T. Perschke

Characterization of silicon microstrip detectors using an infrared laser system

Abstract An infrared laser system with variable wavelength is used to study fundamental properties of silicon microstrip detectors. Results of measurements concerning charge sharing among adjacent readout strips and depletion mapping are presented. The results are interpreted in a model framework which describes the charge sharing with the help of the so-called η -function. The wavelength dependence of the η -function is studied. Surface effects important for short wavelengths are observed.

Performance of the HERA-B vertex detector system

Abstract The Vertex Detector System (VDS) of the HERA-B experiment is a forward microvertex detector integrated into the HERA proton storage ring at DESY. Double-sided silicon microstrip detectors mounted in Roman pots are operated at typically 1 cm distance from the beam in a LHC-like high radiation environment. This paper presents results from the commissioning of the VDS that show its performance to meet the specifications.

First experience and results from the HERA-B vertex detector system

The HERA-B collaboration is building a detector to realize the ambitious goal of observing CP violation in decays of neutral B-mesons. A central element of the apparatus is the silicon vertex detector used to selectively trigger on these decays in a high charged particle multiplicity background environment and to reconstruct secondary vertices from such decays with high precision. The vertex detector, the supporting infrastructure and first results using prototype detectors are described. Results include imaging of the proton interaction region on the HERA-B target, hit distributions in the detector planes, and alignment of the detectors with each other and the target. ( 1998 Elsevier Science B.V. All rights reserved.

Status of the HERA-B vertex detector

Abstract The HERA-B experiment is a forward magnetic spectrometer with good particle identification for hadrons and leptons designed to study violation of CP symmetry in the neutral B meson system. The silicon vertex detector operates in a high-rate environment similar to the ones expected at LHC. In this paper we report on our R&D on strip detector design, frontend ASICs, mechanical and thermal engineering, low-mass RF shielding of the HERA proton beam and on the status of our reconstruction software. First experiences with last years installation are discussed.

The HERA-B vertex detector system

Abstract The HERA-B experiment is being built to measure CP violation in the B-system using internal targets at the HERA proton storage ring at DESY. This paper presents an overview of its vertex detector which – apart from an additional superlayer – is realized by a system of 20 Roman pots containing seven superlayers of double-sided silicon microstrip detectors that are operated at 10 mm distance from the proton beam in a high-radiation environment.

Radiation hardness of the HERA-B silicon microstrip detectors

SummaryThis paper presents results of a non-uniform irradiation of a single-sided ac-coupledp-on-n siliconstrip detector integrated ona HERA-B detector module. The fluences received by different areas of the detector wafer ranged from less than2 × 1013 MIP/cm2 to a maximum of 2.7 × 1014 MIP/cm2 which allowed a systematic study of the detector performance both in the originaln-type and type-inverted regime as well as in the transition region. Charge collection efficiency, noise, leakage current and full depletion voltage were determined as a function of strip number,i.e. fluence. Full functionality of the whole detector area has been established.

Cluster shapes and cluster sizes in the HERA-B silicon vertex detector

Abstract We report on investigations of shape and size of the clusters on the silicon detectors of the HERA-B vertex detector. The data taken during the commissioning run of 1999 are compared to predictions of model calculations.

Update on the performance of the HERA-B Vertex Detector System

The HERA-B Vertex Detector System (VDS) is a Roman Pot system integrated into the proton ring of the HERA accelerator at DESY and serves as an independent part of the tracking system of the HERA-B forward spectrometer. The performance of the VDS meets the design specification. It is based on double-sided silicon micro-strip detectors which are operated as close as 1 cm to the beam and are thus exposed to extremely high and inhomogeneous radiation levels. At the design luminosity the peak irradiation is around 3 � 10 14 minimum ionizing particles per cm 2 per year. Test measurements have shown adequate radiation tolerance on the required time scale of 1 year. New long-term studies presented here indicate that on periods longer than 1 year charge collection efficiencies might drop. r 2003 Elsevier B.V. All rights reserved. PACS: 13.85.� t; 13.25.Gv

Radiation hardness of the HERA-B double-sided silicon strip detectors

Abstract Irradiation studies of double-sided silicon strip-detectors for the HERA-B experiment have been performed using a setup at a 21 MeV proton beam. A novel method of fluence monitoring has been implemented. The study presented here gives results of a non-uniform irradiation of two HERA-B detector modules built with double-sided detectors made of oxygenated as well as non-oxygenated wafers. The maximum exposed fluence corresponds to about 3×10 14 MIP / cm 2 . The characterization of the detectors was done with a laser and a 106 Ru source. In regions of low-radiation dose, signal over noise ratios of 22 and 16 were measured for n- and p-side, respectively. In the region of maximum fluence, S/N values of ≈17 and ≈15 were obtained at a bias voltage of 450 V for n- and p-strips, respectively. Our measurements establish for both detector types full functionality at fluences varying by two orders of magnitude. Standard and oxygenated detectors do not show any significant difference.

The HERA-B vertex detector

The design of the vertex detector of the HERA-B experiment at DESY is reviewed, and its components are described. The silicon microstrip detectors were optimized for radiation hardness: results from irradiation tests, reproducing the challenging situation in the experiment, are presented. Since spring 1999, much of the system has been installed and is operational. The detector performance and results from track and vertex reconstruction are presented.