Emission of Protons in Inelastic Nucleus-Nucleus Collisions at High Energy

Based on the participant-spectator model and the analysis of particle producing proce-ss, the rapidity distribution and the noninvariant center-of-mass energy spectrum of final pro-tons produced in inelastic nucleus-nucleus collisions are studied.

On The Hardening of The Spectrum of High-Energy Particles Formed in Heavy-Ion Collisions Considered within The Framework of The Hydrodynamic Approach

The emission of high-energy particles in 16O + 197Au collisions at energy 20 MeV / nucleon is considered within the framework of the time evolution of a hot spot taking into account the hydrodynamic compression and expansion stages. In addition, the evaporation of the particles that are formed in the early (hot) stage of the evolution of the hot spot is included in the calculation of the spectrum. This leads to a hardening of the particle spectrum in its high-energy part, which is in agreement with experimental data.

HIGH-ENERGY PROTON IRRADIATION EFFECTS ON GaAs/Ge SPACE SOLAR CELLS

This paper reports the high-energy proton irradiation effects on GaAs/Ge space solar cells. The solar cells were irradiated by protons with energy of 5-20 MeV at fluence ranging from 1×109 to 7×1013 cm-2, and then their electric parameters were measured at AM0. It was shown that the Isc, Voc and Pmax decrease as the proton energy increasing, and the degradation is relative to proton irradiation-induced defect with a level of Ec-0.41 eV in irradiated GaAs/Ge cells.

Measurement of the Energy Spectrum of a 6 MV Linear Accelerator Using Compton Scattering Spectroscopy and Monte Carlo-Generated Corrections

Purpose: The energy spectrum of a linear accelerator used for dose calculations is determined during beam commissioning by iteratively adjusting the spectrum and comparing calculated and measured percent depth-dose curves. Direct measurement of the energy spectrum using pulse mode detectors is particularly challenging because of the high-energy, high fluence nature of these beams and limitations of the detector systems. This work implements a Compton scattering (CS) spectroscopy setup and presents detector corrections and spectral unfolding techniques to measure the spectrum of a 6 MV linear accelerator using a pulse mode detector. Methods: Spectral measurements were performed using a Varian Clinac 21EX linear accelerator and a high-purity germanium (HPGe) detector. To reduce fluence to the detector, a custom-built lead shield and a CS spectrometry setup were used. The detector was placed at CS angles of 46°, 89°, and 125°. At each of these locations, a detector response function was generated to account for photon interactions within the experimental geometry. Gold’s deconvolution algorithm was used to unfold the energy spectrum. The measured spectra were compared to simulated spectra, which were obtained using an experimentally benchmarked model of the Clinac 21EX in MCNP6. Results: Measurements were acquired and detector response corrections were calculated for all three CS angles. A comparison of spectra for all CS angles showed good agreement with one another. The spectra for all three angles were averaged and showed good agreement with the MCNP6 simulated spectrum, with all points above 400 keV falling within 4%, which was within the uncertainty of the measurement and statistical uncertainty. Conclusions: The measurement of the energy spectrum of a 6 MV linear accelerator using a pulse-mode detector is presented in this work. For accurate spectrum determination, great care must be taken to optimize the detector setup, determine proper corrections, and to unfold the spectrum.

Enhancement of proton collimation and acceleration by an ultra-intense laser interacting with a cone target followed by a beam collimator

A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acceleration mechanism.In addition,the problems involved are studied by using two-dimensional particle-in-cell simulations.The results show that the proton beam can be collimated,accelerated and guided effectively through this type of target.Theoretically,a formula is derived for the combined electric field of accelerating protons.Compared with a proton beam without a beam collimator,the proton beam density and cut-off energy of protons in the type II are increased by 3.3 times and 10%respectively.Detailed analysis shows that the enhancement is mainly due to the compact and strong sheath electrostatic field,and that the beam collimator plays a role in focusing energy.In addition,the simulation results show that the divergence angle of the proton beam in type II is less than 1.67 times that of type I.The more prominent point is that the proton number of type II is 2.2 times higher than that of type I.This kind of target has important applications in many fields,such as fast ion ignition in inertial fusion,high energy physics and proton therapy.

Calculation of Nuclear Data for Proton Induced Reactions on ^(56)Fe and ^(57)Fe

Available nuclear data(absorption cross sections,angular distributions,energyspectra,double differential cross sections of single particle emission and global sets of cross sec-tions of 56,57Fe)are collected,evaluated and calculated by the new theoretical program.Goodagreements are obtained between the experimental data and the calculated data,respectively.

