A negative-type image recording material comprising a support having a rear surface and an image recording layer disposed on the support, the image recording layer having a front surface and including a radical-generating agent and a radically polymerizable compound, wherein a static friction coefficient between the front surface and the rear surface is less than 0. The interrogator, which is located and typically movable inside the wellbore, is effectively a toroidal transformer which includes an elongate conducting body surrounded by a core of high magnetic permeability material and carrying a winding. The second ring has a radial inner face defining a central opening that includes a first portion extending from a first axial face of the second ring and a second portion extending from a second axial face of the second ring, and the second ring is mounted to the first ring with the second portion in contact with the radially outer surface of the flange.