Three-body correlations in the ground-state decay ofO26

Abstract

Background: Theoretical calculations have shown that the energy and angular correlations in the three-body decay of the two-neutron unbound 26 O can provide information on the ground-state wavefunction, 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 26 O, including the decay mechanism and ground-state resonance energy. Method:26 O was produced in a one-proton knockout reaction from 27 F and the 24 O +n + n decay products were measured using the MoNA-Sweeper setup. The three-body correlations from the 26 O 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 26 O. A 1σ upper-limit of 53 keV was extracted for the ground-state resonance energy of 26 O.Conclusions: Future attempts to measure the three-body correlations from the ground-state decay of 26 O will be very challenging due to the need for a precise measurement of the 24 O momentum at the reaction point in the target.

In-medium similarity renormalization group for closed and open-shell nuclei

“…All methods predict the 26 O resonance at an energy E x ≈ 1 − 2 MeV above the 24 O ground state, which is considerably higher than the current experimental limits E x ≈ 50 keV [171][172][173]. In part, this is due to the omission of continuum effects in all calculations that are shown here.…”

Exploring the manifestation and nature of a dineutron in two-neutron emission using a dynamical dineutron model

“…This process is sometimes discussed in terms of "dineutron emission". The declared discovery of "dineutron emission" in decay of 16 Be has recently produced a heated discussion, see Refs. [11][12][13].…”

Two-neutron sequential decay ofO24

“…Several of these systems have been interpreted to decay by emission of a di-neutron [11,13]. So far, there has been no correlation measurement of a state decaying by sequential emission of two neutrons, although evidence for sequential decay has been reported for the high-energy continuum of 14 Be [12]. The structure of 24 O, the heaviest bound isotope for which the neutron drip-line is established [17], has been well studied and there is substantial evidence for the appearance of a new magic number N = 16 [18][19][20][21][22].…”