In some embodiments, an apparatus and a system, as well as a method and an article, may operate to determine a compressional velocity of a geological formation, to determine a reflection coefficient associated with the geological formation, and to determine a density of the geological formation based on the CV and the RC. The cam operator includes a rotary shaft having an anti-friction thrust bearing on one end and an anti-friction cam mechanism on the other end. A single introduction port is formed at an end surface of the nozzle on one side in the longitudinal direction, and a plurality of discharge ports are formed at an end surface of the nozzle on the other side in the longitudinal direction. In addition, the protective layer has a luminescence peak in a wavelength ranging from not less than 350 nm to not more than 550 nm under irradiation of light having a wavelength of 173 nm. The housing body has a top wall, a bottom wall and a pair of side walls disposed apart from one another to interconnect the top and bottom walls.