Precise Measurements of Hyperfine Structure in the2P3State ofHe3

Transitions within the $2{}_{}{}^3{}_{}{}^{}P$ state of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ were measured to determine the parameters $C$, $D$, and $E$ which represent respectively the contact, dipole, and tensor terms in the hyperfine Hamiltonian. For the first time, the effect of core polarization on the hyperfine structure has been detected. The present results are $C=-4283.84\mathrm{}\left(1\right)\mathrm{}$ MHz, $D=-28.02\mathrm{}\left(6\right)\mathrm{}$ MHz, and $E=+7.08\mathrm{}\left(2\right)\mathrm{}$ MHz and are consistent with the theoretical values after the combined fine and hyperfine interactions with the $2{}_{}{}^1{}_{}{}^{}P$ state are taken into account in the analysis of the data.