[en] Using a short-bunched beam of electrons from a linear accelerator, 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 3deg. (author)

[en] The decay of low energy isomeric state of ²²⁹Th was explored applying a novel radiochemical technique to the (γ, xn) reaction products on ²³⁰Th target. The decaying α-emitter was observed between 4.687 MeV α-peak of ²³⁰Th and the α-peaks of the (γ, 2n) product ²²⁸Th. The energy of the decaying component is consistent with the expected energy for the α-particles from ^229mTh. The half-life of the decaying component was determined to be 13.9±3 hours. It seems that the present determination of the half-life is the longest value for ^229mTh, because fluoride has no valence electrons that undergo electronic bridge interaction with the thorium nucleus. (author)

[en] The formation of Se atom-incorporated fullerenes has been investigated by using radionuclides produced by nuclear reactions. From the trace of radioactivities of ⁷⁵Se after High Performance Liquid Chromatography (HPLC), it was found that the formation of endohedral fullerenes or hetrofullerenes is possible by a recoil process following the nuclear reaction. To confirm the produced materials, ab initio molecular-dynamics simulations based on an all-electron mixed-basis approach were carried out. We found that the insertion of Se atom into C₆₀ cage is much easier than that of As and Ge atoms. (author)

[en] A compact silica aerogel Cherenkov counter with fine-mesh type photo-multiplier tubes has been developed to reject e⁺e^- pair created events at a trigger level. The silica aerogel is covered with a highly reflective material to lead emitted Cherenkov photons into the photo-cathodes. The efficiency of e⁺e^- event identification is obtained to be more than 97%. (author)

[en] A new electro-magnetic (EM) calorimeter complex FOREST consists of three independent calorimeters, covering a solid angle of about 4π sr in total. An SF-5 lead glass Cerenkov counter array Rafflesia II is employed to cover backward angles from 110 to 170 degrees of FOREST. The energy resolution of the SF-5 counter has been measured using a positron beam with energies up to 800 MeV. (author)

[en] A dipole electromagnet RTAGX has been installed in the GeV-γ experimental hall. It sweeps out charged particles contaminated in the incident γ beam for meson photo-production experiments. It also supplies momentum-analyzed electrons or positrons in a newly constructed test beamline. (author)

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No abstract available

[en] Coherent radiation emitted from a Photonic crystal of a cylindrical tube of Teflon with periodic grooves is observed in the millimeter wave region. The observed spectra show a sharp peak at frequency of 4.625 cm^-1. The inter-bunch coherence of the radiation is confirmed with an interferometer. (author)

[en] We have successfully measured neutral kaons, bombarding a liquid deuterium target with a photon beam in the threshold region from 0.8 to 1.1 GeV. It was the first data for K⁰ photoproduction on the deuteron in this energy region. The momentum spectra of K⁰ production were compared with theoretical spectra calculated assuming isobar models for the elementary process and a realistic deuteron wave function for the target nucleus. The present experiment has demonstrated a usefulness of the neutral kaon measurement for the investigation of photo strangeness production reactions. (author)