In 1956 A. Kerman explained the observed energy levels of the lowest K = 1/2 and K = 3/2 bands in 183W as resulting from rotational perturbations due to the effects of the Coriolis force. Following from that seminal paper, in this work we consider Kerman's problem when one of the Nilsson single-particle levels involved is a resonant state. This is the simplest model of Coriolis mixing that allows for analytical expressions derived in first-order perturbation theory, without losing the main physical ingredients of the continuum effects. We present results for the perturbed solution of the ground state band energies as a function of the state width, which suggest a general behavior of both increased moment of inertia and staggering.

Background: The giant pairing vibration (GPV), a correlated two-nucleon mode in the second shell above the Fermi surface, has long been predicted and expected to be strongly populated in two-nucleon transfer cross sections similar to those of the normal pairing vibration. Recent experiments have provided evidence for this mode in C14,15 but, despite sensitive studies, it has not been definitively identified in either Sn or Pb nuclei where pairing correlations are known to play a crucial role. Purpose: Our aim is to test whether features inherent to the mixing of bound and unbound levels might account for this and to study the effect in a simple and intuitively clear approach. Method: We study the mixing of unbound levels in a set of toy models that capture the essential physics of the GPV, along with a more realistic calculation including distorted-wave Born approximation transfer amplitudes. Results: The calculated (relative) cross section to populate a simulated GPV state is effectively low, compared to the case of bound levels with no widths Conclusions: The mixing turns out to be only a minor contributor to the weak population. Rather, the main reason is the melting of the GPV peak due to the width it acquires from the low orbital angular momentum single-particle states playing a dominant role in two-nucleon transfer amplitudes. This effect, in addition to a severe Q-value mismatch, may account for the elusive nature of this mode in (t,p) and (p,t) reactions.

More than 200 states up to 4.1 MeV excitation have been populated in Er168 with the Er170(p,t) reaction at 25 MeV incident energy. About 80 of these states, with 0+ and 2+ assignments, were reported in a previous publication [D. Bucurescu et al., Phys. Rev. C 73, 064309 (2006)0556-281310.1103/PhysRevC.73.064309]. The present work considerably enriches the knowledge of this nucleus. A multistep coupled-channels analysis of the angular distributions is now presented for all the states observed in this experiment. Spin and parity values between 0+ and 7- are newly assigned for more than 100 states. For the states already reported in the ENSDF database with Jπ values there is a good agreement with our values. The Er168 nucleus remains one of the best experimentally known nuclei for states with low and medium spins below 4 MeV excitation energy, representing a challenge for future microscopic structure model calculations aiming to disentangle the contributions of different excitation degrees of freedom.

Two separate experiments using the Differential Decay Curve Method have been performed to extract mean lifetimes of excited states in 106Cd. The medium-spin states of interest were populated by the 98Mo( 12C, 4n) 106Cd reaction performed at the Wright Nuclear Structure Lab., Yale University. From this experiment, two isomeric state mean lifetimes have been deduced. The low-lying states were populated by the 96Mo(13C, 3n)106Cd reaction performed at the Institut für Kernphysik, Universität zu Köln. The mean lifetime of the Iπ = 21+ state was deduced, tentatively, as 16.4(9) ps. This value differs from the previously accepted literature value from Coulomb excitation of 10.43(9) ps.