Dynode control circuit for a photomultiplier tube using cascaded transistors

Claim 1

IN A CIRCUIT PROVIDING TWO POINTS ADAPTED TO HAVE DIFFERENT POTENTIALS APPLIED THERETO BY APPROPRIATE CONNECTION THEREOF TO A POWER SUPPLY, THE COMBINATION OF: A MULTIPLIER PHOTOTUBE HAVING A CATHODE CONNECTED WITH ONE OF SAID POINTS, AN ANODE CONNECTED WITH THE OTHER OF SAID POINTS, AND A GROUP OF DYNODES FOR AMPLIFYING THE CATHODE CURRENT IN PROPORTION TO THE VALUES OF THE POTENTIALS RESPECTIVELY APPLIED TO SAID DYNODES; AND A REGULATOR CIRCUIT FOR AUTOMATICALLY ADJUSTING THE CURRENT AMPLIFICATION OF SAID PHOTOTUBE TO MAINTAIN THE AVERAGE ANODE CURRENT THEREOF SUBSTANTIALLY CONSTANT COMPRISING VOLTAGE-DETERMINING MEANS CONNECTED WITH A PLURALITY OF SAID DYNODES FOR RESPECTIVELY APPLYING VOLTAGES THERETO OF PROGRESSIVELY HIGHER VALUES IN AN INCREASING ORDER IN THE DIRECTION FROM THE FIRST SUCH DYNODE ADJACENT SAID CATHODE TO THE FINAL DYNODE ADJACENT SAID ANODE AND INCLUDING A PLURALITY OF SERIALLY CONNECTED RESISTANCES COUPLED WITH SAID POINTS AND PROVIDING A CURRENT PATH THEREBETWEEN AND BEING RESPECTIVELY COUPLED WITH SAID PLURALITY OF DYNODES FOR APPLYING VOLTAGES THERETO PROPORTIONAL TO THE MAGNITUDE OF THE CURRENT FLOW THROUGH SAID RESISTANCES, CURRENT CONTROL MEANS CONNECTED WITH SAID ANODE AND WITH SAID RESISTANCES AND BEING OPERATIVE TO REGULATIVELY ADJUST THE MAGNITUDE OF THE CURRENT FLOW THROUGH SAID RESISTANCES IN RESPONSE TO DEVIATIONS IN THE ANODE CURRENT FROM A PREDETERMINED AVERAGE VALUE AND THEREBY ALTER THE VOLTAGES RESPECTIVELY APPLIED TO SAID PLURALITY DYNODES TO CORRECTIVELY CHANGE THE CURRENT AMPLIFICATION OF SAID MULTIPLIER PHOTOTUBE TO MAINTAIN THE AVERAGE ANODE CURRENT THEREOF SUBSTANTIALLY CONSTANT AT SUCH PREDETERMINED VALUE, SIGNAL ISOLATION MEANS FOR MAKING SAID REGULATOR CIRCUIT NONRESPONSIVE TO RELATIVELY RAPID FLUCTUATIONS IN THE ANODE CURRENT OF SAID MULTIPLER PHOTOTUBE SO THAT THE REGULATOR CIRCUIT IS OPERATIVE TO MAINTAIN THE AVERAGE ANODE CURRENT SUBSTANTIALLY CONSTANT, SAID CURRENT CONTROL MEANS FURTHER INCLUDING A PLURALITY OF TRANSISTORS EACH HAVING AN EMITTER, BASE AND COLLECTOR AND BEING CASCADE-CONNECTED EMITTER-TO-COLLECTOR AND COUPLED WITH SAID POINTS, THE EMITTER-COLLECTOR JUNCTIONS OF CERTAIN SUCCESSIVE TRANSISTORS BEING RESPECTIVELY CONNECTED TO SAID PLURALITY OF DYNODES AND THE BASES OF THE CERTAIN SUCCESSIVE TRANSISTORS BEING RESPECTIVELY CONNECTED TO THE SUCCESSIVE JUNCTIONS OF THE RELATIVELY CORRESPONDING RESISTANCES, WHEREBY THE POTENTIALS APPLIED TO SAID PLURALITY OF DYNODES ARE ESSENTIALLY EQUAL RESPECTIVELY TO THE VOLTAGE DROPS ACROSS THE ASSOCIATED RESISTANCES AS A CONSEQUENCE OF THE EMITTER FOLLOWER ACTION OF SAID TRANSISTORS.