Excited states in Pd-106 were studied with the (n, n gamma.) reaction, and comprehensive information for excitations with spin <= 6h was obtained. The data include level lifetimes in the femtosecond regime, spins and parities, transition multipolarities, and multipole mixing ratios, which allow the determination of reduced transition probabilities. The E2 decay strength to the low-lying states is mapped up to approximate to 2.4 MeV in excitation energy. The structures associated with quadrupole collectivity are elucidated and organized into bands.

Level lifetimes in 106Pd were measured with the Doppler-shift attenuation method following inelastic neutron scattering, and electric monopole transition strengths between low-lying 2+ states were deduced. The large \( \rho^{2}\)(E0) values obtained provide evidence for shape coexistence, extending observation of such structures in the N = 60 isotones. Included in these results is the first determination of the E0 transition strength in the Pd nuclei between levels with K = 2 .

Excited states in 106Pd and 106Cd have been studied using the (n,n′γ) reaction. The data include level lifetimes, spins, branching ratios, and multipole mixing ratios, and give a comprehensive view of excitations with spin ≤6ħ. The determined E2 strengths show serious discrepancies with the quadrupole phonon structure expected in these nuclei.

A. Chakraborty, F.M. Prados-Estevez, E.E. Peters, M.G. Mynk, D. Bandyopadhyay, N. Boukharouba, S.N. Choudry, B.P. Crider, P.E. Garrett, S.F. Hicks, A. Kumar, S.R. Lesher, C.J. McKay, M.T. McEllistrem, S. Mukhopadhyay, J.N. Orce, M. Scheck, J.R. Vanhoy, J.L. Wood, and S.W. Yates Department of Physics, Krishnath College, Berhampore, Murshidabad, West Bengal-742101, INDIA Department of Physics & Astronomy and Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA Department of Physics, University of Guelph, Guelph, Ontario, N1G2W1, Canada Department of Physics, University of Dallas, Irving, TX 75062, USA Department of Physics, University of the Western Cape, P/B X17, Bellville, ZA-7535, South Africa Department of Physics, United States Naval Academy, Annapolis, MD 21402, USA and Department of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA

The low-lying level structure of the "so-called" transitional nucleus Nd-150 has been explored using the (n,n'gamma) reaction. A significant extension of the level scheme was made within the energy and spin regime of 2 MeV and 6 (h) over bar, respectively. Level lifetimes were extracted through a Doppler-shift attenuation analysis, and the level decay properties have been investigated. The observed low-lying level structure of Nd-150 indicates a close resemblance to its neighboring isotone, Sm-152.

Excited states in Nd-150 have been investigated with the Nd-150(n,n'gamma) reaction. In addition to the previously known K-pi = 0(-) band, a new K-pi = 2(-) band is established, and level lifetimes are determined for all the reported band members. These lifetime data reveal a pattern of enhanced E1 transition strengths, similar to that observed in Sm-152 and unprecedented in other nuclei, thus suggesting a systematic pattern for octupole collectivity in the N = 90 isotones. The pattern lies outside of the various model descriptions that have been put forward for nuclei in this or any other region. DOI:10.1103/PhysRevC.86.064314

Understanding the nuclear structure of Sm-152, along with other N = 90 isotones, has long posed a challenge. A rapid transition in shape between the spherical N = 88 Sm-150 and well-deformed N = 92 Sm-154 is observed, along with strong evidence for shape coexistence. Competing ideas have been put forward over the decades, with the most recent being that N = 90 is at the critical point of a shape phase transition. Until recently, the lack of high-precision data has not allowed the competing models to be extensively tested. In a coordinated program of investigation, a series of complementary experiments, which include high-statistics beta decay, multi-step Coulomb excitation, the Nd-150(alpha,2n) reaction, and the (n,n'gamma) reaction, have been performed for Sm-152. These experiments have revealed the existence of a pairing-isomer band, a hexadecapole band, the lack of multi-phonon beta vibrational bands, and the repetition of structures built on the first excited K-pi=0(+) as built on the ground state. The status of these coordinated studies is examined.

Low-lying collective states in Ba-136 were investigated with (n,n'gamma) techniques, including Doppler-shift attenuation lifetime measurements. The level spins, lifetimes, branching ratios, multipole-mixing ratios and transition strengths reveal candidates for symmetric-phonon states up to third order. The 2(ms)(+) mixed-symmetry state was confirmed as unfragmented and a candidate for a [2(1)(+) circle times 2(ms)(+)](3+) two-phonon mixed-symmetry state is proposed.