Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005. / Includes bibliographical references (p. 85-87). / 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. / by Brian Paul Tamm. / S.B.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/32905 |
| Date | January 2005 |
| Creators | Tamm, Brian Paul |
| Contributors | Ulrich J. Becker., Massachusetts Institute of Technology. Dept. of Physics., Massachusetts Institute of Technology. Dept. of Physics. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 87 p., 4390260 bytes, 4394385 bytes, application/pdf, application/pdf, application/pdf |
| Rights | M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission., http://dspace.mit.edu/handle/1721.1/7582 |
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