Total reaction and neutron-removal cross sections of (30–60)A MeV He and Li isotopes on Pb

Total reaction cross sections σ_R of (30–60)A MeV ^4,6,8He and ^6,7,8,9,11Li on Pb, and 2n-removal cross sections σ_-2n of ^6,8He and ¹¹Li on Pb, were measured by injecting magnetically separated, focused, monoenergetic, secondary beams of those projectiles into a telescope containing Pb targets separated by thin Si detectors. All these σ_R’s (except ⁴He), and σ_-2n for ⁶He and ¹¹Li, are underpredicted by microscopic model calculations which include only nuclear forces. Better agreement is achieved by including electromagnetic dissociation in the model, for those projectiles for which either the electric dipole response functions or the dominant photodissociation cross sections were known. The cross sections σ_-4n for ⁸He, σ_-xn for ^7,8,9Li, and (σ_-3n+σ_-4n) for ¹¹Li were found to be ⩽0.7 b. All σ_R’s were measured to better than 5% accuracy, showing that the method is usable for other target elements sandwiched into a Si telescope.