Stevenson, M.Lohmann, B.2008-06-202008-06-202008Physical Review A: Atomic, Molecular and Optical Physics, 2008; 77(3):032708-01-032708-061050-29471094-1622http://hdl.handle.net/2440/45506The triple differential cross section for electron-impact ionization of the 3p orbital of argon by 113.5 eV incident electrons has been measured using a magnetic angle changer in a conventional (e,2e) spectrometer. Results are presented for 2 eV ejected electrons over an extended angular range, and over the complete coplanar scattering plane for 5 eV ejected electrons. The data reveal previously unobserved structures, and are compared with recent distorted-wave Born approximation (DWBA) and hybrid DWBA R-matrix calculations. Large discrepancies exist between experiment and both calculations in the accessed regions.en© 2008 The American Physical SocietyJournal article00200804612008062016010410.1103/PhysRevA.77.0327080002545411001142-s2.0-4094911456143587