Equivalent properties of single event burnout induced by different sources

The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the "turn-off" state is more susceptible to single event burnout than it is in the "turn-on" state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.     

合肥光源测量束团纵向精细结构的单光子计数系统设计

本文介绍了用单光子计数法测量束团纵向精细结构的原理.介绍了合肥同步辐射光源测量束团纵向精细结构的单光子计数系统的设计.由于单光子计数法具有高时间分辨率(2ps)和大的动态测量范围(10⁵)等优点,所以该系统不仅可以测量束团长度,而且可以精密测量单束团的纯净度.最后,分析了该系统的性能,并讨论了该系统在尾场和纵向阻抗的研究、束团伸长效应的研究以及影响单束团不纯净机理的研究中的应用.     

Recent advances on single photon sources based on single colloidal nanocrystals

Single colloidal quantum dots (QDs) are increasingly exploited as triggered sources of single photons. This review reports on recent results on single photon sources (SPS) based on colloidal quantum dots, whose size, shape and optical properties can be finely tuned by wet chemistry approach. First, we address the optical properties of different colloidal nanocrystals, such as dots, rods and dot in rods and their use as single photon sources will be discussed. Then, we describe different techniques for isolation and positioning single QDs, a major issue for fabrication of single photon sources, and various approaches for the embedding single nanocrystals inside microcavities. The insertion of single colloidal QDs in quantum confined optical systems allows one to improve their overall optical properties and performances in terms of efficiency, directionality, life time, and polarization control. Finally, electrical pumping of colloidal nanocrystals light emitting devices and of NC-based single photon sources is reviewed.     

多声源共同作用下的混合声剂量值预测方法研究

本文借助单一声样本与人工合成的混合声样本,重点研究了由多个单一声源共同作用形成的混合声的剂量值预测方法.首先,提出了一种基于对作用时长短时化处理的声音样本剂量值确定流程,并利用该方法分别确定了单一声样本与人工合成的混合声样本的剂量值.随后,分析了混合声样本剂量值(亦称总剂量,记为LTotal)与构成混合声样本的每个单一声样本剂量值(亦称组分剂量,记为Li,i=1,2,···,K;K为单一噪声样本的个数亦称组分数量)之间的关系,实现了在已知所有单一声剂量值的前提下成功预测混合声的剂量值,为深入开展复杂声环境下的噪声源控制和噪声总剂量控制、实现高效的环境噪声治理提供了理论依据.     

Nonlinear absorption microspectroscopy of single perylene nanocrystals with a multichannel double lock-in amplifier

Nonlinear confocal absorption microspectroscopy of single nanocrystals at low temperatures was introduced in the study of perylene nanocrystals. By the stationary pump-probe method, single nanocrystals were photoexcited into metastable excited states, and difference absorption spectra due to excited-state absorption and ground-state depletion were simultaneously recorded using a multichannel lock-in amplifier. It was revealed that the free Frenkel exciton band for single perylene nanocrystals is broader in width than that for the bulk crystal at low temperatures, suggesting that the exciton band is inhomogeneously broadened even for single perylene nanocrystals.     

Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q＋ ions

In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^＋ （q = 1 - 4） ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization （or the single capture） of argon associated with single electron loss （or single electron capture） by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.     

纳米静态随机存储器低能质子单粒子翻转敏感性研究

针对65, 90, 250 nm三种不同特征尺寸的静态随机存储器基于国内和国外质子加速器试验平台, 获取了从低能到高能完整的质子单粒子翻转截面曲线. 试验结果表明, 对于纳米器件1 MeV以下低能质子所引起的单粒子翻转截面比高能质子单粒子翻转饱和截面最高可达3个数量级. 采用基于试验数据和器件信息相结合的方法, 构建了较为精确的复合灵敏体积几何结构模型, 在此基础上采用蒙特卡罗方法揭示了低能质子穿过多层金属布线层, 由于能量岐离使展宽能谱处于布拉格峰值的附近, 通过直接电离方式将能量集中沉积在灵敏体积内, 是导致单粒子翻转截面峰值的根本原因. 并针对某一轨道环境预估了低能质子对空间质子单粒子翻转率的贡献.     

