Temperature stabilized radioactivity well logging unit

Claim 1

IN A WELL LOGGING SYSTEM, A TUBULAR HOUSING, AN ELONGATED MEMBER HAVING INNER AND OUTER TUBULAR WALLS OF STAINLESS STEEL WHICH ARE SEALED AT ONE END TO DEFINE AN EVACUATED ZONE THEREBETWEEN, A HOLLOW COVER MEMBER REMOVABLY SECURED IN ONE END OF SAID INNER WALL AND HAVING A TUBE EXTENDING THROUGH THE CENTER THEREOF, THE SPACE WITHIN SAID HOLLOW COVER MEMBER ALSO BEING EVACUATED, A TEMPERATURE REGULATING ASSEMBLY COMPRISING A FIRST TUBULAR SLEEVE OF STAINLESS STEEL POSITIONED WITHIN SAID INNER WALL OF SAID ELONGATED MEMBER AND HAVING TRANSVERSE END WALLS AT EITHER END THEREOF, A REMOVABLE PLUG IN ONE OF SAID END WALLS, A WIRING CONDUIT OF STAINLESS STEEL EXTENDING THROUGH THE LENGTH OF SAID TUBULAR SLEEVE AND THROUGH SAID END WALLS, A SECOND TUBULAR SLEEVE WITHIN SAID INNER WALL AND CONNECTED AT ONE END TO SAID ONE END WALL OF SAID FIRST SLEEVE AND CLOSED AT THE OTHER END THEREOF, A MASS OF MATERIAL IN SAID FIRST TUBULAR SLEEVE HAVING SUBSTANTIAL SPECIFIC HEAT, A HEAT CONDUCTING ROD IN SAID FIRST SLEEVE IN INTIMATE CONTACT WITH SAID MASS OF MATERIAL AND CONNECTED TO SAID REMOVABLE PLUG, A RADIATION DETECTING UNIT POSITIONED WITHIN SAID SECOND SLEEVE, THERMAL INSULATING AND SHOCK MOUNTING MATERIAL POSITIONED IN SAID ELONGATED MEMBER AT EITHER END OF SAID TEMPERATURE REGULATING ASSEMBLY, AND ELECTRIC CABLE MEANS EXTENDING THROUGH SAID OPENING IN SAID COVER MEMBER AND SAID WIRING CONDUIT TO SAID RADITION DETECTING UNIT.