Gas electron multipliers and a scanner for automated quality control
Name
62626635-MIT.pdf
Description
Full printable version
Size
4.19 MB
Format
Adobe PDF
Checksum (MD5)
2ec87e777ccc0a08aa3a5eb13f557321
Author(s)
Tamm, Brian Paul
Advisor(s)
Ulrich J. Becker.
Alternative Title
GEMs and a scanner for automated quality control
Date Issued
2005
Publisher
Massachusetts Institute of Technology
Abstract
The gas electron multiplier (GEM) is a novel charge amplification element for use in gaseous particle detectors. Because of their high gain ([approx.] 10⁵ when cascaded) and ability to withstand harsh radiation conditions, GEMs have been selected for use in the time projection chambers of the latest high-energy experiments, including COMPASS, STAR, and the planned ILC. Foil quality has been found to be critical for optimal GEM performance. If an irregularity in just one of the roughly 600, 000 amplification holes of a 10 x 10 cm GEM induces a spark discharge, the entire GEM is useless. Computer simulations have also shown that amplification behavior is strongly dependent on hole diameter and shape. To improve foil quality control, an automated scanner has been constructed to optically examine every hole in a GEM. The machine can measure each hole's outer copper diameter and inner Kapton diameter and locate and geometrically classify any foil imperfections. The scanner has been used to characterize GEMs recently manufactured by Tech-Etch. These scans indicate a general absence of etching defects, but measured diameter inhomogeneity may result in gain variations as large as i20% over the active foil area.
Description
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.
Includes bibliographical references (p. 85-87).
Subjects
Physics.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Terms of Use
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