基于单频2D-Gabor滤波器的虹膜识别算法研究

针对2D-Gabor滤波器设计的问题,提出了一种单频2D-Gabor滤波器设计方法。该方法在详细分析了2D-Gabor滤波器中各个参数意义的基础上,通过二分法的思想确定适合虹膜纹理的单一频率ω,再根据其它参数与其关系确定出各个参数取值,从而获得单一频率下的2D-Gabor滤波器。实验结果表明使用设计的单频2D-Gabor滤波器对虹膜图像进行特征提取可以使虹膜识别的识别率达到98.61%以上。使用单频2D-Gabor滤波器不仅可以提高特征提取速度,降低存储空间,同时也利于硬件实现。     

The single diffractive component in hadron-hadron collisions within the two-component Dual Parton model

The single diffractive component in hadronhadron interactions is studied in the two-component Dual Parton Model. We distinguish high mass single diffraction represented by a triple-Pomeron exchange and low mass single diffraction described via a two channel eikonal method. The calculated single diffractive cross sections, and the distributions agree quite well with data from collider and fixed target experiments. The fit of the model parameters to cross section data gives a extrapolation of the total, elastic, and single diffractive cross sections to supercollider energies which depends on the parton structure functions used for the minijet component.     

CoTiSb基体中Ni元素诱导的单自旋通道研究

沿半Heusler结构CoTiSb合金的[001]晶体学方向, 利用Ni元素连续替换一条原子链上的Ti, Sb原子, 在半导体性CoTiSb基体中设计了一系列均匀分布的Ni基单原子链阵列. 采用第一性原理方法, 研究了Ni基单原子链的电子结构和磁性质, 发现Ni-Sb单原子链具有高度自旋极化率和空穴导电特性, Ni-Ti及Ni-Ni单原子链具有100%的自旋极化率, 并且在CoTiSb基体中形成了以这种Ni基单原子链为中心的、尺寸非常小的单自旋纳米柱通道.     

基于光电双开关的单光子同步探测

提出了一种基于光电双开关进行同步测量单光子的方法.这种测量方法能够有效抑制背景光以及由背景光引起的后脉冲和死时间对单光子测量的影响,有效地减少了单光子探测中的误计数,改善了单光子测量的信噪比.同时,避免了单光子探测器通常工作在门控电压方式下产生自发光子辐射的缺点.     

近红外光谱法快速无损识别普通、高油、超高油玉米籽粒

以75粒普通玉米、72粒高油玉米和73粒超高油玉米共计220粒玉米籽粒样品为实验材料,通过玉米籽粒的近红外光谱结合主成分信息提取技术建立了不同油分含量的玉米籽粒样品的BPANN识别模型.为考察模型的实际应用效果,连续10次随机划分样品集,每次在各类别玉米籽粒中随机选取4/5作为建模集,剩余1/5作为预测集,选择光谱信息的第2～15个主成分作为网络输入,样品以3个类别值-1,0,1作为目标输出,10次建模的学习识别率均达到100%.以所建BPANN模型对预测集样品进行分类识别,普通玉米、高油玉米和超高油玉米籽粒平均正确识别率分别为99.33%,97.88%和91.43%,总体正确识别率平均达到95%以上.研究结果表明BP人工神经网络近红外光谱法建立玉米籽粒识别模型可对不同油分含量的玉米籽粒进行快速、无损识别,对于玉米籽粒的选育工作具有一定的指导意义.另外还探讨了选择主成分建模对不同油分含量的玉米籽粒种类识别效果的影响,结果显示具有方差贡献率99%以上的光谱第一主成分参与建模,对模型预测效果有负影响,说明不同主成分包含的区分普通、高油与超高油玉米籽粒的分类信息不同,因此近红外光谱法建立样品分类识别模型时选择不同主成分建模是有必要的.     

