Measurement of projected mass density - A basic problem of neutrino geophysics

The measurement and calculation of the projected mass density of the earth (I) in neutrino experiments is examined analytically. The formula used in calculating I is explained, and the measurement arrays, comprising a neutrino-beam-generation system based on a monochromatic beam of pi-mesons of energy E(pi) and a detection system with one or two (on-beam and off-beam) detectors, are classified according to the accuracy of both major components. Modifications to the basic formula to allow for measurement of neutrino fluxes, for determination of I from the means of known-distribution moments, or for measurements of neutrino beams with different values of E(pi) are proposed. The importance of these measurements for determining the density and chemical composition of the earth's interior is stressed, and their potential applicability to oil and heavy-element prospecting is indicated.