110024675
A sequential processing strategy for the ATLAS event selection
A new processing strategy for the ATLAS event selection system is proposed for use downstream of the first level trigger. It aims to achieve a reduction of the event rate to a level suitable for recording on permanent storage via a sequential treatment of the "regions of interest" selected by the level 1 trigger. A possible Trigger/DAQ architecture which exploits this concept is presented. It is based on a single processing farm and a network which transports data and protocol traffic. The resources necessary for the implementation of this architecture are estimated. A set of performance figures obtained by calculations and computer simulations are given assuming the use of ATM networking technology.
47335045
Design and test of prototype boards for the L1 calorimeter trigger upgrade at the D0 experiment
This paper presents the development and test of some of the electronic boards that have been designed for the upgrade of the L1 calorimeter trigger at the D0 experiment. The analog to digital converter and filter board (ADF) digitizes 32 calorimeter channels, applies digital filtering, and sends data to the next processing stage via 2 Gb/s links. The board is designed for sustained operation at 7.57 MHz with an end-to-end latency of less than ~1 mus. In order to test the high-speed output links of the ADF board, we made a tester that comprises a custom made Channel Link receiver card. To connect a prototype ADF board to the D0 detector without disturbing the existing trigger system, we designed a splitter board that duplicates the analog signals from eight calorimeter channels. The serial command link distribution card (SCLD) is designed to accurately distribute synchronization signals to the 80 ADF boards of the final system. We made single channel versions of the ADF and SCLD boards. These cards run in a simple desktop PC environment and are helpful for tests and collaborative work. We describe the hardware, firmware and software aspects of the various developments and show the operation of the different boards. We present performance measurements made on the prototype ADF board, and explain how we defined the production model of this board
19547951
A review of technologies for the transport of digital data in recent physics experiments
This paper describes past and present techniques and technologies for the transport of digital data in recent physics experiments. After an overview of the typical requirements for modern data acquisition systems in the field of large scale experimental physics, we detail the successes and failures observed over the last 20 years of evolution of high-speed point-to-point link technology, networking standards and products. Modtextern data transport technology is presented along with several applications to experiments under construction. Advanced techniques, emerging technologies and trends in the field of high-speed digital data transport are outlined in the perspective of future experiments.
39418354
SIMDAQ-a system for modelling DAQ/trigger systems
The Atlas detector for the LHC accelerator at CERN requires a trigger and data acquisition (DAQ) system capable of handling bunch crossings every 25 ns. A three level trigger has been proposed. While the first level, which processes events synchronously, can be investigated analytically, the second level onwards, which processes events asynchronously, requires detailed modelling. SIMDAQ, a tool to model trigger and DAQ systems, is described in this paper, along with preliminary results from simulation studies of the Atlas trigger and DAQ system using SIMDAQ.
118645473
The topological second-level trigger of the H.E.S.S. phase 2 telescope
H.E.S.S is an array of atmospheric Cherenkov telescopes dedicated to GeV-TeV γ-ray astronomy. The original array has been in operation since the beginning of 2004. It is composed of four 12-meter diameter telescopes. The installation of a fifth 28-meter diameter telescope is being completed. This telescope will operate both in stereoscopic mode and in monoscopic mode i.e. without a coincident detection on the smaller telescopes. A second-level trigger system is needed to supress spurious triggers of the 28-meter telescope when operated in monoscopic mode. This paper gives the motivation and principle of the second-level trigger. The principle of operation is illustrated by an example algorithm. The hardware implementation of the second level trigger system of H.E.S.S. phase 2 is described and its expected performances are then evaluated.
53769716
On the integration of high performance ATM-based event builders
A first demonstrator has shown encouraging results for the use of Asynchronous Transfer Mode (ATM) switching networks in the implementation of high performance parallel event builders. Our present goal is to show that the integration of event builders, including the implementation of the source and destination functions and the bandwidth adaptation to the switching network, can be realized with commercially available products and that good performance can be achieved. We shall review some critical issues, present results from performance measurements and analyse the overheads.
109862390
Test system for the production of the Atlas Tile Calorimeter front-end electronics
Abstract The Atlas hadronic Tile Calorimeter front-end electronics is fully included in the so-called “super-drawers”. The 256 super-drawers needed for the entire calorimeter are assembled and extensively tested in Clermont-Ferrand before being sent to CERN to be inserted in the calorimeter modules. A mobile system has been developed to perform a complete test of the super-drawers during their insertion.
27426193
MCC: The Module Controller Chip for the ATLAS pixel detector
In this article we describe the architecture of the Module Controller Chip for the ATLAS Pixel Detector. The project started in 1997 with the definition of the system specifications. A first fully-working rad-soft prototype was designed in 1998, while a radiation hard version was submitted in 2000. The 1998 version was used to build pixel detector modules. Results from those modules and from the simulated performance in ATLAS are reported. In the article we also describe the hardware/software tools developed to test the MCC performance at the LHC event rate.
119605019
H1 FORWARD PROTON SPECTROMETER UPGRADE WITH SILICON PIXELS DETECTORS
Abstract The H1 experiment is already equipped with a four roman pots Forward Proton Spectrometer (FPS), using scintillating fibers. The H1 CPPM group has made a proposal to upgrade the FPS by adding silicon pixels detectors in the 90 m roman pot.
121719013
Electrical characteristics of silicon pixel detectors
Prototype sensors for the ATLAS silicon pixel detector have been electrically characterized. The current and voltage characteristics, charge-collection efficiencies, and resolutions have been examined. Devices were fabricated on oxygenated and standard detector-grade silicon wafers. Results from prototypes which examine p-stop and standard and moderated p-spray isolation are presented for a variety of geometrical options. Some of the comparisons relate unirradiated sensors with those that have received fluences relevant to LHC operation.
37159826
A measurement of Lorentz angle and spatial resolution of radiation hard silicon pixel sensors
Silicon pixel sensors developed by the ATLAS collaboration to meet LHC requirements and to withstand hadronic irradiation to fluences of up to $10^{15} n_eq/cm^{2}$ have been evaluated using a test beam facility at CERN providing a magnetic field. The Lorentz angle was measured and found to alter from 9.0 deg. before irradiation, when the detectors operated at 150 V bias at B=1.48 T, to 3.1 deg after irradiation and operating at 600 V bias at 1.01 T. In addition to the effect due to magnetic field variation, this change is explained by the variation of the electric field inside the detectors arising from the different bias conditions. The depletion depths of irradiated sensors at various bias voltages were also measured. At 600 V bias 280 micron thick sensors depleted to ~200 micron after irradiation at the design fluence of 1 10^{15} 1 MeV n_eq/cm2 and were almost fully depleted at a fluence of 0.5 * 10^{15} 1 MeV n_eq/cm2. The spatial resolution was measured for angles of incidence between 0 deg and 30 deg. The optimal value was found to be better than 5.3 micron before irradiation and 7.4 micron after irradiation.