Developing cold-resistant high-adhesive electronic substrate for WIMPs detectors at CDEX

Herein we report a prototypical electronic substrate specifically designed to serve the weakly interacting massive particles(WIMPs)detectors at the China Dark Matter Experiment(CDEX).Because the bulky high-purity germanium(HPGe)detectors operate under liquid-nitrogen temperatures and ultralow radiation backgrounds,the desired electronic substrates must maintain high adhesivity across different layers in such cold environment and be free from any radioactive nuclides.To conquer these challenges,for the first time,we employed polytetrafluoroethylene((C2F4)n)foil as the base substrate,in conjunction with ion implantation and deposition techniques using an independently developed device at Beijing Normal University for surface modification prior to electroplating.The remarkable peeling strengths of 0.88±0.06 N/mm for as-prepared sample and 0.75±0.05 N/mm for that after 2.5-days of soaking inside the liquid nitrogen were observed,while the regular standards commonly require 0.4 N/mm^0.6 N/mm for electronic substrates.

Metal-Halide Perovskite Submicrometer-Thick Films for Ultra-Stable Self-Powered Direct X-Ray Detectors

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.

High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)

High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.

Low-noise and low-power pixel sensor chip for gas pixel detectors

Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.

Flexibility potential of Cs_(2)BX_(6)(B=Hf,Sn,Pt,Zr,Ti;X=I,Br,Cl)with application in photovoltaic devices and radiation detectors

As interest in double perovskites is growing,especially in applications like photovoltaic devices,understanding their mechanical properties is vital for device durability.Despite extensive exploration of structure and optical properties,research on mechanical aspects is limited.This article builds a vacancyordered double perovskite model,employing first-principles calculations to analyze mechanical,bonding,electronic,and optical properties.Results show Cs_(2)Hfl_(6),Cs_(2)SnBr_(6),Cs_(2)SnI_(6),and Cs_(2)PtBr_(6)have Young's moduli below 13 GPa,indicating flexibility.Geometric parameters explain flexibility variations with the changes of B and X site composition.Bonding characteristic exploration reveals the influence of B and X site electronegativity on mechanical strength.Cs_(2)SnBr_(6)and Cs_(2)PtBr_(6)are suitable for solar cells,while Cs_(2)HfI_(6)and Cs_(2)TiCl_(6)show potential for semi-transparent solar cells.Optical property calculations highlight the high light absorption coefficients of up to 3.5×10^(5) cm^(-1)for Cs_(2)HfI_(6)and Cs_(2)TiCl_(6).Solar cell simulation shows Cs_(2)PtBr_(6)achieves 22.4%of conversion effciency.Cs_(2)ZrCl_(6)holds promise for ionizing radiation detection with its 3.68 eV bandgap and high absorption coefficient.Vacancy-ordered double perovskites offer superior flexibility,providing valuable insights for designing stable and flexible devices.This understanding enhances the development of functional devices based on these perovskites,especially for applications requiring high stability and flexibility.

Self-powered UVC detectors based on α-Ga_(2)O_(3) with enchanted speed performance

Detectors were developed for detecting irradiation in the short-wavelength ultraviolet(UVC)interval using high-quality single-crystallineα-Ga_(2)O_(3) films with Pt interdigital contacts.The films ofα-Ga_(2)O_(3) were grown on planar sapphire substrates with c-plane orientation using halide vapor phase epitaxy.The spectral dependencies of the photo to dark current ratio,responsivity,external quantum efficiency and detectivity of the structures were investigated in the wavelength interval of 200−370 nm.The maximum of photo to dark current ratio,responsivity,external quantum efficiency,and detectivity of the structures were 1.16×10^(4) arb.un.,30.6 A/W,1.65×10^(4)%,and 6.95×10^(15) Hz^(0.5)·cm/W at a wavelength of 230 nm and an applied voltage of 1 V.The high values of photoelectric properties were due to the internal enhancement of the photoresponse associated with strong hole trapping.Theα-Ga_(2)O_(3) film-based UVC detectors can function in self-powered operation mode due to the built-in electric field at the Pt/α-Ga_(2)O_(3) interfaces.At a wavelength of 254 nm and zero applied voltage,the structures exhibit a responsivity of 0.13 mA/W and an external quantum efficiency of 6.2×10^(−2)%.The UVC detectors based on theα-Ga_(2)O_(3) films demonstrate high-speed performance with a rise time of 18 ms in self-powered mode.

FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks.In this study,real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps,12-bit digitizer,and the neutron and gamma spectra were calculated directly on an FPGA.A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2 M tokamak at the Southwestern Institute of Physics,China.The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 ms.At count rates of up to 1 Mcps,the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV.

Structural design of mid-infrared waveguide detectors based on InAs/GaAsSb superlattice

In the realm of near-infrared spectroscopy,the detection of molecules has been achieved using on-chip waveguides and resonators.In the mid-infrared band,the integration and sensitivity of chemical sensing chips are often constrained by the reliance on off-chip light sources and detectors.In this study,we demonstrate an InAs/GaAsSb superlattice mid-infrared waveguide integrated detector.The GaAsSb waveguide layer and the InAs/GaAsSb superlattice absorbing layer are connected through evanescent coupling,facilitating efficient and highquality detection of mid-infrared light with minimal loss.We conducted a simulation to analyze the photoelectric characteristics of the device.Additionally,we investigated the factors that affect the integration of the InAs/GaAs⁃Sb superlattice photodetector and the GaAsSb waveguide.Optimal thicknesses and lengths for the absorption lay⁃er are determined.When the absorption layer has a thickness of 0.3μm and a length of 50μm,the noise equiva⁃lent power reaches its minimum value,and the quantum efficiency can achieve a value of 68.9%.The utilization of waveguide detectors constructed with Ⅲ-Ⅴ materials offers a more convenient means of integrating mid-infra⁃red light sources and achieving photoelectric detection chips.

Effect of multiple coulomb scattering on the beam tests of silicon pixel detectors

In the research and development of new silicon pixel detectors,a collimated monoenergetic charged-particle test beam equipped with a high-resolution pixel-beam telescope is crucial for prototype verification and performance evaluation.When the beam energy is low,the effect of multiple Coulomb scattering on the measured resolution of the Device Under Test(DUT)must be considered to accurately evaluate the performance of the pixel chips and detectors.This study aimed to investigate the effect of multiple Coulomb scattering on the measured resolution,particularly at low beam energies.Simulations were conducted using Allpix^(2) to study the effects of multiple Coulomb scattering under different beam energies,material budgets,and telescope layouts.The simulations also provided the minimum energy at which the effect of multiple Coulomb scattering could be ignored.Compared with the results of a five-layer detector system tested with an electron beam at DESY,the simulation results were consistent with the beam test results,confirming the reliability of the simulations.

Countermeasure against blinding attack for single-photon detectors in quantum key distribution

Quantum key distribution(QKD),rooted in quantum mechanics,offers information-theoretic security.However,practi-cal systems open security threats due to imperfections,notably bright-light blinding attacks targeting single-photon detectors.Here,we propose a concise,robust defense strategy for protecting single-photon detectors in QKD systems against blinding attacks.Our strategy uses a dual approach:detecting the bias current of the avalanche photodiode(APD)to defend against con-tinuous-wave blinding attacks,and monitoring the avalanche amplitude to protect against pulsed blinding attacks.By integrat-ing these two branches,the proposed solution effectively identifies and mitigates a wide range of bright light injection attempts,significantly enhancing the resilience of QKD systems against various bright-light blinding attacks.This method forti-fies the safeguards of quantum communications and offers a crucial contribution to the field of quantum information security.

In-flight Energy Calibration of the GECAM Gamma-ray Detectors

The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)mission is designed to monitor the Gamma-Ray Bursts(GRBs)associated with gravitational waves and other high-energy transient sources.The mission consists of two microsatellites which are planned to operate at the opposite sides of the Earth.Each GECAM satellite could detect and localize GRBs in about 8 keV-5 MeV with its 25 Gamma-Ray Detectors(GRDs).In this work,we report the in-flight energy calibration of GRDs using the characteristic gamma-ray lines in the background spectra,and show their performance evolution during the commissioning phase.Besides,a preliminary cross-calibration of energy response with Fermi GBM data is also presented,validating the energy response of GRDs.

