Professor Tony Weidberg

Abstract:

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 radiation length for use in the ATLAS SemiConductor Tracker. Bit error rate measurements were performed for the data links and for the links distributing the Timing, Trigger and Control data from the counting room to the front-end modules. The effects of cross-talk between the emitters and receivers were investigated. The advantages of using Vertical Cavity Surface Emitting Lasers (VCSELs) instead of LEDs are discussed.

Abstract:

The radiation hard opto-electronic links being developed for the ATLAS Semiconductor Tracker (SCT) and Pixel detectors are described. The results of the radiation tests on all the on-detector components are reviewed. Results of environmental tests of irradiated opto-packages are mentioned. New results on Single Event Upset Studies are presented and the implications for ATLAS operation are discussed.Two versions of the ATLAS SCT style on-detector opto-package are described. The performance of these packages are compared to the ATLAS specifications. These packages have been integrated into the SCT system and extensive system tests have been performed. The experience with the assembly of the first larger scale integration is discussed.

Abstract:

This paper reports the radiation hardness of optical components to be used in the binary readout of one of the next generation of detectors in high energy physics. The optical components will have to sustain a total ionising dose of 500 kGy and a 1 MeV equivalent neutron fluence of 10(15)n cm(-2). Emitters of VCSEL type have been chosen and have shown a shift of 1 mA in the laser threshold current after irradiation, but are still suitable for our purpose. The epitaxial Si PIN photodiode receivers have an acceptable 30% drop in responsivity providing a higher reverse bias is applied. Speed and lifetime of both components appear to be unaffected by the radiation damage. Temperature characteristics showing differences from un-irradiated materials will be also presented.

Abstract:

The ATLAS experiment is currently in the final pre-production design phase to allow timely installation at the CERN Large Hadron Collider in 2005. The sub-systems closest to the interaction point - the tracking detectors, will be subject to significant total radiation dose at high flux. Optical data transmission has been chosen for the Pixel and SemiConductor Tracker (SCT) to both deliver timing and control information to the detector modules and transmit tracking data to the remote counting room Of considerable concern is the radiation hardness, both transient and total dose, of not just the optoelectronic components but also the driver/receiver electronics. In this paper we report on total dose radiation testing of the VCSEL driver and photodiode receiver ASICs designed using a range of techniques in a nominally radiation-soft process. Both ASICs will be shown to be tolerant to a total gamma dose of 100kGy and a total neutron fluence (1 MeV equiv.) of 2x10(14) n/cm(2), as required for this system. Single-event upset (SEU) studies have also been carried out using a high-energy pion beam, showing the system to be sufficiently robust to SEU at an ATLAS-Like particle flux.

Abstract:

Optical data transmission has been chosen for the ATLAS Pixel and SemiConductor Tracker to deliver both timing and control information to the detector modules and transmit tracking data to the remote computer room. Radiation hardness of individuals optical components and their ASICs drivers have been reported in previous papers. We will report here the Single Event Upset studies carried out on a customised optopackage using a high-energy pion beam. It will be shown that the system is sufficiently robust to SEU at the ATLAS SCT level.