Silicon Vertex Detector Research Articles

An experiment to study CP violation using an internal target at the HERA proton ring

The main goal of HERA-B is the detection of CP-violation in the B-system using a dedicated Jψ trigger. The HERA-B detector is a forward spectrometer designed to run with high efficiency at a 10 MHz rate of multiple interactions. The requirements for detector components like the silicon vertex detector, the high granularity tracker, and the detectors for particle identification, as well as those for the first level trigger are in many aspects similar to the demands on LHC experiments.

The SVX II silicon vertex detector upgrade at CDF

The SVX vertex detector has been very successful in heavy flavor physics at CDF, playing a significant role in both top and bottom analyses. SVX′, a radiation hard version of SVX, is presently taking data. In 1998 the Main Injector upgrade to the accelerator complex at Fermilab will provide a significant increase in luminosity, and will require a new vertex detector, SVX II. The specifications and design considerations for this detector are discussed.

SVX', the new CDF silicon vertex detector

The Collider Detector at Fermilab (CDF) radiation hardened silicon vertex detector (SVX') is described. The new detector has several improvements over its predecessor such as better signal to noise and higher efficiency. It is expected to have a radiation tolerance in excess of 1 Mrad. It has been taking data for several months and some preliminary results are shown.

The Cornell high luminosity upgrade

The Cornell University electron storage ring is starting on a staged, four year upgrade program to attain luminosities of greater than 10 33 cm −2 s −1. The CLEO II detector will be upgraded immediately with a silicon vertex detector and will be taking data during CESR Phase II at a luminosity of about 6 × 10 32 cm −2 s −1 (accumulating a data set of about 20 fb −1). During 1998 CESR will be upgraded to Phase III and CLEO will get all new tracking and particle identification at high momenta. CLEO III will start accumulating data at about 10 fb −1/yr.

Gas cooling for silicon strip detectors

A gas cooling method of silicon strip detectors is presented. Based on it, a concept of a silicon vertex detector has been developed. Calculations of temperature distributions and mechanical deformation of a detector module have been performed with the help of Finite Elements Analysis. Results of thermal and mechanical measurements for a one-to-one dummy detector module cooled in air and helium are presented.

Measurement of the B+ and B0 meson lifetimes.

The lifetimes of the B+ and B0 mesons have been measured using fully reconstructed decays. In a sample of ∼49 600J/ψ→μ+μ− decays recorded with the Collider Detector at Fermilab, 148±16 B+ and 121±16B0 mesons have been reconstructed using the silicon vertex detector. Unbinned likelihood fits to the proper lifetime distributions of these B mesons give τ+=1.61±0.16 (stat)±0.05 (syst) ps, τ0=1.57±0.18 (stat) ±0.08 (syst) ps, and τ+/τ0=1.02±0.16 (stat) ±0.05 (syst).Received 25 January 1994DOI:https://doi.org/10.1103/PhysRevLett.72.3456©1994 American Physical Society

Nuclear dependence of neutral-D-meson production by 800 GeV/c protons.

The nuclear dependence for 800 GeV/[ital c] proton production of neutron [ital D] mesons has been measured near [ital x][sub [ital F]]=0 in Experiment 789 at Fermilab. [ital D] mesons from beryllium and gold targets were detected with a pair spectrometer and a silicon vertex detector via their decay [ital D][r arrow][ital K][pi]. No nuclear dependence is found, with a measured [alpha]=1.02[plus minus]0.03[plus minus]0.02. The measured differential cross section, [ital d][sigma]/[ital dx][sub [ital F]], for neutral-[ital D]-meson production at [l angle][ital x][sub [ital F]][r angle]=0.031 is 58[plus minus]3[plus minus]7 [mu]b/nucleon. The integrated cross section obtained by extrapolation of the measured cross section to all [ital x][sub [ital F]] is 17.7[plus minus]0.9[plus minus]3.4 [mu]b/nucleon and is consistent with previous measurements.

Vertex detector for the KEK B-factory

We are designing a silicon vertex detector to be installed in a detector for the KEK Asymmetric B-factory project. In order to fulfill the accuracy required for the vertex resolution from the physics motivation we made several studies about the various aspects of the construction technology as well as the studies, is presented. The validity and performance of the design are also discussed through which was derived from the above studies, is presented. The validity and performance of the design are also discussed through results of a study of the detector simulation which incorporated a capacitive network model for the distribution of collected charge.