时空异质性视角下华北地区碳足迹评估及驱动因子分析

碳足迹是衡量碳排放的重要指标,削减碳足迹是实现“双碳”目标的前提条件。华北地区作为我国高耗能、高排放的集中区域,客观量化碳足迹并探究主要驱动因子对加快推进碳减排具有重要意义。为此,论文基于IPCC法对华北地区“十五”至“十三五”期间的碳足迹进行测算,运用标准差椭圆分析碳足迹的分布及转移特征,使用地理探测器识别碳足迹的主要驱动因子。研究发现:(1)“十五”至“十三五”期间碳足迹总量经历了“先增长—后下降”两个阶段,由“十五”期间的425452万吨上升至1066353万吨,而后逐渐下降到“十三五”期间的898908万吨。(2)标准差椭圆呈稳定的“南—北”分布,重心分布于山西大同和河北张家口之间,呈向西北方向偏移趋势,已偏移72.56千米。(3)能源强度、产业结构、城镇化率对碳足迹驱动因子解释力度较大,且关键交互因子均含有能源强度、产业结构、研发投入。华北地区不同时期碳足迹分布及影响因子存在时空差异,在制定碳减排政策时应充分考虑区域碳足迹的时空异质性。

不同格网尺度下生态系统服务价值空间分异及影响因素分析--以秦岭西安段为例

[目的]探究生态系统服务价值空间分异的尺度效应,为秦岭地区的生态保护和经济发展决策提供参考。[方法]运用改进当量因子法,计算了2020年秦岭西安段5 km,3 km,2 km,1 km和0.5 km共5个格网尺度水平上的生态系统服务价值;采用空间自相关分析和冷热点分析归纳了不同尺度下地均ESV空间分异特征;并利用地理探测器对各尺度下的影响因素作用强度进行定量分析。[结果](1)地均ESV总体上呈北低南高的分布格局,具有小分散、大集聚的空间分布特征,并随尺度降低,其局部越丰富,但整体性降低;(2)2 km尺度适合进行宏观分析和做整体性布局规划,1 km尺度适合进行水域变化对区域ESV影响的研究;(3)格网尺度越小,各影响因素内部差异增加,其整体性特征减少,局部特征差异凸显,空间分异性增强;(4)人类活动带来的土地利用方式转变显著影响区域生态系统服务价值,多因素耦合作用显著影响区域地均ESV空间分异,随尺度降低,其影响减弱。[结论]秦岭西安段的生态保护要重点关注区域土地利用性质的转变,可继续加强退耕还林政策,管控建设用地的规模,在兼顾生态保护的基础上,制定经济发展的布局规划。

旅游产业碳排放效率时空分布差异性及驱动因子变动研究——以西南地区为例

旅游业碳排放效率是反映旅游业可持续发展的重要指标,能更好评价负面环境影响与经济收入之间的关系,提高碳排放效率可促使旅游业不断发展的同时降低碳排放,加速旅游业转型升级、高质量发展。西南地区拥有全国19.12%的A级景区,52.89%的少数民族特色村寨,是中国旅游业不可缺少的重要组成部分,因此根据各省份的面板数据,估算西南地区旅游碳排放量、测算旅游产业碳排放效率、探测影响旅游产业碳排放效率的驱动因子强度。结果表明:(1)旅游碳排放量与旅游收入呈正相关,但贵州在旅游收入快速提升的同时,旅游碳排放量也迅速增加。(2)西南地区旅游碳排放效率整体上逐年增加,但重庆、西藏的旅游碳排放效率明显低于其余三省。(3)西南地区旅游碳排放效率受到多种因素的作用,其中旅游教育与人才培养、旅游总收入、旅游产业碳排放量对碳排放效率的影响强度突出。

