J. Richardson

Radiation damage studies of field plate and p-stop n-side silicon microstrip detectors

Abstract We present results from studies of the properties of dedicated n-side microstrip structures before and after irradiation, with photons to 7 Mrad and fast neutrons to 8 × 10 13 ncm −2 . Both p-stop and field plate devices were investigated, each having a range of strip geometries in order to determine optimal configurations for long-term viability and performance.

Annealing effects on irradiated n+n silicon detectors

The performance of ATLAS forward region full-sized n+n prototype silicon micro-strip detectors has been studied after irradiation with 2×1014 protons/cm2 and 52 days annealing at 20°C. The signal-to-noise ratio measured at −10°C with LHC speed read-out was found to be degraded primarily due to increased noise. The reduction in the reverse current and the changes in the voltage needed for maximum charge collection have both been studied as a function of annealing time. Above the depletion voltage, no effect on the charge collection efficiency has been observed during this annealing period.

ATLAS beam test results

Abstract Many different configurations of electronics and semiconductor strip detectors were studied in 1995 using the ATLAS tracking detector test area at the H8 beam-line of the CERN SPS. A significant fraction of these investigations are presented elsewhere in this volume and this paper will concentrate on the results with silicon strip detectors read out with electronics preserving the pulse height information. Data has been collected with the ADAM, APV5 and FElix read-out chips on a number of different detectors. The first results are presented for read out with LHC electronics of detectors to the ATLAS-A specification of 112.5 μm pitch, employing n-strips in n-type silicon, capacitive coupling and intermediate strips. It is demonstrated that with adequate signal/noise, a spatial resolution of ⋍13 μm is attainable with these detectors.

Radiation tests of ATLAS full-sized n-in-n prototype detectors

Abstract ATLAS Technical Proposal, CERN/LHCC/94-43 has adopted n-side read out single-sided detectors as the baseline technology for the silicon microstrips due to the anticipated radiation tolerance of such a design ATLAS Inner Detector Technical Design Report, CERN/LHCC/97-17. This results from the reasonable efficiencies anticipated for charge collection, even when the detectors are run well below the final depletion voltage. Full-sized prototypes 64×63.6 mm 2 detectors have been produced with a range of manufacturers to a common specification and shown to work well in test-beam with ATLAS electronics. A selection of detectors was also scanned in the CERN PS beam for runs of two weeks giving an integrated dose over the full surface of 2×10 14 p/cm 2 . This dose corresponds to the highest charged hadron fluence expected in 10xa0yr of operation in ATLAS. Results are presented on these detectors both from parametric measurements and from studies using analogue LHC speed electronics. The detectors are shown to remain fully operational after these doses and to yield high signal/noise for read-out of 12xa0cm strip length. The performance partially depleted is also shown to match expectations and operation at down to half the final depletion voltage gives adequate efficiencies. Uncertainties in the anticipated dose and damage effects argue strongly for this additional robustness in detectors which must operate with very limited access in the hostile environment of the LHC for 10xa0yr.

Beam test of the ATLAS silicon detector modules

Abstract Results are reported from a beam test of prototype silicon microstrip detectors and front-end electronics developed for use in the LHC detector ATLAS. The detector assemblies (“modules”) were 12xa0cm long and were read out with binary electronics. Both irradiated and unirradiated modules were measured in a 1.56xa0T magnetic field for efficiency, noise occupancy, and position resolution as a function of bias voltage, binary hit threshold, and detector rotation angle with respect to the beam direction.

Performance of the ATLAS silicon strip detector modules

Abstract The performance of the silicon strip detector prototypes developed for use in ATLAS at the LHC is reported. Baseline detector assemblies (“modules”) of 12 cm length were read out with binary electronics at 40 MHz clock speed. For both irradiated and unirradiated modules, the tracking efficiency, noise occupancy, and position resolution were measured as a function of bias voltage, binary hit threshold, and detector rotation angle in a 1.56 T magnetic field. Measurements were also performed at a particle flux comparable to the one expected at the LHC.

Inclusive π0 andη 0 production in π− p interactions at 360 GeV/c

Theπ0 andη0 production is studied inπ−p interactions at 360 GeV/c. The cross section forπ0 production in the forward hemisphere (X>0) isσ(π0)=(49.7 ± 1.0 ± 1.1) mb and for η withX>0.1,Nch>2,σ(η0)=(3.1 ± 0.5) mb. The ratio of theπ0 toη0 cross section forX>0.1,Nch>2 isσ(π0)/σ(η0). Results on FeynmanX andpT distributions are presented. The data were obtained using the European Hybrid Spectrometer EHS and the bubble chamber LEBC at CERN.

Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics

ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

Silicon detectors for forward tracking in ATLAS

Abstract A 12 cm long silicon microstrip detector module with a fan geometry has been designed and constructed. The performance of the detector has been studied in a test beam at CERN. Results are presented on the hit efficiency and the position resolution as a function of position along the strips. With a hit efficiency of 99.5% and a spatial resolution of typically 35 μm the performance of these detectors exceeds that of other candidate technologies for the precision forward tracker of the ATLAS inner detector.

Pulse height of MIP's in an n-side silicon microstrip detector after proton irradiation with a fluence of 1x10**15 p cm**(-2)

We have irradiated an n-side silicon microstrip detector to an equivalent high energy fluence of 1/spl times/10/sup 15/ p cm/sup -2/ using 55 MeV protons. We determined the median pulse height to be 0.7 fC at a bias voltage of 180 V, and deduced a depletion region of about 80 /spl mu/m.