Abstract
Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying excitations is the coupling of quadrupole and octupole phonons.
Purpose: In this work, the -decay behavior of candidates for the state in the doubly magic nucleus and in the heavier and semimagic nucleus is investigated.
Methods: experiments have been carried out at the High Intensity -ray Source facility in combination with the high-efficiency -ray spectroscopy setup consisting of HPGe and detectors. The setup enables the acquisition of coincidence data and, hence, the detection of direct decay paths.
Results: In addition to the known ground-state decays, for the decay into the state was observed, while for the direct decays into the and the state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for isotones. In addition, negative parities for two states in were deduced simultaneously.
Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the excitation in the light-to-medium-mass nucleus as well as in the stable even-even nuclei.
- Received 27 January 2016
DOI:https://doi.org/10.1103/PhysRevC.93.034311
©2016 American Physical Society