青年发展型城市环境指数测度及空间差异分析

基于国家45个青年发展型试点城市的宏观数据,构建青年发展型城市环境指数测度指标体系。采用EM-TOPSIS模型测度各城市的维度得分以及综合水平,使用变异系数法测量四大地区内城市的环境指数差异,结合地理探测器来探测七大环境因子的空间分异解释和驱动能力。结果显示:生活环境的评价均分最高,其次是规划环境,就业环境评价均分最低;四大地区内部城市在各维度表现上具有一定的差异性,其中西部和东部地区差异性最大,部分城市在各环境指数间具有明显的不平衡性;通过计算,将45个城市划分为高水平、中等水平、低水平等级;在因子与交互探测上,健康环境因子和就业环境因子的解释能力最强,其次是规划环境因子和经济环境因子,且两因子间的交互驱动力都强于各个单因子的驱动力。

高速红外测温系统

针对于高速测温系统存在的响应时间慢、校准复杂、不适用特殊环境等问题,设计了以STM32F429IGT6微控制器为控制核心,以光学系统、制冷型红外探测器为主体的制冷型高速红外测温系统。光学系统采用金属抛物面反射镜构建光学组件,结合制冷型红外探测器完成光电转换,由微控制器进行高速采集。系统采样率为1 MHz,采用SD卡进行数据存储,可在屏幕上显示温度变化波形。采用黑体炉静态标定法进行温度标定,对温度与电压信号之间的关系进行最小二乘拟合,得到了电压-温度关系式,测量误差为±1℃,温度测量有效范围为10~200℃。标定后使用霍普金森压杆冲击实验进行了系统应用测试。测试结果表明,制冷型高速红外测温系统具有微秒级温度变化的探测能力,响应时间快,操作与校准简单,在动态高速测温领域具有广泛的应用前景。

湖南省耕地非粮化空间分异及驱动因子研究

粮食安全是总体国家安全观的重要组成部分,探索湖南省耕地非粮化的空间分异格局及其驱动因子,可为湖南省耕地非粮化防治、耕地资源配置优化等提供决策依据。利用遥感地理信息技术测算湖南省各县域、各乡镇的耕地非粮化率,运用社会经济数据,从自然资源、经济水平、社会发展3个维度15个方面构建驱动因子指标体系,采用空间自相关模型、地理探测器等方法,探究湖南省耕地非粮化的空间分异格局及其驱动因子。结果表明:(1)湖南省耕地非粮化率略低于全国平均水平,其中洞庭湖地区耕地非粮化率最低,湘西地区非粮化率最高;(2)湖南省耕地非粮化呈现一定程度的空间分异,耕地非粮化率高的地区主要集中在城市周边、山区以及具有特色经济作物产业的地区,耕地非粮化率低的地区主要集中在地势平坦、土地肥沃以及农业重视程度高的地区;(3)湖南省耕地非粮化是多种因素综合作用的结果,不同区域间表现出特定的一致性与差异性。根据湖南省不同区域的耕地非粮化现状与研究结论,从尊重种植习惯、加强整体谋划,提高种粮效益、保障农民权益,建立耕地数据库、精细化管理耕地等3个方面提出对策建议。

山地高密度城市空间形态对冬季气溶胶格局的约束力探测——重庆中心城区案例研究

城市大气环境质量是城市环境质量的关键性控制因素,解耦城市空间形态与大气环境质量间的约束性耦合关系,是建构城市环境高质量发展策略的基础和前提。基于多年MODIS、高精度矢量建筑等多源空间数据,通过暗像元法反演2020-2022年重庆中心城区大气气溶胶光学厚度,以此量化城市大气环境质量,从平面、立体、功能3个维度建立10项表征城市形态的量化指标,借助地理探测器分析各因子对冬季气溶胶的独立和叠加约束效应。研究发现:1)在中心城区全域,冬季气溶胶空间异质性显著,城市表面高程、植被覆盖度、天空开阔度、土地利用因子具有全局约束力,其他因子如建筑密度、容积率等只具有局部约束效果;2)在城市建成区内部,影响气溶胶的主要单因子包括城市表面高程(q=0.574)、植被覆盖度(q=0.524)、土地利用(q=0.506)、距主要道路距离(q=0.352);其他城市形态因子的解释力相对较弱且贡献值大致相同(q=0.29);3)在城市建成区内部,各解释因子表现出明显的叠加约束效应,且叠加解释力q(Xi∩Xj)均强于独立作用,叠加q值处于0.29-0.65之间。该研究为明确城市形态与大气质量的关系提供了科学依据,对城市规划和环境治理具有一定理论和实践意义。

