C. Buttar

Prospects for the search for a standard model Higgs boson in ATLAS using vector boson fusion

The potential for the discovery of a Standard Model Higgs boson in the mass range mH < 2 mZ in the vector boson fusion mode has been studied for the ATLAS experiment at the LHC. The characteristic signatures of additional jets in the forward regions of the detector and of low jet activity in the central region allow for an efficient background rejection. Analyses for the H → WW(*) and H → ττ decay modes have been performed using a realistic simulation of the expected detector performance. The results obtained demonstrate the large discovery potential in the H → WW(*) decay channel and the sensitivity to Higgs boson decays into τ-pairs in the low-mass region around 120xa0GeV/c2.

GaAs solid state detectors for particle physics

Abstract We report on progress with Schottky diode and p-i-n diode GaAs detectors for minimum ionising particles. The radiation hardness and potential speed of simple diodes is shown to be more than competitive with silicon detector. A discussion is given of the present understanding of the charge transport mechanism in the detectors since it influences their charge collection efficiency. Early results from microstrip detectors are also described.

Silicon microstrip detectors for the ATLAS SCT

Abstract The ATLAS Semiconductor Tracker at the Large Hadron Collider (LHC) will incorporate ∼20,000 individual silicon microstrip sensors representing ∼60 m 2 of silicon. Production and delivery of the sensors is already underway and scheduled for completion by late 2002. The sensors have been optimised for operation in the harsh radiation environment of the LHC, and subjected to an extensive qualification program in which their pre- and post-irradiation characteristics have been evaluated. The sensor design features are reviewed, together with their electrical characteristics and the Quality Control procedures adopted by ATLAS during production.

The radiation environment in the ATLAS inner detector

Abstract The radiation environment in the inner detector has been simulated using the particle transport program FLUKA with a recent description of the ATLAS experiment. Given in this paper are particle fluences and doses at positions relevant to the three inner detector subsystems; the Pixel, SCT and TRT detectors. In addition, studies are reported on in which (1) information concerning the optimization of the inner detector neutron-moderators is obtained and (2) the impact of including additional vacuum-equipment material is assessed.

Charge transport properties of undoped SI LEC GaAs solid-state detectors

Abstract The GaAs detectors for minimum ionizing particles fabricated with commercial undoped SI GaAs show good quality as minimum ionizing particle detectors. A discussion is given of the present understanding of the charge transport mechanism in the detectors since it influences their charge collection efficiency.

Gallium arsenide microstrip detectors for charged particles

Microstrip detectors have been constructed from gallium arsenide (GaAs) wafers made from undoped LEC (liquid-encapsulated Czochralski) semi-insulating substrate material. Tests were performed using minimum ionising particles to ascertain their properties as charged particle detectors. The results show that the devices work wellm, with good signal-to-noise ratio (typically 7). The effects of gamma ray and neutron irradiation have been studied and shown to be small up to levels exceeding 20 Mrad and 1014 n/cm2, respectively.

Gallium arsenide charged particle detectors; trapping effects

The progress on the development of gallium arsenide particle detectors is reviewed. The limitation to the performance is the presence of traps. Studies of the trap properties using α particle DLTS measurements and C-V measurements are described.

Recent results from the ATLAS SCT irradiation programme

Abstract The irradiation facility at the CERN proton synchrotron, set up to irradiate full-size prototypes of silicon microstrip detectors for the ATLAS semiconductor tracker, is described and measurements of the detector currents during irradiation are reported. The detector dark currents can be described by bulk radiation damage models demonstrating the radiation hardness of the detector design and allowing the current damage factor α and the acceptor introduction term β to be determined. Results from testbeam studies of a module with an irradiated detector and binary readout in a magnetic field and with the beam incident over a range of angles are reported. The hit efficiency and spatial resolution satisfy the requirements for the SCT provided the detector is operated at the full charge collection voltage. The Lorentz angle was not found to be affected by the irradiation.

A comparison of the performance of irradiated p-in-n and n-in-n silicon microstrip detectors read out with fast binary electronics

Abstract Both n-strip on n-bulk and p-strip on n-bulk silicon microstrip detectors have been irradiated at the CERN PS to a fluence of 3×10 14 p cm −2 and their post-irradiation performance compared using fast binary readout electronics. Results are presented for test beam measurements of the efficiency and resolution as a function of bias voltage made at the CERN SPS, and for noise measurements giving detector strip quality. The detectors come from four different manufacturers and were made as prototypes for the SemiConductor Tracker of the ATLAS experiment at the CERN LHC.

Evolution of silicon microstrip detector currents during proton irradiation at the CERN PS

Prototype ATLAS silicon microstrip detectors have been irradiated to the dose predicted for 10 years of LHC operation with 24 GeV protons at the CERN PS whilst cooled to the ATLAS design operating temperature. The detector currents were monitored during irradiation, which allows the predictions of bulk radiation damage parameterizations to be tested. Values for the damage constant a and the rate of acceptor creation b have been calculated and are in agreement with those previously published for the irradiation of silicon diodes. r 2002 Elsevier Science B.V. All rights reserved. PACS: 29.40.Wk; 61.82.Fk