All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been ...All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.展开更多
Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron s...Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.展开更多
Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n w...Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.展开更多
A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallati...A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallation Neutron Source(CSNS)Back-n white neutron source in the double-bunch and single-bunch operation modes,respectively.Under the two operational modes,the relative neutron sensitivity curves of the LaBr_(3)(Ce)scintillator in the energy regions of 1–20 MeV and 0.5–20 MeV were obtained for the first time.In the energy range of 1–20 MeV,the two curves were nearly identical.However the relative neutron sensitivity uncertainties of the double-bunch experiment were higher than those of the single-bunch experiment.The above results indicated that the single-bunch experiment's neutron sensitivity curve has a lower minimum measurable energy than the double-bunch experiment.Above the minimum measurable energy of the double-bunch experiment,there is little difference between the measured relative neutron sensitivity curves of the single-bunch and double-bunch experiments of the LaBr_(3)(Ce)scintillator and those of other scintillators with a similar neutron response signal intensity.展开更多
We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic ra...We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic range for an OSA based spectral measurement.展开更多
High-power broadband near-infrared(NIR)light sources have attracted extensive interest toward emerging non-invasive imaging and detection applications.However,exploring highly stable luminescent materials with targete...High-power broadband near-infrared(NIR)light sources have attracted extensive interest toward emerging non-invasive imaging and detection applications.However,exploring highly stable luminescent materials with targeted broadband NIR emission remains a great challenge.Here,MgAl_(2)O_(4):Cr^(3+)translucent ceramics have been designed and fabricated by a spark plasma sintering method,and a giant redshift of the emission band occurs from 686 to 928 nm due to the decreasing local structural symmetry around the isolated Cr^(3+)ions induced by the abundant cation vacancies.As Cr^(3+)content increases,MgAl_(2)O_(4):6%Cr^(3+)ceramic realizes the optimized external quantum efficiency of 73%with broadband NIR emission centered at 890 nm and a full-width at half-maximum of 315 nm under 450 nm excitation.The next-generation laser-driven light source containing NIR ceramic provides an output power exceeding 2 W and a light conversion efficiency of 22%when pumped with a blue laser of 10 W·mm^(-2).The proofof-concept demonstrations in imaging and detection reveal the advantages of high-power and high-efficiency laser-driven broadband NIR light sources and promote future development in the chemical design of NIR emitters.展开更多
A system with uniform light reflection in the inner surface within a horizontal 2/3 cylindrical structure for line-scan CCD of the print testing was designed. The design was based on diffuse reflection uniformity of t...A system with uniform light reflection in the inner surface within a horizontal 2/3 cylindrical structure for line-scan CCD of the print testing was designed. The design was based on diffuse reflection uniformity of the integrating sphere and requirement of the strip uniform illumination region. This system was called dome light. White light LED array light sources were used for uniform illumi- nation. The LEDs were filtrated to composite array light source based on coefficient of variation of a single LED. The standard white board and SG color checkers were used in the line-scan CCD imaging experiments under the dome light and ordinary illumination light source. The average color difference （AE） of SG color checkers in CIELAB space was 2. 091 under the dome light and 2. 286 under ordinary illumination light source respectively. Experimental results indicate that the dome light can satisfy illumination uniformity and color rendering consistency for line-scan CCD and provide a standard light source for uniform calibration of different cameras.展开更多
