476 research outputs found

    Lidar observation of ozone over Tsukuba (36 deg N, 140 deg E)

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    An ozone lidar system was installed at the National Institute for Environmental Studies (NIES) in Tsukuba, Japan in March 1988 and has been measuring vertical profiles of ozone (15 - 45 km) since September 1988. The lidar system consists of a XeCl (308 nm) excimer laser, its deuterium Raman shifter (339 nm), a XeF excimer laser (351 nm), a 2 m telescope, a receiving system and a data processing system. The precision of the derived ozone concentration is about 10 percent of an altitude of 40 km for a 4 hr observation. Temperature profiles (30 - 80 km) are also obtained from the Rayleigh scattering signals at 351 nm. Approximate 50 ozone measurements are carried out in a year and variations of vertical profiles of ozone such as seasonal variations and shorter-term variations are observed. Systematic errors due to aerosols had been negligible until the arrival of the stratospheric aerosols injected by the eruption of Mt. Pinatubo. Effects of the volcanic aerosols on ozone measurements depend on the differences between wavelengths used as the on- and off-resonance

    Precision measurement of vector and tensor analyzing powers in elastic deuteron-proton scattering

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    High precision vector and tensor analyzing powers of elastic deuteron-proton d+p scattering have been measured at intermediate energies to investigate effects of three-nucleon forces (3NF). Angular distribution in the range of 70-120 degree in the center-of mass frame for incident-deuteron energies of 130 and 180 MeV were obtained using the RIKEN facility. The beam polarization was unambiguously determined by measuring the 12C(d,alpha)10B(2+) reaction at 0 degree. Results of the measurements are compared with state-of-the-art three-nucleon calculations. The present modeling of nucleon-nucleon forces and its extension to the three-nucleon system is not sufficient to describe the high precision data consistently and requires, therefore, further investigation

    Performance of the neutron polarimeter NPOL3 for high resolution measurements

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    We describe the neutron polarimeter NPOL3 for the measurement of polarization transfer observables DijD_{ij} with a typical high resolution of \sim300 keV at TnT_n \simeq 200 MeV. The NPOL3 system consists of three planes of neutron detectors. The first two planes for neutron polarization analysis are made of 20 sets of one-dimensional position-sensitive plastic scintillation counters with a size of 100 cm ×\times 10 cm ×\times 5 cm, and they cover the area of 100 ×\times 100 cm2\mathrm{cm}^2. The last plane for detecting doubly scattered neutrons or recoiled protons is made of the two-dimensional position-sensitive liquid scintillation counter with a size of 100 cm ×\times 100 cm ×\times 10 cm. The effective analyzing powers Ay;effA_{y;\mathrm{eff}} and double scattering efficiencies ϵD.S.\epsilon_{\mathrm{D.S.}} were measured by using the three kinds of polarized neutrons from the 2H(p,n)pp{}^{2}{\rm H}(\vec{p},\vec{n})pp, 6Li(p,n)6Be(g.s.){}^{6}{\rm Li}(\vec{p},\vec{n}){}^{6}{\rm Be}(\mathrm{g.s.}), and 12C(p,n)12N(g.s.){}^{12}{\rm C}(\vec{p},\vec{n}){}^{12}{\rm N}(\mathrm{g.s.}) reactions at TpT_p = 198 MeV. The performance of NPOL3 defined as ϵD.S.(Ay;eff)2\epsilon_{\mathrm{D.S.}}(A_{y;\mathrm{eff}})^2 are similar to that of the Indiana Neutron POLarimeter (INPOL) by taking into account for the counter configuration difference between these two neutron polarimeters.Comment: 28 pages, 18 figures, submitted to Nucl. Instrum. Methods Phys. Res.

    Analyzing power for the proton elastic scattering from neutron-rich 6He nucleus

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    Vector analyzing power for the proton-6He elastic scattering at 71 MeV/nucleon has been measured for the first time, with a newly developed polarized proton solid target working at low magnetic field of 0.09 T. The results are found to be incompatible with a t-matrix folding model prediction. Comparisons of the data with g-matrix folding analyses clearly show that the vector analyzing power is sensitive to the nuclear structure model used in the reaction analysis. The alpha-core distribution in 6He is suggested to be a possible key to understand the nuclear structure sensitivity.Comment: 5 pages, 3 figures, accepted for publication as a Rapid Communication in Physical Review

    Search for point sources of neutrinos with KGF underground muon detectors

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    The proton decay detectors operated underground in the Kolar Gold Fields in India during 1980-1993 have recorded a large number of muon events. Out of these, 243 large zenith angle events were selected as being due to muons arising from neutrino interactions in the surrounding rock. This selection was based on the different zenith angular distributions of the atmospheric and neutrino-induced muons. These selected events are analysed here to look for powerful point sources of neutrinos