Electrical performance of the CDF silicon vertex detector

D. Amidej d P. Azzi ', N. Bacchetta ', M. Bailey h, B. Barnett ', F. Bedeschi 9, D. Bisello 1, V. Bolognesi 9, C. Boswell 1, G. Busetto ', W.C. Carithers , H. Carter ', A. Castro S. Dell'Agnello 9, P.F. Derwent d, R. Ducar t A. Dunn d, R.P. Ely a, B. Flaugher S. Galeotti 9, A. Barbaro-Galtieri 1, A.F. Garfinkel h, C. Haber a,* *, S. Holland, M. Hrycyk b D. HerrUp b, R. Hughes ~, S. Kleinfelder , M. Loreti f, M. Mariotti ', J. Matthews ', A. Menzione 9, T. Merrick , C. Nelson b, L. Pescara f, N. Produit G. Punzi 11 F. Raffaelli 9, L. Ristori 11 0. Schneider 1, S . Segler b,, M.D . Shapiro N.M. Shaw h, T. ShaW b, j. Skarha ', F.R. Snider 1, T.Y. Song d, A. Spies , F. Tartarelli 9, b b P. Tipton ', S. Tkaczyk J. Tseng c, N. Turini 9, K. Turner S. Veicik c, G. Watts', T.R. Wesson b, W.C. Wester III ', H. Wenzel L', M. Wong , W. Yao ', F. Zetti 9 The University of California at Berkeley and Lawrence Berkeley Laboratory, Berkeley, California 94720, USA Fermi National Accelerator Laboratory, Bataria, Illinois 60510, USA c The Johns Hopkins University, Baltimore, Maryland 21218, USA d The University of Michigan, Ann Arbor, Michigan 48109, USA ' The University of New Mexico, Albuquerque, New Mexico 87131, USA f University of Padova, 1-35100 Padova Italy 11 Istituto Nazionale di Fisica Nucleare. and Universitv and Scuola Normale Superiore of Pisa, 1-56100 Asa, haly h Purdue University, West Lafayette, Indiana 47907, USA ' 7he University of Rochester, Rochester, New York 14627, USA

SPY: a monitoring system for the silicon vertex detector of CDF

The basic principles and fundamentals of the design of the system for monitoring the CDF silicon vertex detector are described. Some results and possible future developments of this way of checking complex detectors with a large number of channels are also described.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Measurement of the average lifetime of B hadrons produced in pp-bar collisions at sqrt s =1.8 TeV.

The average b-hadron lifetime has been measured using a high statistics sample of {ital B} {r_arrow} {ital J}/{psi}{Chi} decays recorded with the Collider Detector at Fermilab. We use a sample with an integrated luminosity of {approx} 90 {ital pb}{sup -1} recorded during the 1994-95 running period. The decay vertices of {approx} 62656 inclusive {ital J}/{psi} {r_arrow} {mu}{sup +}{mu}{sup -} candidates have been reconstructed using information from a silicon vertex-detector. The measured {ital B}lifetime, which is the average over all b-hadrons produced in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV weighted by their branching ratios into {ital J}/{psi}, is 1.524 {+-} 0.015 ({ital stat}){sup +0.035}{sub -0.026} ({ital sys}) ps. The precision of this measurement is significantly improved compared to the inclusive lifetime measurement published previously using {approx} 10 {ital pb}{sup -1}.

A first approach to mechanical construction and cooling of a composite 3D silicon vertex detector

This paper presents first results on mechanical and cooling studies for a 3D silicon vertex detector designed for B physics at a hadron collider. Prototype modules were built from raw silicon wafers. One module was instrumented with resistors to simulate readout electronics. Both module movement and temperature variations were recorded. A cooling method utilizing simple air/helium flow was investigated, but proved inadequate because of too large temperature anisotropies.

A precise measurement of Γ Z→b [formula omitted]/Γ Z→hadrons

A measurement of the partial width ratio Γ b b Γ had using a method which tags the Z → b b decays through the lif etime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both Γ b b Γ had and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of Γ b b Γ had = 0.2192±0.0026( stat.)±0.0016(Γ c c / Γ had ) is found. Combining this result with other recent ALEPH Γ b b Γ had measurements gives a 95% confidence upper limit on the Standard Model top mass of M t < 228 GeV.

