Yrast spectroscopy and g-factor measurements in 199Pb, 201Pb and 203Pb

The half-lives and g-factors of high-spin states in 199,201,203Pb were studied using 198,200,202Hg(α, 3n) reactions at Eα = 41 and 53 MeV. In-beam γ-ray spectroscopy including γγt-coincidence measurements were performed in order to interpret the level schemes. The measured half-lives are T1/2 = 7.5(3) ns, 10.0(2) μs and 55(5) ns for the previously known 25/2-, 29/2- and 33/2+ states, respectively, in 199Pb and T1/2 = 508 (5) ns and 63 (3) ns for the 29/3- and the 25/2- states, respectively, in 201Pb. A new isomer at 4559.2 + δ keV excitation energy with T1/2 = 43 (3) ns and Jπ 41/2+ is observed in 201Pb and a 25/2- isomer at 2922.7 + Δ keV excitation energy with T1/2 = 122(4) ns in 203Pb. The g-factors of the isomeric states were determined using the time differential perturbed angular distribution technique and the results are g(29/2-) = -0.0742 (2) and g(29/2-) = -0.0697 (4) for the 29/2- states in 199Pb and 201Pb, respectively, indicating a predominantly three-neutron-hole configuration i-213/2 f-15/2 for these states. The g-factor of the 33/2+ state in 199Pb is obtained as g = -0.145 (9) which agrees with a ν(i-313/2) configuration. The g-factor of the 41/2+ state in 201Pb g(41/2+) = -0.18 (4) indicates a five-quasiparticle configuration. The probable configuration for the 25/2- isomer has also been suggested on the basis of the measured value of the g-factor g(25/2-) = -0.063 (3) in 201Pb and g(25/2-) = -0.059 (3) in 203Pb and the B(E2) values for the 29/2- → 25/2- and the 25/2- → 21/2- transitions in the odd Pb isotopes. (orig.)