Multiple sample coincidence counter

Claim 2

In a liquid scintillation coincidence counting apparatus comprising a counting chamber for receiving samples to be measured, photomultiplier tubes located adjacent to said chamber for producing electrical pulses responsive to energy received from scintillations occurring in the samples, coincidence detection means coupled to said photomultiplier tubes for passing electrical pulses when coincident pulses are received from at least two of said photomultiplier tubes, and pulse registration means connected to said coincidence detection means for recording pulses received therefrom, the improvement wherein partition means divide said chamber into at least two isolated sections and each of said isolated sections of said chamber simultaneously accomodates a separate sample and is in visual communication with at least two and less than all of said photomultiplier tubes, and said coincidence detection means passes electrical pulses only when coincident electrical pulses are received from all of the photomultiplier tubes in visual communication with a single isolated section of said chamber.

Claim 3

The liquid scintillation counting apparatus of claim 1 further characterized in that said partition means divides said chamber into first and second isolated sections, and said first section is in visual communication with first and second photomultiplier tubes, and said second section is in visual communication witH said second photomultiplier tube and a third photomultiplier tube, and said coincidence detection means passes electrical pulses upon receipt of coincident electrical pulses from said first and second photomultiplier tubes generated in response to a scintillation from a sample in said first section of the said chamber and upon receipt of coincident electrical pulses from said second and third photomultiplier tubes generated in response to a scintillation from a sample in said second section of said chamber.

Claim 4

The liquid scintillation counting apparatus of claim 1 wherein said partition means divides said chamber into a predetermined number of isolated sections, and the same number of photomultiplier tubes are in visual communication with said sections and each photomultiplier tube is in visual communication with each of two different sections, and each of said sections is in visual communication with two different photomultiplier tubes.

Claim 5

The liquid scintillation counting apparatus of claim 3 wherein a coincidence blocking means is interposed between said coincidence detection means and said pulse registration means for blocking pulses from said coincidence detection means resulting from pulses received by the coincidence detection means from photomultiplier tubes lacking visual communication with a common isolated section.

Claim 6

The liquid scintillation counting apparatus of claim 3 wherein said partition means divides said chamber into first, second, and third sections, and said first section is in visual communication with first and second photomultiplier tubes, said second section is in visual communication with said second photomultiplier tube and a third photomultiplier tube, and said third section is in visual communication with said third and first photomultiplier tubes, and said coincidence detection means passes electrical pulses upon receipt of coincident electrical pulses from said first and second photomultiplier tubes generated in response to a scintillation from a sample in said first section, upon receipt of coincident electrical pulses from said second and third photomultiplier tubes in response to a scintillation from a sample in said second section, and upon receipt of coincident electrical pulses from said third and first photomultiplier tubes in response to a scintillation from a sample in said third section.

Claim 7

The liquid scintillation counting apparatus of claim 5 wherein a triple coincidence blocking means is interposed between said coincidence detection means and said pulse registration means for blocking pulses from said coincidence detection means resulting from pulses received by said coincidence detection means from all three of the photomultiplier tubes.

Claim 8

The liquid scintillation counting apparatus of claim 6 wherein: a. said pulse registration means is comprised of a scintillation counting AND gate for each possible combination of two photomultiplier tubes, b. said coincidence detection means has coincidence activated monostable multivibrator means associated with each possible combination of two photomultiplier tubes for providing input signals of predetermined duration to said scintillation counting AND gates, c. a pulse detection means and signal inverting means are connected to all of said photomultiplier tubes and provide inhibiting gating pulses of predetermined duration to said scintillation counting AND gates, and said inhibiting pulses terminate prior to the termination of said input signals, d. enabling gating means normally in an enabling condition connected to the inputs of said scintillation counting AND gates, and e. said triple coincidence blocking means is comprised of a triple coincidence AND gate having inputs connected to the outputs of at least two of said coincidence activated monostable multivibrator means and having an output leading to an input of the aforesaid enabling gating means for switching said enabling gating means to a disabling condition.

Claim 9

The liquid sciNtillation counting apparatus of claim 6 further characterized in that said triple coincidence blocking means is modified for selective blocking and has differential amplitude measuring means for measuring the amplitude difference between the largest and intermediate pulses and between the intermediate and smallest pulses produced by said photomultiplier tubes and for generating a difference signal proportional to the difference between the aforesaid intermediate and smallest pulses, and comparator means for comparing said difference signal against a control signal proportional to a predetermined minimum difference value and for selectively passing signals to said means for allowing said enabling gating means to block those pulses from said coincidence detection means that result from pulses from all three of the photomultiplier tubes where the aforesaid difference signal is less than said control signal, and for passing that pulse from said coincident detection means that results from the largest and intermediate pulses from the photomultiplier tubes where the aforesaid difference signal is at least as large as said control signal.

Claim 10

The liquid scintillation counting apparatus of claim 1 further comprising an accidental coincidence discrimination means for separately registering, in said pulse registration means, accidentally coincident pulses from said photomultiplier tubes reproduced on a statistical basis.

