N. Kundu

The LCFIVertex package: vertexing, flavour tagging and vertex charge reconstruction with an ILC vertex detector

The precision measurements envisaged at the International Linear Collider (ILC) depend on excellent instrumentation and reconstruction software. The correct identification of heavy flavour jets, placing unprecedented requirements on the quality of the vertex detector, will be central for the ILC programme. This paper describes the LCFIVertex software, which provides tools for vertex finding and for identification of the flavour and charge of the leading hadron in heavy flavour jets. These tools are essential for the ongoing optimisation of the vertex detector design for linear colliders such as the ILC. The paper describes the algorithms implemented in the LCFIVertex package as well as the scope of the code and its performance for a typical vertex detector design.

Radiation-tolerant optical links for the ATLAS Semiconductor Tracker

The Large Hadron Collider (LHC), currently under construction at CERN, Geneva, will collide proton beams of energy 7 TeV. The high luminosity of the machine will lead to a severe radiation environment for detectors such as ATLAS. The ATLAS Semiconductor Tracker (SCT) must be able to tolerate a radiation field equivalent to an ionising dose of 10 Mrad (Si) and a neutron fluence of 2x1014cm-2 (1MeV,Si) over the 10 year lifetime of the experiment. The SCT is instrumented by silicon microstrip detectors and their front-end chips (ABCDs). Data is transferred from, and control signals to, the ABCDs using multimode optical links carrying light at 840 nm. The incoming timing, trigger and control (TTC) link uses biphase mark encoding to send 40 Mbit/s control signals along with a 40 MHz clock down a single fibre. Optical signals are received by a p-i-n diode and decoded by DORIC chips. Data in electrical form from the ABCDs is used to moderate two VCSELs by means of a VCSEL driver chip (VDC). Each detector module carries 12 ABCDs and is served by two optical fibres for data readout and one for TTC signals. There are 4088 such modules within the SCT. The system performance specifications and architecture are described, followed by test results on individual components and complete links. The optical fibre, active optical components, chips, packaging and interconnects have all been qualified to the necessary radiation levels. This has involved studies of total dose effects, single event upset and ageing at elevated temperatures and details of these studies are presented.

Status Report of the ATLAS SCT Optical Links

The readout of the ATLAS SCT and Pixel detectors will use optical links, assembled into harnesses. The final design for the barrel SCT opto-harness is reviewed. The most recent radiation tolerance studies are described. Test results from the first pre-series opto-harness are summarised. Results are given for the new 12 way VCSEL and PIN arrays to be used for the off-detector optoelectronics. Mechanical and cooling issues are addressed.

The SDC silicon tracker DAQ

Abstract Planned large scale trackers for high energy physics experiments mandate several qualitative changes to data acquisition systems for silicon tracking systems. A large fraction of the functionality of the DAQ system must reside on the detector, which imposes stringent constraints on size, radiation hardness, power consumption and reliability. An approach developed to address these issues for the SDC silicon tracker is outlined. There is no reference to the analogue systems; only the DAQ is described.