高精度数据驱动型TDC在高能物理实验中应用的研究

目前国际国内高能物理方面时间数字转换的发展趋势是使用集成的、高精度、多次击中型TDC,数据驱动型TDC(Data Driven TDC)是其中的热点.研究高性能TDC的具体指标以及改进的方法对高能物理实验中的应用具有指导作用.我们对北京谱仪(BESⅢ)中考虑使用的一种新型高精度TDC进行了测量研究.本文介绍了我们为此建立的测量平台,和对该TDC进行非线性、分辨率、双脉冲分辨等测量的手段和结果,探讨了对其进行甚高精度(24.4 ps)修正的方法,给出了修正的效果.     

高能物理实验中电子学逻辑在线升级功能的实现

大型物理实验中电子学逻辑经常需要在线升级,现场可编程门阵列器件(FPGA)的大量使用使得在线升级成为可能.介绍了一种通过串行Flash和复杂可编程逻辑器件(CPLD)采用被动串行模式(PS)配置FPGA芯片的方案,可以实现电子学系统的上电自动配置、远程更新配置文件和系统运行模式的切换.给出了方案的基本原理、系统框图和硬件电路.     

The scientific value of high energy physics

In this paper I will discuss two aspects of the role of accelerators in the development of modern physical science: first, the increasing prominence of high energy/elementary particle physics in the past two decades, relative to other areas of physics, with suggestions about how the significance and cost of discoveries in different areas of science might be estimated; second, the justification of substantial funding for this kind of research on the grounds that it is ‘fundamental’ to science, with remarks on the change in judgements of fundamentality from a long-term historical perspective.     

高能物理实验中CAEN系列高压系统自动控制方案

针对高能物理实验中常用的CAEN系列高压系统SY1527、SY127／227,基于TCP／IP网络通讯技术、CAMAC总线技术、PCI总线技术和RS232串口总线通讯技术,实现并开发了适用于Linux／Win32系统不同版本的自动控制软件。用户可以依次编译独立的程序,按照设定自动开启,升降高压,并可实时监测高压系统的运行状态;亦可将此自动控制软件集成于数据获取系统,实现控制与采集同步,极大提高实验效率。     

USB/RS485转换器的设计及其在高能实验物理慢控制数据采集系统中的应用

传统的基于RS232／485的数据采集系统只能实现点对点的连接,各个分支不能独立工作,给系统的调试、安装和维护带来很大不便。早已成为PC标准的通用串行总线USB具有热插拔、多点、高速、安装简便等优点。将USB应用于数据采集系统后,各分支能实现独立工作,给系统带来了极大的便利。介绍了USB／485转换器的设计及其在高能实验物理BESIII Slow Control数据采集系统中的应用。     

Industry roles in the Tokamak physics experiment

Journal of Fusion Energy -     

反应堆物理实验中的源倍增法研究

给出了反应堆物理实验中临界测量和次临界度测量通常所采用的源倍增方法研究。首先从有源的扩散理论出发,导出了与以前不同的源倍增方法的公式。源倍增方法测量的参数实际是次临界系统在外源作用下的有源次临界中子倍增因子ks,而不是在这之前的中子有效倍增因子keff,然后研究了实验装置的临界质量,研究了ks与外源位置和能谱的关系,证明了导出的源倍增方法的理论是正确的。该方法可像过去那样用于反应堆物理实验中的临界外推测量,但不能用于次临界度测量。解决了长期困扰人们有关源倍增方法测量的参数问题。最后讨论了ks和keff的差别和关系以及对临界外推测量和核临界安全的影响。     

高能物理与网格计算

概略介绍了高能物理实验计算环境的最新发展情况．包括近一些年来国际高能物理实验发展和对计算需求的增长变化;以正在建造中的LHC上的实验为例介绍了为满足这些需求而制订的计算环境规划;网格计算技术诞生的历史及国际高能物理网格技术研究的现状;高能物理网格所需要的网络基础设施的发展情况等。最后介绍了正在起步中的我国高能物理网格技术研究。     

用于核物理实验研究中的束流脉冲调制器

描述了一台用于核物理实验研究中的束流脉冲调制器,它已成功地用于兰州重离子加速器（HIRFL）的放射性离子束流线（RIBLL）的两个核物理实验中。     

V-F变换在激光物理实验中的新型应用

介绍了一套十分适合应用于准连续激光物理实验的变换装置.该套装置不但可以将热电偶激光功率计输出的直流型模拟电压量变换成计数脉冲输出,还可以对光离子引起的、探测器给出的脉冲型模拟电压量进行累计变换.经过详细的模拟测试得知它变换激光功率的积分线性≤±0.015%,变换光离子脉冲信号的积分线性≤±0.23%.以上测试结果表明该套变换装置已经满足了一般激光物理实验的精度要求.     

