Silicon Vertex Detector Research Articles

PROSPECTS FOR RUN II BEAUTY PHYSICS AT DØ

In the spring of 2001, the upgraded Fermilab Tevatron will begin its collider physics run with [Formula: see text] collisions at [Formula: see text], where it is expected to deliver an integrated luminosity of 2 fb -1 in the first two years. The DØ detector is undergoing an extensive upgrade in order to take full advantage of the high luminosity running conditions. The upgraded detector's new silicon vertex detector, fiber tracker, and lepton trigger capabilities make a rich B physics program possible at DØ. This paper describes the prospects for several DØ B physics measurements, including CP violation in [Formula: see text] decays, Bs mixing and [Formula: see text] lifetime.

Dense Optical-electrical Interface Module

The DOIM (Dense Optical-electrical Interface Modules) is a custom-designed optical data transmission module employed in the upgrade of Silicon Vertex Detector of CDF experiment at Fermilab. Each DOIM module consists a transmitter(TX) converting electrical differential input signals to optical outputs, a middle segment of jacketed fiber ribbon cable, and a receiver (RX) which senses the light inputs and converts them back to electrical signals. The targeted operational frequency is 53 MHz, and higher rate is achievable. This article outlines the design goals, implementation methods, production test results, and radiation hardness tests of these modules.

THE CLEO III DETECTOR

After a long shutdown in 1999, the CLEO Collaboration at Cornell University's Wilson Laboratory began taking data in 2000 using its third generation detector, CLEO III. Several improvements to the detector system have been made in order to take advantage of the possibility of unprecedented luminosities of well over 2×1033 expected from CESR, and to explore new territory in the physics of B mesons. These improvements include a new drift chamber, a four layer silicon vertex detector and a RICH detector. These features will be described, and its performance will be presented.

Performance of the BELLE silicon vertex detector

The performance of the Silicon Vertex Detector (SVD) in the Belle experiment is reviewed based on 6.8 fb/sup -1/ of data taken between October 1999 and July 2000. The main purpose of the SVD is to make precise measurements of the B decay vertex position, which are essential for the observation of CP asymmetries. Excellent vertex resolution and a good detection efficiency are required for the SVD. Basic performance parameters such as signal pulse height, noise, strip yield and intrinsic resolution are reported. The SVD performance parameters which are directly related to physics analysis such as track matching efficiency, impact parameter resolution and vertex resolution are also shown.

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

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.

Halny: a digital signal processor based module for the readout of silicon strip detectors

We describe a four-channel, digital-signal-processor-based readout board, equipped with analog-to-digital converters. A series of identical boards work in parallel in the Belle experiment at KEK, performing a zero-suppressing readout of the silicon vertex detector. A cluster-searching algorithm executes quickly enough to allow low deadtime readout at a 500 Hz trigger rate. DSP code downloaded to the boards can be easily modified, affording a high degree of flexibility. We describe the board hardware, the algorithms employed in the experiment, and the software used to implement them.

Optical alignment system for the ZEUS micro vertex detector

The electron–proton scattering experiment ZEUS will be equipped with a silicon vertex detector in preparation for the upgrade of the HERA collider. An optical alignment system for the vertex detector is being developed. The alignment system measures the position of the vertex detector with respect to the outer tracking detector as well as the shape of the vertex detector using semi-transparent amorphous-silicon sensors and diode lasers. A test of the alignment system was performed using the support structures of the vertex detector. The results are presented and discussed.

The BELLE silicon vertex detector

The silicon vertex detector of the BELLE experiment has been built to provide the vertex information of B meson decays at the KEKB accelerator. It consists of three cylindrical layers of double sided, double metal silicon sensors read out by VA1 chips. The analog signals are transmitted to a system of fast analog-to-digital converters and are reduced on a system based on Motorola Digital Signal Processors. Performance during the initial data taking period and a brief description of the upgrade plan are also presented.

The port card for the silicon vertex detector upgrade of the Collider Detector at Fermilab

The collider detector at Fermilab is approaching the completion of the silicon vertex detector upgrade for Run II. The port card is a Beryllia multichip module developed to control, read out, and regulate power for the silicon strip readout chips. It has two radiation hard application-specific integrated circuits, parallel fiber-optic transmitters, and voltage regulators. It resides 14 cm from the accelerator beam inside the tracking volume. The function and location of the port card impose severe constraints on its design. This paper presents the port card and describes the adopted solutions to address the main design issues, as well as the result of many characterization tests.

Radiation hardness of VA1 with submicron process technology

We have studied the radiation hardness of the VA1, a Viking-architecture preamplifier VLSI chip. Large-scale integrated (LSI) samples are fabricated in 0.8 and 0.35 /spl mu/m process technologies to improve the radiation hardness of the LSI for the Belle silicon vertex detector upgrade. We have observed significant improvement of the radiation hardness with 0.8-/spl mu/m technology compared to 1.2-/spl mu/m technology. Little degradation of noise and gain is observed up to a total dose of 20 Mrd for the VA1 fabricated in the 0.35-/spl mu/m technology. We find that the radiation hardness improves with a scaling of better than t/sub ox//sup -6/ (t/sub ox/: oxide thickness). Basic parameters of MOSFETs are also studied to understand the mechanism of radiation damage in the VA1.

