Software Upgrades

During the shutdown between HERA-I and HERA-II, ZEUS and H1 launched a number of software upgrade projects. In this section the most prominent among these projects are briefly described.

• The H1 Collaboration has upgraded its analysis software. The new integrated object-oriented physics analysis environment is based on the RooT framework and comprises a new data storage scheme, a data access front-end, and a new event display [238]. The analysis data is stored in three layers of separate files. The upper most event summary layer (HAT) facilitates a fast selection via event classification and kinematic event quantities. At the particle level (second layer, $\mu$ODS) a custom-built pointer relation (H1Pointer) allows for direct access from the particle 4-vectors to the corresponding track and cluster information which is stored at reconstruction level (ODS). The user access to the data files is encapsulated using extensions to the RooT tree classes. The framework contains information, software tools and calibrations for most of the H1 physics analysis topics, thus allowing efficient exchange of results between different analysis groups.
• ZEUS has developed a new event display program 'ZeVis' which is a distributed application and based on client-server technology [239]. On the client side, requests to the server are handled by classes embedded in RooT [240] with extensions allowing for the passing of parameters and version qualifiers. The display provides various views (2d and 3d) which can be displayed simultaneously and for collections of selected detector components. It encompasses a GUI toolkit, object inspection, and histogramming and statistics functionality. The average response time between request of an event from the server and display on the client is less than 2s.
• In preparation of the LHC the resources of computing hardware available for high energy physics experiments are being restructured. The GRID infrastructure already contains large amounts of CPU and storage capacity which are accessible through the GRID middleware. Both H1 and ZEUS have started to use the GRID software framework for the mass production of Monte Carlo simulation event samples. The experiments have developed toolkits which contain general interfaces to the GRID services and book keeping facilities. Particular emphasis is put on the fault tolerance of the custom software as the GRID software is not yet perfect. Incomplete or corrupt jobs can be recognized by automatic job submission monitoring and output analysis tools which are able to recover most errors without human intervention. ZEUS started production running in 2004 and between November 2004 and February 2005 in excess of 60 million events were produced. H1 is in the process of launching mass production in 2005.