Three-body correlations in the ground-state decay of 26O

TL;DR

This study investigates the three-body decay correlations of unbound oxygen-26 to understand its ground-state properties, finding the resonance energy to be below 53 keV, but decay mechanism details remain elusive due to experimental limitations.

Contribution

The paper provides the first experimental constraints on the resonance energy of O26 using three-body correlations, highlighting the challenges in measuring decay mechanisms.

Findings

Resonance energy of O26 is below 53 keV.

Three-body correlations are sensitive to resonance energy.

Decay mechanism could not be conclusively determined.

Abstract

Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound O26 can provide information on the ground-state wave function, which has been predicted to have a dineutron configuration and 2n halo structure. Purpose: To use the experimentally measured three-body correlations to gain insight into the properties of O26, including the decay mechanism and ground-state resonance energy. Method: O26 was produced in a one-proton knockout reaction from F27 and the O24+n+n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the O26 ground-state resonance decay were extracted. The experimental results were compared to Monte Carlo simulations in which the resonance energy and decay mechanism were varied. Results: The measured three-body correlations were well reproduced by the Monte Carlo simulations but were not sensitive to the decay mechanism due to the experimental resolutions. However, the three-body correlations were found to be sensitive to the resonance energy of O26. A 1{\sigma} upper limit of 53 keV was extracted for the ground-state resonance energy of O26. Conclusions: Future attempts to measure the three-body correlations from the ground-state decay of O26 will be very challenging due to the need for a precise measurement of the O24 momentum at the reaction point in the target.