PHOTON W-VALUES FOR Ar IN THE SOFT X-RAY REGION Norio Saito and Isao H. Suzuki Electrotechnical Laboratory, Umezono, Tsukuba, Ibaraki 305-8568 Japan Photon W-values for Ar in the region of 50-1000 eV have been measured using a multiple ion chamber and the data on mean charge states of Ar. The obtained photon W-values are reproduced with a model proposed here, which includes multiple photoionization effects, together with utilization of the previous data of Ar W-values for electrons with low kinetic energies. Abstract and Related Information