Abstract: Disclosed is a method and apparatus for providing pathways for electrical conductors and conduits through radiation shielding without effectively diminishing the degree of shielding. A pathway is formed by providing a helical groove on the surface of a cylindrical shielding member which is fitted with close tolerance inside a tubular housing. Specific embodiments provide for the passage of electrical conductors through a cylinder of shielding material positioned within a well logging sonde between a radiation source and a radiation detector. One or more grooves may be provided in the shielding member. The shielding member may be constructed of two or more individual, coaxially aligned, abutting, cylindrical shielding submembers. The shielding submembers making up a shielding member may be of the same or different shielding material.

Abstract: A well-logging sonde employes a neutron generator. It has a high-voltage supply for the target of the neutron generator tube. The sonde includes an insulated high-voltage conductor for connecting the supply to target, and there is a metallic ring supported on the insulation surrounding the conductor. The ring and conductor form a capacitor that is connected to a circuit for controlling the deenergization of the high-voltage supply if an arc occurs.