Channel electron multipliers: detection efficiencies with opaque MgF2 photocathodes at XUV wavelengths
Abstract
Detection 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.
- Publication:
-
Applied Optics
- Pub Date:
- May 1976
- DOI:
- 10.1364/AO.15.001218
- Bibcode:
- 1976ApOpt..15.1218L
- Keywords:
-
- Far Ultraviolet Radiation;
- Magnesium Fluorides;
- Photocathodes;
- Photomultiplier Tubes;
- Photosensitivity;
- Radiation Detectors;
- Electromagnetic Scattering;
- Geiger Counters;
- Ionization Chambers;
- Rare Gases;
- Signal Detection;
- Instrumentation and Photography;
- DETECTORS;
- PHOTOCATHODES;
- PHOTOMULTIPLIERS