Epithermal neutron detection

Claim 1

A SYSTEM FOR DETERMINING THE CHARACTER OF FORMATIONS TRAVERSED BY A BORE HOLE, COMPRISING A SUB-SURFACE UNIT CAPABLE OF BEING LOWERED INTO SAID BORE HOLE, SAID UNIT COMPRISING A SOURCE OF NEUTRONS AND A DETECTOR MEANS RESPONSIVE TO INCIDENT NEUTRONS RETURNED TO SAID UNIT FROM THE FORMATIONS SURROUNDING SAID BORE HOLE, SAID DETECTOR MEANS COMPRISING A PHOSPHOR CAPABLE WITHIN THIS BODY OF INTERACTING WITH NEUTRONS, THE PROBABILITY OF SUCH INTERACTION DECREASING AS THE ENERGY OF THE NEUTRONS INCREASES, SAID PHOSPHOR HAVING THE PROPERTY OF EMITTING SCINTILLATIONS AS A RESULT OF SAID INTERACTIONS, A NEUTRON SHIELD SURROUNDING SAID PHOSPHOR FOR SELECTIVE TRANSMISSION OF NEUTRONS, SAID TRANSMISSION INCREASING AS THE ENERGY OF THE NEUTRONS INCREASES, THE NEUTRON-INTERACTION CHARACTERISTIC OF SAID PHOSPHOR AND THE NEUTRON-TRANSMISSION CHARACTERISTIC OF SAID SHIELD COOPERATING TO PROVIDE AN OVER-ALL BAND-PASS CHARACTERISTIC AFFORDING TO SAID DETECTOR MEANS MAXIMUM RESPONSE TO INCIDENT NEUTRONS WITHIN A SPECIFIC ENERGY RANGE, AND DISCRIMINATING AGAINST DETECTION OF NEUTRONS HAVING ENERGIES EITHER ABOVE OR BELOW SAID RANGE, SAID DETECTOR MEANS ALSO COMPRISING A PHOTOMULTIPLIER OPTICALLY COUPLED TO SAID PHOSPHOR AND OPERATIVE TO PROCUCE ELECTRIC PULSES RESPONSIVELY TO SAID SCINTILLATIONS, MEANS SURROUNDING SAID DETECTOR MEANS OPERATIVE TO DEFINE A HEAT-INSULATED ZONE THEREAROUND, MEANS IN SAID ZONE FOR MAINTAINING THE TEMPERATURE THEREIN NO GREATER THAN ABOUT 120*F. WHEN SAID INSTRUMENT IS IN A BORE HOLE, A SELECTIVE NETWORK WITHIN SAID UNIT FED BY THE ELECTRIC PULSES FROM SAID PHOTOMULTIPLIER OPERATIVE TO TRANSMIT AT LEAST SOME OF SAID PULSES EXCEEDING A PREDETERMINED MAGNITUDE AND SUPPRESSING THE REMAINDER OF SAID PULSES, MEANS FOR LOWERING SAID UNIT TO VARIOUS DEPTHS IN SAID BORE HOLE, AND MEANS FOR RECORDING THE REPETITION RATE OF SAID TRANSMITTED PULSES IN CORRELATION WITH DEPTH.

Claim 2

A SYSTEM FOR DETERMINING THE CHARACTER OF FORMATIONS TRAVERSED BY A BORE HOLE, COMPRISING A SUB-SURFACE UNIT CAPABLE OF BEING LOWERED INTO SAID BORE HOLE, SAID UNIT COMPRISING A SOURCE OF NEUTRONS AND A DETECTOR MEANS RESPONSIVE TO INCIDENT NEUTRONS RETURNED TO SAID UNIT FROM THE FORMATIONS SURROUNDING SAID BORE HOLE, SAID DETECTOR MEANS COMPRISING A PHOSPHOR CAPABLE WITHIN THIS BODY OF INTERACTING WITH NEUTRONS, THE PROBABILITY OF SUCH INTERACTION DECREASING AS THE ENERGY OF THE NEUTRONS INCREASES, SAID PHOSPHOR HAVING THE PROPERTY OF EMITTING SCINTILLATIONS AS A RESULT OF SAID INTERACTIONS, A NEUTRON SHIELD SURROUNDING SAID PHOSPHOR FOR SELECTIVE TRANSMISSION OF NEUTRONS, SAID TRANSMISSION INCREASING AS THE ENERGY OF THE NEUTRONS INCREASES, THE NEUTRON-INTERACTION CHARACTERISTIC OF SAID PHOSPHOR AND THE NEUTRON-TRANSMISSION CHARACTERISTIC OF SAID SHIELD COOPERATING TO PROVIDE AN OVER-ALL BAND-PASS CHARACTERISTIC AFFORDING TO SAID DETECTOR MEANS MAXIMUM RESPONSE TO INCIDENT NEUTRONS WITHIN A SPECIFIC ENERGY RANGE, AND DISCRIMINATING AGAINST DETECTION OF NEUTRONS HAVING ENERGIES EITHER ABOVE OR BELOW SAID RANGE, SAID DETECTOR MEANS ALSO COMPRISING A PHOTOMULTIPLIER OPTICALLY COUPLED TO SAID PHOSPHOR AND OPERATIVE TO PROCUCE ELECTRIC PULSES RESPONSIVELY TO SAID SCINTILLATIONS, MEANS SURROUNDING SAID DETECTOR MEANS OPERATIVE TO DEFINE A HEAT-INSULATED ZONE THEREAROUND, MEANS IN SAID ZONE FOR MAINTAINING THE TEMPERATURE THEREIN NO GREATER THAN ABOUT 120*F. WHEN SAID INSTRUMENT IS IN A BORE HOLE, A SELECTIVE NETWORK WITHIN SAID UNIT FED BY THE ELECTRIC PULSES FROM SAID PHOTOMULTIPLIER OPERATIVE TO TRANSMIT AT LEAST SOME OF SAID PULSES EXCEEDING A PREDETERMINED MAGNITUDE AND SUPPRESSING THE REMAINDER OF SAID PULSES, MEANS FOR LOWERING SAID UNIT TO VARIOUS DEPTHS IN SAID BORE HOLE, AND MEANS FOR RECORDING THE REPETITION RATE OF SAID TRANSMITTED PULSES IN CORRELATION WITH DEPTH.