We estimate the Coulomb energy component of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^3{}_{}{}^{}\mathrm{H}$ binding energy difference, using the latest elastic electron scattering form factor data, to be 639±19 keV, in agreement with previous estimates. We estimate the Coulomb energy of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ to be 757±23 keV. We discuss the Coulomb energy contribution to the $\Lambda$ separation energy difference $B_{\Lambda }\left({}_{\Lambda }{}^4{}_{}{}^{}\mathrm{He}\right)-B_{\Lambda }\left({}_{\Lambda }{}^4{}_{}{}^{}\mathrm{H}\right)$.

NUCLEAR STRUCTURE Coulomb energy, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{\Lambda }{}^4{}_{}{}^{}\mathrm{He}$, $\Lambda$-separation energy.

• Received 14 February 1978

DOI:https://doi.org/10.1103/PhysRevC.18.908