R值扫描实验中触发效率的测量

介绍了北京正负电子对撞机(BEPC)/北京谱仪(BES)R值扫描实验中触发效率的测量方法,BES触发判选系统触发条件表的设置,给出了R值测量实验期间各触发条件、触发道以及不同类型事例的触发效率.     

北京谱仪Ⅲ电磁量能器触发系统的模拟研究

利用北京谱仪Ⅲ探测器模拟和触发系统模拟程序,研究了北京谱仪Ⅲ电磁量能器的触发方案.根据物理目标设计了中性事例触发,巴巴事例判选和带电事例触发的方案,优化了各触发条件的参数,并仔细研究了对本底的排斥能力.研究了一批典型的物理道,给出了它们的触发效率,同时给出了预期的本底触发事例率.     

BESⅢ触发系统MDC子系统的物理设计

介绍北京谱仪BESⅢ触发系统MDC子系统的物理设计. 该设计根据BESⅢ的物理研究目标,用软件模拟的方法研究了不同触发方案的可行性,并优化了触发参数. 对触发方案的效率进行了仔细研究,给出一些重要反应道的触发效率和本底事例率.     

铅-闪烁光纤夹层电磁量能器高能γ触发方案的研究

在电磁量能器探测高能γ射线的实验中,主要本底来源于高通量的宇宙线质子事例.为了有效排除质子本底,本文利用蒙特卡洛方法研究了γ事例在铅–闪烁光纤夹层电磁量能器中的触发方案,并且使用束流测试数据对判选条件进行检验.通过分析质子和γ事例在量能器中的能量沉积和纵向发展的特征,提出了一种有效的触发方法,使得质子的事例率被限制在1?0?0Hz以内,同时能量高于1?0GeV的γ事例获得了99%的触发效率.     

神经元网络在τ→ρV_τ极化分析中的应用

在ＬＥＰ／Ｌ３的τ→ρＶτ极化物理分析中，用人工神经元网络法选择事例，获得了比较高的选择效率．详细研究表明，网络本身不会引入明显的系统偏差．使用在Ｚ０能区采集到的８９７７个τ＋τ－对事例，得到τ→ρＶτ道的极化率Ｐτ＝－０．１２９±０．０５０±０．０５０．本文介绍在这一工作中使用的神经网络训练方法和技巧     

1992年中科院高能所青年优秀论文摘要(部分)

 1.郭愚益:BES产生的J/φ总数本论文完成了北京谱仪触发判选系统主要触发条件的离线模拟和触发效率计算.通过得到BES对于不同事例的触发效率、事例分类、单事例扫描等一系列过程,对北京谱仪第一批获取的J/φ事例总数进行了计算,得到了北京谱仪产生的J/φ总数为:N_J/φ^prod=（2.46±0.02（stat.）±0.50（sys.））×10⁶这为J/φ物理分析提供了基本参数.BES所有分支比的计算都引用了该数据,并已在国际高能物理会议上发表.2 包化成:VEC用于VMEbus的以太网控制器研制在利用VMEbus对BES数据获取系统进行改进研究的工作中,开发研制了一种基于VMEbus的以太网控制器--VEC.作为智能化插件,VEC能够访问VMEbus系统的公共缓冲区,以简单的服务界面为VMEbus系统提供自动式数据流服务.作为标准的以太网接口,VEC又能够将公共缓冲区中的待发送数据按照IEEE802.3帧格式发送入以大网电缆,并完成必要的链路控制,同时正确地将以太网中的有关数据按规定格式送入VMEbus公共缓冲区.VEC还能够按主机要求,适当调整数据格式.在已通过鉴定的BESDAQ改进研究样机系统中,VEC与VAX2000的通信速度达到1.6 Mbit/s,连续发送速度不低于3 Mbit/s.     

