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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Structure and Dynamics of Nuclei IV
HK 13.3: Vortrag
Montag, 14. März 2016, 17:15–17:30, S1/01 A04
Fast-timing lifetime measurement of 178,180Hf — •Johannes Wiederhold1, Ralph Kern1, Volker Werner1, Norbert Pietralla1, Nico Marginean2, Raluca Marginean2, Cristina Roxana Nita2, Sorin Pascu2, Dorel Bucurescu2, Dan Mihai Filipescu2, Nicoleta Florea2, Dan Gabriel Ghita2, Constantin Mihai2, Razvan Lica2, Patrick Regan3, Robert Carroll3, Terver Daniel3, Laila Gurgi3, Ralitsa Ilieva3,4, Nathan Cooper4, and Farheen Naqvi4 — 1IKP, TU-Darmstadt — 2IFIN-HH, Bucharest — 3Physics Department at Surrey — 4Yale University
Deformed nuclei in the rare earth region should show a saturation of the B(E2;01+→21+)-transition strength near the mid-shell. Recent measurements of lifetimes of W-isotopes show discrepancies to literature values and seem to maximize the B(E2)-strength off mid-shell. An analog investigation is done on Hf-isotopes. The lifetimes τ(21+) of 178Hf and 180Hf have been measured using fast electronic scintillation timing (FEST) at the 9 MV tandem accelerator of the IFIN-HH near Bucharest. Excited States of 180Hf were populated via coulomb excitation and of 178Hf via β+-decay following the reaction 174Yb(7Li,3n)178Ta. Because the target of 180Hf was contaminated by 5% of 178Hf and both isotopes have nearly the same transition energies (ΔE ≤ 1 keV) for the 41+→21+- and 21+→0gs+-transitions, a correction has to be applied using the lifetime of the 21+-state of 178Hf. Preliminary results for these lifetimes will be presented. This work was supported by the DFG under the Grant No. SFB 634 and the U.S. DOE Grant No. DE-FG02-91ER40609.