The present invention relates to a device for determining the mass per unit volume of an elementary volume of material.
Although not exclusively, the invention is particularly adapted to the construction of a non destructive testing device for following the progression of a deposit on a wall and/or measuring a dimension or distance in an ambience where rigorous conditions prevail.
By way of particular example, the invention may be used for monitoring a zinc-lead deposit on the wall of a a zinc blast furnace.
A process is already known for obtaining an indication of the mass per unit volume of the contents of an elementary volume in which :
said elementary volume is defined as the intersection of a directional X or gamma radiation beam and a directional reception channel of a photo-electronic photon detector;
said radiation beam and/or said reception channel are made movable in rotation about an axis orthogonal to the plane defined by the axes of said radiation beam and said reception channel; and
after making said intersection coincide with said elementary volume by rotation of said radiation beam and/or said reception channel, the number of photons received by said detector is measured.
Thus, as will be explained in greater detail further on, said detector receives the photons diffused by Compton effect in the direction of said detector by said radiation beam passing through said elementary volume, i.e. said detector delivers information about the number of electrons contained by said elementary volume and so about the mass per unit volume thereof.