Three-body model for the two-neutron emission of ~(16)Be

摘要

Background: While diproton emissionwas first theorized in 1960 and firstmeasured in 2002, itwas first observed only in 2012. The measurement of ~(14)Be in coincidence with two neutrons suggests that ~(16)Be does decay through the simultaneous emission of two strongly correlated neutrons. Purpose: In this work, we construct a full three-body model of ~(16)Be (as ~(14)Be+n + n) in order to investigate its configuration in the continuum and, in particular, the structure of its ground state. Method: In order to describe the three-body system, effective n-~(14)Be potentials were constructed, constrained by the experimental information on ~(15)Be. The hyperspherical R-matrix method was used to solve the three-body scattering problem, and the resonance energy of ~(16)Be was extracted from a phase-shift analysis. Results: In order to reproduce the experimental resonance energy of ~(16)Be within this three-body model, a three-body interaction was needed. For extracting the width of the ground state of ~(16)Be, we use the full width at half maximum of the derivative of the three-body eigenphase shifts and the width of the three-body elastic scattering cross section. Conclusions: Our results confirm a dineutron structure for ~(16)Be, dependent on the internal structure of the subsystem ~(15)Be.