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Channel electron multipliers - Detection efficiencies with opaque MgF2 photocathodes at XUV wavelengthsDetection efficiencies of channel electron multipliers (CEM) with opaque MgF2 photocathodes obtained in the extreme ultraviolet (XUV), 44 A to 990 A, are reported. A stable highly efficient response is reported for that interval, with no adverse effects on CEM performance. Efficiencies twice those of uncoated CEMs are obtained for 50 A to 350 A. The Mullard B419BL and Galileo 4510WL single-stage cone-cathode CEMs were used in the experiments. A rare-gas double ionization chamber was employed as absolute standard detector for 406 A to 990 A, and a flow Geiger counter filled with 96% argon and 4% isobutane for 44 A to 256 A. Absolute detection efficiencies are 10% higher from 67 A to 990 A when photocathodes are illuminated at an angle of incidence 45 deg. The photocathodes suffered no loss of response in storage (in vacuum or air) after an initial aging period. Effects of scattered UV radiation are greatly reduced when MgF2-coated CEMs are used in the XUV.
Document ID
19760047325
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lapson, L. B.
(Harvard Coll. Observatory Cambridge, MA, United States)
Timothy, J. G.
(Smithsonian Astrophysical Observatory and Harvard College Observatory Cambridge, Mass., United States)
Date Acquired
August 8, 2013
Publication Date
May 1, 1976
Publication Information
Publication: Applied Optics
Volume: 15
Subject Category
Instrumentation And Photography
Accession Number
76A30291
Funding Number(s)
CONTRACT_GRANT: NAS5-3949
CONTRACT_GRANT: NAS5-22343
Distribution Limits
Public
Copyright
Other

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