Hyperfine Interaction of ¹⁴⁰Ce(←¹⁴⁰La) in CaB₆

Abstract

A ¹⁴⁰La(I^π=3⁻, T_1⁄2=40.3 h)-doped layer has been produced in CaB₆ by means of radioactive isotope (RI) beam technique: ¹⁴⁰Cs(I^π=1⁻, T_1⁄2=63.7 s) was implanted into CaB₆ and the radioactive equilibrium of ¹⁴⁰Ba–¹⁴⁰La was achieved. The concentration of La in CaB₆ was La/Ca∼0.001 and ∼0.005. Obtained TDPAC spectra of the 2083 keV level of ¹⁴⁰Ce (I^π=4⁺, T_1⁄2=3.4 ns, μ=+4.35±0.10μ_N) followed by the β decay of ¹⁴⁰La showed the existence of hyperfine magnetic fields: B_hyp=−15.0±0.5 T and −1.00±0.15 T for La/Ca∼0.001 and B_hyp=−1.51±0.12 T for La/Ca∼0.005.