Electromagnetic properties of 21O for benchmarking nuclear Hamiltonians

T. Hüther ,B. A. Brown ,K. Whitmore ,Klaus Vobig ,Robert Roth ,Alexander G. Hufnagel ,M. Mathy ,B. Longfellow ,E. Lunderberg ,N. Kobayashi ,A. Schwenk ,J. D. Holt ,C. Loelius ,A. Gade ,Robert Elder ,S. Heil ,T. Haylett ,M. Petri ,I. Syndikus ,D. Bazin ,J. Belarge ,H. Iwasaki ,D. Weißhaar ,B. Elman ,S. Paschalis ,J. Simonis ,J. Fernández Menéndez ,P. C. Bender

doi:10.1016/j.physletb.2020.135678

Abstract

The structure of exotic nuclei provides valuable tests for state-of-the-art nuclear theory. In particular electromagnetic transition rates are more sensitive to aspects of nuclear forces and many-body physics than excitation energies alone. We report the first lifetime measurement of excited states in 21O, finding τ1/2+=420−32+35(stat)−12+34(sys) ps. This result together with the deduced level scheme and branching ratio of several γ-ray decays are compared to both phenomenological shell-model and ab initio calculations based on two- and three-nucleon forces derived from chiral effective field theory. We find that the electric quadrupole reduced transition probability of B(E2;1/2+→5/2g.s.+)=0.71−0.06−0.06+0.07+0.02 e2fm4, derived from the lifetime of the 1/2+ state, is smaller than the phenomenological result where standard effective charges are employed, suggesting the need for modifications of the latter in neutron-rich oxygen isotopes. We compare this result to both large-space and valence-space ab initio calculations, and by using multiple input interactions we explore the sensitivity of this observable to underlying details of nuclear forces.

Highlights

The structure of exotic nuclei provides valuable tests for state-of-the-art nuclear theory
This result together with the deduced level scheme and branching ratio of several γ -ray decays are compared to both phenomenological shell-model and ab initio calculations based on two- and three-nucleon forces derived from chiral effective field theory
E2 fm4, derived from the lifetime of the 1/2+ state, is smaller than the phenomenological result where standard effective charges are employed, suggesting the need for modifications of the latter in neutron-rich oxygen isotopes. We compare this result to both large-space and valence-space ab initio calculations, and by using multiple input interactions we explore the sensitivity of this observable to underlying details of nuclear forces

Summary

Introduction

The structure of exotic nuclei provides valuable tests for state-of-the-art nuclear theory. In particular electromagnetic transition rates are more sensitive to aspects of nuclear forces and many-body physics than excitation energies alone. This result together with the deduced level scheme and branching ratio of several γ -ray decays are compared to both phenomenological shell-model and ab initio calculations based on two- and three-nucleon forces derived from chiral effective field theory.

Results

Conclusion