3 research outputs found
The ATLAS semiconductor tracker end-cap module
The challenges for the tracking detector systems at the LHC are unprecedented in terms of the number of channels, the required readout
speed and the expected radiation levels. The ATLAS Semiconductor Tracker (SCT) end-caps have a total of about 3 million
electronics channels each reading out every 25 ns into its own on-chip 3:3 ms buffer. The highest anticipated dose after 10 years operation
is 1:4 1014 cm2 in units of 1 MeV neutron equivalent (assuming the damage factors scale with the non-ionising energy loss). The
forward tracker has 1976 double-sided modules, mostly of area �70 cm2, each having 2 768 strips read out by six ASICs per side. The
requirement to achieve an average perpendicular radiation length of 1.5% X0, while coping with up to 7W dissipation per module (after
irradiation), leads to stringent constraints on the thermal design. The additional requirement of 1500e equivalent noise charge (ENC)
rising to only 1800e ENC after irradiation, provides stringent design constraints on both the high-density Cu/Polyimide flex read-out
circuit and the ABCD3TA read-out ASICs. Finally, the accuracy of module assembly must not compromise the 16 mm ðrfÞ resolution
perpendicular to the strip directions or 580 mm radial resolution coming from the 40 mrad front-back stereo angle.
A total of 2210 modules were built to the tight tolerances and specifications required for the SCT. This was 234 more than the 1976 required
and represents a yield of 93%. The component flow was at times tight, but the module production rate of 40–50 per week was maintained
despite this. The distributed production was not found to be a major logistical problem and it allowed additional flexibility to take advantage
of where the effort was available, including any spare capacity, for building the end-cap modules. The collaboration that produced the ATLAS
SCT end-cap modules kept in close contact at all times so that the effects of shortages or stoppages at different sites could be rapidly resolved
Beam tests of ATLAS SCT silicon strip detector modules
The design and technology of the silicon strip detector modules for the Semiconductor Tracker (SCT) of the ATLAS experiment have been finalised in the last several years. Integral to this process has been the measurement and verification of the tracking performance of the different module types in test beams at the CERN SPS and the KEK PS. Tests have been performed to explore the module performance under various operating conditions including detector bias voltage, magnetic field, incidence angle, and state of irradiation up to 3 multiplied by 1014 protons per square centimetre. A particular emphasis has been the understanding of the operational consequences of the binary readout scheme