蒙特卡罗粒子输运软件JMCT抽样工具库设计

为通用型蒙特卡罗粒子输运程序JMCT设计了抽样工具库,通过两种技术途径提供各分布的抽样。一是针对各种常见分布提供特定抽样子程序;二是提供一个通用型的抽样子程序,可以实现任意离散分布和任意一维有限区间上连续分布的自动抽样。在设计任意一维有限区间上连续分布的自动抽样工具时利用了部分开源代码,利用其功能提供给用户最大的方便性。对抽样工具库的检验表明,其可以正确、方便地实现各种输运模拟中常见分布的抽样。     

一种改进的计算探测器校正因子的相关抽样方法

对于小尺寸探测器处于大块介质的情形, 在探测器的校正因子的Monte Carlo模拟中, 存在两个难题: 一是由于探测器尺寸很小粒子难以到达探测器并发生碰撞; 二是两个随机变量比值难以达到要求精度. 本文使用经过改进的粒子碰撞自动重要抽样方法, 再结合相关抽样方法, 解决了这两个难题, 并在MCNP-4C程序平台上加以实现. 除了粒子碰撞自动重要抽样以外, 还选用了其他3种方法: 直接模拟、区域分裂、强迫碰撞+Dxtran球分别与相关抽样方法结合, 对一个简化的探测器校正因子计算模型进行了计算. 实际计算结果表明, 相关抽样方法无论与哪种方法结合, 都起到了提高相关量计算效率的作用; 而它与粒子碰撞自动重要抽样结合, 比其他方法具有明显的优越性.     

AGS能量下核系统的强阻止性

本文给出了一个简单的相对论性强子级联模型,并用它模拟了Si(14.6A GeV/c)+Au的反应.研究了共振态对质子π的快度分布以及质子横质量分布的影响.在此模型中,碰撞粒子的纵动量变化(非弹情形)由阻止律给出;而粒子的横动量分布通过指数分布或高斯分布抽样.我们的结果与E810(814)数据和E802的新结果较好地符合.这表明:共振态△的引入能更好地反映碰撞的物理过程;AGS能量下核系统的强阻止性已无可非议.     

30MeV/u 40Ar+58,64Ni、115In反应中IMF的元素分布

在5°—140°范围内测量了30MeV/u40Ar束流轰击不同靶核(58Ni、64Ni、115In)时出射的中等质量碎片的元素分布.在20°—80°之间,观察到了原子序数大于弹核原子库数的出射碎片(Z=3—24),发现中等质量碎片的微分截面在其原子库数从小于弹核原子库数向大于弹核原子库数变化过程中是连续变化的,该角区出就碎片的元素分布与弹核原子库数关系不大.对中能区核反应的过渡性质做了讨论,指出了探测阈对所测得的元素分布的影响,并讨论了元素分布的幂指数规律.     

干涉图数据处理中的几个合理性判据

在干涉图数据处理中,构成波差多项式的基底函数的性质,正则方程的求解方法,抽样点的分布与数量等对确定波差函数的解都有影响;同时在数值化的过程中,不可避免地要引入测量误差,它对波差函数的解也有较大的影响.本文利用数理统计分析的方法对上述问题产生的误差进行精确的定量分析,并给出了各自模拟计算的结果及判断波差多项式的基底函数与项数的选择、抽样点的分布与数量、拟合结果等是否合理的定量判据.     

ITER试验包层模块的中子学分析与设计

ITER试验包层模块(TBM)的中子学的设计和计算结果为TBM的其它大多数系统设计提供重要的数据依据。本文首先应用TRANSX程序完成基于FENDL2.0新库制作,以及中子输运程序和数据库的基准检验;然后应用二维中子输运程序TWODANT,计算和分析了中国氦冷Li₄SiO₄固体氚增殖剂的试验包层模块的功率密度分布、增殖区产氚特性、结构材料的中子辐照特性、结构材料和增殖材料的产氢和产氦等特性,并给出一个经合理优化的 TBM中子学初步设计结果。     

逆Compton散射的MonteCarlo模拟

研究模拟均匀、各向同性介质内的逆康普顿散射过程的Monte Carlo方法,分析电子速度分布乘抽样法和光子散射方向分布乘抽样法的抽样效率,完善电子速度分布的直接抽样法、光子散射能量分布的乘加抽样法.通过对这四种抽样方法抽样费用的分析和比较,得出各种方法的最适条件,该方法可以模拟更高能的辐射.     

