The new ALEPH Silicon Vertex Detector

The ALEPH collaboration, in view of the importance of effective vertex detection for the Higgs boson search at LEP 2, decided to upgrade the previous vertex detector. Main changes were an increased length (±20 cm), a higher granularity for rφ view (50 µm), a new preamplifier (MX7 rad hard chip), a polymide (upilex) fan-out on z side to carry the signals from the strips to the front-end electronics outside the fiducial region reducing consequently the passive material in the central region by a factor of two. The detector, the running experience and its performance will be described

The new ALEPH Silicon Vertex Detector

The ALEPH collaboration, in view of the importance of effective vertex detection for the Higgs boson search at LEP 2, decided to upgrade the previous vertex detector. Main changes were an increased length (±20 cm), a higher granularity for rφ view (50 µm), a new preamplifier (MX7 rad hard chip), a polymide (upilex) fan-out on z side to carry the signals from the strips to the front-end electronics outside the fiducial region reducing consequently the passive material in the central region by a factor of two. The detector, the running experience and its performance will be described

Monitoring the stability of the ALEPH vertex detector

The ALEPH Silicon Vertex Detector features an optical fibre laser system to monitor its mechanical stability. The operating principle and the general performance of the laser system are described. The experience obtained during 1997 and 1998 operations confirms the important role that such a system can have with respect to the detector alignment requirements. In particular, the laser system has been used to monitor short-term temperature-related effects and long-term movements. These results and a description of the laser-based alignment correction applied to the 1998 data are presented.Comment: 6 pages, 9 figures, to be published in proceedings of "6th International Conference on Advanced Technology and Particle Physics" Como (Italy), October 199

The DELPHI Silicon Tracker at LEP-2

The DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over $70~{\rm pb^{-1}}$ of high energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three dimensional $b$ tagging information is available down to a polar angle of $25^\circ$. Impact parameter resolutions have been measured of $28~\mu {\rm m} \oplus 71/(p~{\rm sin} ^{\frac{3}{2}} \theta)~\mu {\rm m}$ in $R \phi$ and $34~\mu {\rm m} \oplus 69/p~\mu {\rm m}$ in $Rz$, where $p$ is the track momentum in $\rm {GeV/c}$. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330~$\times$~330~\m u{\rm m}$^2$ and the ministrips have a readout pitch of 200~$\mu {\rm m}$. The forward part of the detector shows average efficiencies of more than 96\%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking efficiency for the region with polar angle less than $25^\circ$

The silicon microstrip sensors of the ATLAS semiconductor tracker.

This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The sensors are now successfully assembled within the detecting modules of the SCT, and the SCT tracker is completed and integrated within the ATLAS Inner Detector. Hamamatsu Photonics Ltd. supplied 92.2% of the 15,392 installed sensors, with the remainder supplied by CiS

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

Legislative History: An Act To Require Nonresident Moose Hunters to Employ the Services of a Licensed Maine Guide (HP91)(LD 100)

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