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松浦 直人*; 川北 至信; 山田 武*; 富永 大輝*; 玉造 博夢; 中川 洋; 大内 啓一*
no journal, ,
DNA is a time-of-flight backscattering spectrometer installed at the Materials and Life Science Experimental Facility (MLF) in Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Its purpose is revealing pico to nano second dynamics in a wide field of sciences and industrial applications including soft matter, bio-molecules, chemical molecules, battery, catalyst, and magnetism. A pulse-shaping chopper equipped at the 7.75 m position from the coupled moderator makes this instrument relatively short in the neutron guide length (42 m from the moderator to the sample position). Its maximum rotation speed of 300 Hz provides us fine energy resolutions up to 1.4 micro second for a sample with dimension of 1 cm wide and 1cm tall. Changing phases of the slit opening of the chopper enables us to select energy bands and even to scan a wide energy transfer range with the highest resolution. Two types of analyzer mirrors of Si111 and Si311 cover large momentum transfer ranges of 0.08 to 1.98 and 1.79 to 3.39
, respectively. Frequently used measurement modes are a high-flux mode without rotating the chopper and a high-resolution mode with 225 Hz. Those provides 12 and 3.6 micro eV energy resolutions for a large sample of 1.4 cm wide and 4 cm tall. The back-coat by neutron absorber such as Gd and Gd
O
for Si analyzer mirrors serves us in realizing extremely high signal-to-noise ratio of
, which allows us to obtain QENS spectra from a tiny amount of sample or a dilute protein solution. Various conditions of sample environment are available; cryo-furnaces (4 K to 700 K), a 2K cryostat, a top-loading sample stick for applying electric field, a humidity control system, a cryostat with a samples changer for three samples, an inner atmosphere controller for cryo-furnaces and so on. A high temperature furnace up to 1000K, 3.5 Tesla cryo-magnet and a sample changer for 20 samples are under commissioning.
柴田 薫
no journal, ,
飛行時間型背面反射分光器DNAはJ-PARCセンター物質生命科学実験施設MLF中性子源に建設され2012年から測定を開始した。DNA分光器はパルス整形のため高速回転ダブルディスクチョッパーを備えた入射パルス幅を調整可能な背面反射分光器として、世界中のスポレーションパルス中性子源に設置されている装置の中でユニークな装置となっている。一方中性子吸収剤を背面に不塗布したSi結晶アナライザーはバックグランド散乱を低減させS/N比は~100,000.を達成している。これらの性能向上により、ナノ秒時間スケールまたはeVエネルギー範囲の生体高分子、機能性物質、強相関電子系の原子、スピン運動まで研究分野を広げている。これらのDNA分光器の特質すべき性能とその研究応用成果について発表予定である。