While diproton decay was first theorized in 1960 and first measured in 2002, it was 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. 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. 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. 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 phase shifts and the width of the three-body elastic scattering cross section. Our results confirm a dineutron structure for $^{ 16}$Be, dependent on the internal structure of the subsystem $^{ 15}$Be.
Categories: nucl-th