Levels in 171Lu from the reactions 169Tn(α, 2nγ) 171Lu and 171Yb(d, 2nγ) 171Lu

Abstract

Gamma radiation following the reactions 169Tm(α, 2nγ) 171Lu and 171Yb(d,2nγ) 171Lu has been studied using Ge(Li) detectors. Measurements of energies and intensities, γγ coincidences and angular distributions have been performed with α-particle and deuteron energies of 27 MeV and 13.5 MeV, respectively. Excitation data were derived from γ-ray intensity measurements at α-particle energies of 21, 23, 25 and 27 MeV. A level scheme is proposed involving Nilsson states 7 2 + [404], 1 2 + [411], 1 2 − [541], 5 2 + [402] and 9 2 − [514] and rotational bands up to spin values 23 2 , 19 2 , 25 2 , 17 2 and 11 2 , respectively. In the band 1 2 − [541] ( a ≈ 3) not only the low-lying sequence I+ 1 2 = odd was found but also 4 levels of the disfavoured sequence I+ 1 2 = even . Energies of rotational states were analysed in terms of a formula with four rotational parameters including one or two alternating sign terms for bands with K ≠ 1 2 or K = 1 2 , respectively. The perturbation of the 1 2 − [541] band caused by Coriolis mixing with the 3 2 − [532] band has been evaluated. The quantities (g K −g R ) 2 Q 2 0 , b 0 or (1−b 0) 2 (g K −g R ) 2 Q 2 0 have been deduced.