Exotic radiation from a photonic crystal excited by an ultra-relativistic electron beam

We report the observation of an exotic radiation (unconventional Smith-Purcell radiation) from a one-dimensional photonic crystal. The physical origin of the exotic radiation is direct excitation of the photonic bands by an ultra-relativistic electron beam. The spectrum of the exotic radiation follows photonic bands of a certain parity, in striking contrast to the conventional Smith-Purcell radiation, which shows solely a linear dispersion. Key ingredients for the observation are the facts that the electron beam is in an ultra-relativistic region and that the photonic crystal is finite. The origin of the radiation was identified by comparison of experimental and theoretical results.Comment: 4 pages, 5 figure

Status Report of LNS Accelerator Complex in 2002(IV. Status Report of LNS Accelerator Complex in 2002)

Operation status of an electron accelerator complex at Laboratory of Nuclear Science, Tohoku University is reported. After a completion of a new building containing an experimental vault, the inspection for the radiation safety was done in the beginning of October, 2003, so that most of user machine time was consumed in the latter half of the fiscal year 2002

Optimum Arrangement of Resonator in Micro-bunch Free Electron Laser(III. Accelerator, Synchrotron Radiation, and Instrumentation)

Using a short-bunched beam of electrons from a linear accelator, the output of the micro-bunch FEL has been studied experimentally to clarify the optimum arrangement of an open resonator on the electron orbit. The output depends sharply on the arrangement, and the maximum output is observed when the resonator axis intersects the electron orbit with the angle of 3°

Status Report of LNS Accelerator Complex in 2001(IV. Status Report of LNS Accelerator Complex in 2001)

The electron accelerator complex at the Laboratory of Nuclear Science, Tohoku University has been operated for various fields of science. A 35-year-old 300 MeV electron linac is still working well. However troubles due to aging is rapidly getting serious. In addition, because of multi-purpose use of the linac many different beam characteristics are requested by the users, so that the operation mode has been complicate. In this report, the operation status of the accelerator complex including major troubles experienced in the fiscal year 2001 is described and future plan is shortly discussed by showing the present machine operation

Measurement of the forward-backward asymmetries for charm- and bottom-quark pair productions at <s><\sqrt{s}>=58GeV with electron tagging

We have measured, with electron tagging, the forward-backward asymmetries of charm- and bottom-quark pair productions at $$=58.01GeV, based on 23,783 hadronic events selected from a data sample of 197pb$^{-1}$ taken with the TOPAZ detector at TRISTAN. The measured forward-backward asymmetries are $A_{FB}^c = -0.49 \pm 0.20(stat.) \pm 0.08 (sys.)$ and $A_{FB}^b = -0.64 \pm 0.35(stat.) \pm 0.13 (sys.)$, which are consistent with the standard model predictions.Comment: 19 pages, Latex format (article), 5 figures included. to be published in Phys. Lett.

Achievements of Hinode in the first eleven years

Hinode is Japan’s third solar mission following Hinotori (1981–1982) and Yohkoh (1991–2001): it was launched on 2006 September 22 and is in operation currently. Hinode carries three instruments: the Solar Optical Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These instruments were built under international collaboration with the National Aeronautics and Space Administration and the UK Science and Technology Facilities Council, and its operation has been contributed to by the European Space Agency and the Norwegian Space Center. After describing the satellite operations and giving a performance evaluation of the three instruments, reviews are presented on major scientific discoveries by Hinode in the first eleven years (one solar cycle long) of its operation. This review article concludes with future prospects for solar physics research based on the achievements of Hinode

Achievements of Hinode in the first eleven years

Hinode is Japan’s third solar mission following Hinotori (1981–1982) and Yohkoh (1991–2001): it was launched on 2006 September 22 and is in operation currently. Hinode carries three instruments: the Solar Optical Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These instruments were built under international collaboration with the National Aeronautics and Space Administration and the UK Science and Technology Facilities Council, and its operation has been contributed to by the European Space Agency and the Norwegian Space Center. After describing the satellite operations and giving a performance evaluation of the three instruments, reviews are presented on major scientific discoveries by Hinode in the first eleven years (one solar cycle long) of its operation. This review article concludes with future prospects for solar physics research based on the achievements of Hinode

Production of gamma rays by pulsed laser beam Compton scattering off GeV-electrons using a non-planar four-mirror optical cavity

As part of the positron source R&D for future $e^+-e^-$ colliders and Compton based compact light sources, a high finesse non-planar four-mirror Fabry-Perot cavity has recently been installed at the ATF (KEK, Tsukuba, Japan). The first measurements of the gamma ray flux produced with a such cavity using a pulsed laser is presented here. We demonstrate the production of a flux of 2.7 $\pm$ 0.2 gamma rays per bunch crossing ($\sim3\times10^6$ gammas per second) during the commissioning