Publications & Preprints


Update on the Performance of the HERA-B Vertex Detector System
I. Abt, T.Perschke, S.Schaller, S.Masciocchi, C.Bauer, M.Bräuer, W.Hofmann, T.Jagla, K.T.Knöpfle, M.A.Pleier, K.Reeves, M.Schmelling, B.Schwingenheuer, F.Sciacca
Nucl. Instr. and Meth. A511 (2003) 24-31.
Abstract 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 3x10^14 minimum ionizing particles per cm^2 per year. Test measurements have shown adequate radiation tolerance on the required time scale of one year. New long term studies presented here indicate that on periods longer than one year charge collection efficiencies might drop.

Performance of the HERA-B Vertex Detector System
C.Bauer, M.Bräuer, T.Glebe, W.Hofmann, T.Jagla, K.T.Knöpfle, M.A.Pleier, V.Pugatch, M.Schmelling, B.Schwingenheuer, F.Sciacca, U.Trunk, M.Zavertiaev, I. Abt, M.Dressel, I.Kisel, S.Masciocchi, T.Perschke, M.Sang, S.Schaller
Nucl. Instr. and Meth. A501 (2003) 39-48.
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.

Radiation hardness of the HERA-B double-sided Silicon Strip Detectors
C.Bauer, T.Glebe, K.T.Knöpfle, V.Pugatch, B.Schwingenheuer, I.Abt, M.Dressel, S.Masciocchi, T.Perschke, S.Schaller
Nucl. Instr. and Meth. A485 (2002) 116-120.
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 3x10^{14} MIP/cm^2. The characterization of the detectors was done with a laser and a 106Ru 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 Volt 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.

Cluster shapes and cluster sizes in the HERA-B silicon vertex detector
I.Abt, C.Bauer, M.Bräuer, M.Dressel, T.Glebe, T.Jagla, I.Kisel, K.T.Knöpfle, S.Masciocchi, T.Perschke, V.Pugatch, M.Sang, S.Schaller, M.Schmelling, B.Schwingenheuer, F.G.Sciacca, E.Sexauer, U.Trunk, W.Wagner, R.Wanke
Nucl. Instr. and Meth. A469 (2001) 147-158.
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 runs of 1999 are compared to predictions of model calculations.

The HERA-B vertex detector system
C.Bauer, M.Bräuer, T.Glebe, W.Hofmann, T.Jagla, F.Klefenz, K.T.Knöpfle, V.Pugatch, M.Schmelling, B.Schwingenheuer, E.Sexauer, U.Trunk, R.Wanke, F.Zurheide, I. Abt, M.Dressel, I.Kisel, S.Masciocchi, B.Moshous, T.Perschke, M.Sang, S.Schaller, W.Wagner
Nucl. Instr. and Meth. A453 (2000) 103-108.
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.

The HERA-B Vertex Detector
S.Masciocchi, I.Abt, C.Bauer, M.Bräuer, M.Dressel, T.Glebe, W.Hofmann, I.Kisel, K.T.Knöpfle, B.Moshous, Th.Perschke, V.Pugatch, M.Sang, S.Schaller, M.Schmelling, B.Schwingenheuer, E.Sexauer, U.Trunk, W.Wagner, R.Wanke, and F.Zurheide
IEEE Trans. Nucl. Sci. 78 (2000) 1775-1780.
Abstract 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.

Challenges in the implementation of the HERA-B vertex detector
K.T.Knöpfle
Proc. Int. Europhysics Conf. on High Energy Physics (HEP99) , Tampere, Finland, 15-21 July 1999, ed. K. Huito, H. Kurki-Suonio, and J. Maalampi, IOP Publishing 2000, p. 991-992.
Abstract This paper outlines some results from R&D work for a forward microvertex detector that is integrated into the HERA proton storage ring.

Radiation Hardness of the HERA-B Silicon Microstrip Detectors
V.Pugatch, I.Abt, C.Bauer, M.Bräuer, M.Dressel, T.Glebe, W.Hofmann, K.T.Knöpfle, S.Masciocchi, B.Moshous, Th.Perschke, K.Riechmann, S.Schaller, M.Schmelling, B.Schwingenheuer, E.Sexauer, U.Trunk, R.Wanke, W.Wagner, and F.Zurheide
Contributed paper to the IVth Int. Conf. on Large Scale Applications and Radiation Hardness of Semiconductor Detectors, Firenze/I (1999), Nuovo Cimento 112A, (1999) 1383-1389.
Abstract This paper presents results of a non-uniform irradiation of a single-sided ac-coupled p-on-n silicon strip detector integrated on a HERA-B detector module. The fluences received by different areas of the detector wafer ranged from less than 2x10^13 MIPs/cm^2 to a maximum of 2.7x10^14 MIPs/cm^2 which allowed a systematic study of the detector performance both in the original n-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. The identification of the type-inverted detector region established the full detector functionality also in the transition region.

Status of the HERA-B Vertex Detector
C.Bauer, M.Bräuer, T.Glebe, W.Hofmann, K.T.Knöpfle, V.Pugatch, M.Schmelling, B.Schwingenheuer, E.Sexauer, L.Seybold, U.Trunk, R.Wanke, I. Abt, M.Dressel, S.Masciocchi, B.Moshous, T.Perschke, K.Riechmann, M.Sang, S.Schaller, W.Wagner, M.Merk, M.Mevius, T.van den Brink
Nucl. Instr. and Meth. A447 (2000) 61-68.
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 proton beam and on the status of our reconstruction software. First experiences with last year's installation are discussed.

