520 research outputs found
Quark and gluon jets in a three-jet environment
No full textSIGLEAvailable from British Library Document Supply Centre-DSC:DXN005089 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
The W mass measurement at LEP
No full textThe LEP2 program has allowed for high precision measurements of the W-boson mass. Last. update of the LEP combined measurement was given at the winter-conferences of 2003. The progress of the measurement during the last year and prospects for the final update are preBented
The new ALEPH silicon vertex detector
Get PDFThe 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 r phi view (50 mu m), 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. (C) 1998 Elsevier Science B.V. All rights reserved
Construction and performance of the new ALEPH vertex detector
No full textA new Silicon Vertex Detector was developed for the ALEPH experiment and first installed for the high energy run at 130 GeV at the end of 1995. The detector has an active length of 40 cm and consists of two concentric layers of silicon wafers with double-sided readout. It extends the angular coverage, has only half the passive material as the former detector in the tracking volume and is radiation hard to cope with the higher level of radiation background expected for the LEP2 phase. The construction and the performance of the detector is described. (C) 1998 Elsevier Science B.V. All rights reserved
Monitoring the stability of the ALEPH vertex detector
No full textThe 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.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
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