Radiant energy – Inspection of solids or liquids by charged particles – Including a radioactive source
Patent
1997-12-05
2000-03-28
Berman, Jack
Radiant energy
Inspection of solids or liquids by charged particles
Including a radioactive source
250307, 250309, H01J 3708
Patent
active
060434899
ABSTRACT:
A positron source with high intensity and low energy bandwidth and small spatial dimensions, has a positron emitter of high specific activity and, following the positron emitter, a reflection moderator with a hole. The hole diameter on the emitter side of the reflection moderator is smaller than 0.4 mm, preferably below 0.1 mm. Because of the small hole diameter and the small energy spread, the phase space of the positrons coming from the positron source corresponds to the phase space of the electrons emitted by a conventional thermionic cathode. The positron source can therefore be used in a conventional scanning electron microscope, which can be selectively changed over between positron operation and electron operation. Two adjusting units and are provided for adjustment of the positron source.
REFERENCES:
patent: 4740694 (1988-04-01), Nishimura et al.
Canter et al., "Measurement of total cross sections for low energy positron-helium collisions", Journal of Physics B: Atomic. Molec. Physics., vol. 5, pp. L167-L169, Aug. 1972.
Greif Holger
Maier Karl
Tongbhoyai Martin
Berman Jack
Leo Elektronenmikroskopie GmbH
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