We measured the betatron oscillation in a phase space near the vertical third-order resonance in the Photon Factory electron storage ring. In the measurement, the fast kicker magnets and the phase space monitor system were employed. Since the vertical resonance is non-structural one, it seemed that its strength was rather week. However, under a certain experimental condition, the stable resonance island was displayed on the phase space. In addition, we observed the island behavior with varying the octupole magnetic field strength. In this paper, we introduce the experimental method and result, and the discussion about the sources of the vertical third-order resonance.

This article introduces KEKB B-factory, which is an asymmetric-energy, two-ring, electron-positron collider for B-physics. The article covers its history, basic scheme and main features, achievements, and the competition with PEP–II, a B-factory at SLAC. SuperKEKB, an upgrade plan of KEKB, is also described.

Through an intimate collaboration, the AIST and the NIRS has succeeded in generating quasimonoenergetic electron beam of 7 MeV energy from a 0.5 mm-long plasma by irradiating a laser pulse of 2 TW for 50 fs to a plasma of electron density as high as 10²⁰ cm^－3, which is an order of magnitude higher than that for the previous experiments. An evidence to demonstrate electron being accelerated by plasma wave has been obtained by diagnosing the laser plasma interaction. While the generation of monoenergetic electron beam with a laser plasma accelerator has been regarded unavailable up to now, the success in this study will provide a great step toward the practical use of the laser plasma accelerator.