Isolated single quantum dot emitters in all-epitaxial microcavities

Data are presented on a fabrication approach that places an isolated single quantum dot at the center of a semiconductor microcavity. The microcavity is based on an all-epitaxial mesa-confined design that is mechanically robust and provides the thermal dissipation needed for a single photon source device technology. Microphotoluminescence is used to reveal single quantum dot emission with the essential optical properties of single quantum emitters.     

Single Photon Scattering in a Pair of Waveguides Coupled by a Whispering-Gallery Resonator Interacting with a Semiconductor Quantum Dot

The single photon scattering properties in a pair of waveguides coupled by a whispering-gallery resonator interacting with a semiconductor quantum dot are investigated theoretically.The two waveguides support four possible ports for an incident single photon.The quantum dot is considered a V-type system.The incident direction-dependent single photon scattering properties are studied and equal-output probability from the four ports for a single photon incident is discussed.The influences of backscattering between the two modes of the whispering-gallery resonator for incident direction-dependent single photon scattering properties are also presented.     

单光子探测器性能对量子密钥分发系统的影响

根据量子密钥分发协议的原理和单光子探测器的工作模式系统分析了单光子探测器性能对量子密钥分发系统影响的物理模型,给出了单光子探测器暗计数和量子效率对系统筛选码率和量子误码率等指标产生影响的计算公式,并通过对各类量子密钥分发系统的比较,推导出了适用于一般量子密钥分发系统的普适结果。结果表明,在同等条件下采用较少的探测时间门可以提高量子密钥分发系统的性能。     

微光像增强器积分灵敏度单次测量误差分析

为了提高批量微光像增强器性能参数的测试速度,通常采信单次测试数据作为测量结果。在该情况下,参数单次测量结果的误差将直接决定性能评价结果的准确性。以微光像增强器积分灵敏度的参数测试为例开展单次测量误差评定,通过对微光像增强器积分灵敏度的测试方法、测量装置、数据计算等误差情况进行综合分析,计算得到的积分灵敏度单次测量最大误差为6.7%;在该基础上,提出了采用更高加工精度光阑、对入射光测量位置进行修正以及阶段性辅助参量重复性测量校对的积分灵敏度单次测量误差控制方案。研究结果对微光像增强器批量化快速测试具有重要的指导意义和参考价值。     

基于Ce:YAG单晶的白光发光二极管性能研究

以Ce:YAG单晶取代传统Ce:YAG荧光粉用于制备白光发光二极管(LED),研究了Ce:YAG单晶厚度及驱动电压的变化对其发射光谱、色坐标、亮度、光视效能和色温的影响。研究结果表明,在基于Ce:YAG单晶的白光LED中,发射光的色坐标以及蓝光与黄绿光之间的相对强度可通过对Ce:YAG单晶片厚度的改变进行调整。在恒定电压驱动下,白光LED样品的亮度、光视效能和色温均随单晶片厚度的减小而增加。当Ce:YAG单晶厚度为0.6mm时,可获得较纯的白发射光,并且其色坐标具有较高的可靠性和稳定性,基本不受驱动电压变化的影响。研究结果表明Ce:YAG单晶是一种可用于新型白光LED的理想荧光材料。     

Linear optical implementation of optimal unambiguous discrimination among quantum states

In this paper, we present a linear optical scheme for optimal unambiguous discrimination among nonorthogonal quantum states in terms of the multiple-rail and polarization representation of a single photon. In our scheme, discriminated quantum states are expressed by using the spatial degree of freedom of a single photon while the polarization degree of freedom of the single photon is used to act as an auxiliary qubit. The optical components used in our scheme are only passive linear optical elements such as polarizing beam splitters, wave plates, polarizers, single photon detectors, and single photon source.     

First-order photon interference of a single photon from a single quantum dot

Photon interference indicating wave-like nature of a single photon emitted from a single quantum dot is demonstrated. Photon state as a superposition of two orthogonal linear polarization modes is prepared inside a solid-state single photon source, which causes the first-order interference analogous to the Young’s double slit experiment. The lack of which-mode information is essential for observing the single photon interference.