Differential cross sections for electron capture from argon by 6-MeV protons

Differential cross sections for the capture of electrons from argon by 6-MeV protons have been measured as a function of the hydrogen-atom scattering angle between 0.020 and 0.140. Cross sections were measured for capture from all shells and from the argon K shell alone. The differential cross section for K-shell capture does not agree with theoretical results obtained using either the Oppenheimer--Brinkman--Kramers approximation or a Born calculation which includes a contribution from the core--core interaction