Double sided microstrip detectors for the high radiation environment in the HERA-B experiment
I. Abt, S.Masciocchi, B.Moshous, T.Perschke, K.Riechmann, W.Wagner
Contributed paper to Elmau '98, Nucl. Instr. and Meth. A439 (2000) 442
Abstract The design of the double sided microstrip detectors for the HERA-B experiment is discussed, in particular with respect to the strong requirements imposed by the high radiation environment and by the challenging mechanical construction. The detectors are tested with an infrared laser setup and first results from operation in the experiment in 1997 are discussed.

First Experience and Results from the HERA-B Vertex Detector System
C.Bauer, I.Baumann, M.Bräuer, M.Eberle, W.Fallot-Burghardt, E.Grigoriev, W.Hofmann, A.Hüpper, F.Klefenz, K.T.Knöpfle, G.Leffers, T.Perschke, J.Rieling, M.Schmelling, B.Schwingenheuer, E.Sexauer, L.Seybold, J.Spengler, R.St.Denis, U.Trunk, R.Wanke, I.Abt, H.Fox, B.Moshous, K.Riechmann, M.Rietz, R.Ruebsam, W.Wagner
Nucl. Instr. and Meth. A418 (1998) 65-79.
Abstract 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.

Gluing Silicon with Silicone
I.Abt, H.Fox, B.Moshous, R.H.Richter, K.Riechmann, M.Rietz, R.St.Denis, and W.Wagner
Nucl. Instr. and Meth. A411 (1998) 191.
Abstract
Problems and solutions concerning the gluing of silicon detectors are discussed. The R&D work for the HERA-B vertex detector system led to gluing studies with epoxy and silicone based adhesives used on ceramics and carbon fiber. The HERA-B solution using a silicone glue is presented.

Overview of the HERA-B Vertex Detector System and First Results from Prototype Runs
K.Riechmann
Nucl. Instr. and Meth. A408 (1998) 221.
Abstract
An overview of the HERA-B silicon vertex detector system is presented. The system is optimized according to the requirements deduced from the physics goals of HERA-B. Due to the high radiation level it is necessary to exchange the modules carrying the silicon detectors once a year. The system is under construction. Data were taken with two prototype setups. Results are presented and compared with expectation.

HERA-B: overview and 1996 engineering run
A.Spengler
Nucl. Instr. and Meth. A384 (1996) 106-112.
Abstract
HERA-B is an experiment designed primarily to study CP violation in decays of B Mesons in the "gold plated" decay mode B^0 -> J/Psi K^0_s. The B mesons are produced in interactions of 820 GeV protons in the HERA proton beam with an internal wire target in the beam halo. Besides a short overview, the conception of the internal target and the results of the target tests are addressed. The detector requirements as well as the main detector components are described, whereas the physics goals of the experiment and some setails of the detector are described elsewhere in this issue.

Physics reach of HERA-B
I.Abt
Nucl. Instr. and Meth. A384 (1996) 113-118.
Abstract
The main physics goals of the HERA-B experiment are described and the experimental performance is dicussed. A comparison with the expected performance of the BABAR experiment is given.

Irradiation Tests of Double-Sided Silicon Strip Detectors with a Special Guard Ring Structure
I.Abt, L.Andricek, C.Bauer, H.Fox, A.Halley, H.Kroha, R.H.Richter, K.Riechmann, M.Rietz, R.Rübsam, H.Seywerd, R.St.Denis, I.Baumann, K.T.Knöpfle
IEEE Transactions on Nuclear Science, 43 (1996) 1113-1118.
Abstract
The results of the first irradiation tests of newly designed silicon microstrip detectors performed with 21 MeV protons at the Max-Planck- Institut in Heidelberg are presented. The detectors were developed and produced by the semiconductor laboratory of the Max-Planck-Institut in Munich. Novel guard ring structures allow operation of the detectors at voltages exceeding 300 V.

Pion and proton induced radiation damage to silicon detectors
K.Riechmann, K.T.Knöpfle, and V.Pugatch
Nucl. Instr. and Meth. A377 (1996) 276 - 283.
Abstract
We report on the radiation damage to silicon detectors at 25°C and 10°C induced by 190 MeV positively charged pions and 21 MeV protons. The deduced damage parameters and annealing time constants characterize the change of the diode leakage currents and full depletion voltages as a function of temperature and fluences. The results are relevant for the optimisation of the operating parameters of the HERA-B silicon vertex detector system.

Forward microvertex detectors for B physics at proton storage rings
K.T.Knöpfle
Nucl. Instr. and Meth. A368 (1995) 192-198.
Abstract
HERA-B and LHC-B are experiments dedicated to the study of CP violation in the neutral B meson system at the HERA proton storage ring and at the LHC collider, respectively. Crucial for each experiment is a forward microvertex detector of novel design whose characteristics are discussed in this paper.

Test of internal halo targets in the HERA proton ring
C. Hast, K.Ehret, W.Hofmann, S.Khan, K.T.Knöpfle, M.Reber, J.Rieling, M.Spahn, J.Spengler, T.Lohse, and V.Pugatch
Nucl. Instr. and Meth. A354 (1995) 224-248.
Abstract

HERA-B, an Experiment to Study CP violation at the HERA Proton Ring Using an Internal Target
P.Krizan, R.Mankel, D.Ressing, S.Shuvalov, and M.Spahn
Nucl. Instr. and Meth. A351 (1994) 111-131.
Abstract

An experiment to study CP violation in the B system using an internal target at the HERA proton ring
W. Hofmann
Nucl. Instr. and Meth. A333 (1993) 153-166.
Abstract

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