Estimation of the proton energy spectrum in knee region by analog read-out of ARGO-YBJ experiment

Based on the six months data set of ARGO-YBJ experiment with analog read-out and its Monte Carlo simulation, we study the difference between different primaries induced showers by using the space-time information of the charged particles in Extensive Air Showers. With five parameters which can efficiently pick out primary proton induced showers as inputs of an artificial neural network, the proton Spectrum from 100 TeV to 10 PeV can be obtained.

Molecular Mechanism of High Energy Proton Radiation——Raman Spectroscopic Character of Microcosmic Damage in the Space Structure of DNA

High energy proton is an important type of the space radiation. The paper investigates the radiatione ffect of high energy proton (27.9 MeV) on DNA aqueous solution in the field of the molecular mechanism. The following information about the microcosmic damage to the space structure of DNA was obtained: (ⅰ) breakage of a part of interbase hydrogen bonds which maintained double helical structure of DNA; (ⅱ) damage on four bases, in which the damage on adenine ring was the most serious; (ⅲ) obvious change of deoxyribose; (ⅳ) serious damage on backbone phosphate ion (PO_2^-) and phosphate diester (PO_2) and the occurrence of scissions of double-stranded and single-stranded DNAs; (ⅴ) obvious decrease in the amount of B-form conformation.

Study of an unfolding algorithm for D-T neutron energy spectra measurement using a recoil proton method

A proton recoil method for measuring D-T neutron energy spectra using polyethylene film and a Si（Au）surface barrier detector is presented. An iteration algorithm for unfolding the recoil proton energy spectrum to the neutron energy spectrum is investigated. The response matrices R of the polyethylene film at angles of 0o and45o were obtained by simulating the recoil proton energy spectra from mono-energetic neutrons using the MCNPX code. With an assumed D-T neutron spectrum, the recoil proton spectra from the polyethylene film at angles of 0oand 45owere also simulated using the MCNPX code. Based on the response matrices R and the simulated recoil proton spectra at 0oand 45o, the respective unfolded neutron spectra were obtained using the iteration algorithm,and compared with the assumed neutron spectrum. The results show that the iteration algorithm method can be applied to unfold the recoil proton energy spectrum to the neutron energy spectrum for D-T neutron energy spectra measurement using the recoil proton method.

The v-v energy transfer of highly vibrationally excited states (I)──Vibrational quenching of CO(v) by CO_2

The relaxation of the highly vibrationally excited CO (v=1-8) by CO\-2 is studied by time_resolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr\-3 with O\-2 generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v=1-8) to CO 2 molecules are obtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (10 -14 cm 3·molecule -1·s -1), respectively. A two_channel energy transfer model can explain the feature of the quenching of CO(v) by CO 2. For the lower vibrational states of CO, the vibrational energy transfers preferentially to the υ\-3 mode of CO 2. For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the υ\-1 mode of CO 2.

高速动能弹撞击装甲结构引起的螺栓连接失效及部件过载损伤研究

目的 验证和揭示高速动能弹对装甲结构的损伤机理。方法 聚焦高速动能弹打击装甲目标时,弹道冲击造成的靶标结构连接失效及部件过载损伤这2种损伤效应,以典型螺栓连接为研究对象,采用高速球形弹丸撞击螺栓连接结构的小尺寸试验对数值模拟方法和材料模型参数进行校验。在此基础上,采用数值模拟和冲击响应谱分析方法对高速动能弹打击全尺寸坦克进行模拟分析,获得撞击过程螺栓连接失效特征、主要影响因素及坦克典型位置部件的冲击加速度曲线和冲击响应谱曲线。结果 在小尺寸试验中,动能输入为0.042MJ时,螺栓连接未发生失效;但25.6MJ动能输入全尺寸坦克时,螺栓发生断裂而使连接失效。数值模拟结果揭示了螺栓发生断裂的主要原因。结论 输入动能大小、连接螺栓直径、模拟设备部件质量和撞击位置为螺栓是否断裂的主要影响因素。坦克某些位置的冲击响应谱曲线高于军用标准给出的临界曲线的下限甚至上限,表明这些位置的部件因高过载损伤导致失效的概率较高。

