Radiant energy – Inspection of solids or liquids by charged particles
Patent
1991-04-12
1992-07-14
Berman, Jack I.
Radiant energy
Inspection of solids or liquids by charged particles
250307, 250308, 25044011, G01N 2300
Patent
active
051305399
ABSTRACT:
Observing and detecting the spatial distribution of beta emissions by placing the specimen on a converter window, which converts the energetic beta particles to low energy, secondary electrons, which emerge from the opposite side of the window. The secondary electrons are then microscopically imaged by an emission microscope, preferably onto a position sensitive detector. The technique is able to achieve microscopic resolution with quantitative and rapid data acquisition. It is particularly suited to detecting the spatial distribution of specimens tagged with tritium. Preferably, the specimen is supported in proximity to the converter window (e.g., directly on one surface of the window); a position-sensitive detector is located at the imaging location; a support grid underlies and supports the converter window; the converter window is exposed to the vacuum of the emission microscope on one side and to a non-evacuated space on the other side; the thickness of the converter window is less than 10 microns and greater than 1 micron. Alternatively, a vacuum enclosure may surround the converter window so that the window has a vacuum on both sides. Preferably, the converter window is a multilayer structure comprising a first layer (e.g., a polycrystalline material such as titanium) capable of moderating beta particles to facilitate secondary electron conversion and a second layer (e.g., polymerized film) adhered to the first layer and serving to prevent gas leakage through said window from the unevacuated side to the evacuated side.
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Berman Jack I.
Brandeis University
Nguyen Kiet T.
LandOfFree
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