LX-Ray Energies of Np, Pu, and Am

Five Np, eight Pu, and five Am $L$ x-ray transitions have been observed in conventional x-ray fluorescence from 200-mg amounts of ${\mathrm{Np}}^{237}$, ${\mathrm{Pu}}^{239}$, and ${\mathrm{Am}}^{241}$ using a Cauchois type curved crystal transmission spectrometer. The energies of these transitions have been determined, with reference to $K{\alpha }_1$ lines of the elements from ${}_{37}{}^{}{}_{}{}^{}\mathrm{R}$b through ${}_{47}{}^{}{}_{}{}^{}\mathrm{A}$g, to an accuracy of 3 to 8 ev. Disagreement with previous measurements by Barton, Robinson, and Perlman; Jaffe, Passell, Browne, and Perlman; and Day has been found while excellent agreement with the Pu measurements of Cauchois, Manescu, and Le Berquier was obtained.