Method and apparatus for compensating of quenching in liquid scintillation counting

Claim 3

The method according to claim 1, wherein said standard solution exhibits substantially no quenching, whereby the change in said high voltage or gain restores the count rate induced by said standard emitter in said sample to the value it would have exhibited had there been no quenching.

Claim 6

The method of claim 3, wherein a value representative of the count rate said standard emitter induces in a standard solution is stored, the count rate induced by the standard emitter in the sample is compared to said stored value and said high voltage or gain is automatically modified until the second-named count rate has been brought back to the stored value.

Claim 7

The method of claim 3, wherein a value representative of the ratio of the count rates in two energy ranges of the spectrum said standard emitter induces in an unquenched sample is stored, and wherein the ratio of the count rates in said energy ranges of the spectrum induced by said standard emitter in said individual samples is compared to said stored information and said high voltage or gain varied until the second-named ratio has been brought back to a predetermined value.

Claim 8

The method of claim 3, comprising alteration of high voltage excitation for first order compensation and of the amplification gain for second order correction.

Claim 9

The method of claim 3, wherein the alteration of operating parameters is such as to restore the standard emitter count rate and count rate ratio to the value which it would have exhibited had there been no quenching.

Claim 10

The method of claim 3, wherein the alteration of operating parameters is such as to restore the standard emitter count rate to a predetermined percentage of its original value, which percentage is close to 100 percent.

Claim 11

The method of claim 8, wherein the percentage of restoration may be automatically varied in response to quenching amount.

Claim 12

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit means for automatically increasing high voltage applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between the count rate induced in samples by a standard ionizing radiation emitter and the count rate induced by said radiation emitter in a standard scintillator solution, whereby the count rate of said sample is made to approximate the count rate that the sample would have exhibited under predetermined sample quenching conditions.

Claim 13

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit means for automatically increasing high voltage applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between the count rate induced in samples by a standard ionizing radiation emitter and the count rate induced by said radiation emitter in a standard scintillator solution, whereby the count rate of said sample is made to approximate the count rate that the sample would have exhibited under predetermined sample quenching conditions.

Claim 14

A system according to claim 10, wherein the standard ionizing radiation emitter is a gamma emitter.

Claim 15

A system according to claim 10 for H-3 and C-14 liquid scintillation counting, wherein said standard emitter induces within an unquenched liquid scintillation sample a spectrum which is appreciably more energetic than the spectrum of C-14 within that sample.

Claim 16

A system according to claim 10, including a generator providing an adjustable DC voltage, a count rate determination ratemeter which provides a DC output and comparator between said voltage and output.

Claim 17

A system according to claim 13, wherein said ratemeter is logarithmic.

Claim 18

In a liquid scintillation spectrometer for analyzing a plurality of test samples each consisting in a vial containing a solution of a scintillator and of radioactive element: shielded obscure chamber; stationary photmultiplier means located adjacent said chamber for producing signal pulses in direct relation with the energy of light scintillations in said chamber; means for introducing a standard scintillation solution and said samples into said chamber and removing them in seriatim order; a standard radiation source adapted to iNduce in said solution and samples an energy spectrum substantially above that of said radioactive element; first means for determining the count rate of said signal pulses induced in said standard solution and samples by said source; for storing the count rate induced by said source in said standard solution; for automatically altering the photomultiplier high voltage to restore the pulse rate induced by said source on each of said samples in seriatim order to said stored value; and second means for counting the pulses from said samples with the respective adjusted high voltages.

Claim 19

In a liquid scintillation spectrometer for analyzing a plurality of test samples each consisting in a vial containing a solution of a scintillator and of radioactive element: shielded obscure chamber; stationary photmultiplier means located adjacent said chamber for producing signal pulses in direct relation with the energy of light scintillations in said chamber; means for introducing a standard scintillation solution and said samples into said chamber and removing them in seriatim order; a standard radiation source adapted to iNduce in said solution and samples an energy spectrum substantially above that of said radioactive element; first means for determining the count rate of said signal pulses induced in said standard solution and samples by said source; for storing the count rate induced by said source in said standard solution; for automatically altering the photomultiplier high voltage to restore the pulse rate induced by said source on each of said samples in seriatim order to said stored value; and second means for counting the pulses from said samples with the respective adjusted high voltages.

