Triple differential cross section of rare gas atoms in different low energy kinematics

Triple differential cross sections have been measured for the electron-impa ct ionization of rare gases in two coplanar geometries. Results are present ed for 20 eV excess energy with respect to ionization threshold for ionizat ion of helium, neon and argon. These enable us to investigate the target de pendence of triple differential cross section angular-distributions. For io nization of helium, we compare our absolute measurements with the convergen t close coupling calculations whereas, for ionization of neon and argon, th e comparison is made with the distorted wave Born approximation calculation s. Additional measurements carried out on argon near threshold are also pre sented.