大型物理实验装置安装定位测量技术和方法探索

通过对国内两个重大科学项目测量实例的介绍,分析了大型物理实验装置测量技术的特点,为大型特种精密测量技术的应用和方法提供了有效的途径和启示.     

基于G-Link的实验数据采集传输系统

详细介绍了一个基于G-Link高速光纤数据传输系统;分析了以HDMP-1022／HDMP-1024为核心的光纤链路的基本构成和配置、激光管驱动电路、CIMT编码等内容。并利用G-Link设计了一个应用在风洞实验中的16通道数据采集和传输系统。     

Discrete energy or multigroup finite element transport calculations in lattice physics

Finite element transport calculations are well suited for reactor lattice analysis, and in particular for benchmark problems involving tight unit cells. They model the cell accurately in two dimensions. Exact symmetry boundary conditions for the flux moments of any truncated spherical harmonics expansion of the angular flux can be imposed at the outer surfaces of a geometrical region representing a unit cell in a periodic array of similar cells. Complementary variational procedures, based on the even- and the odd-parity components of the angular flux and used to solve the finite element equations, provide upper and lower bounds for the desired lattice parameters. In a simple slab lattice problem, excellent convergence of the flux disadvantage factors in a single thermal energy group was obtained in the past by these complementary procedures. The even-and odd-parity results converged rapidly to the same value when the number of the flux moments was increased. The present study of resonance absorption over a limited energy range in a two-dimensional lattice shows, however, that the convergence is problematic when multigroup or discrete-energy models are employed. The effective resonance integral values for a single pronounced resonance in the fuel rod of a PWR type unit cell were found to converge well with increasing number of flux moments for both variational procedures, but there is a discrepancy between the separate converged results. The cause of this discrepancy is investigated and is discussed in the present paper.     

Towards sustainable nuclear energy: Putting nuclear physics to work

We have developed a new method to propagate the uncertainties of fundamental nuclear physics models and parameters to the design and performance parameters of future, clean nuclear energy systems. Using Monte Carlo simulation, it is for the first time possible to couple these two fields at the extremes of nuclear science without any loss of information in between. With the help of a large database of nuclear reaction measurements, we have determined the uncertainties of theoretical nuclear reaction models such as the optical, compound nucleus, pre-equilibrium and fission models. A similar assessment is done for the parameters that describe the resolved resonance range. Integrating this into one simulation program enables us to describe all open channels in a nuclear reaction, including a complete handling of uncertainties. Moreover, in one and the same process, values and uncertainties of nuclear reactor parameters are computed. This bypasses all the intermediate steps which have been used so far in nuclear data and reactor physics. Two important results emerge from this work: (a) we are able to quantify the required quality of theoretical nuclear reaction models directly from the reactor design requirements and (b) our method leads to a deviation from the commonly assumed normal distribution for uncertainties of safety related reactor parameters, and this should be taken into account for future nuclear energy development. In particular, calculated k_eff distributions show a high-value tail for fast reactor spectra.     

NSRL可变包含角光栅单色器的计算机控制

随着同步辐射光束线技术的发展,单色器的分辨率越来越高,采用的复杂机构要求极高的机械转动和直线运动精度,对光束线控制软件的性能提出了新的要求。另一方面,同就辐射实验室新建光束线的数量逐渐增多,对控制软件设计的压力增大,希望有一种可移植的、标准化的控制软件。变包含角球面光栅单色器使用分层控制技术,层之间用以太网联接。底层是硬件抽象层,直接处理与所有硬件有关操作;上层为高级用户界面层,提供用户控制的指今,可以满足不同用户端软件的需求。同时还介绍了一种变包含角光栅单色器的数值解法。