Blind identification-blind equalization for Finite Impulse Response (FIR) Multiple Input-Multiple Output (MIMO) channels can be reformulated as the problem of blind sources separation. It has been shown that blind ide...Blind identification-blind equalization for Finite Impulse Response (FIR) Multiple Input-Multiple Output (MIMO) channels can be reformulated as the problem of blind sources separation. It has been shown that blind identification via decorrelating sub-channels method could recover the input sources. The Blind Identification via Decorrelating Sub-channels(BIDS)algorithm first constructs a set of decorrelators, which decorrelate the output signals of subchannels, and then estimates the channel matrix using the transfer functions of the decorrelators and finally recovers the input signal using the estimated channel matrix. In this paper, a new approximation of the input source for FIR-MIMO channels based on the maximum likelihood source separation method is proposed. The proposed method outperforms BIDS in the presence of additive white Gaussian noise.展开更多
Two magnetic monopole models (i.e., model (I, II)) are presented to discuss the energy resources problem based on magnetic monopole catalytic nuclear decay in massive white dwarfs. We find that the luminosities for mo...Two magnetic monopole models (i.e., model (I, II)) are presented to discuss the energy resources problem based on magnetic monopole catalytic nuclear decay in massive white dwarfs. We find that the luminosities for most of massive white dwarfs increase as the temperature increases. The luminosities of model (II) are agreed well with those of the observations at relativistic high temperature (e.g., T6=1,10), However, the luminosities of the observations can be five orders of magnitude larger than those of model (I).展开更多
针对钍基熔盐堆白光中子源(Thorium Molten Salt Reactor with a Particle and Neutron Source,TMSRPNS)在运行过程中出现中子束流掉束或打火导致的束流不稳定的问题,有必要设计研发一种具有高计数率、低中子束流影响、高中子/伽马甄别...针对钍基熔盐堆白光中子源(Thorium Molten Salt Reactor with a Particle and Neutron Source,TMSRPNS)在运行过程中出现中子束流掉束或打火导致的束流不稳定的问题,有必要设计研发一种具有高计数率、低中子束流影响、高中子/伽马甄别性能的中子束流监测器。基于蒙特卡罗模拟软件Geant4,系统研究了薄膜塑料闪烁中子束流监测器的中子转换层厚度、闪烁体厚度,以及入射窗材料等关键参数对薄膜闪烁体的影响规律,分析结果表明:闪烁体中子转换层厚度约为2μm时具有相对合适的本征探测效率;闪烁体厚度为0.5 mm、甄别阈值为0.8 MeV时监测器具备γ射线不灵敏性能。同时,通过对比不同入射窗材料对于γ射线产生电子以及对中子散射的影响,选取电子产生较少且中子散射较小的铝作为入射窗材料。研究结果可为后续的中子束流监测器实物制备提供理论依据。展开更多
High-brightness laser lighting faces grave challenges in the development of laser-driven color converters that simultaneouslypossess excellent optical performance and superior heat dissipation.Herein,a reflective sand...High-brightness laser lighting faces grave challenges in the development of laser-driven color converters that simultaneouslypossess excellent optical performance and superior heat dissipation.Herein,a reflective sandwich color converter of phosphor-in-glass film with sapphire and alumina(sapphire@PiGF@alumina,abbreviated as S@PiGF@A)is designed and prepared via a thermocompression bonding method.Owing to the high thermal conductivity and double-sided heat dissipation channels of alumina and sapphire,the S@PIGF@A color converter can withstand high laser power density and produce ultrahigh luminescence.Consequently,the optimized S@PIGF@A converter yields white light with an ultrahigh luminous flux of 6749 Im at a laser power density saturation threshold of 47.70 W/mm,which is 2.44 times that of traditional PIGF@alumina colorl converter(2522 Im@19.53 W/mm).These findings provide valuable guidelines to design high-quality PiGF color converter for high-brightness laser-driven white lighting.展开更多
To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The m...To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.展开更多
Why no late type M and much later type N white dwarfs with surface temperatures less than 3000 K had ever been observed? What are the heat sources of these later type white dwarfs? In this paper, we find that the ener...Why no late type M and much later type N white dwarfs with surface temperatures less than 3000 K had ever been observed? What are the heat sources of these later type white dwarfs? In this paper, we find that the energy source of white dwarfs is the nucleons decay catalyzed by magnetic monopoles.展开更多
目的探讨不同噪声条件下健听人群水平声源定位能力的差异。方法选取2022年8月~2023年8月在我院检查的听力正常者78例,测试在安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下,受试者应答扬声器与发声扬声器的均方根误差(root...目的探讨不同噪声条件下健听人群水平声源定位能力的差异。方法选取2022年8月~2023年8月在我院检查的听力正常者78例,测试在安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下,受试者应答扬声器与发声扬声器的均方根误差(root mean square error,RMSE)和平均应答时间。结果不同噪声条件下受试者平均应答时间比较无显著差异(P>0.05);安静条件下受试者RMSE为10.21°±1.55°,明显低于白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下(P<0.05);白噪声40 dB SPL、言语噪声40 dB SPL条件下受试者RMSE分别为15.02°±2.22°和15.16°±2.06°,明显高于白噪声35 dB SPL(P<0.05);安静、白噪声35 dB SPL、白噪声40 dB SPL和言语噪声40 dB SPL条件下受试者对低频、中频和高频刺激声的平均应答时间无显著差异(P>0.05);白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对高频刺激声的RMSE均高于低频、中频刺激声(P<0.05),对中频刺激声的RMSE均高于低频刺激声(P<0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对前方声源的RMSE明显低于其他方位(P<0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对前方和其他方位声源的平均应答时间无显著差异(P>0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下,不同性别、年龄受试者RMSE及平均应答时间无显著差异(P>0.05)。结论噪声对健听人群声源识别定位能力有明显影响,在不同噪声条件下,受试者更容易定位来自前方的声源。展开更多