确定τ~＋τ~－→eμ（υ）衰变道事例选择效率的一种半实验方法

在τ质量的测量中，事例的选择效率是一个重要的参数．本工作采用半实验的方法，给出了，ττ→ｅμ（υ）的事例选择效率ε＝（１４．５±０．７±０．８）％，并讨论了各种修正因素．此结果与τ质量双参数拟合所给结果相一致．     

发现顶夸克的最新证据

介绍了美国费米国家实验室ＣＤＦ合作组关于顶夸克的证据。从１９．３ｐｂ－１积分亮度的质子反质子对撞的数据中，ＣＤＦ找到了一些顶夸克对的可能事例。其中包括两个双轻子事例，１０个轻子加带ｂ夸克标记的强子事例，其中三个事例中ｂ夸克由次级顶点标记，四个事例由半轻子衰变标记，另外三个事例同时由次级顶点和半轻子衰变标记，共１３个标记．这些事例由本底引起的几率为０．２６％。由这些事例拟合得顶夸克质量为１７４±１０ＧｅＶ／ｃ２，其产生截面为１３．９±ｐｂ。     

粒子物理实验

利用BES在τ质量测量期间获取的√S=3．55GeV的约5pb^-1的数据开展R值测量的预先实验研究。详细研究了与R值测量有关的各种因素．如强子事例挑选、本底扣除、亮度测量、辐射修正、效率确定等。特别是利用挑选出的强子事例的各种形态特征分布与现有的LUND模型的强子事例产生子Jetset 74相比较，调整其有关参数，首次得到适合于低能区的强子事例产生子，从而比较可靠地确定了效率。以上研究为下一步的R值扫描测量打下了良好基础。     

羊八井ARGO实验数据获取系统

羊八井ARGO实验采用全覆盖式RPC阵列探测小空气簇射事例,其数据获取系统基于多级高速缓存和高速事例驱动机制,硬件实现数据获取和事例组建,从而避免了软件对数据采集速度的影响和CPU的开销,满足了21.7kHz的触发率和6.4M字节/s的数据率的实验要求.     

The digital trigger system for the RED-100 detector

The system for forming a trigger for the liquid xenon detector RED-100 is developed. The trigger can be generated for all types of events that the detector needs for calibration and data acquisition, including the events with a single electron of ionization. In the system, a mechanism of event detection is implemented according to which the timestamp and event type are assigned to each event. The trigger system is required in the systems searching for rare events to select and keep only the necessary information from the ADC array. The specifications and implementation of the trigger unit which provides a high efficiency of response even to low-energy events are considered.     

Introduction of the Trigger System and the Measurement for Trigger Efficiency at L3+Cosmics Experiment

The trigger process of L3+Cosmics experiment at CERN is introduced briefly. Also we checked whether the settings of L3+Cosmics trigger system by simulation are correct or not and introduced a method on trigger efficiency calculation. To get trigger efficiency for μ spectrum measurement, an experimental data sample, which includes events passing the trigger set to measure the μ spectrum and not passing, is needed. Then L?3+C trigger process is simulated with these events in this sample to know how many events should pass the trigger. By checking a trigger bit recorded in the experimental data, one can know how many events passed the trigger in hardware in these simulated events. The ratio then determines the trigger efficiency for μ spectrum measurement. And the systematic error is analyzed. The results on trigger efficiency have been used to the measurement of μ spectrum.     

Simulation Study of the Electromagnetic Calorimeter Triggers in BESⅢ

Based on the detector and trigger simulation of beijing spectrometer Ⅲ (besⅢ), schemes of besⅢ emc triggers are studied. neutral triggers, bhabha triggers and charged event triggers are designed to fulfill the requirements of the physics goals. the trigger parameters are optimized and the ability of backgrounds rejection are carefully studied. trigger simulation for some typical physics channels are studied and the expected backgrounds event rates are obtained     

A hardware fast tracker for the ATLAS trigger

The trigger system of the ATLAS experiment is designed to reduce the event rate from the LHC nominal bunch crossing at 40 MHz to about 1 kHz, at the design luminosity of 10³⁴ cm^–2 s^–1. After a successful period of data taking from 2010 to early 2013, the LHC already started with much higher instantaneous luminosity. This will increase the load on High Level Trigger system, the second stage of the selection based on software algorithms. More sophisticated algorithms will be needed to achieve higher background rejection while maintaining good efficiency for interesting physics signals. The Fast TracKer (FTK) is part of the ATLAS trigger upgrade project. It is a hardware processor that will provide, at every Level-1 accepted event (100 kHz) and within 100 microseconds, full tracking information for tracks with momentum as low as 1 GeV. Providing fast, extensive access to tracking information, with resolution comparable to the offline reconstruction, FTK will help in precise detection of the primary and secondary vertices to ensure robust selections and improve the trigger performance. FTK exploits hardware technologies with massive parallelism, combining Associative Memory ASICs, FPGAs and high-speed communication links.     

