Detecting radioactive potassium in the presence of uranium and thorium

Claim 1

THE METHOD OF INDICATING THE PRESENCE OF RADIOACTIVE POTASSIUM IN AN EARTH FORMATION WHICH MAY ALSO CONTAIN URANIUM AND THORIUM COMPRISING: (A) DETECTING THE TOTAL GAMMA-RAY EMISSION FROM SAID FORMATION BY MEANS OF A SCINTILLATION DETECTOR; (B) SIMULTANEOUSLY FILTERING THE OUTPUT PULSES FROM SAID SCINTILLATION DETECTOR TO PRODUCE A FIRST TRAIN OF PULSES CONTAINING ONLY THOSE PULSES IN THE SCINTILLATION DETECTOR OUTPUT SIGNAL CORRESPONDING TO PULSE AMPLITUDES BETWEEN A FIRST AND A SECOND PREDETERMINED VALUE AND A SECOND TRAIN OF PULSES CONTAINING ONLY THOSE PULSES IN THE SCINTILLATION DETECTOR OUTPUT CORRESPONDING TO PULSE AMPLITUDES BETWEEN SAID SECOND A THIRD PREDETERMINED VALUE, SAID FIRST AND SECOND VALUES BEING RESPECTIVELY BELOW AND ABOVE THE VALUES OF PULSE AMPLITUDES CORRESPONDING TO VALUES AT WHICH THOSE PRODUCED BY POTASSIUM RADIATION ARE MOST PREVALENT, AND SAID THIRD PREDETERMINED VALUE BEING GREATER THAN THE HIGHEST PULSE AMPLITUDE DUE TO POTASSIUM BUT LESS THAN SAID SECOND PREDETERMINED VALUE, SAID FIRST AND SECOND VALUES BEING SELECTED SUCH THAT THE RATIO OF PULSES FALLING BETWEEN SAID SECOND AND THIRD PREDETERMINED VALUE TO THOSE FALLING BETWEEN SAID FIRST AND SECOND PREDETERMINED VALUES IS THE SAME FOR BOTH URANIUM AND THORIUM; (C) SEPARATELY INTEGRATING EACH OF SAID FIRST AND SECOND TRAINS OF PLUSES OF PRODUCES RESPECTIVE FIRST AND SECOND INTERGRATED SIGNALS; (D) ADJUSTING THE RELATIVE AMPLITUDES OF SAID FIRST AND SECOND INTEGRATED OUTPUT SIGNALS SO THAT THE AMPLITUDE OF SAID SECOND INTEGRATED OUTPUT SIGNAL IS EQUAL TO THE PROPORTION OF THE AMPLITUDE OF SAID FIRST INTEGRATED OUTPUT SIGNAL DUE TO URANIUM AND THORIUM; (E) PRODUCING A SIGNAL PROPORTIONAL TO THE DIFFERENCE BETWEEN SAID RELATIVELY ADJSUTED FIRST AND SECOND INTEGRATED SIGNALS; AND, (F) RECORDING SAID DIFFERENCE SIGNAL AS AN INDICATION OF THE POTASSIUM PRESENT IN THE FORMATION.