Exclusive measurement of breakup reactions with the one-neutron halo nucleus11Be

Abstract

Electromagnetic and nuclear inelastic scattering of the halo nucleus ${}^{11}\mathrm{Be}$ have been investigated by a measurement of the one-neutron removal channel, utilizing a secondary ${}^{11}\mathrm{Be}$ beam with an energy of 520 MeV/nucleon impinging on lead and carbon targets. All decay products, i.e., ${}^{10}\mathrm{Be}$ fragments, neutrons, and $\gamma$ rays have been detected in coincidence. Partial cross sections for the population of ground and excited states in ${}^{10}\mathrm{Be}$ were determined for nuclear diffractive breakup as well as for electromagnetically induced breakup. The partial cross sections for ground-state transitions have been differentiated further with respect to excitation energy, and the dipole-strength function associated solely with transitions of the halo ${2s}_{1/2}$ neutron to the continuum has been derived. The extracted dipole strength integrated from the neutron threshold up to 6.1 MeV excitation energy amounts to ${0.90\left(6\right)e}^2{\mathrm{fm}}^2.$ A spectroscopic factor for the $\nu {2s}_{1/2}{\otimes }^{10}\mathrm{Be}{(0\mathrm{}}^{+})$ single-particle configuration of 0.61(5) and a root-mean-square radius of the ${2s}_{1/2}$ neutron wave function of 5.7(4) fm have been deduced.