Liquid scintillation measurement system with active guard shield
Patent 4833326 Issued on May 23, 1989. Estimated Expiration Date: 
March 14, 2008. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 14, 2008. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3842278 3898460 3898463 Scintillation spectrometer Nuclear radiation measuring method and apparatus having blanking time inversely related to count rate Method and apparatus for measuring radioactive decay Reduced background scintillation counting Patent #: 4651006 InventorsAssigneeApplicationNo. 07/167407 filed on 03/14/1988US Classes:250/362, Methods250/364, With fluent source handling or collecting means250/366, Plural electric signalling means250/367, Plural or composite luminophor250/369With output systemExaminersPrimary: Howell, Daniel W.Assistant: Hannaher, Constantine Attorney, Agent or FirmInternational ClassesG01T 1/202 (20060101)G01T 1/204 (20060101) G01T 1/172 (20060101) G01T 1/00 (20060101) AbstractA low-level liquid scintillation measurement system for counting sample optical events resulting from the radioactive decay of a constituent of a sample to be measured while reducing the counting of background optical events which are optical events produced by background radiation and which create electrical pulses other than pulses representing a sample optical event. This system includes detection means located adjacent the sample for detecting optical events and for converting optical events into electrical pulses, coincidence sensing means for receiving the electrical pulses from the detection means and producing a trigger pulse when the electrical pulses from the detection means coincide with each other, burst detection means for receiving the trigger pulses from the coincidence sensing means and the electrical pulses from the detection means for determining the number of electrical pulses present in a selected interval following each of the trigger pulses, evaluation means connected to the burst detection means for determining, in response to the number of pulses detected in the selected interval, the extent to which the optical event represented by the corresponding trigger pulse should be treated as a sample optical event or a background event, and an active guard shiled arrangement comprising an auxiliary scintillator optically coupled to the detection means. The shield is adapted to be excited by background radiation and to effectively increase the number of electrical pulses present in the selected interval following a trigger pulse generated as a result of the coincident pulses produced due to the background radiation. This allows the measurement system to accurately evaluate the number of pulses detected in the selected interval and determine the extent to which a trigger pulse is to be treated as a sample optical event.Other References
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