Abstract: A cooling system for use in conjunction with rotating anode and stationary anode x-ray tubes. The cooling system includes a reservoir containing a volume of coolant in which a portion of the x-ray tube is immersed. A bladder incorporated in the reservoir and in communication with the atmosphere automatically permits thermal expansion of the coolant while maintaining the coolant at atmospheric pressure. An external cooling unit directs a flow of coolant through a pressure drop device proximate to the x-ray tube so that the flowing coolant removes heat from the x-ray tube. Upon exiting the pressure drop device, the heated coolant is directed to the reservoir and ultimately returned to the external cooling unit where heat is removed from the coolant and the coolant then redirected back to the pressure drop device to repeat the cycle.

Abstract: The present invention provides an improved thin layer nuclear density gauge comprising a gauge housing having a vertical cavity therethrough and a base, a first radiation detector located at a first position within said housing and adjacent to said base of said housing, a second radiation detector located at a second position within said housing and adjacent to said base of said housing, a vertically moveable source rod extending into said cavity of said gauge housing, a radiation source operatively positioned within a distal end of said source rod, at least one bearing operatively positioned to guide said source rod within said cavity, and means for vertically extending and retracting said source rod to a plurality of predetermined source rod positions so as to change the spatial relationship between said radiation source and said first and second radiation detectors. The source rod has a maximum radial movement of less than about 0.003 inch at each predetermined position.