Limitations of the distorted-wave impulse approximation in describing the energy dependence of the 10B(n,p)10Be (g.s.) reaction

We report differential cross section measurements for the stretched transition from the 10B ground state (Jπ=3+) to the 10Be ground state (Jπ=0+) in the 10B(n,p)10Be (g.s.) reaction. These data were obtained over the energy range from 70 to 240 MeV, covering momentum transfer values from 0.6 to 2.5 fm-1. In this momentum transfer range, the isovector tensor effective interaction dominates the transition. Cross sections are compared to zero- and finite-range distorted wave impulse approximation calculations using modern free and density-dependent effective interactions and a transition density consistent with (e,e') data. Good agreement is observed at energies above 120 MeV, but below this energy the cross sections are larger than the calculated values by more than 40%. The implications for DWIA calculations are discussed