Claim 20

In a spectrometer according to claim 15, means for moving said source between a position in disoperative association with said solution and samples when located in said chamber, wherein said standard source is a gamma emitter inducing in said solution and samples a pulse height spectrum which overlaps the spectrum from said radioactive element and said first means have a counting energy window above the energy spectrum of said radioactive element.

Claim 21

In a liquid scintillation spectrometer for analyzing a plurality of test samples each consisting in a vial containing a solution of a scintillator and of a radioactive element; a shielded obscure chamber; stationary photomultiplier means located adjacent said chamber for producing signal pulses in direct relation with the energy of light scintillations in said chamber; means for introducing a standard scintillation solution and said samples into said chamber and removing them in seriatim order; a standard radiation source adapted to induce in said solution and samples an energy spectrum substantially above that of said isotope; first means fed by said photomultiplier means for counting the ratio of the signal pulses induced in two energy channels into said standard solution and samples by said source, for storing the pulse ratio induced by said course in said standard solution, and for automatically at altering the photomultiplier high voltage substantially to restore the ratio of pulses of the spectrum induced by said source in each of said samples in seriatim order to said stored value; and second means for counting the pulses from said samples with the respective adjusted high voltages.

Claim 22

In a liquid scintillation spectrometer for analyzing a plurality of test samples each consisting in a vial containing a solution of a scintillator and of a radioactive element; a shielded obscure chamber; stationary photomultiplier means located adjacent said chamber for producing signal pulses in direct relation with the energy of light scintillations in said chamber; means for introducing a standard scintillation solution and said samples into said chamber and removing them in seriatim order; a standard radiation source adapted to induce in said solution and samples an energy spectrum substantially above that of said isotope; first means fed by said photomultiplier means for counting the ratio of the signal pulses induced in two energy channels into said standard solution and samples by said source, for storing the pulse ratio induced by said course in said standard solution, and for automatically at altering the photomultiplier high voltage substantially to restore the ratio of pulses of the spectrum induced by said source in each of said samples in seriatim order to said stored value; and second means for counting the pulses from said samples with the respective adjusted high voltages.

Claim 23

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit, means for automatically increasing high voltage excitation applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between count rate ratio induced in samples by a standard ionizing radiation emitter and count rate ratio induced by said standard radiation emitter in a standard scintillator solution, whereby the count rate ratio of said sample is made to approximate the count ratio of said standard scintillator solution.

Claim 24

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit, means for automatically increasing high voltage excitation applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between count rate ratio induced in samples by a standard ionizing radiation emitter and count rate ratio induced by said standard radiation emitter in a standard scintillator solution, whereby the count rate ratio of said sample is made to approximate the count ratio of said standard scintillator solution.

Claim 25

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit, means for automatically increasing high voltage excitation applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between count rate ratio induced in samples by a standard ionizing radiation emitter and count rate ratio induced by said standard radiation emitter in a standard scintillator solution, whereby the count rate ratio of said sample is made to approximate the count ratio that the sample would have exhibited under predetermined sample quenching conditions.

Claim 26

In a liquid scintillation system for analyzing a plurality of test samples in seriatim order, including photomultiplier means, amplification means and a pulse counting circuit, means for automatically increasing high voltage excitation applied to said photomultiplier means or increasing gain of said amplification means in response to a measured difference between count rate ratio induced in samples by a standard ionizing radiation emitter and count rate ratio induced by said standard radiation emitter in a standard scintillator solution, whereby the count rate ratio of said sample is made to approximate the count ratio that the sample would have exhibited under predetermined sample quenching conditions.

Claim 27

A system according to claim 19 for H-3 and C-14 liquid scintillation counting, wherein said standard emitter induces within an unquenched liquid scintillation sample a spectrum which is appreciably more energetic than the spectrum of C-14 within that sample.