Abstract
We investigate to what extent a description of as a three-body system made of an inert core and two neutrons is able to reproduce the experimental data. Three-body wave functions are obtained with the hyperspherical adiabatic expansion method. We study the discrete spectrum of , the structure of the different states, the predominant transition strengths, and the continuum energy spectrum after high-energy fragmentation on a light target. Two , one , one , and one bound states are found; the first four are known experimentally, whereas the is predicted as an isomeric state. An effective neutron charge, reproducing the measured transition and the charge rms radius in , leads to a computed transition strength for in agreement with the experimental value. For the and transitions, the contributions from core excitations could be more significant. The experimental -neutron continuum energy spectrum is also well reproduced, except in the energy region corresponding to the resonance in where core excitations contribute.
2 More- Received 5 December 2007
DOI:https://doi.org/10.1103/PhysRevC.77.054313
©2008 American Physical Society