M.C. Morrissey

The Design and construction of the ZEUS central tracking detector

Abstract The mechanical, electrical and electronic design and construction of the ZEUS central tracking detector are described, together with the chamber monitoring and environmental control. This cylindrical drift chamber is designed for track reconstruction, electron identification and fast event triggering in a high beam-crossing rate, high magnetic field application.

Construction and performance of the ATLAS silicon microstrip barrel modules

Abstract The ATLAS Semiconductor Tracker (SCT) consists of four barrel cylinders and 18 end-cap disks. This paper describes the SCT modules of the barrel region, of which more than 2000 are about to be constructed. The module design is fixed. Its design concept is given together with the electrical, thermal and mechanical specifications. The pre-series production of the barrel modules is underway using mass-production procedures and jigs. The pre-series modules have given satisfactory performances on noise, noise occupancy, electrical as well as mechanical and thermal properties. In addition, irradiated modules were demonstrated to work successfully. Also first results from a 10-module system test are given.

The data acquisition and calibration system for the ATLAS Semiconductor Tracker

The SemiConductor Tracker (SCT) data acquisition (DAQ) system will calibrate, configure, and control the approximately six million front-end channels of the ATLAS silicon strip detector. It will provide a synchronized bunch-crossing clock to the front-end modules, communicate first-level triggers to the front-end chips, and transfer information about hit strips to the ATLAS high-level trigger system. The system has been used extensively for calibration and quality assurance during SCT barrel and endcap assembly and for performance confirmation tests after transport of the barrels and endcaps to CERN. Operating in data-taking mode, the DAQ has recorded nearly twenty million synchronously-triggered events during commissioning tests including almost a million cosmic ray triggered events. In this paper we describe the components of the data acquisition system, discuss its operation in calibration and data-taking modes and present some detector performance results from these tests

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 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.

A monolithic charge multiplexer with 0.5% accuracy

Abstract This paper describes a 16 channel monolithic charge multiplexer providing a close tolerance, low cost, low power solution to the problem of handling the signals from detectors with large numbers of channels. Outputs may be wire-orred to increase the degree of multiplexing. A system designed with this chip and with suitably close tolerance processing downstream will have a gain match of ±0.5% and a front end chip cost of approximately

The combined response of the ALEPH electromagnetic and hadronic calorimeter to pions

1 per channel. The chip is fabricated in CMOS technology and the test of a 1500 channel system has demonstrated the feasibility of CMOS in this context. The chip produceds a prompt sum of the charges from the 16 signal sources and integrates and stores the individual charges for later serial readout. A single network provides amplifier bias and releases area to facilitate optimum noise performance and signal handling. Amplifier and bias network design together with p-well screens to isolate storage capacitors from the substrate provide the power line rejection essential in systems generating a trigger from large numbers of channels.

The ATLAS SCT grounding and shielding concept and implementation

Abstract The response to pions of an ALEPH electromagnetic calorimeter petal combined with the ALEPH hadron calorimeter prototype has been studied in the energy range between 2 and 30 GeV. The resolution of the combined calorimeters was found to be lower than that for the hadron calorimeter alone at low energies and approached this value at higher energies.

Multiprocessor system controlling power supply distribution for the ATLAS SCT

This paper describes the design and implementation of the grounding and shielding system for the ATLAS SemiConductor Tracker (SCT). The mitigation of electromagnetic interference and noise pickup through power lines is the critical design goal as they have the potential to jeopardize the electrical performance. We accomplish this by adhering to the ATLAS grounding rules, by avoiding ground loops and isolating the different subdetectors. Noise sources are identified and design rules to protect the SCT against them are described. A rigorous implementation of the design was crucial to achieve the required performance. This paper highlights the location, connection and assembly of the different components that affect the grounding and shielding system: cables, filters, cooling pipes, shielding enclosure, power supplies and others. Special care is taken with the electrical properties of materials and joints. The monitoring of the grounding system during the installation period is also discussed. Finally, after connecting more than four thousand SCT modules to all of their services, electrical, mechanical and thermal within the wider ATLAS experimental environment, dedicated tests show that noise pickup is minimised.

Results of early phase of series production of ATLAS SCT barrel hybrids and modules

A system of many thousands of DC isolated power supplies for ATLAS Semi-Conductor Tracker (SCT) controlled by about 14 000 microprocessors forms a large system which temporal properties are essential for reliability. This system passes now various integration tests. Highlights of the system architecture are presented and details of communication aspects for the high voltage (HV) subsystem are described.