混合评价核数据库HENDL1.0/MG/MC研制

根据世界几个主要核评价数据库,如ENDF/B 6(美国)、JEF 2.2(欧盟)、JENDL 3.2(日本)、BROND 2.2(俄罗斯)、CENDL 2.1(中国)和FENDL 2(IAEA/NDS),兼顾聚变、裂变以及聚变 裂变次临界混合堆设计研究的多种需要,经过甄别、筛选,最后集成为包含213个核素的基本评价文件,名为HENDL1.0/E的核评价数据库.在此基础上,利用目前流行的群常数加工程序系统NJOY和输运截面制备程序TRANSX制作两套用于中子或/和光子输运计算的输运截面工作库:①参考Vitamin J能群结构制作了175群中子和42群光子、中子 光子耦合多群工作数据库HENDL1.0/MG,可用于离散纵标Sn法程序计算;②连续能群结构、紧凑ENDF(ACE)格式中子截面库HENDL1.0/MC,可用于蒙特卡罗方法输运计算,如MCNP.另外还制作了可用于燃耗(嬗变)计算的燃耗库BURNUP.LIB和响应函数库RESPONSE.LIB两个专用数据库.同时,也对HENDL1.0综合评价核数据库的有效性进行了抽样测试、基准检验和初步确认. A Hybrid Evaluated Nuclear Data Library(HENDL) named as HENDL1.0 has been developed by Fusion Design Study (FDS) team of Institute of Plasma Physics, Academia Sinica (ASIPP) to take into account the requirements in design and research relevant to fusion, fission and fusion-fission sub-critical hybrid reactor. HENDL1.0 contains one basic evaluated sub-library naming HENDL1.0/E and two processed working sub-libraries naming HENDL1.0/MG and HENDL1.0/MC, respectively. Through carefully comparing...     

通用光路计算程序

本文是我所光路计算程序的一个说明.它介绍了程序的功能,列出了程序中所用的全部计算公式,并说明其来源和物理意义.程序仅追迹了四个视场的三十四条光线,算出这四个视场的点列图和每个视场的五个离焦位置、四个特征频率和两种方位物分布的光学传递函数(OTF)值.程序通过光路计算直接算出几何像差(视场和孔径),样点虽然不多(34个样点),但因它们是按切比雪夫求积公式的节点分布的,所以这些几何像差值的等权平均就能相当好地反映整个画面、整个光瞳内的像差情况.本计算程序由于运用像差理论,其优点可少算光线,而获得较多的有用信息,且能较准确全面地评价光学系统质量,是一个通用性强、计算速度快的光学计算程序.     

光子与相对论麦克斯韦分布电子散射截面的蒙特卡罗计算方法

高温全电离等离子体的辐射输运问题中,光子与电子的Compton散射与逆Compton散射是其中重要的特性,光子与相对论麦克斯韦电子散射的描述及截面的计算非常复杂且费时.本文提出了一种用于模拟计算光子与相对论麦克斯韦速度分布电子散射截面的蒙特卡罗计算方法.给出了各步骤的具体实现办法,推导了对应的计算公式,研究了相对论电子速率抽样方法,编写了光子与相对论电子散射的微观截面的蒙特卡罗计算程序.开展了高温全电离等离子体中,不同能量光子与不同温度电子散射的微观散射截面计算和分析.模拟计算结果显示,在电子温度低于25 keV情况下,本文方法与多重数值积分方法的计算结果非常接近;但随着电子温度继续升高,二者差异逐渐增大并较明显,经分析,可能是本文方法目前的电子速率抽样偏差所致,希望将来能够找到更好的相对论电子速率抽样方法以克服此缺陷.     

电光Q开关电路的研究

分别使用冷阴极触发管和弧光放电充气管(Krytron)作为开关器件制作了加压式、退压式毫微秒脉冲发生器,主要是针对电光Q开关电路来研究的。由于脉冲幅度以及宽度可以很方便的调整,也可应用于其它需要高压单脉冲的场合。     

High-voltage pulse production using transformer-coupled LC vectorinversion generators

The analysis, design, and operation of high-voltage, transformer-coupled LC vector inversion generators are presented and discussed. The transformer-coupled LC inversion generator is easy to construct and, compared with Marx-type generators and conventional LC vector inversion generators, requires only one inversion switch, independent of the number of voltage multiplication stages. The transformer-coupled LC generator, therefore, satisfies a niche area need for some high-voltage pulse applications. The primary factor that limits the performance of the transformer-coupled LC generator is magnetic saturation in the transformer core. This investigation develops theoretical scaling relationships for magnetic saturation in the transformer core and other performance-limiting factors. The results of transformer-coupled LC vector inversion generator numerical simulations are also compared with theoretical results     

一种实用型数字信号发生器

本介绍的数字信号发生器具有电路简单、元器件易购、调试方便、实用性强等特点。     

Dijet physics with CMS detector at the Large Hadron Collider

The results from various dijet distributions in proton?Cproton collisions at a centre-of-mass energy of 7 TeV, with 2010 and 2011 data from the CMS experiment, are presented. The measurements of the dijet mass spectra, centrality ratio, azimuthal decorrelation and angular distribution are shown. Sensitivity of the phenomenological parameters used to model different event generators is also investigated. Prospects for observing evidence for new physics in these distributions are presented.     

