Test chamber for alpha spectrometry
AssigneeThe United States of America as represented by the United States Energy Research and Development Administration
InventorRobert P. Larsen
Life of this patent
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Abstract
Alpha emitters for low-level radiochemical analysis by measurement of alpha spectra are positioned precisely with respect to the location of a surface-barrier detector by means of a chamber having a removable threaded planchet holder. A pedestal on the planchet holder holds a specimen in fixed engagement close to the detector. Insertion of the planchet holder establishes an O-ring seal that permits the chamber to be pumped to a desired vacuum. The detector is protected against accidental contact and resulting damage.
Claims5
A test chamber for alpha spectrometry comprising:
- a detector responsive to alpha radiation to generate therefrom an electrical signal;
- means for supporting the detector in a fixed reproducible position;
- means for disposing an alpha emitter an a metal planchet in reproducible close proximity to the detector;
- means for maintaining the alpha emitter and the detector in a vacuum environment;
- and
- means connected to the detector for coupling the electrical signal outside the vacuum environment.
A structure for measurement of a spectrum of alpha radiation from an alpha emitter disposed on a round test planchet, the structure comprising in combination:
- a hollow tube having an axis, an upper end and a lower end, each of said ends grooved for an O-ring and threaded;
- a guard ring disposed within and connected to the tube, the guard ring perpendicular to the axis and including a passaage through the guard ring along the axis;
- a surface-barrier detector disposed within the hollow tube against the guard ring to shadow the passage through the guard ring and accept alpha radiation therethrough;
- a detector support threaded to engage the hollow tube at the upper end thereof, the detector support including coaxial feedthrough means to establish electrical contact with and support the detector;
- a first O-ring disposed in a groove at the upper end of the tube and forming with the detector support a vacuum seal;
- a sample holder threaded to engage the hollow tube at the lower end thereof, the sample holder including a pedestal sized and shaped to hold a planchet containing an alpha emitter in closer repeatable proximity to the passage through the guard ring and to the surface-barrier detector when the sample holder is screwed into the hollow tube;
- a second O-ring disposed in a groove at the lower end of the tube and forming with the sample holder a vacuum seal;
- an
- a vacuum line connected through the hollow tube to permit the establishment of a vacuum therein.
Dependencies are inferred from the claim text.