高通量快堆辐照生产^(252)Cf关键因素分析

^(252)Cf放射源是一种高强度同位素中子源,在科学研究、装置研发等领域具有重大需求,但长期以来依赖于进口。基于高通量快堆初步设计方案开展辐照靶件设计,结合模拟计算结果得出影响^(252)Cf核素生产的关键因素。在5×10^(15)n·cm^(-2)·s^(-1)中子通量水平下,对三种采用不同氢化锆和Eu_(2)O_(3)吸收体辐照靶件设计方案进行裂变沉积能、能谱计算,并通过燃耗计算程序开展重锔、轻锔靶件燃耗计算,与美国辐照生产^(252)Cf实验值对比。结果表明:方案3的计算值与基准值吻合较好且最适用于重锔靶辐照生产^(252)Cf,方案2适用于通过短的辐照周期辐照生产重锔核素。本文的计算与分析可为高通量快堆辐照生产^(252)Cf提供理论与技术支撑。

高能X射线光谱分析工具——SasalPy

等离子体模型是天文学家解析高能天体观测数据的重要工具,发展精确便利的等离子体模型有助于研究者高效的进行高能X射线光谱分析工作.在现有的SASAL等离子体模型的基础上进一步提出一种新的基于Python语言的高能X射线光谱分析工具包SasalPy,并从理论框架、功能性和差异性方面阐述SasalPy的可靠性和精确性.线辐射和连续辐射计算结果表明,原子参数如跃迁速率、碰撞强度等会对合成光谱产生明显地影响.以Capella星冕的体微分发射度为基础开展了三个温度的光谱合成应用,并通过与其他等离子体模型辐射损失结果的对比,说明SasalPy在X射线能段比较精确可靠.

300 MeV质子重离子加速器及电子器件单粒子效应试验研究

300 MeV质子重离子加速器主要用于模拟空间环境中高能粒子辐照,探索高能粒子与材料、器件以及生命体的相互作用机理。该加速器主要由离子源、直线加速器、注入线、同步加速器、引出线和3个实验终端组成。自2022年11月验收以来,该加速器已完成质子束、氦束、碳束、氪束、钽束、铋束、铀束等离子束的调试,相继开展了材料、电子器件、农作物种子、微生物、小鼠等样品的辐照试验,成为基础研究的实验平台。在基于该加速器的辐照试验平台中,开展了国产SiC功率MOSFET器件单粒子效应研究。300 MeV质子重离子加速器产生能量为1864.3 MeV的^(181)Ta^(31+)离子束,在经过钛窗和空气中传输后,达到SiC表面时LET值为80.7 MeV·cm^(2)·mg^(-1)。通过在SiC功率MOSFET器件漏极上施加不同偏置电压,对栅极和漏极泄漏电流检测分析,获取了在不同偏置条件下SiC MOSFET器件的漏电退化行为。

利用均匀密度等离子体通道加速质子的辐射压力增强方案

提出了辐射压力加速与激光尾波场加速相结合的高能质子加速方案.该方案中在临界密度薄靶后端增加一个均匀密度等离子体通道获得了峰值能量为22.2 GeV、截止能量为36.4 GeV和电荷量为0.67 nC的高能质子束,与质子在纯辐射压力加速中相比,其高能质子的截止能量可以提升2个数量级.结果证实了通过在近临界密度薄靶后面连接一个均匀密度等离子体通道,等离子体通道中激光激发的尾波场可以捕获经辐射压力过程预加速的质子并维持长时间的加速,最终获得高能质子,本文还研究了不同均匀密度等离子体通道中质子的加速情况,发现密度越高,则被加速质子的峰值能量和截止能量越高,电荷量也越大.该组合加速方案对高能质子束的产生与应用具有一定的指导意义.

基于VMD和KFCM-SVM的高压断路器声振联合故障诊断方法

针对高压断路器机械故障复杂、故障特征提取困难的问题,提出一种变分模态分解(variational mode decomposition,VMD)与KFCM-SVM相结合的高压断路器声振联合故障诊断方法。首先利用VMD对去噪后的振动和声音信号进行分解,得到一系列反映断路器操动过程机械状态信息的本征模态函数(IMF);然后对各IMF分量进行Hilbert变换,构造相应的Hilbert边际谱,求取能量熵作为特征向量;最后采用模糊核C—均值聚类(kernel fuzzy C means,KFCM)对特征进行预分类,再利用支持向量机(SVM)建立训练模型实现机械状态辨识。实验结果表明:声振信号Hilbert边际谱能量熵对高压断路器机械状态变化敏感,KFCM-SVM能够准确识别高压断路器分闸操动过程中的机械故障。

