A gas avalanche photomultiplier with a CsI-coated GEM Mörmann, D; Breskin, A; Chechik, R ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2002, Letnik:
478, Številka:
1
Journal Article
Recenzirano
We describe the operation principle and properties of a CsI-coated GEM photodetector. This type of detector performs photon detection with reflective photocathodes, which are easy to produce and have ...high quantum efficiency. In the proposed configuration, the detector is practically free of avalanche-induced photon feedback effects. The influence of the GEM voltage and the electric fields close to the CsI-GEM electrode on the photon detection efficiency is studied. The conditions for obtaining full extraction of photoelectrons from the photocathode and their transfer through the GEM apertures are presented.
Gas microstrip detectors have been integrated with low noise preamplifier and shaper electronics on a common silicon substrate. These devices were fabricated at the Hewlett-Packard company using a ...standard 0.8
μm process. This unique approach offers advantages over conventional microstrip design: ease of fabrication, lower noise, and higher channel density. The detector/electronics assembly was tested in a small drift chamber. An energy resolution of 18% FWHM and a noise level of 80
e
− r.m.s per channel were obtained with a gas gain of about 200. These integrated microstrip detectors are being developed as the readout devices for a small, high-resolution Time Projection Chamber (MicroTPC). Low mass and high resolution make the MicroTPC well suited for use as a vertex detector, especially in high track-density environments such as RHIC and the LHC.
The results of a search for pair production of the scalar partners of bottom quarks in 2.05 fb(-1) of pp collisions at sqrts=7 TeV using the ATLAS experiment are reported. Scalar bottom quarks are ...searched for in events with large missing transverse momentum and two jets in the final state, where both jets are identified as originating from a bottom quark. In an R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom quark decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits are obtained in the b(1) - χ(1)(0) mass plane such that for neutralino masses below 60 GeV scalar bottom masses up to 390 GeV are excluded.
The first measurements from proton–proton collisions recorded with the ATLAS detector at the LHC are presented. Data were collected in December 2009 using a minimum-bias trigger during collisions at ...a centre-of-mass energy of 900 GeV. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transverse momentum and charged-particle multiplicity are measured for events with at least one charged particle in the kinematic range |η|<2.5|η|<2.5 and pT>500 MeVpT>500 MeV. The measurements are compared to Monte Carlo models of proton–proton collisions and to results from other experiments at the same centre-of-mass energy. The charged-particle multiplicity per event and unit of pseudorapidity at η=0η=0 is measured to be 1.333±0.003(stat.)±0.040(syst.)1.333±0.003(stat.)±0.040(syst.), which is 5–15% higher than the Monte Carlo models predict.
Aging studies for the ATLAS Transition Radiation Tracker (TRT) Akesson, T.; Barberio, E.; Bondarenko, V. ...
International Workshop on Aging Phenomena in Gaseous Detectors,Hamburg, Germany,2001-10-02 - 2001-10-05,
12/2003, Letnik:
515, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
A summary of the aging and material validation studies carried out for the ATLAS Transition Radiation Tracker (TRT) is presented. Particular emphasis is put on the different phenomena observed in ...straw tubes operating with the chosen Xe/CF
4/CO
2 mixture. The most serious effects observed are silicon deposition on the anode wire and damage of the anode wire gold plating. Etching phenomena and active radical effects are also discussed. With a careful choice of all materials and components, and with good control of the water contamination in the active gas, the ATLAS TRT will operate reliably for 10 years at the LHC design luminosity. To demonstrate this fully, more work is still needed on the gas system purification elements, in particular to understand their interplay with the active species containing fluorine created in the avalanche process under irradiation.
The ATLAS Transition Radiation Tracker (TRT) performance depends critically on the choice of the active gas and on its properties. The most important operational aspects, which have led to the final ...choice of the active gas for the operation of the TRT at the LHC design luminosity, are presented. The TRT performance expected at these conditions is reviewed, including pile-up effects at high luminosity.
An X-ray scanner for wire chambers Akesson, T.; Arik, E.; Assamagan, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2003, Letnik:
507, Številka:
3
Journal Article
Recenzirano
The techniques to measure the position of sense wires and field wires, the gas gain and the gas flow rate inside wire chambers using a collimated and filtered X-ray beam are reported. Specific ...examples are given using barrel modules of the Transition Radiation Tracker of the ATLAS experiment.
Helpful for a better understanding of the intrinsic processes in the various gas avalanche detectors are simulations, involving three-dimensional finite element method (FEM) field map computations in ...order to describe the more and more complex geometries. Drift, multiplication and attachment procedures are simulated using Monte Carlo techniques. Recent results show a remarkable agreement with gain and energy resolution measurements thanks to the refined computations of gas transport properties and improved avalanching models. As examples the influence of wire eccentricity on gas gain and energy resolution in the ATLAS TRT straws is shown as well as performed studies of the Micromegas detector.
Readout devices are being developed for use in a gas based vertex detector called the MicroTPC. The readout devices will consist of either integrated microstrip or microgap detectors, These devices ...are unique in that they have the detector fabricated directly onto the silicon with the preamplifier and shaper electronics. This offers lower noise and higher channel density compared to conventional microstrip design, Both devices were fabricated at Hewlett Packard using a standard 0.8 /spl mu/m, 3 metal process. Integrated gas microstrip detectors have been tested and an energy resolution of 18% FWHM, an electronics noise of 80 e/sup -/ r.m.s. and a gas gain of 200 was achieved, Integrated gas microgap detectors have also been fabricated and tested but only limited success has been achieved in comparison to the microstrip detectors. These devices, in conjunction with a low mass, high resolution MicroTPC should make a vertex detector well suited for heavy-ion physics environments such as RHIC and the LHC.
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