Experimental Determination of Rate of Energy Loss for Slow ${\mathrm{H}}^1$, ${\mathrm{H}}^2$, ${\mathrm{He}}^4$, ${\mathrm{Li}}^6$ Nuclei in Au and Al

A description is given of the use of a variable energy source of monoenergetic ${\mathrm{H}}^1$, ${\mathrm{H}}^2$, ${\mathrm{He}}^4$, ${\mathrm{Li}}^6$ nuclei, an energy analyzer, and an electron multiplier tube to measure the decrease in energy of these particles as they pass through a Au foil of known thickness; the measurements are carried out for protons from an energy of 30 kev to 400 kev, for deuterons from 30 kev to 650 kev, for alpha-particles from 30 kev to 1400 kev, and for the ${\mathrm{Li}}^6$ nuclei from 750 kev to 850 kev. Similar measurements are carried out for the energy loss of protons and deuterons in Al over the energy range from 60 kev to 300 kev. Integrated range energy curves are given for these low energies. Although current theory predicts that the energy loss rates will be precisely equal for protons and deuterons of the same velocity, it is found that the loss rate for deuterons of low velocity is a few percent higher than that for protons of the same velocity. A qualitative explanation for the discrepancy is advanced.