Odd Systems in Deformed Relativistic Hartree Bogoliubov Theory in Continuum

In order to describe the exotic nuclear structure in unstable odd-A or odd-odd nuclei,the deformed relativistic Hartree Bogoliubov theory in continuum is extended to incorporate the blocking effect due to the odd nucleon.For a microscopic and self-consistent description of pairing correlations,continuum,deformation,blocking effects,and the extended spatial density distribution in exotic nuclei,the deformed relativistic Hartree Bogoliubov equations are solved in a Woods Saxon basis in which the radial wave functions have a proper asymptotic behavior at large r.The formalism and numerical details are provided.The code is checked by comparing the results with those of spherical relativistic continuum Hartree Bogoliubov theory in the nucleus 19O.The prolate deformed nucleus 15 C is studied by examining the neutron levels and density distributions.

Relativistic Quasiparticle Random Phase Approximation with a Separable Pairing Force

In our previous work [Phys. Lett. （to be published）, Chin. Phys. Lett. 23 （2006） 3226], we introduced a separable pairing force for relativistic Hartree-Bogoliubov calculations. This force was adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. By using the well known techniques of Talmi and Moshinsky it can be expanded in a series of separable terms and converges quickly after a few terms. It was found that the pairing properties can be depicted on almost the same footing as the original pairing interaction, not only in nuclear matter, but also in finite nuclei. In this study, we construct a relativistic quasiparticle random phase approximation （RQRPA） with this separable pairing interaction and calculate the excitation energies of the first excited 2^＋ states and reduced B（E2; 0^＋ → 2^＋） transition rates for a chain of Sn isotopes in RQRPA. Compared with the results of the full Gogny force, we find that this simple separable pairing interaction can describe the pairing properties of the excited vibrational states as well as the original pairing interaction.

Search for two-neutrino double-beta decay of^(136)Xe to the 0^(+)_(1)excited state of 136Ba with the complete EXO-200 dataset

A new search for two-neutrino double-beta(2νββ)decay of^(136)Xe to the 0+1 excited state of 136Ba is performed with the full EXO-200 dataset.A deep learning-based convolutional neural network is used to discriminate signal from background events.Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two.With the addition of the Phase II dataset taken with an upgraded detector,the median 90%confidence level half-life sensitivity of 2νββdecay to the 0+1 state of 136Ba is 2.9×10^(24)yr using a total^(136)Xe exposure of 234.1 kg yr.No statistically significant evidence for 2νββdecay to the 0^(+)_(1)state is observed,leading to a lower limit of T2ν1/2(0^(+)→0^(+)_(1))>1.4×10^(24)yr at 90%confidence level,improved by 70%relative to the current world's best constraint.