Positron backscattering from elemental solids

New measurements and Monte Carlo simulations of the total coefficients eta + for the backscattering of positrons from elemental solids are reported as a function of atomic number Z between 13 and 82, incident energies E from 1 to 50 keV, and incident angles between 0 degrees and 65 degrees . The measurements and simulations show generally good agreement with each other and with the recent measurements of Massoumi et al (1992) and Makinen et al (1992). Both experiment and simulations suggest that the monotonic increase of eta + with Z seen at high E is not observed for E below 10 keV. Where possible, the new results are compared with earlier measurements of electron coefficients.