A method to measure the detailed performance of polycapillary x-ray optics by a pinhole and charge coupled device(CCD)detector was proposed in this study.The pinhole was located between the x-ray source and the polyca...A method to measure the detailed performance of polycapillary x-ray optics by a pinhole and charge coupled device(CCD)detector was proposed in this study.The pinhole was located between the x-ray source and the polycapillary x-ray optics to determine the illuminating region of the incident x-ray beam on the input side of the optics.The CCD detector placed downstream of the polycapillary x-ray optics ensured that the incident x-ray beam controlled by the pinhole irradiated a specific region of the input surface of the optics.The intensity of the output beam of the polycapillary x-ray optics was obtained from the far-field image of the output beam of the optics captured by CCD detector.As an application example,the focal spot size,gain in power density,transmission efficiency,and beam divergence of different parts of a polycapillary focusing x-ray lenses(PFXRL)were measured by a pinhole and CCD detector.Three pinholes with diameters of 500,1000,and 2000μm were used to adjust the diameter of the incident x-ray beam illuminating the PFXRL from 500μm to the entire surface of the input side of the PFXRL.The focal spot size of the PFXRL,gain in power density,transmission efficiency,and beam divergence ranged from 27.1μm to 34.6μm,400 to 3460,26.70%to 5.38%,and 16.8 mrad to 84.86 mrad,respectively.展开更多
Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradi...Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradiation experiment.The hot pixels,random telegraph signal(RTS),mean dark signal,dark current and dark signal non-uniformity(DSNU)induced by Back-n are presented.The dark current is calculated according to the mean dark signal at various integration times.The single-particle displacement damage and transient response are also observed based on the online measurement data.The trends of hot pixels,mean dark signal,DSNU and RTS degradation are related to the integration time and irradiation fluence.The mean dark signal,dark current and DSNU2 are nearly linear with neutron irradiation fluence when nearly all the pixels do not reach saturation.In addition,the mechanisms of the displacement damage effects on the CCD are demonstrated by combining the experimental results and technology computer-aided design(TCAD)simulation.Radiation-induced traps in the space charge region of the CCD will act as generation/recombination centers of electron-hole pairs,leading to an increase in the dark signal.展开更多
Graphene is a one-atom-thick planar sheet of sp2-hybridized orbital bonded honeycomb carbon crystal. Its gapless and linear energy spectra of electrons and holes lead to the unique carrier transport and optical proper...Graphene is a one-atom-thick planar sheet of sp2-hybridized orbital bonded honeycomb carbon crystal. Its gapless and linear energy spectra of electrons and holes lead to the unique carrier transport and optical properties, such as giant carrier mobility and broadband flat optical response. As a novel material, graphene has been regarded to be extremely suitable and competent for the development of terahertz （THz） optical devices. In this paper, the fundamental electronic and optic properties of graphene are described. Based on the energy band structure and light transmittance properties of graphene, many novel graphene based THz devices have been proposed, including modulator, generator, detector, and imaging device. This progress has been reviewed. Future research directions of the graphene devices for THz applications are also proposed.展开更多
Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has a...Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has also been recently demonstrated in both bulk materials and thin films.However,the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours,often reporting degradation of the detection performance.Here it is shown that self-powered direct X-ray detectors,fabricated starting from a FAPbBr_(3)submicrometer-thick film deposition onto a mesoporous TiO_(2)scaffold,can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss,demonstrating ultra-high operational stability and excellent repeatability.No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy,revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film.In addition,trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy^(−1)cm^(−3)at 0 V,an unprecedented value in the field of thin-film-based photoconductors and photodiodes for“hard”X-rays.Finally,prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11675019,12105020,and 12075031)the Bud Project of Beijing Academy of Science and Technology(Grant No.BGS202106)the National Key Research and Development Program of China(Grant No.2021YFF0701202)
文摘A method to measure the detailed performance of polycapillary x-ray optics by a pinhole and charge coupled device(CCD)detector was proposed in this study.The pinhole was located between the x-ray source and the polycapillary x-ray optics to determine the illuminating region of the incident x-ray beam on the input side of the optics.The CCD detector placed downstream of the polycapillary x-ray optics ensured that the incident x-ray beam controlled by the pinhole irradiated a specific region of the input surface of the optics.The intensity of the output beam of the polycapillary x-ray optics was obtained from the far-field image of the output beam of the optics captured by CCD detector.As an application example,the focal spot size,gain in power density,transmission efficiency,and beam divergence of different parts of a polycapillary focusing x-ray lenses(PFXRL)were measured by a pinhole and CCD detector.Three pinholes with diameters of 500,1000,and 2000μm were used to adjust the diameter of the incident x-ray beam illuminating the PFXRL from 500μm to the entire surface of the input side of the PFXRL.The focal spot size of the PFXRL,gain in power density,transmission efficiency,and beam divergence ranged from 27.1μm to 34.6μm,400 to 3460,26.70%to 5.38%,and 16.8 mrad to 84.86 mrad,respectively.
