Molecular structures in T=1 states of B-10

Background: Multicenter (molecular) structures can play an important role in light nuclei. The highly deformed rotational band in Be-10 with a bandhead at 6.179 MeV has been observed recently and suggested to have an exotic alpha:2n:alpha configuration. Purpose: Search for states with alpha:pn:alpha two-center molecular configurations in B-10 that are analogous to the states with alpha:2n:alpha structure in Be-10. Methods: The T = 1 isobaric analog states in B-10 were studied in the energy range of E-x = 8.7-12.1MeV using the reaction H-1(Be-9,alpha)Li-6*(T = 1, 0(+), 3.56 MeV). An R-matrix analysis was used to extract parameters for the states observed in the (p, alpha) excitation function. Results: Five T = 1 states in B-10 have been identified. The known 2(+) and 3(-) states at 8.9 MeV have been observed and their partial widths have been measured. The spin parities and partial widths for three higher-lying states were determined. Conclusions: Our data support theoretical predictions that the 2(+) state at 8.9 MeV (isobaric analog of the 7.54-MeV state in Be-10) is a highly clustered state and can be identified as a member of the alpha:np:alpha rotational band. The next member of this band, the 4(+) state, has not been found. A very broad 0(+) state at 11 MeV that corresponds to pure alpha + Li-6(0(+), T = 1) configuration is suggested and it might be related to similar structures found in C-12, O-18, and Ne-20.