Proton scattering by the unstable neutron-rich isotopes ^42,44Ar

Elastic and inelastic proton scattering to the 2₁⁺ states of the neutron-rich argon isotopes ⁴²Ar and ⁴⁴Ar have been measured in inverse kinematics with a beam energy of 33 MeV/nucleon. Phenomenological distorted wave Born approximation calculations are compared with the data and quadrupole deformation parameters of |β₂|=0.32±0.05 and |β₂|=0.31±0.05 are extracted for the 2₁⁺ states in ⁴²Ar and ⁴⁴Ar, respectively. A consistent microscopic proton scattering analysis has been applied to all even-even argon isotopes from A=36 to A=44. This analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux nucleon-nucleon effective interaction. The predicted cross sections agree very well with the experimental data, suggesting this microscopic analysis as a tool to test the structure of nuclei far from stability.