Photon scattering experiments on the quasistable, odd-odd mass nucleus {sup 176}Lu

• Published in: Physical review. C, Nuclear physics Vol. 75; no. 3
• Main Authors: Walter, S., Stedile, F., Garrel, H. von, Kneissl, U., Kohstall, C., Pitz, H. H., Scheck, M., Carroll, J. J., Fransen, C., Friessner, G., Hollmann, N., Jolie, J., Linnemann, A., Muecher, D., Scholl, C., Werner, V., Karg, O., Neumann-Cosel, P. von, Pietralla, N., Kaeppeler, F.
• Format: Journal Article
• Language: English
• Published: United States 15-03-2007
• Subjects: BREMSSTRAHLUNG; DIPOLES; DYNAMITRONS; EXCITATION; INTERMEDIATE STATE; KEV RANGE 100-1000; LUTETIUM 176; MASS; MEV RANGE 01-10; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEAR STRUCTURE; ODD-EVEN NUCLEI; PHOTONS; SCATTERING
• ISSN: 0556-2813; 1089-490X
• DOI: 10.1103/PHYSREVC.75.034301

The quasistable odd-odd-mass nucleus {sup 176}Lu is of special interest in nuclear structure physics and, above all, in nuclear astrophysics. Systematic photon scattering experiments have been performed at the bremsstrahlung facility of the 4.3-MV Stuttgart Dynamitron accelerator with bremsstrahlung end-point energies of 2.3 and 3.1 MeV to determine the low-energy dipole strength distribution in the s-only isotope {sup 176}Lu. The main goal was to pin down possible intermediate states (IS) for the photoactivation of the short-lived 123-keV isomer, which is the key process determining the effective lifetime of {sup 176}Lu in a stellar photon bath and hence for the use of this isotope as a stellar chronometer. Using an enriched sample, 29 transitions ascribed to {sup 176}Lu were detected below 2.9-MeV excitation energy. The corresponding excitation strengths were determined. For the previously proposed lowest IS at 839 keV, an upper limit for the excitation strength corresponding to a lifetime of {tau}{>=} 1.5 ps can be given. Astrophysical consequences, also in view of new Stuttgart photoactivation experiments, are discussed. The fragmentation of the dipole strength is compared to those in neighboring even-even and odd-even nuclei.