The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system will select potentially interesting ...events in order to reduce the read-out rate to about 200 Hz. The first trigger level is implemented in custom-built electronics and makes an initial fast selection based on detector data of coarse granularity. It has to reduce the rate by a factor of to less than 100 kHz. The other two consecutive trigger levels are in software and run on PC farms. We present an overview of the first-level central trigger and the muon barrel trigger system and report on the current installation status. Moreover, we show analysis results of cosmic-ray data recorded in situ at the ATLAS experimental site with final or close-to-final hardware.
RPCs will be used as trigger detectors in the barrel region of the Muon Spectrometer of the ATLAS experiment at LHC. The total number of RPC units to be installed is 1088, covering a total surface of ...about 3500m2. ATLAS RPCs work in avalanche mode with C2H2F4/C4H10/SF6 (94.7%/5%/0.3%) gas mixture. A cosmic ray test stand has been designed and built in Naples laboratories in order to carry out a complete test of the ATLAS RPC units. Since August 2002 about 300 units have been tested. A description of the test stand, test procedure and results are presented.
Abstract
Detectors for direct dark matter search using noble gases in the liquid phase as a detection medium need to be coupled to liquefaction, purification and recirculation systems. A dedicated ...cryogenic system has been assembled and operated at the INFN-Naples cryogenic laboratory with the aim to liquefy and purify the argon used as an active target in liquid argon detectors to study the scintillation and ionization signals detected by large SiPM arrays. The cryogenic system is mainly composed of a double wall cryostat hosting the detector, a purification stage to reduce the impurities below one part per billion level, a condenser to liquefy the argon, and a recirculation gas panel connected to the cryostat equipped with a custom gas pump. The main features of the cryogenic system are reported as well as the performance, long term operation and stability in terms of the most relevant thermodynamic parameters.
The RPC detectors in the L3 experiment at LEP work as a trigger system for the Forward–Backward Muon Spectrometer. It consists of 192 bi-gap RPCs working in streamer mode. We monitored the behaviour ...of the system over seven years of data taking at LEP. To investigate the ageing of the RPCs after this long-term operation, we report the main results obtained from 1994 to 2000, together with the results of tests performed on some RPC chambers in our test site in Napoli with cosmic rays after the dismantling of L3.
Cosmic ray test station for ATLAS RPC Alviggi, M; Canale, V; Caprio, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2003, Letnik:
508, Številka:
1-2
Journal Article
The Atlas Trigger System has been designed to reduce the LHC interaction rate of about 1 GHz to the foreseen storage rate of about 100 Hz. Three trigger levels are applied in order to fulfill such a ...requirement. A detailed simulation of the ATLAS experiment including the hardware components and the logic of the Level-1 Muon trigger in the barrel of the muon spectrometer has been performed. This simulation has been used not only to evaluate the performances of the system but also to optimize the trigger logic design. In the barrel of the muon spectrometer the trigger will be given by means of resistive plate chambers (RPCs) working in avalanche mode. Before being mounted on the experiment, accurate quality tests with cosmic rays are carried out on each RPC chamber using the test station facility of the INFN and University laboratory of Napoli. All working parameters are measured and the uniformity of the efficiency on the whole RPC surface is required. A summary of the Napoli cosmic rays tests, together with a brief description of the Atlas Trigger, in particular of the Level-1 Muon Trigger in the barrel, and the results of the trigger simulation will be given.
Long-term performance of the L3 RPC system Aloisio, A; Alviggi, M.G; Patricelli, S ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2000, Letnik:
456, Številka:
1
Journal Article
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Odprti dostop
Started in 1994 the L3 experiment has been equipped with a forward–backward muon spectrometer triggered by an RPC system. Made of 192 double-gap RPCs, it has been working for six years in streamer ...mode and it will continue to run at least one year more. We monitored the behaviour of the system during the L3 run periods and in this paper we report on its present status and long-term performance.
We present results on efficiency and time resolution of a large-resistive plate chamber prototype, equipped with the final ATLAS front-end electronics, at the Gamma Irradiation Facility installed on ...the X5 beam of the CERN.
The presence of humidity into experimental gas mixtures is generally nocuous for some kind of equipments used in the gas distribution systems and for the filtering units. Conversely it can be ...required in many applications: in the RPC detectors of the ATLAS experiment for instance, the humidity is mandatory for the correct usage of detectors under radiation, but it tends to quickly saturate the filtering modules installed on the gas distribution system. A method to intensively extract the moisture or, in alternative, to exchange it from the incoming gas line stream toward the filtering system to the outgoing one is presented: based on special porous membranes, the solution can reduce the rate of the filters regeneration from the estimated 1 regeneration every 24-36 hours to 0.5-2 regenerations per month, saving up sizable amount of regeneration gas, expenditures of energy and fresh experimental gas to recondition the filtering cartridges.
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