【作者】 汤睿；

【导师】 曾云；

【作者基本信息】 湖南大学 ， 微电子学与固体电子学， 2006， 硕士

【摘要】 北京正负电子对撞机II(Beijing Electron Positron Collider II,BEPCII)和北京谱仪III(BEijing Spectrometer III,BESIII)是我国正在建造的新一代大型加速器和谱仪,与BEPCI和BESII相比它的主要特点是多束团,对撞周期短,信号通道多,事例率高。本文介绍了BESIII的软件开发环境,以及在此环境下进行设计开发的用于BESIII在线事例选择的软件。BESIII的软件开发环境使用Linux系统以及面向对象的C++语言,借鉴了国际上许多大型高能物理实验采用的Gaudi软件框架,并使用了配置管理工具(Configuration Management Tools ,CMT)和并发版本管理系统(Concurrent Versions System ,CVS)作为软件开发设计的配置管理软件。这使整个软件开发过程处于一种良好的可控状态,减少了软件开发的风险,提高了开发人员的效率和软件开发速度。BEPCII和BESIII采用了“多束团”机制。在BEPCⅡ的设计亮度上取数运行时, BESⅢ的事例率将高达107Hz。为了能将感兴趣的物理事例记录下来,整个事例选择设计为二级。第一级为硬件触发。即触发判选系统(Trigger System)利用快速的电子学硬件进行实时的事例选择,将事例率压缩到～4 kHz左右。第二级为在线事例选择(Online Event Filter)。它利用运行在计算机集群上的程序,对通过一级触发的事例进行进一步选择,使得最后记录的事例率降低为～3 kHz。我们调研了国外高能物理实验的相关部分,采取在线事例选择和离线数据处理使用同一软件框架的模式,将在线事例选择软件分成两个大的部分:一部分是可以独立运行于离线环境中的事例选择流程控制软件(Event Selection);另一部分是将事例选择流程控制软件与在线环境下的事例筛选任务处理器(Processing Task)结合起来的事例选择控制器(Event Selection Controller)。这样可以实现软件的最大程度的重用,减少研发成本和提高软件系统的可维护性。初步测试结果表明,基于Gaudi框架开发的在线事例筛选软件可以正常运行,为进一步的调试和性能优化奠定了良好的基础。更多还原

【Abstract】 The BESIII is a general purpose experiment at BEPCII collider, which is currently under construction in Beijing. The main character of BEPCII is multiple bunch, high luminosity and the extremely high data rate. This thesis concerns the BESIII software R&D environment and the BESIII online Event Filter, which is developed in the BESIII software R&D environment.The BESIII software R&D environment uses Linux system and object oriented C++ language. The underlying software framework is Gaudi, which is also used by many other HEP experiments. The Configuration Management Tool (CMT) and Concurrent Versions System (CVS) are adopted for the configuration management of our software. All of these make the whole software R&D process under control, programs more reliable and also ensure the software development in an efficient way.The BEPCII is a multiple-bunch machine. When it works on the designed luminosity, the event rate is 107Hz. The trigger system is divided into two levels so that we can record the physics event that we are interested in. The Level 1 is a hardware trigger, which uses front-end electronic (FEE) to do the real time event selection, in order to suppress the event rate to about 4 kHz. The Level 2 is an online event filter, which uses the computer farm to do the further suppression, to reduce event rate to 3 kHz. We studied many other HEP experiment’s trigger systems, decided to use one software framework for both online event filter and offline data processing. The online event filter software is designed to have two parts: 1) the event selection, which can run in the offline data processing system independently. 2) The event selection controller, which is the interface between event selection and processing task. By using this method, we can reuse the offline software for online event selection, so that we can reduce the cost and improve the system’s maintainability. From the test results, we find the online event filter software, which is developed based on Gaudi framework, can work properly. This will be a good foundation for the further test and performance tuning.更多还原