R. Wastie

Irradiation studies of multimode optical fibres for use in ATLAS front end links

The radiation tolerance of three multimode optical fibres has been investigated to establish their suitability for the use in the front-end data links of the ATLAS experiment. Both gamma and neutro ...

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 ...

Radiation hardness and lifetime studies of photodiodes for the optical readout of the ATLAS semiconductor tracker

AbstractA large sample (96) of epitaxial Si PIN photodiodes has been irradiated by &1MeV neutrons and 24GeV protonswith#uencesupto1015equivalent1MeVneutronscm~2inordertotesttheirsuitabilityforuseintheopticalreadoutofthe ATLASsemiconductortrackerandpixel detector at the CERNLargeHadronCollider. After an initialreductionof30% the responsivity remains constant up to the maximum #uence. The rise and fall times are not signicantly a!ectedand remain below 1ns. Although the dark current increases linearly with increasing neutron #uence, its level remainsbelow 100 nAwhich is negligible incomparison tothe operatingphotocurrentwhich is above 100lA. Enhancedageingstudies at 603C have also been carried out and no failure has occurred after an equivalent of 360 years of opera-tion. ( 2001 Elsevier Science B.V. All rights reserved. Keywords: Epitaxial Si PIN photodiodes; Neutron (1MeV) and proton (24 GeV) irradiation; Dark current; Responsivity; Ageing;Lifetime; ATLAS semiconductor tracker; ATLAS pixel detector; LHC

Single event upset studies with the optical links of the ATLAS semiconductor tracker

Abstract Studies have been performed of Single Event Upsets in the ATLAS SemiConductor Tracker optical links system. The measurements were made using low energy neutrons, and pion and proton beams in the momentum range 300–465xa0MeV/c. The implications for the operation of the system in ATLAS during high luminosity LHC operation are discussed.

Irradiation tests of photodiodes for the ATLAS SCT readout

Abstract Two kinds of photodiodes have been investigated for the ATLAS SCT readout. We present in this paper the results of irradiating bulk and epitaxial Si PIN diodes with 1xa0MeV-equivalent neutrons and 24xa0GeV protons. The devices were biased during some of the tests. They were exposed to a fluence of around 2.5 × 10 14 n cm −2 followed by a fluence of approximately 2.5×10 14 p cm −2 .

Radiation hardness and lifetime of VCSELs and PIN photodiodes for use in the ATLAS SCT

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 ionizing dose of 500 kGy and a 1 MeV equivalent neutron fluence of 1015 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.

Radiation-hard optoelectronic data readout for the ATLAS SCT

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 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 100 kGy and a total neutron fluence (1 MeV equiv.) of 2 X 1014 n/cm2, 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.

Beam test of the ATLAS silicon detector modules

Abstract Results are reported from a beam test of prototype silicon microstrip detectors and front-end electronics developed for use in the LHC detector ATLAS. The detector assemblies (“modules”) were 12xa0cm long and were read out with binary electronics. Both irradiated and unirradiated modules were measured in a 1.56xa0T magnetic field for efficiency, noise occupancy, and position resolution as a function of bias voltage, binary hit threshold, and detector rotation angle with respect to the beam direction.

A prototype LED/PIN diode optical data link for the ATLAS semiconductor tracker

Abstract An optical data transmission system based on LED/fibre/PIN diodes is described. This system is suitable for the read out of data from the ATLAS SemiConductor Tracker (SCT). The elements of the system are described and results are given for the performance of a complete chain. The system will be used for beam tests of SCT detector modules. Adaptations of the prototype planned for the production system are discussed.

Performance of the ATLAS silicon strip detector modules

Abstract The performance of the silicon strip detector prototypes developed for use in ATLAS at the LHC is reported. Baseline detector assemblies (“modules”) of 12 cm length were read out with binary electronics at 40 MHz clock speed. For both irradiated and unirradiated modules, the tracking efficiency, noise occupancy, and position resolution were measured as a function of bias voltage, binary hit threshold, and detector rotation angle in a 1.56 T magnetic field. Measurements were also performed at a particle flux comparable to the one expected at the LHC.