深层肌肉刺激与肌电生物反馈干预脑卒中后患者小腿三头肌痉挛和步态的改变

背景:深层肌肉刺激疗法具有松解粘连、缓解痉挛、改善和恢复肌肉顺应性和弹性等作用;肌电生物反馈疗法能有效促进神经恢复和改善下肢运动功能和步态。目的:利用数字化肌肉检测仪和三维步态分析仪等手段综合评估深层肌肉刺激联合肌电生物反馈对脑卒中后小腿三头肌痉挛及步态改变的影响。方法:选取2020年10月至2023年10月在广东药科大学附属第一医院康复科住院且符合纳入标准的患者72例,随机分为对照组和联合组,每组36例。对照组接受常规康复治疗+肌电生物反馈+假性深层肌肉刺激,联合组在对照组基础上增加真性深层肌肉刺激治疗,5次/周,连续4周。统计分析两组治疗前、后患侧腓肠肌内外侧振荡频率和动态刚度、踝背屈主动关节活动度、胫骨前肌肌电信号、下肢Fugl-Meyer评分量表和三维步态分析相关参数。结果与结论:①两组患者治疗后患侧腓肠肌内外侧的振荡频率和动态刚度值较治疗前明显降低(P<0.05),联合组较对照组降低更明显(P<0.05);②两组患者治疗后踝背屈主动活动度、胫骨前肌肌电信号和下肢Fugl-Meyer量表评分较治疗前明显增大或提高(P<0.05),联合组较对照组增大或提高更明显(P<0.05);③两组患者步速、步频、步幅均较治疗前明显增大(P<0.05),联合组较对照组增大更明显(P<0.05);健患侧支撑相百分比时间较治疗前降低(P<0.05),联合组较对照组降低更明显(P<0.05);④除健侧支撑百分比治疗前后变化量两组间比较差异无显著性意义(P>0.05)外,其余指标治疗前后的变化量联合组均较对照组效果更明显(P<0.05);⑤结果说明,深层肌肉刺激治疗仪联合肌电生物反馈短期内能有效缓解脑卒中后小腿三头肌痉挛、改善踝背屈功能和提高下肢运动功能及改善步态,治疗效果显著。

黄土高原生态系统碳汇时空变化及其影响因素

[目的]探究黄土高原生态系统碳汇时空变化特征,可为深入分析和科学评估生态系统固碳能力以及制定应对气候变化的策略提供科学依据。[方法]基于现有长时间序列遥感产品、地形和土壤属性等数据,运用线性趋势分析和地理探测器等工具,计算了2000-2022年黄土高原净生态系统生产力(Net Ecosystem Productivity,NEP),分析了NEP时空变化及其影响因素。[结果]黄土高原2000-2022年NEP平均值为33.44 gC/m^(2),2022年黄土高原NEP现状水平为39.9 gC/m^(2),年碳汇总量达到25.40 Tg C。NEP年际变化特征表现为显著上升且逐渐趋于稳定,总体增长速率为0.70 gC/(m^(2)·a),每年增加0.45 Tg C,其中山西省和陕西省贡献最大。黄土高原森林植被的碳汇能力(NEP)和增汇能力(NEP趋势)虽最高,但由于草地面积较大,因此草地碳汇总量和增汇贡献均高于森林。与草地、农田和裸地相比,草地-森灌、农田-林草,裸地-林草等生态修复工程能提升原地表覆盖碳汇能力的83.2%,14.0%和81.1%,且提升增汇能力5.6%,15.8%,127.7%。单一影响因子中,NDVI作为植被生物量指标,是驱动黄土高原生态系统NEP时空动态变化的主要因素,然而NDVI与降雨、NDVI与土壤容重的交互作用对NEP空间分异以及NEP趋势变化的影响也不可忽视。[结论]结合气候特性和土壤条件的全面考量,通过调整土地利用结构和增加植物覆盖度等一系列生态恢复措施,可有效提升黄土高原生态系统碳汇能力。