SNO+

Abstract:

The MONALISA group develops novel, accurate, nanometre resolution, interferometric systems to monitor relative motions between key accelerator components. We use cost-effective technology developed for the telecommunications market, providing readily scalable, adaptable solutions. Key magnets and diagnostics in the beam-delivery section of the International Linear Collider (ILC) will need to maintain stable relative positions. In particular, the final focus quadrupole magnets require nanometre level stability. Even greater stability requirements will be placed on components for the Compact Linear Accelerator (CLIC). Interferometers provide the only means of monitoring relative positions over long timescales, at the nanometre and sub-nanometre level. The latest results from our novel design, fibre-coupled interferometers will be presented.

Abstract:

The StaFF (stabilisation of final focus) system will use interferometers to monitor the relative positions and orientations of several key components in the beam-delivery and interaction region. Monitoring the relative positions of the ILC final focus quadrupole magnets will be the most demanding application, where mutual and beam-relative stability will have a direct impact on machine luminosity. Established, laser-based frequency scanning interferometry (FSI) and fixed-frequency interferometry (FFI) offer positional resolution at length scales of the laser wavelength (1500 nm to 1560 nm) and a thousandth of the wavelength, respectively. As part of the ATF at KEK, StaFF will use interferometers to measure lines of a geodetic network to record relative motion between two beam position monitors. Interferometers are being designed and tested in Oxford prior to deployment at the ATF.

Abstract:

We present a comprehensive black-hole event generator, BlackMax, which simulates the experimental signatures of microscopic and Planckian black-hole production and evolution at the LHC in the context of brane world models with low-scale quantum gravity. The generator is based on phenomenologically realistic models free of serious problems that plague low-scale gravity, thus offering more realistic predictions for hadron-hadron colliders. The generator includes all of the black-hole graybody factors known to date and incorporates the effects of black-hole rotation, splitting between the fermions, non-zero brane tension and black-hole recoil due to Hawking radiation (although not all simultaneously). The generator can be interfaced with Herwig and Pythia.

Abstract:

The challenges for the tracking detector systems at the LHC are unprecedented in terms of the number of channels, the required read-out 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 μ s buffer. The highest anticipated dose after 10 years operation is 1.4 × 10¹⁴ cm^{- 2} 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 7 W dissipation per module (after irradiation), leads to stringent constraints on the thermal design. The additional requirement of 1500 e^- equivalent noise charge (ENC) rising to only 1800 e^- 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 μ m (r φ) resolution perpendicular to the strip directions or 580 μ m 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. © 2007 Elsevier B.V. All rights reserved.