Geant4模拟在特洛伊木马方法中的应用

由于低能带电粒子核反应截面直接测量遇到的库仑位垒和电子屏蔽势的困难,基于准自由反应机制的特洛伊木马方法得到特别关注。利用Geant4模拟的结果,与在中国原子能研究院串列加速器上通过三体反应9Be+2H→8Be+2H+n对两体反应9Be+1H→8Be+2H的反应截面做的间接测量实验数据进行了比较,这是Geant4模拟在特洛伊木马方法中的首次应用。通过对模拟数据研究,提高了对实验数据的理解,也检验了模拟系统的可靠性,对今后的实验设计和改进提供了有益的意见。     

(S_(nn))~(1/2)=200GeV下Au-Au中心碰撞中Di-omega产额上限的蒙特卡罗模拟(英文)

根据现有的关于(ΩΩ)0 的生成截面的理论计算,利用HIJING事例产生器研究了(S_(nn))~(1/2)=200GeV下Au- Au中心碰撞中(ΩΩ)0 和(NΩ)022产生过程,分别对(ΩΩ)0 的电磁作用产生过程和两步产生过程中的第一步过程进行了(ΩΩ)0 产率的计算,给出了(ΩΩ)0 产额的上限,对于电磁作用过程,其产率为(1.097±0.293)×10-10 同时我们也对(NΩ)022进行了初步的模拟,初步给出了它的产率为(0.894±0.005)×10-4.     

TOFr在STAR实验中的标定方法

基于多气隙电阻板室(MRPC)的STAR飞行时间探测器的一个板条的原型(TOFr)参加了2003年STAR实验的质子–质子对撞和氘–金对撞的物理运行.利用STAR实验中原有的赝顶点位置探测器(pVPD)和时间投影室(TPC),结合TOFr的时间及幅度信号,并考虑TOFr每个探测单元的尺寸,对影响时间分辨的各种因素进行了修正,实现了对TOFr的标定.实验数据给出的TOFr的本征时间分辨为85ps,在两倍标准方差下,其对π/K及K/p分辨的动量分别达到了1.6GeV/c和3.0GeV/c,大大提高了STAR探测器的粒子鉴别能力.     

Spatial anisotropy: a method to study anisotropic flow in heavy ion collisions

We introduce a method to study anisotropic flow parameter v_n as a collective probe to Quark Gluon Plasma in relativistic heavy ion collisions. The emphasis is put on the use of the Fourier expansion of initial spatial azimuthal distributions of participant nucleons in the overlapped region. The coefficients ε_n of Fourier expansion are called the spatial anisotropy parameter for the n-th harmonic. We propose that collective dynamics can be studied by v_n/ε_n. In this paper, we will discuss in particular the second (n=2) and the fourth (n=4) harmonics.     

MRPC噪声和暗电流对温度和工作高压的依赖

不同混合气体不同高压,6个气隙的阻性板室工作在不同的环境温度下,测试其噪声和漏电流.噪声和漏电流随温度升高指数上升.     

多气隙电阻板室蒙特卡洛模拟与实验的比较

介绍了一个在电阻板室雪崩增长与信号发展的模型,模拟了多气隙电阻板室的电荷谱和时间分布谱,并与试验做了比较.     

一种精密触发定时系统

提出并研制了一种精密触发定时系统.它主要利用多个光电倍增管和闪烁体组成的探测系统,对同一事件的时间信息进行多次测量.通过对多个时间信息的离线处理,来获得时间分辨为57ps的精密触发定时系统.该系统可以用于快时间探测器性能的研究.     

多气隙电阻板室的时间特性研究

一种具有10个气隙的多气隙电阻板室,在欧洲核子研究中心实验束上进行了性能测试.该探测器采用几何上串联和电极上并联的特殊结构,使用国产玻璃(厚度1?.1mm)作为高压电极,有效灵敏面积为200mm×63mm²,并具有2×6读出条.对7GeV/c的π^－粒子,其探测效率大于99%,时间分辨达到45ps.     

Experimental study of multi-photon contamination on the measurement of fluorescent decay time

In the measurement of fluorescent lifetime based on time correlation-single photon counting technique by means of TAC, due to the contamination of multi-photons a deviation of fluorescent lifetime measured from the expected value is experimentally studied. A correction function instead of a simple exponential function is used to fit the experiment data. The validation of the correction function is checked using the experimental data of several test samples: YAP, NaI(Tl) and LSO. The results show that the correction function well fits the data and the reasonable fluorescent lifetimes are obtained.     

Experimental spectra analysis in THM with the help of simulation based on the Geant4 framework

The Coulomb barrier and electron screening cause difficulties in directly measuring nuclear reaction cross sections of charged particles at astrophysical energies. The Trojan-horse method (THM) has been introduced to solve the difficulties as a powerful indirect tool. In order to understand experimental spectra better, Geant4 is employed to simulate the method. Validity and reliability of simulation data are examined by comparing the experimental data with simulated results. The Geant4 simulation of THM improves data analysis and is beneficial to the design for future related experiments.