S. J. Haywood

The FASTBUS readout system for the Aleph time projection chamber

The readout system for the Aleph central tracking detector, a large time projection chamber (TPC), consists of more than 100 FASTBUS crates with approximately 1000 FASTBUS modules. The detector and its associated electronics are briefly presented, followed by a more detailed description of the readout and control system. The discussion covers the sector readout, electronics calibration, front-end data acquisition, data pipelining, and service request handling. Experiences with the system are discussed. >

Organization, management, and documentation of ATLAS offline software releases

We update our CHEP06 [2] presentation on the ATLAS experiment software infrastructure used to build, validate, distribute, and document the ATLAS offline software. The ATLAS collaborations computational resources and software developers are distributed around the globe in about 35 counties. The ATLAS offline code base is currently over 7 million source lines of code in 10,000+ C++ classes organized into about 2,000 packages. More than 400 developers contribute code each month. Since our last report, we have developed a powerful, flexible system to request code versions to be included in software builds, made changes to our software building tools, increased the number of daily builds used to validate significant code changes, improved the tools for distributing the code to our computational sites around the world, and made many advancements in the tools to document the code.

The ATLAS SCT grounding and shielding concept and implementation

This paper describes the design and implementation of the grounding and shielding system for the ATLAS SemiConductor Tracker (SCT). The mitigation of electromagnetic interference and noise pickup through power lines is the critical design goal as they have the potential to jeopardize the electrical performance. We accomplish this by adhering to the ATLAS grounding rules, by avoiding ground loops and isolating the different subdetectors. Noise sources are identified and design rules to protect the SCT against them are described. A rigorous implementation of the design was crucial to achieve the required performance. This paper highlights the location, connection and assembly of the different components that affect the grounding and shielding system: cables, filters, cooling pipes, shielding enclosure, power supplies and others. Special care is taken with the electrical properties of materials and joints. The monitoring of the grounding system during the installation period is also discussed. Finally, after connecting more than four thousand SCT modules to all of their services, electrical, mechanical and thermal within the wider ATLAS experimental environment, dedicated tests show that noise pickup is minimised.

Management and control of the read out processors (TPPs) of the Aleph time projection chamber

The readout of the Aleph time projection chamber (TPC) relies on a set of 72 time projection processors (TPPs), which are based on a Motorola 68020 microprocessor running a real-time operating system. The advanced processing capabilities of the TPPs allow them to perform in parallel a number of tasks, both during and outside of data acquisition, which are outlined. The management and control of such a large number of intelligent devices is presented. The discussion covers the hardware configuration of the TPPs; the software running the TPPs; their management, status, and control; exception handling and message logging; and the TPP monitoring tasks. >