Total reaction and neutron-removal cross sections of (30-60)A MeV He and Li isotopes on Pb - art. no. 024608

Total reaction cross sections sigma(R) of (30-60)A MeV He-4,He-6,He-8 and L i-6,Li-7,Li-8,Li-9,Li-11 on Ph, and 2n-removal cross sections sigma-(2n) of He-6,He-8 and Li-11 on Pb, were measured by injecting magnetically separat ed, focused, monoenergetic, secondary beams of those projectiles into a tel escope containing Pb targets separated by thin Si detectors. All these sigm a(R)'s (except He-4), and sigma-(2n) for He-6 and Li-11, are underpredicted by microscopic model calculations which include only nuclear forces. Bette r agreement is achieved by including electromagnetic dissociation in the mo del, for those projectiles for which either the electric dipole response fu nctions or the dominant photodissociation cross sections were known. The cr oss sections sigma-(4n) for He-8, sigma-(xn) for Li-7,Li-8,Li-9, and (sigma -(3n)+ sigma-(4n)) for Li-11 were found to be less than or equal to 0.7 b. All sigma(R)'s were measured to better than 5% accuracy, showing that the m ethod is usable for other target elements sandwiched into a Si telescope.