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AssigneePackard Instrument Company, Inc.
InventorsLyle E. Packard, Edward F. Polic, Robert E. Cavanaugh, Jr.
Estimating the term…
A data analyzing system for scintillation spectrometers of the type for measuring activity levels of samples containing radioactive isotopes and subjected to varying degrees of quench, including methods and apparatus for optimizing counting conditions and thereby improving statistical counting validity irrespective of the degree of quenching present in any given sample, and wherein a measured parameter indicative of the effective quench condition of each sample is utilized to automatically adjust, by preselected preset amounts, the counting window for any given isotope relative to the observed energy spectrum for that isotope. Various methods and apparatus are described which, although suitable for optimizing counting conditions for both multiple-labeled and single-labeled test samples, are particularly effective in creating significantly improved isotope separations when dealing with multiple-labeled samples -- for example, a double-labeled sample containing tritium (.sup.3 H) and carbon-14 (.sup.14 C).
Apparatus for optimizing counting conditions in test samples containing n radioactive isotopes disposed in a liquid scintillator with each isotope being of the type that produces an observable energy spectrum, said apparatus comprising a light transducer, means for positioning a sample adjacent said transducer in light transmissive relationship therewith, means for measuring a selected quench indicating parameter indicative of the quench level of the sample, n pulse height analyzers for analyzing pulses emanating from said transducer, said n pulse height analyzers each including means for discriminating pulses on the basis of pulse heights, and means responsive to the value of said measured quench indicating parameter for automatically adjusting said discriminating means relative to the observed spectrum for each isotope, said adjusting means being characterized by its ability to adjust said discriminating means relative to the observed spectrum for each isotope by one of m predetermined, preset, amounts selected in response to the value of said measured parameter and corresponding to preselected quench levels at which counting efficiencies are accurately known.
An apparatus of the type for analyzing test samples subject to quench and of the type containing one or more radioactive isotopes disposed singly or multiply in a liquid scintillator with each isotope being of the type that produces an observable energy spectrum, and wherein said apparatus includes means for creating a simulated quench condition for each sample so as to establish for such sample a selected one of m predetermined effective quench levels for each of which isotope counting efficiencies are accurately known, the combination with said means for simulating quenching of n pulse height analysis means for discriminating pulses on the basis of their heights, means for measuring a quench indicating parameter for each sample so as to determine the actual quench level of each sample, and means responsive to the value of the measured parameter for adjusting each of said n pulse height analysis means independently of one another by controlled predetermined fixed amounts which are a function of the value of the measured parameter, so that when utilizing said apparatus for analyzing multiple labeled samples the contributions of isotopes not of interest in any given one of said n analysis means are maintained constant and so that when analyzing a single-labeled sample in any given one of said n analysis means the ratio E.sup.2 /B is maximized (where E equals the counting efficiency and B equals background noises).
The method of optimizing counting conditions when measuring activity levels of test samples containing n one or more radioactive isotopes disposed in a liquid scintillator comprising the steps of
Dependencies are inferred from the claim text.