Experimental study of the halo nucleus He6 using the Li6(γ,π+)He6 reaction

The reaction {sup 6}Li({gamma},{pi}{sup +}){sup 6}He was studied over the angular range {theta}{sub {pi}}=40-150 degree sign with the aim of investigating the halo structure of {sup 6}He. Photons from a bremsstrahlung beam were tagged in the energy range E{sub {gamma}}=170-220 MeV at a resolution of {delta}E{sub {gamma}}=630 keV, and positively charged pions detected using high resolution stacked HpGe detectors. The measured angular distributions for the resolved {sup 6}He ground and 1.80 MeV excited states are compared to previous measurements and theoretical calculations based on the impulse approximation. It is deduced that the ground state rms radius of the {sup 6}He nucleus may be larger than previously thought and that the first excited 1.80 MeV state may also be a halo state.