal is an issue of major importance. The ...The inorganic CsI（Tl） crystal scintillator is a candidate anti-compton detector for the China Dark matter Experiment. Studying the intrinsic radiopurity of the CsI（Tl） crystal is an issue of major importance. The timing, energy and spatial correlations, as well as the capability of pulse shape discrimination provide powerful methods for the measurement of intrinsic radiopurities. The experimental design, detector performance and event-selection algorithms are described. A total of 359×3 kg-days data from three prototypes of CsI（Tl） crystals were taken at China Jinping Underground Laboratory （CJPL）, which offers a good shielding environment. The contamination levels of internal isotopes from 137Cs, 232Th and 238U series, as well as the upper bounds of 235U series are reported. Identification of the whole α peaks from U/Th decay chains and derivation of those corresponding quenching factors are achieved.展开更多
The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, ...The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.展开更多
CsI film has been one of the most extensively used scintillators for indirect X-ray imaging because of its needle-like micro-structure. The purpose of this paper is to investigate the imaging performance of CsI screen...CsI film has been one of the most extensively used scintillators for indirect X-ray imaging because of its needle-like micro-structure. The purpose of this paper is to investigate the imaging performance of CsI screen as a function of thickness and radiation quality. Four multilayer scintillation screens with microcolumnar CsI：T1 film （thicknesses of 50 μm, 100 μm, 200μm and 300 μm） included were prepared and coupled to an optical imaging sensor. The modulation transfer function （MTF）, normalized noise power spectrum （NNPS） and detective quantum efficiency （DQE） of these screens were evaluated based on the standard IEC 62220-1, and the results indicated that, in the medium spatial frequency range （1-6 lp/mm）, the MTF of CsI screens with the same thickness was lower when the incident X-ray photon energy was higher, possibly owing to scattering and K-fluorescence re-absorption effects. The NNPS in the higher spatial frequency range （above 8 lp/mm） is dominated by stochastic noise while the entrance surface air Kerma （ESAK） decreases. For 100 μm, 200 μm and 300 μm thick CsI screens, the DQE under RQA7 and RQA9 is lower than that under RQA3 and RQA5 due to low absorption efficiency.展开更多
基金supported by the Major Program of the National Natural Science Foundation of China (Grant No. 60532090)
文摘In order to push the grating-based phase contrast imaging system to be used in hospitM and laboratories, this paper designs and develops a novel structure of x-ray scintillator functioning also as an analyser grating, which has been proposed for grating-based x-ray differential phase contrast imaging. According to this design, the scintillator should have a periodical structure in one dimension with the pitch equaling the period of self-image of the phase grating at the Talbot distance, where one half of the pitch is pixellated and is made of x-ray sensitive fluorescent material, such as CsI（T1）, and the remaining part of the pitch is made of x-ray insensitive material, such as silicon. To realize the design, a deep pore array with a high aspect ratio and specially designed grating pattern are successfully manufactured on 5 inch silicon wafer by the photo-assisted electrochemical etching method. The related other problems, such as oxidation-caused geometrical distortion, the filling of CsI（T1） into deep pores and the removal of inside bubbles, have been overcome. Its pixel size, depth and grating pitch are 3 p.m^7.5 ~m, 150 p^m and 3 Ixm, respectively. The microstructure of the scintillator has been examined microscopically and macroscopically by scanning electron microscope and x-ray resolution chart testing, respectively. The preliminary measurements have shown that the proposed scintillator, also functioning as an analyser grating, has been successfully designed and developed.
文摘CDEX(China Dark matter EXperiment)合作组将在中国锦屏极深地下实验室(CJPL China Jin-Ping deep underground Laboratory)利用极低能阈高纯锗(ULE-HPGe)探测器进行暗物质的直接探测。在地下实验之前,对CsI(Tl)晶体反符合探测器进行了地面的实验研究。主要包括光导的选择,光反射层的选择,CsI(Tl)晶体的高度一致性测试,不同侧面非均匀性的测试,以及所有晶体的测试结果。通过地面实验的前期工作,我们对反符合探测器有了一定认识,为地下实验做了准备。
文摘In the last years, the production of optical fibers cables has made possible the development of a range of spectroscopic probes for in situ analysis performing beyond nondestructive tests, environmental monitoring, security investigation, application in radiotherapy for dose monitoring, verification and validation. In this work, a system using an optical fiber cable to electromagnetic signal transmission from a NaI（TI） radiation detector is presented. The innovative device takes advantage mainly of the optical fibers large passband, small signal attenuation and immunity to electromagnetic interference to application for radiation detection systems. The main aim was to simplify the detection system making it to reach areas where the conventional device cannot access due to its lack of mobility and external dimensions. Some tests with this innovative system are presented and the results stimulate the continuity of the researches.
基金Supported by National Natural Science Foundation of China(11275107,11175099)
文摘The inorganic CsI（Tl） crystal scintillator is a candidate anti-compton detector for the China Dark matter Experiment. Studying the intrinsic radiopurity of the CsI（Tl） crystal is an issue of major importance. The timing, energy and spatial correlations, as well as the capability of pulse shape discrimination provide powerful methods for the measurement of intrinsic radiopurities. The experimental design, detector performance and event-selection algorithms are described. A total of 359×3 kg-days data from three prototypes of CsI（Tl） crystals were taken at China Jinping Underground Laboratory （CJPL）, which offers a good shielding environment. The contamination levels of internal isotopes from 137Cs, 232Th and 238U series, as well as the upper bounds of 235U series are reported. Identification of the whole α peaks from U/Th decay chains and derivation of those corresponding quenching factors are achieved.
文摘The CsI（T1） crystal modules of the Beijing Spectrometer Ⅲ （BESⅢ） electro-magnetic calorimeter （EMC） were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.
基金Supported by National Key Scientific Instrument and Equipment Development Project(2011YQ03011205,2013YQ03062902)Basic and Frontier Research Programs (General) Project of Chongqing(CSTC2013JCYJA1640)
文摘CsI film has been one of the most extensively used scintillators for indirect X-ray imaging because of its needle-like micro-structure. The purpose of this paper is to investigate the imaging performance of CsI screen as a function of thickness and radiation quality. Four multilayer scintillation screens with microcolumnar CsI：T1 film （thicknesses of 50 μm, 100 μm, 200μm and 300 μm） included were prepared and coupled to an optical imaging sensor. The modulation transfer function （MTF）, normalized noise power spectrum （NNPS） and detective quantum efficiency （DQE） of these screens were evaluated based on the standard IEC 62220-1, and the results indicated that, in the medium spatial frequency range （1-6 lp/mm）, the MTF of CsI screens with the same thickness was lower when the incident X-ray photon energy was higher, possibly owing to scattering and K-fluorescence re-absorption effects. The NNPS in the higher spatial frequency range （above 8 lp/mm） is dominated by stochastic noise while the entrance surface air Kerma （ESAK） decreases. For 100 μm, 200 μm and 300 μm thick CsI screens, the DQE under RQA7 and RQA9 is lower than that under RQA3 and RQA5 due to low absorption efficiency.