基金Project supported by the Foundation of State Key Laboratory of China(Grant Nos.SKLIPR1903Z,1803)the National Natural Science Foundation of China(Grant Nos.U2167208 and 11875223).
文摘Displacement damage effects on the charge-coupled device(CCD)induced by neutrons at the back-streaming white neutron source(Back-n)in the China Spallation Neutron Source(CSNS)are analyzed according to an online irradiation experiment.The hot pixels,random telegraph signal(RTS),mean dark signal,dark current and dark signal non-uniformity(DSNU)induced by Back-n are presented.The dark current is calculated according to the mean dark signal at various integration times.The single-particle displacement damage and transient response are also observed based on the online measurement data.The trends of hot pixels,mean dark signal,DSNU and RTS degradation are related to the integration time and irradiation fluence.The mean dark signal,dark current and DSNU2 are nearly linear with neutron irradiation fluence when nearly all the pixels do not reach saturation.In addition,the mechanisms of the displacement damage effects on the CCD are demonstrated by combining the experimental results and technology computer-aided design(TCAD)simulation.Radiation-induced traps in the space charge region of the CCD will act as generation/recombination centers of electron-hole pairs,leading to an increase in the dark signal.
基金supported by the 973 Program of China under Grant No.2013CBA01702the National Natural Science Foundation of China under Grant No.11204188,61205097,91233202,11374216,and 11174211+2 种基金the National High Technology Research and Development Program of China under Grant No.2012AA101608-6the Beijing Natural Science Foundation under Grant No.KZ201110028035the Program for New Century Excellent Talents in University under Grant No.NCET-12-0607,and the CAEP THz Science and Technology Foundation
文摘Graphene is a one-atom-thick planar sheet of sp2-hybridized orbital bonded honeycomb carbon crystal. Its gapless and linear energy spectra of electrons and holes lead to the unique carrier transport and optical properties, such as giant carrier mobility and broadband flat optical response. As a novel material, graphene has been regarded to be extremely suitable and competent for the development of terahertz （THz） optical devices. In this paper, the fundamental electronic and optic properties of graphene are described. Based on the energy band structure and light transmittance properties of graphene, many novel graphene based THz devices have been proposed, including modulator, generator, detector, and imaging device. This progress has been reviewed. Future research directions of the graphene devices for THz applications are also proposed.
基金supported by the project“PARIDE”(Perovskite Advanced Radiotherapy&Imaging Detectors),funded under the Regional Research and Innovation Programme POR-FESR Lazio 2014-2020(project number:A0375-2020-36698).
文摘Metal-halide perovskites are revolutionizing the world of X-ray detectors,due to the development of sensitive,fast,and cost-effective devices.Self-powered operation,ensuring portability and low power consumption,has also been recently demonstrated in both bulk materials and thin films.However,the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours,often reporting degradation of the detection performance.Here it is shown that self-powered direct X-ray detectors,fabricated starting from a FAPbBr_(3)submicrometer-thick film deposition onto a mesoporous TiO_(2)scaffold,can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss,demonstrating ultra-high operational stability and excellent repeatability.No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy,revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film.In addition,trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy^(−1)cm^(−3)at 0 V,an unprecedented value in the field of thin-film-based photoconductors and photodiodes for“hard”X-rays.Finally,prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.