Possible modification of level 1 trigger of the CDF muon system at increased Tevatron luminosity

The increase in the Tevatron (FNAL) luminosity up to ≥ 2.0 × 10³² cm^?2 s^?1 and the level 1 (L1) trigger rate limitation resulted in tougher event selection conditions at CDF II; this led, in particular, to elimination from L1 muon trigger data from muon detectors in the pseudorapidity interval 1 < |η| < 1.25. A new muon trigger is proposed and investigated; this trigger includes signals from an additional layer of scintillation counters in the above η interval. The modified L1 muon trigger provides an acceptable for CDF II rate of lower than 1 kHz.     

Impact-parameter dependences of the number of interacting nucleons and mean multiplicities in heavy-ion collisions

The impact-parameter dependence of the mean number of interacting nucleons in high-energy heavy-ion collisions is considered in the case of identical atomic weights of colliding nuclei and in the case where one nucleus is much heavier than the other. It is shown that the use of a rare event—for example, an event of J/ψ or ? production—as a trigger may change significantly quantities representing the averages of the multiplicities for accompanying secondaries over impact-parameter values. The multiplicities of accompanying particles in central collisions can have but a slight dependence on the trigger. The observed multiplicity ratios for various secondaries in central and minimum-bias events can be used as a test in searches for quark-gluon plasma.     

基于EPICS的CSRe束流诊断控制系统升级

兰州重离子加速器(HIRFL)冷却存储环的实验环（CSRe）提供高品质的束流用于高精度的质量测量、原子物理等实验研究,实现束流参数的准确测量是进行物理实验的前提保障。目前,CSRe加速器控制系统已升级为EPICS架构。介绍了基于EPICS的束流诊断控制系统现状,并利用升级后的控制系统测量了束流相关参数。其中,束流位置系统能够测量注入束流的逐圈位置信息,测量结果发现束流在注入过程中存在一定程度的震荡,影响注入效率。流强测量系统通过高分辨的数据采集卡实现对DCCT信号的精确测量,同时增加了D事例触发功能。升级后的控制系统,可以实现束流参数的测量,并集成于加速器控制系统的EPICS CSS界面。     

J/ψ→μ+μ- reconstruction in the CMS experiment

In this paper the J/ψ→μ+μ- reconstruction performance in the CMS experiment at the LHC is studied in detail by using B5→ J/ψψ →μμКК events. The reconstruction efficiencies of J/ψ mesons and their decay muons are obtained as a function of the transverse momentum PT and the pseudo-rapidity η. We also study the muon trigger efficiency for this channel with the planned Level-1 trigger and High Level Trigger selection criteria. It was observed that the muon reconstruction efficiency decreases when the two decay muons have a small or large 3D angular separation, which further affects the overall J/ψ reconstruction efficiency.     

Flavour tagging of parton jets and separation of parton subprocesses in hard proton-proton collisions at the ISR

High energy proton-proton interactions yielding a single trigger particle with large transverse momentum give rise to a four-jet event structure with two transverse jets and two jets along the beam direction. The transverse jets are due to the fragmentation of point like scattered partons. It is shown that the quantum numbers of triggering charged pions and positive kaons are correlated with the flavour of the scattered parent parton; thus one can enhance data samples with a particular flavour of a scattered parton. The analysis, which is independent of detailed model calculations, exploits (a) the identification of the leading particles in the trigger jets (trigger particles), (b) the measurement of their relative production rates, (c) short range quantum number correlations within the trigger jets, and (d) long range correlations between leading particles from different jets. The data were obtained at \(\sqrt s \) =62 GeV with the Split Field Magnet detector at the CERN ISR.