Results from Belle on sin 2φ 1

A measurement of the CP violation parameter sin 2φ 1 at the KEKB asymmetric e + e − collider is reported. A data sample of 6.2 fb −1 recorded at the ϒ(4 S) resonance with the Belle detector is used. In this analysis, we select B 0 meson decay modes to the J/ψ K S , ψ′ K S , χ c1 K S and J/ψ K L CP eigenstates. The flavor of the other B meson is identified using high and medium momentum leptons, K ±, or a slow pion. The proper-time difference between the two B mesons are obtained from the vertices measured with a silicon vertex detector, and sin 2φ 1 is obtained from a fit to the proper-time difference distribution. The current preliminary result is sin 2φ 1 = 0.45 +0.43 −0.44( stat) +0.07 −0.08( sys).

Experience with HERA-B vertexing

The reconstruction of the decay vertices of long-lived particles like B mesons and their separation from the primary interaction is one of the primary tasks at the HERA-B experiment. Using data collected in the year 2000, the design and performance of the silicon vertex detector are reviewed. Results from track and vertex reconstruction are presented.

Prospects for DØ beauty physics measurements in run II

The Main Injector era of the Fermilab Tevatron is about to begin. Its first collider physics run (Run II) will start in the spring of 2001, with p p collisions at √ s = 2.0 TeV and a expected integrated luminosity of 2 fb −1 delivered in the first two years. The DØ detector is undergoing an extensive upgrade in order to take full advantage of this high luminosity running. The upgraded detector's silicon vertex detector, inner tracker, and muon trigger arrays, will make a rich B physics program possible at DØ. In this paper we discuss our prospects for key measurements which include CP violation in B → J/Ψ + K s decays, CP asymmetries in two body hadronic B decays, B s mixing, as well as spectroscopy and lifetime measurements of beauty baryons such as the Λ b .

Keeping track of the big event

The BaBar detector at the B meson factory at the Stanford Linear Accelerator Laboratory (SLAC) is physically large. It represents a collaboration of more than 600 researchers at 73 institutions in Europe and North America. The experiment is primarily designed to answer a really big question: why more matter than anti matter survived a fraction of a second after the Big Bang. Several times a person's height and weighing more than 1000 tons, the BaBar detector sits at the intersection point of the electron and positron beams. A silicon vertex detector, comprising strips of silicon spaced 100 microns apart, provides 150000 channels of raw data. The software that controls and processes data from this experiment is also large; an estimated three million lines of code primarily written in C++, with small amounts of Java and Fortran. Because of the complexity, coding standards and tools for managing the code have been developed. The computing environment for BaBar is divided into two parts: the online system and the offline system.

The H1 silicon vertex detector

The design, construction and performance of the H1 silicon vertex detector is described. It consists of two cylindrical layers of double-sided, double-metal silicon sensors read out by a custom designed analog pipeline chip. The analog signals are transmitted by optical fibres to a custom-designed ADC board and are reduced on PowerPC processors. Details of the design and construction are given and performance figures from the first data-taking periods are presented.

Intermediate silicon layers detector for the CDF experiment

The Intermediate Silicon Layers (ISL) detector is currently being built as part of the CDF II detector upgrade project. The ISL detector will significantly improve tracking in the central region and, together with the Silicon Vertex detector, provide stand-alone 3D track information in the forward/backward regions. In this article, we present the quality of the production sensors manufactured by Hamamatsu Photonics, which account for roughly half of the silicon sensors used in the ISL detector.

The BELLE silicon vertex detector

A silicon vertex detector has been developed for the BELLE experiment at the KEK B-factory to be used to determine the relative displacements of B-meson decay vertices for CP violation measurements. The device has been successfully installed and operated with high-luminosity beam conditions. The average strip yield is larger than 96%, including the preamplifier electronics yield and the detector is currently working stably with a signal-to-noise ratio of 17–40. The measured impact parameter resolution agrees with expectations based on Monte Carlo simulations, and the measured D 0 lifetime is in good agreement with the particle data group's average of other measurements. Several B→J/ψK events produced at the ϒ(4S) resonance have been detected and separate decay vertices have been found.

The silicon vertex detector for BELLE

The silicon vertex detector (SVD) for the BELLE detector for the KEK B-factory project has been constructed and commissioned successfully. In this report, the design and construction of the SVD are first described. The result of the first one-month operation is then presented. Finally plans for upgrading the SVD are discussed.

Silicon vertex tracker: a fast precise tracking trigger for CDF

The Silicon Vertex Tracker (SVT), currently being built for the CDF II experiment, is a hardware device that reconstructs 2-D tracks online using measurements from the Silicon Vertex Detector (SVXII) and the Central Outer Tracker (COT). The precise measurement of the impact parameter of the SVT tracks will allow, for the first time in a hadron collider environment, to trigger on events containing B hadrons that are very important for many studies, such as CP violation in the b sector and searching for new heavy particles decaying to b b ̄ . In this report we describe the overall architecture, algorithms and the hardware implementation of the SVT.

The DELPHI Silicon Tracker in the global pattern recognition

ALEPH and DELPHI were the first experiments operating a silicon vertex detector at LEP. During the past 10 years of data taking the DELPHI Silicon Tracker was upgraded three times to follow the different tracking requirements for LEP 1 and LEP 2 as well as to improve the tracking performance. Several steps in the development of the pattern recognition software were done in order to understand and fully exploit the silicon tracker information. This article gives an overview of the final algorithms and concepts of the track reconstruction using the Silicon Tracker in DELPHI.