Process for detecting gamma rays

Claim 1

IN A PROCESS INVOLVING DETECTION OF GAMMA RAYS IN A DETECTOR HAVING AN ANODE AND A CATHODE WITH AN IONIZABLE MEDIUM DISPOSED BETWEEN THEM, THE IMPROVEMENT WHICH COMPRISES INTRODUCING AT LEAST ONE OF THE GAMMA RAYS HAVING AN ENERGY ABOVE A LEVEL OF ABOUT 0.5 MEGAVOLTS INTO A SECOND MEDIUM IN WHICH AT LEAST SOME OF THE INTRODUCED GAMMA RAYS ARE PARTIALLY DEENERGIZED BELOW SAID ENERGY LEVEL, INTRODUCING AT LEAST SOME OF THE GAMMA RAYS THUS DEENERGIZED AND SOME OF THE GAMMA RAYS HAVING AN ENERGY ABOVE THE 0.5 MEGAVOLT LEVEL INTO THE DETECTOR, AND PROVIDING THE CATHODE THEREOF WITH A METAL OF A HIGH ATOMIC NUMBER WHICH IMPARTS TO THE DETECTOR AS COMPARED WITH ONE PROVIDED WITH A METAL CATHODE OF LOW ATOMIC NUMBER AN INCREASE IN DETECTION EFFICIENCY WHICH IS PROPORTIONALLY GREATER FOR GAMMA RAYS BELOW ABOUT THE 0.5 MEGAVOLT LEVEL THAN FOR GAMMA RAYS ABOVE SAID LEVEL, WHEREBY THE DETECTION OF THE GAMMA RAYS BELOW ABOUT THE 0.5 MEGAVOLT LEVEL IS EMPHASIZED WHILE THE DETECTION OF THE GAMMA RAYS ABOVE THE LEVEL IS DEEMPHASIZED.