M. Gruwe

The ROD Crate DAQ of the ATLAS data acquisition system

In the ATLAS experiment at the LHC, the ROD Crate DAQ provides a complete framework to implement data acquisition functionality at the boundary between the detector specific electronics and the common part of the data acquisition system. Based on a plugin mechanism, it allows selecting and using common services (like data output and data monitoring channels) and developing simple libraries to control, monitor, acquire and/or emulate detector specific electronics. Providing also event building functionality, the ROD Crate DAQ is intended to be the main data acquisition tool for the first phase of detector commissioning. This paper presents the design, functionality and performance of the ROD Crate DAQ and its usage in the ATLAS DAQ and during detector tests

The base-line DataFlow system of the ATLAS trigger and DAQ

The base-line design and implementation of the ATLAS DAQ DataFlow system is described. The main components of the DataFlow system, their interactions, bandwidths, and rates are discussed and performance measurements on a 10% scale prototype for the final ATLAS TDAQ DataFlow system are presented. This prototype is a combination of custom design components and of multithreaded software applications implemented in C++ and running in a Linux environment on commercially available PCs interconnected by a fully switched gigabit Ethernet network.

The ROD crate DAQ software framework of the ATLAS data acquisition system

In the ATLAS experiment at the LHC, the ROD Crate DAQ provides a complete software framework to implement data acquisition functionality at the boundary between the detector specific electronics and the common part of the data acquisition system. Based on a plugin mechanism, it allows selecting and using common services (like data output and data monitoring channels) and developing software to control and acquire data from detector specific modules providing the infrastructure for control, monitoring and calibration. Including also event building functionality, the ROD Crate DAQ is intended to be the main data acquisition tool for the first phase of detector commissioning. This paper presents the design, functionality and performance of the ROD Crate DAQ and its usage in the ATLAS data acquisition system and during detector tests.

Deployment and use of the ATLAS DAQ in the combined test beam

The ATLAS collaboration at CERN operated a combined test beam (CTB) from May until November 2004. The prototype of ATLAS data acquisition system (DAQ) was used to integrate other subsystems into a common CTB setup. Data were collected synchronously from all the ATLAS detectors, which represented nine different detector technologies. Electronics and software of the first level trigger were used to trigger the setup. Event selection algorithms of the high level trigger were integrated with the system and were tested with real detector data. A possibility to operate a remote event filter farm synchronized with ATLAS TDAQ was also tested. Event data, as well as detectors conditions data were made available for offline analysis

Performance of the ATLAS DAQ DataFlow system

The baseline DAQ architecture of the ATLAS Experiment at LHC is introduced and its present implementation and the performance of the DAQ components as measured in a laboratory environment are summarized. It will be shown that the discrete event simulation model of the DAQ system, tuned using these measurements, does predict the behaviour of the prototype configurations well, after which, predictions for the final ATLAS system are presented. With the currently available hardware and software, a system using ~140 ROSs with 3GHz single cpu, ~100 SFIs with dual 2.4 GHz cpu and ~500 L2PUs with dual 3.06 GHz cpu can achieve the dataflow for 100 kHz Level 1 rate, with 97% reduction at Level 2 and 3 kHz event building rate. ATLAS DATAFLOW SYSTEM The 40 MHz collision rate at the LHC produces about 25 interactions per bunch crossing, resulting in terabytes of data per second, which has to be handled by the detector electronics and the trigger and DAQ system [1]. A Level1 (L1) trigger system based on custom electronics will reduce the event rate to 75 kHz (upgradeable to 100 kHz – this paper uses the more demanding 100 kHz). The ________________________________________ #. Also affiliated with University of California at Irvine, Irvine, USA *. On leave from Henryk Niewodniczanski Institute of Nucl. Physics, Cracow +. Presently at CERN, Geneva, Switzerland 91 DAQ system is responsible for: the readout of the detector specific electronics via 1630 point to point read-out links (ROL) hosted by Readout Subsystems (ROS), the collection and provision of “Region of Interest data” (ROI) to the Level2 (L2) trigger, the building of events accepted by the L2 trigger and their subsequent input to the Event Filter (EF) system where they are subject to further selection criteria. The DAQ also provides the functionality for the configuration, control, information exchange and monitoring of the whole ATLAS detector readout [2]. The applications in the DAQ software dealing with the flow of event and monitoring data as well as the trigger information are called “DataFlow” applications. The DataFlow applications up to the EF input and their interactions are shown in Figure 1. Figure 1 ATLAS DAQ-DataFlow applications and their interactions (up to the EventFilter) SFI L2PU L2SV DFM pROS ROS ROI data

On the possibility of measuringF L (x, Q 2) at HERA using radiative events

It is shown that a significant measurement of the longitudinal structure functionFL(x, Q2) can be performed at HERA, forQ2=2 GeV2 andQ2=5 GeV2 and forx around 10−4, using radiative events with hard photon emission collinear to the incident lepton beam, under the present running conditions and with an integrated luminosity of 10 pb−1. The influence of experimental conditions is discussed.

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.

High speed multiplexed pipelined optoelectronic devices: CCDs and EBCCDs

Abstract CCDs and EBCCDs are very performant optoelectronic devices for detection of optical images. By making use of features such as frame transfer, fast clearing and multiport systems, CCDs may be considered as being fast devices and may be used in a wide range of applications. The principle of operation of CCDs and EBCCDs is explained and some of their optional features are overviewed.