基金Project supported by the Science and Technology Project of Shenzhen City (JSGG20210802154213040)the Guangdong Basic and Applied Basic Research Foundation (2024A1515010001)the Shenzhen Postdoctoral Research Funding Project。
文摘All-inorganic reflective phosphor-in-glass film(PiGF) converter has garnered widespread attentions for high brightness laser-driven white lighting,while its poor color quality and low luminescence stability have been inevitable roadblocks.Herein,the bicolor PiGF containing green-emitting Y3Al3.08Ga1.92O12:Ce3+(YAGG) and red-emitting CaAlSiN_(3):Eu^(2+)(CASN) phosphors bonded on Al2O3substrate was prepared for enabling high color quality laser-driven white lighting in reflective configuration.The bicolor PiGF has high quantum efficiency and good structure stability.By optimizing the CASN content,PiGF thickness and Al_(2)O_(3) content,the reflective bicolor PiGF based white laser diode(LD)displays good luminescence performance with a luminous flux of 451.5 lm and a luminous efficacy of142.3 lm/W and high color quality with a color rendering index(CRI) of 85.3 and a correlated color temperature(CCT) of 5177 K under the incident laser power of 3.15 W,and still has excellent luminescence and color stabilities(CRI and CCT) under the continuous laser excitation of 5.61 W,attributed to the good thermal conductivity and high reflectivity of Al_(2)O_(3) substrate and scattering enhancement effect of Al_(2)O_(3) particles.It can be foreseen that the reflective bicolor PiGF converter provides a promising strategy for enabling high quality laser-driven white lighting.
基金supported by the National Natural Science Foundation of China(No.12035017)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030074)。
文摘Neutron resonance imaging(NRI)has recently emerged as an appealing technique for neutron radiography.Its complexity surpasses that of conventional transmission imaging,as it requires a high demand for both a neutron source and detector.Consequently,the progression of NRI technology has been sluggish since its inception in the 1980s,particularly considering the limited studies analyzing the neutron energy range above keV.The white neutron source(Back-n)at the China Spallation Neutron Source(CSNS)provides favorable beam conditions for the development of the NRI technique over a wide neutron energy range from eV to MeV.Neutron-sensitive microchannel plates(MCP)have emerged as a cutting-edge tool in the field of neutron detection owing to their high temporal and spatial resolutions,high detection efficiency,and low noise.In this study,we report the development of a 10B-doped MCP detector,along with its associated electronics,data processing system,and NRI experiments at the Back-n.Individual heavy elements such as gold,silver,tungsten,and indium can be easily identified in the transmission images by their characteristic resonance peaks in the 1–100 eV energy range;the more difficult medium-weight elements such as iron,copper,and aluminum with resonance peaks in the 1–100 keV energy range can also be identified.In particular,results in the neutron energy range of dozens of keV(Aluminum)are reported here for the first time.
基金This work was jointly supported by the National Key Research and Development Program of China(No.2016YFA0401600)National Natural Science Foundation of China(Nos.11235012 and 12035017)+1 种基金the CSNS Engineering Projectthe Back-n Collaboration Consortium fund。
文摘Back-streaming neutrons from the spallation target of the China Spallation Neutron Source(CSNS)that emit through the incoming proton channel were exploited to build a white neutron beam facility(the so-called Back-n white neutron source),which was completed in March 2018.The Back-n neutron beam is very intense,at approximately 29107 n/cm2/s at 55 m from the target,and has a nominal proton beam with a power of 100 kW in the CSNS-I phase and a kinetic energy of 1.6 GeV and a thick tungsten target in multiple slices with modest moderation from the cooling water through the slices.In addition,the excellent energy spectrum spanning from 0.5 eV to 200 MeV,and a good time resolution related tothe time-of-flight measurements make it a typical white neutron source for nuclear data measurements;its overall performance is among that of the best white neutron sources in the world.Equipped with advanced spectrometers,detectors,and application utilities,the Back-n facility can serve wide applications,with a focus on neutron-induced cross-sectional measurements.This article presents an overview of the neutron beam characteristics,the experimental setups,and the ongoing applications at Backn.
