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Search for GUT monopoles at Super-Kamiokande
The Super-Kamiokande Collaboration,Ueno, K.,Abe, K.,Hayato, Y.,Iida, T.,Iyogi, K.,Kameda, J.,Koshio, Y.,Kozuma, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Sekiya, H.,Shiozawa, M. North-Holland ; Elsevier Science Ltd 2012 Astroparticle physics Vol.36 No.1
GUT monopoles captured by the Sun's gravitation are expected to catalyze proton decays via the Callan-Rubakov process. In this scenario, protons, which initially decay into pions, will ultimately produce ν<SUB>e</SUB>,ν<SUB>μ</SUB> and ν@?<SUB>μ</SUB>. After undergoing neutrino oscillation, all neutrino species appear when they arrive at the Earth, and can be detected by a 50,000 metric ton Water Cherenkov detector, Super-Kamiokande (SK). A search for low energy neutrinos in the electron total energy range from 19 to 55MeV was carried out with SK and gives a monopole flux limit of F<SUB>M</SUB>(σ<SUB>0</SUB>/1mb)<6.3x10<SUP>-24</SUP>(β<SUB>M</SUB>/10<SUP>-3</SUP>)<SUP>2</SUP>cm<SUP>-2</SUP>s<SUP>-1</SUP>sr<SUP>-1</SUP> at 90% C.L., where β<SUB>M</SUB> is the monopole velocity in units of the speed of light and σ<SUB>0</SUB> is the catalysis cross section at β<SUB>M</SUB>=1. The obtained limit is several orders of magnitude more stringent than the current best cosmic-ray supermassive monopole flux limit for β<SUB>M</SUB><10<SUP>-2</SUP> and also two orders of magnitude lower than the result of the Kamiokande experiment, which used a similar detection method.
Phonon echoes in Si:P at very low temperature
Jeong, M,Song, M,Ueno, T,Mizusaki, T,Matsubara, A,Lee, S Institute of Physics 2009 Journal of physics. Conference series Vol.150 No.4
<P>We observed phonon echoes in P-doped Si (Si:P) at very low temperatures. We applied two radio-frequency pulses separated by a time delay of τ on Si:P and observed echo signal at <I>t</I> &equal; 2τ in both insulating and metallic samples with varying dopant concentrations and of different sample forms of powders and bulk plates at temperature between 45 mK and 4 K. The echoes were much more pronounced in insulating powder samples than in metallic ones and in bulk ones. The echo intensity for a fixed τ increased very strongly as temperature was lowered but the echoes disappeared toward the superfluid-to-normal transition temperature of helium mixture in which the samples were immersed. We observed no appreciable change in the echo intensities as external magnetic field was varied up to 8 T. The echoes are interpreted to be dynamical polarization phonon echoes in piezoelectric powders of insulating Si:P with a dopant concentration <I>n</I> &equal; 6 x 10<SUP>17</SUP> cm<SUP>-3</SUP>.</P>
RETRIEVAL OF LOCAL INTERPLANETARY DUST EMISSIVITY BY ASTRO-F
HONG S. S.,KWON S. M.,PYO J.,UENO M.,ISHIGURO M.,USUI F.,WEINBERG J. L. The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.4
This is a proposal to probe local part of the interplanetary dust (IPD) cloud complex and retrieve mean volume emissivity of the local IPDs at mid-infrared wavelengths. This will be done by monitoring, with Infrared Camera (IRC) aboard the ASTRO-F, the annual modulation of the zodiacal emission. In pointing mode of the ASTRO-F mission the spacecraft can make attitude maneuvering over approximately ${\pm}1^{\circ}$ range centered at solar elongation $90^{\circ}$ in the ecliptic plane. The attitude maneuvering combined with high sensitivity of the IRC will provide us with a unique opportunity observationally to take derivatives of the zodiacal emission brightness with respect to the solar elongation. From the resulting differential of the brightness over the ${\pm}1^{\circ}$ range, one can directly determine the mean volume emissivity of the local IPDs with a sufficient accuracy to de-modulate the annual emissivity variations due to the Earth's elliptical motion and the dis-alignment of the maximum IPD density plane with respect to the ecliptic. The non-zero eccentricity ($e_{\oplus}$= 0.0167) of the Earth's orbit combined with the sensitive temperature dependence of the Planck function would bring modulations of amplitude at least $3.34\%$ to the zodiacal emission brightness at mid-infrared wavelengths, with which one may determine the IPD temperature T(r) and mean number density n(r) as functions of heliocentric distance r. This will in turn fix the power-law exponent $\delta$ in the relation $T(r) = T_o(r/r_o)^{-\delta}$ for the dust temperature and v in $n(r) = n_o(r/r_o)^-v$ for the density. We discuss how one may de-couple the notorious degeneracy of cross-section, density, reference temperature $T_o$ and exponent $\delta$.
Search for proton decay viap→νK+using260 kiloton·yeardata of Super-Kamiokande
Abe, K.,Hayato, Y.,Iyogi, K.,Kameda, J.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Wendell, R. A.,Sekiya, H.,Shiozawa, M.,Suzuki, Y.,Takeda, A.,Takenaga, Y.,Ueno, K.,Yokozawa, T.,Kaji, H.,Kajita American Physical Society 2014 PHYSICAL REVIEW D - Vol.90 No.7
Tanaka, T.,Abe, K.,Hayato, Y.,Iida, T.,Kameda, J.,Koshio, Y.,Kouzuma, Y.,Miura, M.,Moriyama, S.,Nakahata, M.,Nakayama, S.,Obayashi, Y.,Sekiya, H.,Shiozawa, M.,Suzuki, Y.,Takeda, A.,Takenaga, Y.,Ueno, IOP Publishing 2011 The Astrophysical journal Vol.742 No.2
<P>We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at Super-Kamiokande. Data sets from SKI-SKIII (3109.6 days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C. L. upper limits of upmu flux induced by WIMPs of 100 GeV c(-2) were 6.4 x 10(-15) cm(-2) s(-1) and 4.0 x 10(-15) cm(-2) s(-1) for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 x 10(-39) cm(-2) and 2.7 x 10(-40) cm(-2) for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.</P>