Hyperfine interactions at Ce-140(<- La-140) in hexaboride - art. no. 132403

A La-140(I-pi = 3(-), T-1/2 = 40.3 h)-doped layer has been produced in CaB6 by means of radioactive-isotope-beam technique: Cs-140(I-pi = 1(-), T-1/2 = 63.7 s) was implanted into CaB6 and the radioactive equilibrium of Ba-140 -La-140 was achieved. The concentration of La in CaB6 was La/Ca similar to0 .001. The measured time-differential perturbed angular correction spectra o f the 2083 keV level of Ce-140(I-pi=4(+),T-1/2=3.4 ns, mu = +4.35 +/-0.10 m u (N)) followed by the beta decay of La-140 showed the existence of hyperfi ne magnetic fields: B-hyp= -15.0+/-0.5 T and -1.00+/-0.15 T.