Di-Jet production in photon-photon collisions at \sqrt{s}_{\rm ee}=161 and 172 GeV

Di-jet production is studied in collisions of quasi-real photons radiated by the LEP beams at ee centre-of-mass energies and 172 GeV. The jets are reconstructed using a cone jet finding algorithm. The angular distributions of direct and double-resolved processes are measured and compared to the predictions of leading order and next-to-leading order perturbative QCD. The jet energy profiles are also studied. The inclusive di-jet cross-section is measured as a function of and and compared to next-to-leading order perturbative QCD calculations. The inclusive di-jet cross-section as a function of is compared to the prediction of the leading order Monte Carlo generators PYTHIA and PHOJET. The Monte Carlo predictions are calculated with different parametrisations of the parton distributions of the photon. The influence of the ‘underlying event’ has been studied to reduce the model dependence of the predicted jet cross-sections from the Monte Carlo generators. Received: 15 July 1999 / Published online: 12 August 1999     

组合发电仪的制作

仪器应用生活中常见的材料,仅仅围绕物理学科知识,通过巧妙设计,组装出一系列发电机。旨在让学生明白各种发电机的工作原理,以及能量之间是如何相互转化的,培养学生节约能源,保护环境利用清洁能源的意识。此外本仪器制作简单,便于学生亲手制作,锻炼动手能力的同时,又可提高学习兴趣。     

Autonomous magnetocumulative power supply

Helical magnetocumulative generators (MCGs) fed from explosive piezo generators (EPGs) are the most compact power supplies with an output energy of 1–10 kJ. EPGs are successfully coupled with MCGs in the operation mode and in structural parameters; these generators are easy to operate and do not require transformers or commutators. We report on the results of designing an autonomous small-size power supply based on EPGs and MCGs. Owing to bidirectional impact loading of the piezoceramic block of an EPG, the energy at the piezo generator output attains values of ～25 J and is transferred to the helical MCG with an initial inductance of ～1000 μH. The power supply is constructed in the form of a monoblock with a volume of ～2 dm³ or in the form of two separate devices connected by a high-voltage cable.     

Heat transfer measurement using thermochromatic liquid crystal

The present study describes the results of an experimental investigation of heat transfer rate on the wall surface downstream of vortex generators and includes the effect of different angles of attack of the vortex generators on heat transfer. Heat transfer measurements are made with thermochromatic liquid crystal (TLC) to provide the local distributions of heat transfer coefficients. The major conclusions are obtained from this study. The boundary layer is thinned in the regions where the secondary flow is directed to the wall and thickened where it is directed away from the wall. The peak augmentation of the local heat transfer occurs in the downwash region near the point of minimum boundary layer thickness, and the common-flow-down cases show better heat transfer enhancement than the common-flow-up cases.     

An elementaryU(2) theory of radiation fields with spinJ

An elementary theory for a radiation field with any spinJ is presented. This is a natural extension of Maxwell's equations for the electromagnetic field. The idea is to use the generators for theU(2) group in a multidimensional representation. These generators are a linear combination of the ones for infinitesimal Lorentz transformations. The constants of the motion in this formalism are discussed. As an example, angular distributions of the Poynting vector are given.Supported in part by grants from the Research Corporation and the Mitsubishi Fund.Parts of this work were done in partial fulfilment of the requirements for the M.A. Degree at Western Michigan University.     

Parton distributions for LO generators

We present a study of the results obtained by combining LO partonic matrix elements with either LO or NLO parton distributions. These are compared to the best prediction using NLO for both matrix elements and parton distributions. The aim is to determine which parton distributions are most appropriate to use in those cases where only LO matrix elements are available, e.g. as in many Monte Carlo generators. Both LO and NLO parton distributions have flaws, sometimes serious, for some processes, so a modified optimal LO set is suggested. We investigate a wide variety of processes, and the new modified LO* PDF works at least as well as, and often better than, both LO and NLO PDFs in nearly all cases.