混响室的概率统计分析方法及其蒙特卡罗模拟

 提出了一种研究混响室问题的理论分析方法,从理想混响室的离散概率模型出发,采用蒙特卡罗模拟来获得室内电磁场量及其相关物理量的概率统计特性。运用该方法获得了混响室内若干场量（均为归一化值）的概率密度函数、室内一段均匀无耗单导体传输线的负载平均耦合截面及负载电流响应模值的概率分布,所得结果与已有文献给出的结果（包括由解析公式计算或测量所得的结果）吻合良好。由于蒙特卡罗方法的普适性,采用该方法可以获得任意待分析参量的全部概率统计特性（只要样本数足够大）。同时该方法无需针对具体混响室进行,只要在其测试区域能较好地与理想混响室的基本概率模型相吻合,就能给出较精确的计算结果,且其计算量远远小于基于全波分析的蒙特卡罗方法。     

External cavity diode laser around 657 nm

Operating a laser diode in an external cavity, which provides frequency-selective feedback, is a very effective method to tune the laser frequency to a range far from its free running frequency. For the Ca atomic Ramsey spectroscopy experiment, we have constructed a 657-nm laser system based on the Littman-Metcalf configuration with a 660-nm commercial laser diode. Continuously 10-GHz tuning range was achieved with about 100-kHz spectral linewidth, measured with beat-note spectrum of two identical laser systems.     

用四叉事例样本确定J/ψ总数

详细介绍了用J/ψ衰变中的四叉事例样本确定J/ψ总数的方法,并用此方法确定了北京谱仪从1999年11月到2001年5月所收集的两批J/ψ数据的事例总数,分别为(27.00±1.48)×10⁶和(30.70±1.62)×10⁶.     

利用可调谐半导体激光光谱技术对含尘气体中NH3的测量

利用可调谐半导体激光吸收光谱技术(TDLAS)并结合波长调制,在近红外波段1531.7nm处对常温常压下的NH3进行浓度测量.在10 m的长程吸收池内得到了25×10-6的浓度信号,并且在25×10-5-400×10-6浓度范围内二次谐波信号与浓度具有良好的线性关系.讨论了粉尘颗粒对于二次谐波信号的干扰,并提出了利用激光强度线性拟合解决颗粒对气体测量干扰的方法.     

The symmetric and antisymmetric superexchange interactions in spin-Peierls system

The influences of Dzyaloshinskii Moriya （DM） interaction and Kaplan-Shekhtman-Entinwohlman-Aharony （KSEA） interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczos numerical method. The ground state of the spin-Peierls system is still dimerized phase when both of the DM and the KSEA interactions have the same value with Heisenberg interaction. It is found that the KSEA interaction and uniform DM interaction are always against systemic dimerization, but the staggered DM interaction acts in favour of dimerization. Furthermore, the influences of the DM and the KSEA interactions are also studied in terms of the ground state index rate and the energy gap index rate of the dimerized Heisenberg system. The results show that the DM interaction makes the index rates larger, while the KSEA interaction makes them smaller.     

Corkscrew运动影响束流发射度的数值分析

在直线加速器中，始终存在束流质心轴、束流传输管道几何轴、束流聚焦传输磁场磁轴等三轴不一致问题。当束轴与磁轴存在夹角，而且束流脉冲（平顶）期间存在能量差别时，将引起束心的Corkscrew运动。斜入射的束流在轴向磁场中传输时，由于束流脉冲（平顶）期间不可避免的能量差别，导致不同时刻的束片质心螺旋运动的相位不同，在束流到达同一个位置时，不同时刻束片的质心在同一个考察点具有不同的横向位置。束心Corkscrew运动会造成很多不良后果。针对束心Corkscrew运动造成束流积分发射度的增长情况开展数值模拟研究，为采取相应的抑制措施提供参考和依据。     

Collision geometry and particle production in high energy heavy ion collision experiments

An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented. This paper includes four parts: 1) Theoretical predictions of quark-gluon plasma and introduction for high energy heavy ion collision experiments. 2) Experimental status on collision     

Configuration of the valence neutrons of 17B

The reaction cross section of ~(17)B on ~(12)C target at(43.7±2.4)MeV/u has been measured at the Radioactive Ion Beam Line in Lanzhou(RIBLL).The root-mean-square matter radius(R_(rms))was deduced to be(2.92±0.10)fm,while the R_(rms)of the core and the valence neutron distribution are 2.28 fm and 5.98 fm respectively.Assuming a"core plus 2n"structure in ~(17)B,the mixed configuration of(2s_(1/2))and(1d_(1/2))of the valence neutrons is studied and the s-wave spectroscopic factor is found to be(80±21)%.     

红外视景仿真技术及其研究进展

从红外视景仿真技术意义出发，介绍了其所包含的几个基本部分；从目标辐射建模、背景辐射建模和大气建模三方面，总结了国内外红外视景仿真技术发展历程和状况。其中列举了国外多个典型红外视景仿真软件和几个较完善红外辐射模型，并统计了2000年以来国内高校在红外视景仿真方面的研究情况。统计数据表明，多个发达国家的红外视景仿真技术已逐步趋于成熟和产品化，而国内尚未开发出功能较完善的红外视景仿真系统，只能仿真较简单场景。     

低剩磁磁芯自复位能力研究

 在MHz重复频率的高压多脉冲下,如何在脉冲间隔对磁芯进行快复位是高压多脉冲感应加速腔研制的关键问题。对低剩磁磁芯在脉冲励磁后磁通量密度的自恢复能力及其影响因素进行了实验研究和理论分析,证实了利用低剩磁磁芯的自恢复能力来实现在高压多脉冲下重复利用磁芯伏秒值的可能。实验证明：在选用合适的材料及工作电路后,磁芯在脉冲励磁后自复位到剩磁处的时间可小于500 ns,可稳定地工作在MHz重复频率的高压多脉冲环境下。