Claim 11

The liquid scintillation counting apparatus of claim 9 wherein: a. three photomultiplier tubes are utilized, b. said pulse registration means is comprised of a total scintillation counting AND gate and an accident counting AND gate for each possible combination of two photomultiplier tubes, c. separate coincidence activated monostable multivibrator means for total pulses and for accidental pulses are associated with each possible combination of two photomultiplier tubes for providing input signals to said total scintillation counting and accident counting AND gates respectively in response to coincident pulses, d. a normal pulse AND gate and a delayed pulse AND gate associated with each photomultiplier tube have outputs operating a total pulse monostable multivibrator and an accidental pulse monostable multivibrator respectively, e. first and second input leads from each photomultiplier tube respectively gate said normal pulse AND gate and said delayed pulse AND gate, f. a summing means is connected across the first and second input leads from each photomultiplier tube, g. coincidence detectors are provided for each possible combination of any two photomultiplier tubes with an output from a coincidence detector gating the normal pulse AND gate and the delayed pulse AND gate associated with one of the photomultiplier tubes and with one input to the same coincidence detector from the summing means associated with that same photomultiplier tube and with another input to the same coincidence detector from the first input lead of one of the other photomultiplier tubes, h. a pulse delay means interposed in each of said second input leads between the photomultiplier tube and the summing means associated therewith, and i. pulse gating means for detecting pulses in said photomultiplier tubes and for gating said total scintillation counting AND gates and said accident counting AND gates.

Claim 12

A batch sample liquid scintillation counting apparatus comprising: a. a housing defining a counting chamber for receiving samples to be measured, b. photomultiplier tubes located adjacent to said chamber for producing electrical pulses responsive to energy received from scintillations occurring in the samples to be measured, c. partition means dividing said chamber into a plurality of isolated sections, each section accomodating a sample, and each section being in visual communication with at least two and less than all of said photomultiplier tubes, d. coincidence detection means coupLed to said photomultiplier tubes for passing electrical pulses only when coincident electrical pulses are received from all of the photomultiplier tubes in visual communication with a single isolated section of said chamber, and e. pulse registration means connected to said coincidence detection means for recording pulses received therefrom.

Claim 13

A batch sample liquid scintillation counting apparatus comprising: a. a housing defining a counting chamber for receiving samples to be measured, b. photomultiplier tubes located adjacent to said chamber for producing electrical pulses responsive to energy received from scintillations occurring in the samples to be measured, c. partition means dividing said chamber into a plurality of isolated sections, each section accomodating a sample, and each section being in visual communication with at least two and less than all of said photomultiplier tubes, d. coincidence detection means coupLed to said photomultiplier tubes for passing electrical pulses only when coincident electrical pulses are received from all of the photomultiplier tubes in visual communication with a single isolated section of said chamber, and e. pulse registration means connected to said coincidence detection means for recording pulses received therefrom.

Claim 14

The batch sample liquid scintillation counting apparatus of claim 11 wherein said partition means is comprised of vertically extending segments located atop an elevator, and said elevator accomodates samples positioned between said partition segments which divide said chamber into sections when said elevator is lowered to below the level of said chamber.

Claim 15

The batch sample liquid scintillation counting apparatus of claim 11 wherein said partition means is comprised of vertically extending segments sealed to said housing and extending into said chamber, and dividing said chamber into the aforesaid isolated sections and said elevator is comprised of separated columnar portions movable in tandum each fully occupying a single isolated section when said elevator is raised and each accomodating a sample placed atop thereof for positioning in said isolated sections of said chamber when said elevator is lowered.

Claim 16

The batch sample liquid scintillation counting apparatus of claim 11 wherein said partition means is comprised of vertically extending segments, and said chamber has a vertically extending elevator shaft in communication therewith, and an elevator accomodates samples positioned thereon and is movable upward to contact said vertically extending segments, thereby defining the aforesaid isolated sections, whereby samples positioned atop said elevator are positionable in separate isolated sections of said chamber.

Claim 17

The batch sample liquid scintillation counting apparatus of claim 11 further comprising a timing means connected to said pulse registration means for determining the time interval within which pulses are received by said pulse registration means, and a pulse gating means is connected to all of said photomultiplier tubes, and a dead time correcting means is connected to said timing means, said pulse gating means, and said coincidence detection means for temporarily preventing the recordation of pulses in said pulse registration means during processing of prior pulses from said photomultiplier tubes, and for correcting said timing means to compensate for the time elapsed during which recordation of pulses is prevented.

Claim 18

The batch sample liquid scintillation counting apparatus of claim 14 further characterized in that: a. said pulse registration means is comprised of scintillation counting AND gates for each possible combination of two photomultiplier tubes, b. said coincidence detection means has coincidence activated monostable multivibrator means equipped with disabling mechanisms associated with each possible combination of two photomultiplier tubes for providing input signals of predetermined duration to said pulse registration means, c. a dead time activating OR gate is additionally connected to the outputs of said coincidence activated monostable multivibrator means, d. said pulse gating means is further comprised of: (i) pulse inverting means for providing inhibiting gating pulses of predetermined duration to said scintillation counting AND gates and said inhibiting pulses terminate one input lead from said dead time activating OR gate and with outputs to said timing means and said disabling mechanisms of said coincidence activated monostable multivibrator means, (ii) a reset monostable multivibrator means having an output gating lead to said time control or gate, and (iii) a capacitor connected between said dead time activating OR gate and said reset monostable multivibrator means.