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.
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.
55013324
Micromegas detector developments for Dark Matter directional detection with MIMAC
The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC using a high precision Micromegas readout plane. We will describe in detail the recent developments done with bulk Micromegas detectors as well as the characterisation measurements performed in an Argon(95%)-Isobutane(5%) mixture. Track measurements with alpha particles will be shown.
195869396
Results from an ATM-based event builder demonstrator
ATM switching fabrics are good candidates to implement high performance parallel event builders for the future data acquisition systems of the LHC experiments. We are studying their feasibility through simulations and implementation of event builder demonstrators. The impact of the event builder characteristic traffic pattern on the switch has been studied and methods to avoid congestion in the switch have been proposed. Event building algorithms and data acquisition protocols have been developed. Measurements made with a demonstrator and comparisons with simulation studies are presented. The scalability of the measurements is discussed.
82263624
A read-out buffer prototype for ATLAS high level triggers
Read-out buffers are critical components in the dataflow chain of the ATLAS Trigger/DAQ system. At up to 75 kHz, after each level-1 trigger accept signal, these devices receive and store digitized data from groups of front-end electronic channels. Several read-out buffers are grouped to form a read-out buffer complex that acts as a data server for the high level trigger selection algorithms and for the final data collection system. This paper describes a functional prototype of a read-out buffer based on a custom made PCI mezzanine card that is designed to accept input data at up to 160 MB/s, to store up to 8 MB of data and to distribute data chunks at the desired request rate. We describe the hardware of the card that is based on an Intel 1960 processor and CPLDs. We present the integration of several of these cards in a read-out buffer complex. We measure various performance figures and we discuss to which extent these can fulfil ATLAS needs.
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.
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.
64504728
MAREBO: A full radhard pixel detector prototype for ATLAS
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.
108645383
The ATLAS Silicon Pixel Sensors
Abstract Prototype sensors for the ATLAS silicon pixel detector have been developed. The design of the sensors is guided by the need to operate them in the severe LHC radiation environment at up to several hundred volts while maintaining a good signal-to-noise ratio, small cell size, and minimal multiple scattering. The ability to be operated under full bias for electrical characterization prior to attachment of the readout integrated circuit electronics is also desired.