Method of and apparatus for exploring radioactive strata

Claim 1

IN THE EXPLORATION OF EARTH STRATA BY THE DETECTION OF SECONDARY GAMMA RADIATION PRODUCED BY IRRADIATING THE STRATA WITH A SOURCE OF PRIMARY RADIATION THE METHOD COMPRISING THE STEPS OF IRRADIATING THE EARTH STRATA WITH PRIMARY RADIATION TO PRODUCE SECONDARY RADIATION INCLUDING RELTIVELY HIGH ENERGY GAMMA RAYS, SELECTIVELY DETECTING THE SAID RELATIVELY HIGH ENERGY GAMMA RAYS TO THE SUBSTANTIAL EXCLUSION OF RELATIVELY LOW ENERGY GAMMA RAYS BY PLACING IN CLOSE PROXIMITY TO SAID STRATA A SUBSTANCE WHICH REACTS WITH GAMMA RAYS OF SELECTED HIGH ENERGY TO PRODUCE NEUTRONS, SAID SUBSTANCE BEING SUBSTANTIALLY NON-SENSITIVE TOWARD GAMMA RAYS OF LOWER ENERGY LEVEL, SUBJECTING SAID SUBSTANCE TO THE ACTION OF SAID HIGH ENERGY GAMMA RAYS EMANATING FROM SAID STRATA WHEREBY NEUTRONS ARE EJECTED FROM SAID SUBSTANCE, MAINTAINING A NEUTRON-SENSITIVE MATERIAL IN CLOSE PROXIMITY TO SAID SUBSTANCE AT A LOCUS OF NEUTRON FORMATION, SUBJECTING SAID MATERIAL TO THE ACTION OF EJECTED NEUTRONS WHEREBY IONIZING PARTICLES ARE EJECTED THEREFROM, AND CONTACTING SAID IONIZING PARTICLES WITH IONIZABLE GAS IN AN ELECTRICAL FIELD THEREBY PRODUCING ELECTRICAL IMPULSES INDICATIVE OF THE QUANTITY OF SAID HIGH ENERGY GAMMA RADIATION.