P.D. Shield

Vertex Triggering Using Time Difference Measurements in the ZEUS Central Tracking Detector

Abstract A method of vertex triggering which uses a time difference measurement to determine the z coordinate of a track is under development for the ZEUS Central Tracking Detector. This incorporates a pipelined readout system. We describe the system and report on its performance.

Development of the ZEUS central tracking detector

Abstract The design concept and development of the ZEUS central tracking detector is described. This is a cylindrical drift chamber designed for track reconstruction, electron identification and event triggering in a high-crossing-rate, high-magnetic-field environment.

The SOUDAN 2 detector: The design and construction of the tracking calorimeter modules

SOUDAN 2 is a 960-ton tracking calorimeter which has been constructed to search for nucleon decay and other phenomena. The full detector consists of 224 calorimeter modules each weighing 4.3 tons. The design and construction of the modules are described. The modules consist of finely segmented iron instrumented with 1 m long drift tubes of 15 mm internal diameter. The tubes enable three spatial coordinates and dE/dx to be recorded for charged particles traversing the tubes.

System tests of radiation hard optical links for the ATLAS semiconductor tracker

A prototype optical data and Timing Trigger and Control transmission system based on LEDs and PIN-diodes has been constructed. The system would be suitable in terms of radiation hardness and radiat ...

The ZEUS first level tracking trigger

Abstract The ZEUS experiment has a three-level trigger system to select electron-proton interaction events from a large anticipated background of proton beam-gas. The first level decision is formed using pipelined hardware processors clocked at the 96 ns beam crossing frequency. A vital component of this decision is discrimination against upstream events using tracking detector information. The processors use three-dimensional space points measured in the central tracking detector to find pointing tracks over most of the θ range, and include forward tracking detector information to improve the resolution and angular coverage in the proton forward direction. The processor design status and performance simulation results are presented.

ATLAS beam test results

Abstract Many different configurations of electronics and semiconductor strip detectors were studied in 1995 using the ATLAS tracking detector test area at the H8 beam-line of the CERN SPS. A significant fraction of these investigations are presented elsewhere in this volume and this paper will concentrate on the results with silicon strip detectors read out with electronics preserving the pulse height information. Data has been collected with the ADAM, APV5 and FElix read-out chips on a number of different detectors. The first results are presented for read out with LHC electronics of detectors to the ATLAS-A specification of 112.5 μm pitch, employing n-strips in n-type silicon, capacitive coupling and intermediate strips. It is demonstrated that with adequate signal/noise, a spatial resolution of ⋍13 μm is attainable with these detectors.

The design, status and performance of the ZEUS central tracking detector electronics

Abstract The readout system developed for the ZEUS central trackign detector (CDT) is described. The CTD is required to provide an accurate measurement of the sagitta and energy loss of charged particles as well as provide fast trigger information. This must be carried out in the HERA environment in which beams cross every 96 ns. The first two aims are achieved by digitizing chamber pulses using a pipelined 104 MHz FADC system. The trigger uses a fast determination of the difference in the arrival times of a pulse at each end of the CTD. It processes this data and gives information to the ZEUS global first level trigger. The modules are housed in custom-built racks and crates and read out using a DAQ system based on Transputer readout controllers. These also monitor data quality and produce data for the ZEUS second level Trigger.

The technique of z-coordinate determination using a time-difference measurement for the zeus central tracking detector

A method to determine the z-coordinate of a track using a time-difference measurement has been developed for the ZEUS Central Tracking Detector. It has been demonstrated that a spatial resolution of 50 mm can be obtained under normal chamber operating conditions. This corresponds to a time-difference resolution of 330 ps. A method of minimizing nonlinearities in the time-to-distance response is described. This uses an inductor to form a matching network to achieve resistive termination of the chamber. Test beam measurements from a prototype chamber are presented, demonstrating the effects of the chamber surface field and beam incidence angle on the time-difference resolution.

The design and performance of the ZEUS Central Tracking Detector z-by-timing system

Abstract The ZEUS Central Tracking Detector utilizes a time difference measurement to provide a fast determination of the z coordinate of each hit. The z -by-timing measurement is achieved by using a Time-to-Amplitude Converter which has an intrinsic timing resolution of 36 ps, has pipelined readout, and has a multihit capability of 48 ns. In order to maintain the required sub-nanosecond timing accuracy, the technique incorporates an automated self-calibration system. The readout of the z -by-timing data utilizes a fully customized timing control system which runs synchronously with the HERA beam-crossing clock, and a data acquisition system implemented on a network of Transputers. Three dimensional space-points provided by the z -by-timing system are used as input to all three levels of the ZEUS trigger and for offline track reconstruction. The average z resolution is determined to be 4.4 cm for multi-track events from positron-proton collisions in the ZEUS detector.

The Optical alignment system of the ZEUS microvertex detector

Abstract The laser alignment system of the ZEUS microvertex detector is described. The detector was installed in 2001 as part of an upgrade programme in preparation for the second phase of electron–proton physics at the HERA collider. The alignment system monitors the position of the vertex detector support structure with respect to the central tracking detector using semi-transparent amorphous-silicon sensors and diode lasers. The system is fully integrated into the general environmental monitoring of the ZEUS detector and data has been collected over a period of 5 years. The primary aim of defining periods of stability for track-based alignment has been achieved and the system is able to measure movements of the support structure to a precision around 10 μ m .