An experiment of X-ray photon–photon elastic scattering with a Laue-case beam collider

• Published in: Physics letters. B Vol. 763; pp. 454 - 457
• Main Authors: Yamaji, T., Inada, T., Yamazaki, T., Namba, T., Asai, S., Kobayashi, T., Tamasaku, K., Tanaka, Y., Inubushi, Y., Sawada, K., Yabashi, M., Ishikawa, T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10-12-2016; Elsevier
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2016.11.003

We report a search for photon–photon elastic scattering in vacuum in the X-ray region at an energy in the center of mass system of ωcms=6.5keV for which the QED cross section is σQED=2.5×10−47m2. An X-ray beam provided by the SACLA X-ray Free Electron Laser is split and the two beamlets are made to collide at right angle, with a total integrated luminosity of (1.24±0.08)×1028m−2. No signal X rays from the elastic scattering that satisfy the correlation between energy and scattering angle were detected. We obtain a 95% C.L. upper limit for the scattering cross section of 1.9×10−27m2 at ωcms=6.5keV. The upper limit is the lowest upper limit obtained so far by keV experiments.