Tb^(3+)掺杂钒磷酸盐蓝绿发光调控及发光机理研究

本文采用高温固相方法合成了不同掺杂浓度的YVO_(4)∶Tb^(3+)、YPO_(4)∶Tb^(3+)和YV_(1-x)P_(x)O_(4)∶Tb^(3+)系列荧光粉,利用差示扫描量热法(DSC)分析了高温固相合成过程中的化学反应,确定将1 350℃作为高温合成温度。利用XRD表征了材料物相结构,结果显示材料物相单一,均为四方晶系结构。研究了YVO_(4)∶Tb^(3+)、YPO_(4)∶Tb^(3+)和YV_(1-x)P_(x)O_(4)∶Tb^(3+)系列荧光粉室温下的发光性质。受晶体场影响,紫外激发下YVO_(4)∶Tb^(3+)中Tb^(3+)发光主要以^(5)D_(3)→^(7)F_(J)(J=6,5,4,2)跃迁发光为主,发光显示为蓝光;P元素的增加改变了YV_(1-x)P_(x)O_(4)∶Tb^(3+)晶体场环境,增强了基质与^(5)D_(3)、^(5)D_(4)能级间的多声子弛豫及^(5)D_(3)→^(5)D_(4)能级间的交叉弛豫,^(5)D_(4)→^(7)F_(J′)(J′=6,5,4,3)发射逐渐占优,发光呈现蓝、青、绿发光变化;掺杂浓度对YPO_(4)∶Tb^(3+)发光调控作用显著,随着掺杂浓度增加,Tb^(3+)的^(5)D_(3)与^(5)D_(4)能级间的交叉弛豫作用增强,^(5)D_(3)发光减弱,^(5)D_(4)发光增强,通过调整掺杂浓度实现材料发光由青光到绿光的调控。综上,通过基质组分及掺杂浓度调节,可实现Tb^(3+)掺杂钒磷酸盐体系蓝绿发光调控。

宇宙高能质子致单粒子翻转率的计算

通过简化半导体器件灵敏单元 ,计算得到了宇宙高能质子在器件灵敏单元内产生的能量沉积。然后利用地面重离子实验单粒子翻转数据得到的Weibull函数 ,计算了CRRES卫星轨道、 33mm铝屏蔽壳体内几种器件的单粒子翻转率 ,并与已有结果进行了比较说明。

低能离子在植物样品中长程穿透行为的研究

采用透射法测量了一定厚度的植物样品在接受低能离子辐照时从其后表面出射的荷能粒子。所测样品包括30、50和100μm芸豆子叶切片和20μm的西红柿皮。测量结果表明低能离子在植物样品中存在长程穿透现象 ,在芸豆切片中的穿透深度至少可达60μm ,此时穿透的概率很小 ,不大于10-5 ;长程穿透的离子产生的损伤空间分布不均匀。样品的高能质子透射能谱显现辐照损伤不是特别严重 ,推测这种长程穿透的现象由植物样品本身的结构决定。

FY-3A卫星与NOAA系列卫星高能带电粒子实测结果的比较

FY-3A卫星是运行于830 km高度的太阳同步轨道气象卫星,其搭载的空间环境监测器可观测3～300 MeV的高能质子和0.15～5.70 MeV的高能电子.FY-3A卫星在轨工作期间,太阳活动处于由谷年向峰年过渡期,空间环境非常平静,探测结果显示3～300 MeV的高能质子分布主要集中在南大西洋辐射带异常区,0.15～5.70 MeV的高能电子分布区域除南大西洋异常区外,还分布在南北两极高纬区域.FY-3A与NOAA卫星测量结果反映出带电粒子强度及分布区域随投掷角变化的空间各向异性特征.本文在充分考虑了带电粒子时间、空间分布差异以及比对探测器之间自身设计差异的前提下,经过归一化处理后,首次对两颗卫星同期探测结果进行相关性分析,验证了两颗卫星相同时空条件下高能带电粒子通量分布的一致性;说明FY-3A空间环境监测器不仅具备空间带电粒子辐射监测能力,且探测结果有效可靠,可用作辐射带环境数据源的组成部分,为发展新的模型,深入研究辐射带高能粒子的分布、起源和传输等提供新的观测依据.