Hyperfine Interaction of <SUP>140</SUP>Ce(&larr;<SUP>140</SUP>La) in CaB<SUB>6</SUB>

Abstract

A 140 La(I π = 3 − , T 1/2 = 40.3 h)-doped layer has been produced in CaB 6 by means of radioactive isotope (RI) beam technique: 140 Cs(I π = 1 − , T 1/2 = 63.7 s) was implanted into CaB 6 and the radioactive equilibrium of 140 Ba-140 La was achieved. The concentration of La in CaB 6 was La/Ca ∼ 0.001 and ∼0.005. Obtained TDPAC spectra of the 2083 keV level of 140 Ce (I π = 4 + , T 1/2 = 3.4 ns, µ = +4.35±0.10µ N ) followed by the β decay of 140 La 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.