基金Project supported by the National Natural Science Foundation of China(Grant No.11905196)。
文摘A scintillator detector consisting of a LaBr_(3)(Ce)(0.5%)scintillator,a photomultiplier tube(PMT),and an oscilloscope were used to study the neutron sensitivities of the LaBr_(3)(Ce)scintillator at the China Spallation Neutron Source(CSNS)Back-n white neutron source in the double-bunch and single-bunch operation modes,respectively.Under the two operational modes,the relative neutron sensitivity curves of the LaBr_(3)(Ce)scintillator in the energy regions of 1–20 MeV and 0.5–20 MeV were obtained for the first time.In the energy range of 1–20 MeV,the two curves were nearly identical.However the relative neutron sensitivity uncertainties of the double-bunch experiment were higher than those of the single-bunch experiment.The above results indicated that the single-bunch experiment's neutron sensitivity curve has a lower minimum measurable energy than the double-bunch experiment.Above the minimum measurable energy of the double-bunch experiment,there is little difference between the measured relative neutron sensitivity curves of the single-bunch and double-bunch experiments of the LaBr_(3)(Ce)scintillator and those of other scintillators with a similar neutron response signal intensity.
文摘We demonstrate a white light fiber source based on Bismuth and Erbium co-doped fiber and a single 830nm laser diode pump. The light spectral intensity from 1100 to 1570nm is over -45dBm, which provide ~40dB dynamic range for an OSA based spectral measurement.
基金supported by the National Natural Science Foundation of China(52425206)the National Key Research and Development Program of China(2021YFB3500401).
文摘High-power broadband near-infrared(NIR)light sources have attracted extensive interest toward emerging non-invasive imaging and detection applications.However,exploring highly stable luminescent materials with targeted broadband NIR emission remains a great challenge.Here,MgAl_(2)O_(4):Cr^(3+)translucent ceramics have been designed and fabricated by a spark plasma sintering method,and a giant redshift of the emission band occurs from 686 to 928 nm due to the decreasing local structural symmetry around the isolated Cr^(3+)ions induced by the abundant cation vacancies.As Cr^(3+)content increases,MgAl_(2)O_(4):6%Cr^(3+)ceramic realizes the optimized external quantum efficiency of 73%with broadband NIR emission centered at 890 nm and a full-width at half-maximum of 315 nm under 450 nm excitation.The next-generation laser-driven light source containing NIR ceramic provides an output power exceeding 2 W and a light conversion efficiency of 22%when pumped with a blue laser of 10 W·mm^(-2).The proofof-concept demonstrations in imaging and detection reveal the advantages of high-power and high-efficiency laser-driven broadband NIR light sources and promote future development in the chemical design of NIR emitters.
基金Supported by the National Natural Science Foundation of China(61078048)
文摘A system with uniform light reflection in the inner surface within a horizontal 2/3 cylindrical structure for line-scan CCD of the print testing was designed. The design was based on diffuse reflection uniformity of the integrating sphere and requirement of the strip uniform illumination region. This system was called dome light. White light LED array light sources were used for uniform illumi- nation. The LEDs were filtrated to composite array light source based on coefficient of variation of a single LED. The standard white board and SG color checkers were used in the line-scan CCD imaging experiments under the dome light and ordinary illumination light source. The average color difference （AE） of SG color checkers in CIELAB space was 2. 091 under the dome light and 2. 286 under ordinary illumination light source respectively. Experimental results indicate that the dome light can satisfy illumination uniformity and color rendering consistency for line-scan CCD and provide a standard light source for uniform calibration of different cameras.
基金Supported by the National Natural Science Foundation of China (No.60172048)
文摘Blind identification-blind equalization for Finite Impulse Response (FIR) Multiple Input-Multiple Output (MIMO) channels can be reformulated as the problem of blind sources separation. It has been shown that blind identification via decorrelating sub-channels method could recover the input sources. The Blind Identification via Decorrelating Sub-channels(BIDS)algorithm first constructs a set of decorrelators, which decorrelate the output signals of subchannels, and then estimates the channel matrix using the transfer functions of the decorrelators and finally recovers the input signal using the estimated channel matrix. In this paper, a new approximation of the input source for FIR-MIMO channels based on the maximum likelihood source separation method is proposed. The proposed method outperforms BIDS in the presence of additive white Gaussian noise.
文摘Two magnetic monopole models (i.e., model (I, II)) are presented to discuss the energy resources problem based on magnetic monopole catalytic nuclear decay in massive white dwarfs. We find that the luminosities for most of massive white dwarfs increase as the temperature increases. The luminosities of model (II) are agreed well with those of the observations at relativistic high temperature (e.g., T6=1,10), However, the luminosities of the observations can be five orders of magnitude larger than those of model (I).
