How likely is Polya's drunkard to stay in x⩾ y⩾z?

In his celebrated paper, Polya has considered the random walk in the three-dimensional (cubic) lattice and showed that the probability of return to the origin is less than 1. Subsequent authors have shown that the probability is %34.053.... Here we consider the same random walk, with the restriction that the drunkard is only allowed to stay inxyz. It is shown that his probability of returning to the originand staying in the allowed region is %6.4844....     

90Mo电磁跃迁几率的测量

利用束流能量为116MeV的⁵⁹Co(³⁵Cl,2p2n)⁹⁰Mo反应布居⁹⁰Mo的高自旋态.用10台反康普顿HPGe探测器组成的探测阵列进行γγ符合测量.通过多普勒展宽峰的形状分析测定⁹⁰Mo高自旋态的寿命.在正宇称衰变系观察到增强的M1跃迁,推断I=13以上是扁椭形变.负宇称高自旋态具有大的B(E2)值,并随自旋增大而起伏变化.正、负宇称态之间的跃迁显示增大的E1跃迁,似有八极关联的可能.但是,⁹⁰Mo并不处在理论预言的存在八极形变的核区内.     

Free probability and the von Neumann algebrasof free groups

This short note summarizes the circumstances of the birth of free probability theory andsome of the recent achievements.     

Lifetime of resonant state in a spherical quantum dot

This paper calculates the lifetime of resonant state and transmission probability of a single electron tunnelling in a spherical quantum dot (SQD) structure by using the transfer matrix technique. In the SQD, the electron is confined both transversally and longitudinally, the motion in the transverse and longitudinal directions is separated by using the adiabatic approximation theory. Meanwhile, the energy levels of the former are considered as the effective confining potential. The numerical calculations are carried out for the SQD consisting of GaAs/InAs material. The obtained results show that the bigger radius of the quantum dot not only leads significantly to the shifts of resonant peaks toward the low-energy region, but also causes the lengthening of the lifetime of resonant state. The lifetime of resonant state can be calculated from the uncertainty principle between the energy half width and lifetime.     

低能C36团簇在金刚石(100)晶面沉积时的影响因素

"使用Brenner-LJ拟合势描述了金刚石与C36团簇原子间的相互作用,并用分子动力学模拟的方法研究单个C36(D6h)在金刚石(100)晶面的沉积机制．通过仿真实验分析了C36团簇的入射能量、入射点位置、入射姿势、入射角度等因素对其成核初期化学吸附过程以及沉积后其稳定性的影响．研究发现：由于C36入射点位置及入射姿势的不同,其在金刚石(100)晶面沉积时的沉积阈值最小值为20 eV,最大值为60 eV;在入射角不超过60o斜射时,由于水平运动分量的存在,C36可能翻滚及平滑至成键能量较小的区域后再成键     

PdⅩⅣ-CdⅩⅥ离子4s24p3和4s4p4组态精细结构能级与跃迁的扩展分析

用多组态HXR理论方法对KrⅣ-CdⅩⅥ离子4s^24p^3和4s4p^4组态的精细结构能级进行了分析计算。在已有研究工作的基础上,通过对4s^24p^3和4s4p^4组态能级的实验观测值与HXR计算结果之差AE沿等电子序列变化规律的分析．找出了△E随有效核电荷数Zc变化的规律,预言并计算了PdⅩⅣ-CdⅩⅥ离子4s^24p^3和4s4p^4组态能级,大部分预言计算值与实验结果的偏差小于100cm^-2。由此还进一步计算了PdⅩⅣ-CdⅩⅥ离子4s^24p^3—4s4p^4跃迁的谱线波长、振子强度和跃迁概率。结果表明：除了4s^24p^3D5/2-4s4p^4^2D5/2跃迁的谱线波长(29．992nm)与实验值相差0．018nm外．对于其余5条谱线．预言值与实验值的偏差均不超过0．005nm。     

Study of Survival Probability of Super Heavy Nuclei

The survival probability of super heavy nuclei produced in cold fusion reactions is studied by using the standard Fermi gas level density formula and analyzed with fission and neutron evaporation characteristics predicted in different theoretical models. The level density formula used in this letter suppresses the ratio of neutron emission width to fission width, Гn/Гf. The dependence of Гn/Гf on the saddle point level density parameter and excitation energy is also investigated.     

Tomography of Binomial States of the Radiation Field

The symplectic, optical, and photon-number tomographic symbols of binomial states of the radiation field are studied. Explicit relations for all tomograms of the binomial states are obtained. Two measures for nonclassical properties of these states are discussed.     

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。