The first fast-timing measurements from nuclides produced via the in-flight fission mechanism are reported. The lifetimes of the first 2+ states in 104,106Zr nuclei have been measured via β-delayed γ-ray timing of stopped radioactive isotope beams. An improved precision for the lifetime of the 21+ state in 104Zr was obtained, τ(21+)=2.90-20+25 ns, as well as a first measurement of the 21+ state in 106Zr, τ(21+)=2.60-15+20 ns, with corresponding reduced transition probabilities of B(E2;21+→0g.s.+)=0.39(2) e2b2 and 0.31(1) e2b2, respectively. Comparisons of the extracted ground-state deformations, β2=0.39(1) (104Zr) and β2=0.36(1) (106Zr) with model calculations indicate a persistence of prolate deformation. The data show that 104Zr is the most deformed of the neutron-rich Zr isotopes measured so far.
Browne, F., Bruce, A. M., Sumikama, T., Nishizuka, I., Nishimura, S., Doornenbal, P., … Wieland, O. (2015). Lifetime measurements of the first 2+ states in 104,106Zr: Evolution of ground-state deformations. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 750, 448–452. https://doi.org/10.1016/j.physletb.2015.09.043