Patent ID: 7745799
Filing Date: 2010-06-29
Classification: G01T,H01J

Abstract:
1. A detector for detecting alpha particle radiation from radioactive elements that decay by alpha particle emission and which enter said detector by natural processes of diffusion and/or fallout requiring no forced airflow, comprising: an electrical conducting enclosure having at least one of a first selectively openable aperture and a second aperture, wherein when the first aperture is open radioactive elements are permitted to enter the electrical conducting enclosure by diffusion or fallout without forced airflow through the first aperture, and wherein radioactive elements are prevented from entering the electrical conducting enclosure through the first aperture when closed and wherein radioactive gases are permitted to enter the electrical conducting enclosure by diffusion without forced airflow through the second aperture; at least two separated electrodes within said enclosure and electrically insulated therefrom; a means for establishing and maintaining an electrical field between said electrodes; a mechanism for sensing by amplifying with large gain the characteristic signals from a radioactive decay by an individual alpha particle occurring within the electric field and with low gain otherwise and producing a signal if the amplified signal exceeds a pre-set threshold responsive thereto and thereafter automatically returning to a state where it can again produce a signal for another individual alpha particle decay; at least one vibration sensor in communication with said enclosure for detecting vibrations thereof; a counter responsive to said vibration sensor for counting the number of signals from alpha particle decay as a function of time within the electric field when vibrations sensed by said vibration sensor are below a preselected level and not counting when vibrations sensed by the said vibration sensor are above said preselected level; a mechanism to determine the rate of alpha particle decay within the field from the count of the number of signals and the time when signals from the vibration sensor are below a preset level; a mechanism to convert the rate of alpha particle decay in the volume of the electric field to the rate of alpha particle decay in a standard volume using a pre-determined relationship between the electric field volume and the standard volume; a mechanism to present to the user of said detector the determined rate of alpha particle decay within the standard volume; a mechanism to present to the user of said detector the time when the signals from the vibration sensor exceed the predetermined levels; and a mechanism to reset the measured level of radioactive decay to zero.