文摘针对钍基熔盐堆白光中子源(Thorium Molten Salt Reactor with a Particle and Neutron Source,TMSRPNS)在运行过程中出现中子束流掉束或打火导致的束流不稳定的问题,有必要设计研发一种具有高计数率、低中子束流影响、高中子/伽马甄别性能的中子束流监测器。基于蒙特卡罗模拟软件Geant4,系统研究了薄膜塑料闪烁中子束流监测器的中子转换层厚度、闪烁体厚度,以及入射窗材料等关键参数对薄膜闪烁体的影响规律,分析结果表明:闪烁体中子转换层厚度约为2μm时具有相对合适的本征探测效率;闪烁体厚度为0.5 mm、甄别阈值为0.8 MeV时监测器具备γ射线不灵敏性能。同时,通过对比不同入射窗材料对于γ射线产生电子以及对中子散射的影响,选取电子产生较少且中子散射较小的铝作为入射窗材料。研究结果可为后续的中子束流监测器实物制备提供理论依据。
基金supported by the Key Research and Development Program of Guanzgxi Zhuang Autonomous Region(No.AB25069373)the Science and Technology Project of Shenzhen City(No.JCYJ20230807110907016)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Nos.2024A1515010001 and 2024A1515011445)the Shenzhen Postdoctoral Research Funding Project.
文摘High-brightness laser lighting faces grave challenges in the development of laser-driven color converters that simultaneouslypossess excellent optical performance and superior heat dissipation.Herein,a reflective sandwich color converter of phosphor-in-glass film with sapphire and alumina(sapphire@PiGF@alumina,abbreviated as S@PiGF@A)is designed and prepared via a thermocompression bonding method.Owing to the high thermal conductivity and double-sided heat dissipation channels of alumina and sapphire,the S@PIGF@A color converter can withstand high laser power density and produce ultrahigh luminescence.Consequently,the optimized S@PIGF@A converter yields white light with an ultrahigh luminous flux of 6749 Im at a laser power density saturation threshold of 47.70 W/mm,which is 2.44 times that of traditional PIGF@alumina colorl converter(2522 Im@19.53 W/mm).These findings provide valuable guidelines to design high-quality PiGF color converter for high-brightness laser-driven white lighting.
基金supported by the National Key Research and Development Plan(No.2016YFA0401603)the National Natural Science Foundation of China(No.11675155)
文摘To verify the performance of the neutron total cross-sectional spectrometer, the neutron total cross section of carbon is initially measured in the energy range of 1 eV to 20 MeV using the time-of-flight method. The measurement is performed at the Back-n white neutron source with a 76-m time-of-flight path using the China Spallation Neutron Source. A multilayer fast fission chamber with 235U and 238U is employed as the neutron detector. The diameter and thickness of the natural graphite sample are 70 mm and 40 mm, respectively. Signal waveforms are collected using a data acquisition system. Off-line data processing was used to obtain the neutron time-of-flight spectra and transmissions. The uncertainty of the counting statistics is generally approximately 3% for each bin in the energy range of 1–20 MeV. It is determined that the results for the neutron total cross section of carbon obtained using ^235U cells are in good agreement with the results obtained using 238U cells within limits of statistical uncertainty. Moreover, the measured total cross sections show good agreement with the broadening evaluated data.
文摘Why no late type M and much later type N white dwarfs with surface temperatures less than 3000 K had ever been observed? What are the heat sources of these later type white dwarfs? In this paper, we find that the energy source of white dwarfs is the nucleons decay catalyzed by magnetic monopoles.
文摘目的探讨不同噪声条件下健听人群水平声源定位能力的差异。方法选取2022年8月~2023年8月在我院检查的听力正常者78例,测试在安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下,受试者应答扬声器与发声扬声器的均方根误差(root mean square error,RMSE)和平均应答时间。结果不同噪声条件下受试者平均应答时间比较无显著差异(P>0.05);安静条件下受试者RMSE为10.21°±1.55°,明显低于白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下(P<0.05);白噪声40 dB SPL、言语噪声40 dB SPL条件下受试者RMSE分别为15.02°±2.22°和15.16°±2.06°,明显高于白噪声35 dB SPL(P<0.05);安静、白噪声35 dB SPL、白噪声40 dB SPL和言语噪声40 dB SPL条件下受试者对低频、中频和高频刺激声的平均应答时间无显著差异(P>0.05);白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对高频刺激声的RMSE均高于低频、中频刺激声(P<0.05),对中频刺激声的RMSE均高于低频刺激声(P<0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对前方声源的RMSE明显低于其他方位(P<0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下受试者对前方和其他方位声源的平均应答时间无显著差异(P>0.05);安静、白噪声35 dB SPL、40 dB SPL和言语噪声40 dB SPL条件下,不同性别、年龄受试者RMSE及平均应答时间无显著差异(P>0.05)。结论噪声对健听人群声源识别定位能力有明显影响,在不同噪声条件下,受试者更容易定位来自前方的声源。
