Anisotropic momentum distribution of 11B and 11C produced from 12C beam at 100 MeV/nucleon

Abstract

Longitudinal (P L) and transverse (P T) momentum distributions of 11B and 11C produced from a 12C beam with C, Al, Nb, Tb, and Au targets observed at E = 100 MeV/nucleon are investigated. The observed P T distribution systematically changes according to the target and this change in behavior can be consistently explained by the orbital deflection effect, which is determined by the competitive contributions of attractive nuclear and repulsive Coulomb potentials acting between the projectile and target. The comprehensive examination of the observed P L and P T distributions resolves the fragmentation reaction into two reaction channels. One is the pure abrasion channel, which is characterized by small momentum transfer and an isotropic Gaussian function. The second is the two-step reaction channel, which is characterized by large momentum transfer and an anisotropic Gaussian function. The anisotropy of the second channel is consistently explained by the momentum of a picked-up nucleon.