Single and double grid long-range alpha detectors
AssigneeUniversity of California Patent, Trademark & Copyright Office
InventorsDuncan W. MacArthur, Krag S. Allander
Life of this patent
Estimating the term…
Abstract
Alpha particle detectors capable of detecting alpha radiation from distant sources. In one embodiment, a voltage is generated in a single electrically conductive grid while a fan draws air containing air molecules ionized by alpha particles through an air passage and across the conductive grid. The current in the conductive grid can be detected and used for measurement or alarm. Another embodiment builds on this concept and provides an additional grid so that air ions of both polarities can be detected. The detector can be used in many applications, such as for pipe or duct, tank, or soil sample monitoring.
Claims11
An alpha particle, detector that operates by detecting air ions created by collisions with alpha particles emitted from a distant alpha particle source comprising:
- an electrically conductive enclosure defining first and second openings for admitting and exhausting air;
- one electrically conductive grid insulatively mounted inside said enclosure;
- means for generating a voltage in said one electrically conductive grid, creating an electric field between said one electrically conductive grid and said electrically conductive enclosure;
- fan means mounted outside said enclosure adjacent to said second opening for drawing air containing said air ions through said first opening in said enclosure and across said electric field between said one electrically conductive grid and said electrically conductive enclosure;
- and
- detecting means connected to said one electrically conductive grid for indicating a current through said one electrically conductive grid produced by said air ions.
An alpha particle detector for detecting both positive and negative air ions created by collisions with alpha particles emitted from a distant alpha particle source comprising:
- an electrically conductive enclosure defining first and second openings for admitting and exhausting air;
- first and second electrically conductive grids insulatively mounted and spaced apart within said enclosure;
- means for generating an electrical voltage, said electrical voltage having its positive terminal connected to said first electrically conductive grid and its negative terminal connected to said electrically conductive enclosure and to said second electrically conductive grid, creating an electric field in said, space between said first and second electrically conductive grids as well as between said first and second electrically conductive grids and said electrically conductive enclosure;
- fan means mounted outside said enclosure adjacent to said second opening for drawing air containing said air ions through said first opening in said enclosure and into said space between said first and second electrically conductive grids;
- first detecting means connected to said first electrically conductive grid for indicating a current through said first electrically conductive grid produced by said negative air ions;
- and
- second detecting means connected to said second electrically conductive grid for indicating a current through said second electrically conductive grid produced by said positive air ions.
A method of detecting a distant source of alpha particles comprising the steps of:
- generating an electrical field between an electrically conductive grid and an electrically conductive enclosure defining first and second air passages;
- drawing air containing air ions created by collisions with alpha particles emitted from said distant source through said first air passage and across said electrically conductive grid;
- and
- detecting a current in said second electrically conductive grid produced by said air ions being attracted to said electrically conductive grid.
Dependencies are inferred from the claim text.