A study of λ +c decays into pK−π+, pK−π+π0and pK−π+π0π0

In the CERN NA32 experiment a high-resolution silicon vertex detector and a purely topological approach were used to collect a clean sample of λ + c decays into pK − π + with or without additional neutral particles. We study the subresonant structure of the λ c + peak obtaining BR(λ c + → p K ∗0(892)) = 0.35 −0.07 +0.06±0.03 with respect to the total λ c + → pK − π + decay. We also determine branching ratios for some channels with neutral decay products, namely BR( λ c + → pK − π + π 0) = 0.73±0.12±0.05 and BR( λ c + → pK − π + π 0 π 0 = 0.16±0.07±0.03, again with respect to the total λ c + → pK − π + decay.

Design and tests for CLEO-II silicon vertex detector

We report on the design and prototype studies for a new double-sided silicon vertex detector for the CLEO-II experiment at CESR. To minimize multiple scattering, two new techniques are employed: (1) the detector is supported by low mass, low Z boron carbide foam U-channels; and (2) the preamplifiers are removed entirely from the tracking volume by using a second layer of metallization on the silicon to provide longitudinal readout traces for the transverse sense strips.

Charmed pair correlations in π−Cu interactions at 230 GeV/ c

In the CERN NA32 experiment a high-resolution silicon vertex detector and a purely topological approach were used to collect 557 events consistent with associated charm production, both decay vertices being observed. The pseudorapidity gap distribution appears to be nearly independent of the nature of the charmed hadrons. This distribution is reasonably consistent with the next-to-leading order QCD calculations. However the azimuthal-angle distribution is significantly broader than the above predictions.

Alignment of the ALEPH tracking devices

The techniques and the requirements on the accuracy for the alignment of the three ALEPH tracking devices, a large Time Projection Chamber (TPC), a cylindrical drift chamber (ITC) and a double sided silicon vertex detector (VDET), are presented. This includes internal VDET and TPC alignment techniques, relative global positioning of the three tracking detectors and calibration of residual distortions. Starting from survey measurements, real data were used to improve on the internal and global positioning of the detectors. The final alignment was done with a sample of 20 000 hadronic Z0 decays and 4000 Z0 → μ+μ− events taken in the 1991 LEP running period. After all corrections a momentum resolution of Δpp2 = 0.6 × 10−3 (GeV/c)−1 and impact parameter resolutions of 25 and 29 μm in the Rφ and Rz directions were achieved for tracks measured in all three tracking devices.

Updated measurement of the average b hadron lifetime

An improved measurement of the average lifetime of b hadrons has been performed with the ALEPH detector. From a sample of 260 000 hadronic Z 0 decays, recorded during the 1991 LEP run with the silicon vertex detector fully operational, a fit to the impact parameter distribution of lepton tracks coming from semileptonic decays yields an average b hadron lifetime of 1.49 ± 0.03 ± 0.06 ps.

Control and data acquisition electronics for the CDF silicon vertex detector

A control and data acquisition system has been designed for the CDF silicon vertex detector (SVX) at Fermilab. The system controls the operations of the SVX Rev D integrated circuit (S.A. Kleinfeeder et al., 1988) that is used to instrument a 46000 microstrip silicon detector (W.C. Corithers et al., 1990). The system consists of a Fastbus sequencer, a crate controller, and digitizer modules. The authors describe the hardware design for the CDF SVX data acquisition electronics. The method chosen for integrating the SVX detector system into the CDF data acquisition network and synchronization with the Fermilab collider beam crossings are discussed. The sequencer, controller, and digitizer are described. Error detection and diagnostics are considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Experience with the ALEPH silicon vertex detector

The ALEPH experiment [1] at LEP is equipped with a vertex detector [2] using two layers of double-sided silicon strip detectors. These detectors allow a real two-dimensional measurement of charged particle tracks. The present (1991) detector has the inner layer at a radius of 6.5 cm and the outer layer at 11.5 cm. The theta angle coverage is ±33° for the inner layer and ±50° for the outer layer. The inner layer is made out of 9 faces with four silicon detectors each, the outer layer has 15 such faces. We use silicon detectors of 5 × 5 cm 2 and 300 μm thickness. The readout pitch is 100 μm at both sides and using capacitive charge division a resolution in the order of 10 μm can be achieved. The signals from 256 readout strips are integrated, amplified and multiplexed using four CAMEX64 chips. An early version of this detector was already installed in spring 1990. Although the detector was not complete and in addition was accidentally damaged by malfunctions of the external electronics, it took data during the 1990 ALEPH run. For the first time double sided silicon detectors were used in a physics experiment. In 1991 the beampipe was replaced by a smaller one. This allowed us to move the inner layer to a radius of 6.5 cm. A completely new detector has been built. This new detector has been installed in spring 1991. Most of the results quoted in this paper refer to this detector.