134 research outputs found
Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --
Twelve high schools in Japan (of which six are in Fukushima Prefecture), four
in France, eight in Poland and two in Belarus cooperated in the measurement and
comparison of individual external doses in 2014. In total 216 high-school
students and teachers participated in the study. Each participant wore an
electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of
his/her whereabouts and activities. The distributions of annual external doses
estimated for each region overlap with each other, demonstrating that the
personal external individual doses in locations where residence is currently
allowed in Fukushima Prefecture and in Belarus are well within the range of
estimated annual doses due to the background radiation level of other
regions/countries
Search for Dark Matter WIMPs using Upward Through-going Muons in Super-Kamiokande
We present the results of indirect searches for Weakly Interacting Massive
Particles (WIMPs) with 1679.6 live days of data from the Super-Kamiokande
detector using neutrino-induced upward through-going muons. The search is
performed by looking for an excess of high energy muon neutrinos from WIMP
annihilations in the Sun, the core of the Earth, and the Galactic Center, as
compared to the number expected from the atmospheric neutrino background. No
statistically significant excess was seen. We calculate flux limits in various
angular cones around each of the above celestial objects. We obtain
conservative model-independent upper limits on WIMP-nucleon cross-section as a
function of WIMP mass and compare these results with the corresponding results
from direct dark matter detection experiments.Comment: 10 pages, 14 figures, Submitted to Phys. Rev.
Limit On the Neutrino Magnetic Moment Using 1496 Days of Super-Kamiokande-i Solar Neutrino Data
A search for a non-zero neutrino magnetic moment has been conducted using
1496 live days of solar neutrino data from {\SK}. Specifically, we searched for
distortions to the energy spectrum of recoil electrons arising from magnetic
scattering due to a non-zero neutrino magnetic moment. In the absence of clear
signal, we found at 90% C.L. by
fitting to the Super-Kamiokande day/night spectra. The fitting took into
account the effect of neutrino oscillation on the shapes of energy spectra.
With additional information from other solar neutrino and KamLAND experiments
constraining the oscillation region, a limit of at 90% C.L. was obtained.Comment: 5 pages, 4 figure
Study of double pion photoproduction on the deuteron
AbstractThe Ï+Ïâ photoproductions on the proton and deuteron have been studied in a photon energy range of 0.8â1.1 GeV at the Laboratory of Nuclear Science, Tohoku University. Charged pions and protons were detected using Neutral Kaon Spectrometer. We obtained the cross sections for the p(Îł,pÏ+Ïâ) and d(Îł,pÏ+Ïâ)n. The quasi-free process with a neutron spectator was extracted by the neutron momentum cut of pn>0.3 GeV/c. The cross section for the Î++Îâ production was deduced in the non-quasi-free process of the ÎłdâpnÏ+Ïâ. It was 13.4±0.4 Όb at EÎł=0.82 GeV
Magnetic-susceptibility and specific-heat studies on the inhomogeneity of superconductivity in the underdoped La_2-x_Sr_x_CuO_4_
The possible inhomogeneity of superconductivity has been investigated by
means of bulk-sensitive probes, using La_2-x_Sr_x_CuO_4_ (LSCO) single crystals
from the underdoped to optimally doped regime. Measurements of the magnetic
susceptibility, chi, on field cooling and specific heat have revealed that both
the absolute value of chi at 2 K, regarded as corresponding to the
superconducting (SC) volume fraction in a sample, and the Sommerfeld constant,
reflecting the density of states of quasiparticles at the Fermi level, exhibit
significant dependence on x, namely, on the hole concentration. This is the
first experimental work strongly suggesting that a phase separation into SC and
normal-state regions takes place in the underodped regime of LSCO as well as in
the overdoped regime.Comment: 7 pages, 4 figures, the version 2 has been accepted for publication
in J. Phys. Soc. Jp
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