Shielding in irradiation well logging

Claim 1

APPARATUS FOR LOGGING WELLS COMPRISING AN ELONGATED HOUSING ADAPTED TO BE MOVED THROUGH A WELL BORE, A SOURCE OF PENETRATING NUCLEAR RADIATIONS IN SAID HOUSING, A DETECTOR OF NUCLEAR RADIATIONS IN SAID HOUSING AT A FIXED SPACING FROM SAID SOURCE, SPRING MEANS FOR HOLDING SAID SOURCE AND DETECTOR AND ONE SIDE OF SAID HOUSING AGAINST THE WALL ON ONE SIDE OF A WELL BORE, A SUBSTANTIAL THICKNESS OF FIXED NUCLEAR-RADIATION SHIELDING AT LEAST PARTIALLY SURROUNDING EACH OF SAID SOURCE AND SAID DETECTOR ON THE SIDE OPPOSITE THAT HELD AGAINST A WELL WALL, FLEXIBLE NUCLEARRADIATION SHIELDING FORMED OF A PLURALITY OF OVERLAPPING RADIATION-ABSORBING ELEMENTS AT LEAST PARTIALLY ENCIRCLING SAID HOUSING AT A POSITION INTERMEDIATE BETWEEN SAID SOURCE AND SAID DETECTOR, SAID ELEMENTS BEING URGED OUTWARDLY TO EXTEND ACROSS A SPACE BETWEEN SAID HOUSING AND A WELL WALL, THE OUTER PERIPHERY OF SAID FLEXIBLE SHIELDING BEING MOVABLE TO MAINTAIN CONTACT WITH A WELL WALL OF CHANGING SHAPE, AND MEANS FOR RECORDING AN INDICATION OF THE OUTPUT OF SAID DETECTOR AS A FUNCTION OF DEPTH IN A WELL.