An Unexpected Effect in ALEPH: Long-Term Displacements of the Silicon Vertex Detector

Giacomo Sguazzoni

An Unexpected Effect in ALEPH: Long-Term Displacements of the Silicon Vertex Detector

Instrumentation and Detectors 2010-08-12 v1

Authors: Giacomo Sguazzoni

Abstract

The ALEPH Silicon Vertex Detector for LEP2 featured a laser survey system to monitor its mechanical stability. The analysis of laser system data from 1997 to 2000 showed that VDET suffered a time-dependent displacement. It resulted to be compatible with a deformation of the support structure that made the device to slowly rotate during the data-taking. A maximal local displacement of ~20 microns was observed, corresponding to a rotation of ~10E-4 rad. The implementation of a time-dependent correction on the alignment by using the laser system data led to sizeable improvements on the ALEPH data quality.

Keywords

ALEPH Silicon Vertex Detector laser survey system mechanical stability time-dependent displacement alignment correction

Cite

@article{arxiv.physics/0205047,
  title  = {An Unexpected Effect in ALEPH: Long-Term Displacements of the Silicon Vertex Detector},
  author = {Giacomo Sguazzoni},
  journal= {arXiv preprint arXiv:physics/0205047},
  year   = {2010}
}

Comments

4 pages, 8 figures. To be published in Proceedings of 'XXXVII Rencontres de Moriond, QCD and Hadronic Interactions', March 2002, Les Arcs, France

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