Puzzling Two-Proton Decay of Kr67

Abstract

Ground-state two-proton (2p) radioactivity is a rare decay mode found in a few very proton-rich isotopes. The 2p decay lifetime and properties of emitted protons carry invaluable information on nuclear structure in the presence of a low-lying proton continuum. The recently measured 2p decay of ^{67}Kr turned out to be unexpectedly fast. Since ^{67}Kr is expected to be a deformed system, we investigate the impact of deformation effects on the 2p radioactivity. We apply the recently developed Gamow coupled-channel framework, which allows for a precise description of three-body systems in the presence of rotational and vibrational couplings. This is the first application of a three-body approach to a two-nucleon decay from a deformed nucleus. We show that deformation couplings significantly increase the 2p decay width of ^{67}Kr; this finding explains the puzzling experimental data. The calculated angular proton-proton correlations reflect a competition between 1p and 2p decay modes in this nucleus.

First Observation of Unbound O11 , the Mirror of the Halo Nucleus LiWebb1, Wang2, Brown3 et al. 2019Phys. Rev. Lett.Self Cite445390View full textAdd to dashboardCite

“…band of the even-A core with J ≤ j max c = 4 + and the odd-A core with J ≤ j max c = 11/2 − , respectively. According to previous work [25], the higher-lying rotational states have little influence on the final energy spectrum and g.s. mass.…”

“…-To describe the spectra and two-proton (2p) decay of 11,12 O, we utilized the three-body core+nucleon+nucleon Gamow coupled-channel (GCC) approach of Refs. [24,25] and we refer to these papers and to the review on the complex-energy shell model [10] for technical details and basic concepts. The core ( 9,10 C) is chosen as a deformed rotor, which can reasonably reproduce the intruder state and allows the pair of nucleons to couple to the collective states of the core.…”

Fermion Pair Dynamics in Open Quantum Systems

“…In the case of the g.s. 2n decay, the only candidate identified so far is the threshold resonance in 26 O [8][9][10]. Theoretically, the mechanism of two-nucleon emission is not fully understood, including the role of the low-lying particle continuum, and the transition from the initial state strongly impacted by the nuclear medium to the scattering domain governed by final-state interaction [11][12][13].…”

Beyond the proton drip line: Bayesian analysis of proton-emitting nuclei

“…In addition, several broad resonances associated with 2p decay were reported in, e.g., 6 Be [19] and 11,12 O [20,21]. The unique experimental data on lifetimes and correlations between emitted protons has triggered considerable theoretical interest [22][23][24][25][26][27][28].…”