MULTI-STEP POST-COLLISION INTERACTION EFFECTS IN Kr K-SHELL PHOTOIONIZATION T. Hayaishi*, Y. Fujita*, M. Izumisawa*, T. Tanaka**, E. Murakami#, E. Shigemasa##, A. Yagishita## and Y. Morioka** *Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan #Department of Physics, Chiba Institute of Technology, Narashino, Chiba 275-0023, Japan **Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan #Photon Factory, National Laboratory for High Energy Physics, Tsukuba 305-0801, Japan Yield spectra of multiply charged ions produced by Auger cascades following Kr K-shell photoionization have been measured by a threshold photoelectron-ion coincidence technique. These observed yield spectra exhibit characteristic profiles of multi-step post-collision interaction effects induced by the Auger cascades.