A Crossed photon-atom beam method for absolute measurement of total photoionization cross sections on isolated metal atoms; Measurements on Ba and Eu atoms

Obara, Satoshi*; Kobayashi, Ryoei*; Yagi, Shuichi*; Toyama, Yuko*; Kutluk, G.*; Osawa, Tetsutaro*; Ogura, Koichi; Shibata, Takemasa; Azuma, Yoshiro*; Nagata, Tetsuo*

A crossed photon-atom beam apparatus has been constructed for absolute measurement of total photoionization cross sections of isolated and neutral metallic atoms. Using this apparatus, measurements on Ba and Eu atoms have been made at their 4d giant resonance regions 110-140 eV and 140-180 eV, respectively. The target atom density was determined using the deposition rate on a quartz crystal sensor and the average velocity of the atoms obtained by a time-of-flight method combined with a pulsed electron gun. The number of photons was determined with use of a double ion chamber. The comparison of the measured cross-section values with previous experimental and theoretical results is reasonable, indicating that the crossed photon-atom beam method is fairly promising technique.