H. Caines

The STAR Silicon Vertex Tracker: A Large Area Silicon Drift Detector

Abstract The Solenoidal Tracker At RHIC-Silicon Vertex Tracker (STAR-SVT) is a three barrel microvertex detector based upon silicon drift detector technology. As designed for the STAR-SVT, silicon drift detectors (SDDs) are capable of providing unambiguous two-dimensional hit position measurements with resolutions on the order of 20 μm in each coordinate. Achievement of such resolutions, particularly in the drift direction coordinate, depends upon certain characteristics of silicon and drift detector geometry that are uniquely critical for silicon drift detectors hit measurements. Here we describe features of the design of the STAR-SVT SDDs and the front-end electronics that are motivated by such characteristics.

Silicon drift detectors for the STAR/SVT experiment at RHIC

Large area linear Silicon Drift Detectors (SDD) were developed to be used in the Silicon Vertex Tracker (SVT) of the STAR experiment at the BNL relativistic heavy ion collider (RHIC). The SDD is in its final design and has been submitted for large scale production. Test results show that the detector exhibits excellent position resolution and low noise. A special characterization procedure was developed to test detector wafers in order to select good detectors for the SVT. Recently, 15 STAR/SVT SDDs were assembled as a tracking device in a BNL-AGS heavy ion experiment (E896). It is the first tracking application of these detectors and their corresponding front-end electronics in an experimental environment. Preliminary results indicating good detector performance are shown and discussed in this paper.

An update on the strangeness production measurements and H0 di-baryon search as performed by the AGS experiment 896

E896 was designed to search for the predicted short-lived six-quark H0 di-baryon. The goal is to enhance the existing knowledge by extending the search into regions of shorter lifetimes (approximately half that of the lambda) and via exploring a new creation channel, that of the coalescence of two lambdas. Two main tracking chambers are used, a distributed drift chamber positioned to measure low-pt and high-rapidity neutral particle decay products and a silicon drift detector array which measures particle production at mid-rapidity. Both detectors are also investigating lambda polarization, over their respective coverages, for Au-Au collisions at 11.3 GeV/nucleon. The current status of the H0 di-baryon search and preliminary results of the strange particle production and polarization measurements will be presented.

Studies of dynamics of electron clouds in STAR silicon drift detectors

Abstract The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measured. Two methods were used to measure the cloud size. The method of cumulative functions was used to extract the electron cloud profiles. Another method obtains the cloud width from measurements of the charge collected on a single anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Experimental results agreed with theoretical expectations.

The silicon drift vertex detector for the STAR experiment at RHIC

Abstract The current status of the STAR Silicon Vertex Tracker (SVT) is presented. The performance of the Silicon Drift Detectors (SDD) is discussed. Results for a recent 15 layer SDD tracker which prototypes all components of the SVT are presented. The enhanced physics capabilities of the STAR detector due to the addition of the SVT are addressed.

Silicon drift detectors as tracking devices

Abstract Silicon drift detectors provide unambiguous two-dimensional position information for charged particle detection in a single detector layer. Like most other semi-conductor technologies, Silicon drift detectors are presently used in vertexing detectors. By taking into account, the drastic reduction in channel count compared to other silicon-based devices this specific technology is also well suited for large coverage tracking detectors. The first larger area Silicon Drift Tracker (6.3 cm ×6.3 cm ) was developed as the inner tracking detector (SVT) of the STAR experiment at the RHIC collider. Advantages and limitations of this detector will be discussed. Recent results of detector performance based on an application in a heavy ion fixed target experiment at the BNL-AGS (E896) are presented.

First results from the H0 di-baryon search and hyperon production measurements by the AGS Experiment 896.

Abstract The AGS Experiment 896 was designed to study strangeness production in Au—Au collisions at 11.6A GeV/c, in particular the formation of a six-quark di-baryon the H 0 . Heavy ion collisions provide favorable conditions for the H 0 formation either via coalescence of two Λ particles (owing to the large Λ production cross section) or direct production from the possible formation of a quark-gluon plasma. E896 also measured strange meson and baryon distributions from mid-rapidity. Preliminary results from this experiment are presented as well as details of the expected sensitivity for the H 0 search.

Strange and multi-strange baryon measurement in Au + Au collisions at 11.6A(GeV/c) with the silicon drift detector array from the AGS experiment E896

Abstract The main purpose of experiment E896 is to study the production of strange hadrons, in particular the predicted six-quark di-baryon, the H 0 . The placement of the silicon drift detector array (SDDA) close to the target in a 6.2T magnetic field is optimized for the reconstruction of a short lived H 0 as well as of strange baryons (Λ, Λ , Ξ − ). Simulations show that with the present data sample a detailed study of the Λ and Ξ − yields and distributions may be performed and a clear Λ signal might be detected. Simulations as well as a preliminary analysis of the SDDA data will be presented.

Distributed drift chamber design for rare particle detection in relativistic heavy ion collisions

This report describes a multi-plane drift chamber that was designed and constructed to function as a topological detector for the BNL AGSE896 rare particle experiment. The chamber was optimized for good spatial resolution, two track separation, and a high uniform efficiency while operating in a 1.6 Tesla magnetic field and subjected to long term exposure from a 11.6 GeV/nucleon beam of 10**6 Au ions per second.

Identified particle elliptic flow in √sNN = 130 GeV

We report first results on elliptic flow of identified particles at mid-rapidity in Au+Au collisions at