68
68
Sep 23, 2013
09/13
by
H. Ikeda
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We investigate interplay between magnetic fluctuations and superconductivity in the effective five-band Hubbard model for iron-oxypnictide superconductors on the basis of the fluctuation-exchange approximation. As for the normal-state properties, we find the pseudogap behavior in the NMR relaxation rate and the spectral weight in the electron-doped region, while we cannot find such behavior in the hole-doped region. The pseudogap behavior originates from the band structure effect, that is,...
Source: http://arxiv.org/abs/0810.1828v2
43
43
Sep 17, 2013
09/13
by
H. Ikeda; S. Hashimoto
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eye 43
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We construct an $O(a^2)$-improved overlap-Dirac operator by designing an improved overlap kernel, based on the Symanzik improvement program. Field rotation terms are also identified to improve off-shell amplitudes for both massless and massive fermions. We check the free dispersion relation and propagator, and show that improved results become to close to the continuum ones at low momentum region. We test the effect of improvement on the full-QCD gauge configuration and find that the...
Source: http://arxiv.org/abs/0912.4119v1
3
3.0
Jun 30, 2018
06/18
by
T. Shibauchi; H. Ikeda; Y. Matsuda
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eye 3
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To resolve the nature of the hidden order below 17.5\,K in the heavy fermion compound URu$_2$Si$_2$, identifying which symmetries are broken below the hidden order transition is one of the most important steps. Several recent experiments on the electronic structure have shown that the Fermi surface in the hidden order phase is quite close to the result of band-structure calculations within the framework of itinerant electron picture assuming the antiferromagnetism. This provides strong evidence...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1406.5043
46
46
Sep 23, 2013
09/13
by
H. Ikeda; S. Shinkai; K. Yamada
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eye 46
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We investigate the Hubbard model on a two-dimensional square lattice by the perturbation expansion to the fourth order in the on-site Coulomb repulsion U. Numerically calculating all diagrams up to the fourth order in self-energy, we examine the convergence of perturbation series in the lattice system. We indicate that the coefficient of each order term rapidly decreases as in the impurity Anderson model for T > 0.1t in the half-filled case, but it holds in the doped case even at lower...
Source: http://arxiv.org/abs/0810.1815v1
49
49
Sep 21, 2013
09/13
by
S. Konbu; K. Nakamura; H. Ikeda; R. Arita
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eye 49
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We study how Co- and Ni-substitution affect the electronic structure of the iron-based superconductor, LaFeAsO. We perform {\it ab initio} supercell calculations and unfold the first Brillouin zone (BZ) to calculate the spectral function in the BZ for the normal cell. The charge density distribution in real space shows that doped extra electrons are trapped around Co (Ni) atom. This seems to mean that Co(Ni)-substitution does not work as carrier doping. However, the present momentum-space...
Source: http://arxiv.org/abs/1108.0585v2
48
48
Sep 17, 2013
09/13
by
K. Hanagaki; H. Kakuno; H. Ikeda; T. Iijima; T. Tsukamoto
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eye 48
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We report on electron identification methods and their performance in the Belle experiment at the KEK-B asymmetric B-Factory $e^{+} e^{-}$ storage ring. Electrons are selected using a likelihood approach that takes information from the electromagnetic calorimeter, the central drift chamber, and the silica aerogel Cherenkov counters as input. We achieve an electron identification efficiency of $(92.4 \pm 0.4)%$ with a $\pi^{\pm}$ fake rate of $(0.25 \pm 0.02)%$ for the momentum range between 1.0...
Source: http://arxiv.org/abs/hep-ex/0108044v1
42
42
Sep 24, 2013
09/13
by
S. Kasahara; K. Hashimoto; H. Ikeda; T. Terashima; Y. Matsuda; T. Shibauchi
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eye 42
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By using high-quality single crystals, we quantitatively compare the transport properties between LiFeAs and LiFeP superconductors with compensated electron and hole carriers. The low-temperature resistivity follows the Fermi-liquid $AT^2$ dependence with a factor of $\sim 3$ difference in the coefficient $A$. This highlights weaker electron correlations in LiFeP, which is consistent with its $\sim 70$ times lower upper critical field than that of LiFeAs. Our analysis of the magneto-transport...
Source: http://arxiv.org/abs/1112.5597v2
83
83
Sep 21, 2013
09/13
by
H. Ikeda; M. -T. Suzuki; R. Arita; T. Takimoto; T. Shibauchi; Y. Matsuda
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eye 83
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Novel electronic states resulting from entangled spin and orbital degrees of freedom are hallmarks of strongly correlated f-electron systems. A spectacular example is the so-called 'hidden-order' phase transition in the heavy-electron metal URu2Si2, which is characterized by the huge amount of entropy lost at T_{HO}=17.5K. However, no evidence of magnetic/structural phase transition has been found below T_{HO} so far. The origin of the hidden-order phase transition has been a long-standing...
Source: http://arxiv.org/abs/1204.4016v3
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55
Sep 23, 2013
09/13
by
S. Kasahara; T. Shibauchi; Y. Nakai; K. Hashimoto; H. Ikeda; T. Terashima; Y. Matsuda
texts
eye 55
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Single crystals of CaFe$_2$(As$_{1-x}$P$_x$)$_2$ are found to exhibit the tetragonal (T) to collapsed-tetragonal (cT) transition at $T_{\rm cT} \lesssim100$\,K for $x>0.05$. The c-axis shrinks by $\sim9$% below $T_{\rm cT}$, which substantially diminishes the interband nesting between the hole and electron bands. In sharp contrast to the superconducting T phase of $A$Fe$_2$(As$_{1-x}$P$_x$)$_2$ ($A=$ Ba, Sr), where the anomalous non-Fermi liquid transport properties are observed, the...
Source: http://arxiv.org/abs/1012.0972v1
51
51
Sep 23, 2013
09/13
by
S. Kitagawa; H. Ikeda; Y. Nakai; T. Hattori; K. Ishida; Y. Kamihara; M. Hirano; H. Hosono
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eye 51
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We report that nonmagnetic heavy-fermion (HF) iron oxypnictide CeFePO with two-dimensional XY-type anisotropy shows a metamagnetic behavior at the metamagnetic field H_M \simeq 4 T perpendicular to the c-axis and that a critical behavior is observed around H_M. Although the magnetic character is entirely different from that in other Ce-based HF metamagnets, H_M in these metamagnets is linearly proportional to the inverse of the effective mass, or to the temperature where the susceptibility...
Source: http://arxiv.org/abs/1111.3749v3
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47
Sep 20, 2013
09/13
by
N. Araki; T. Nagao; K. Matsuoka; A. Marconi; R. Maiolino; H. Ikeda; T. Hashimoto; Y. Taniguchi; T. Murayama
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eye 47
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We present near-infrared spectroscopy of the z=3.2 quasar SDSS J1707+6443, obtained with MOIRCS on the Subaru Telescope. This quasar is classified as a "nitrogen-loud" quasar because of the fairly strong NIII] and NIV] semi-forbidden emission lines from the broad-line region (BLR) observed in its rest-frame UV spectrum. However, our rest-frame optical spectrum from MOIRCS shows strong [OIII] emission from the narrow-line region (NLR) suggesting that, at variance with the BLR, NLR gas...
Source: http://arxiv.org/abs/1205.5092v1
7
7.0
Jun 29, 2018
06/18
by
S. Murai; A. Ishikawa; T. Sanuki; A. Miyamoto; Y. Sugimoto; C. Constantino; H. Sato; H. Ikeda; Y. Hitoshi
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eye 7
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The Fine Pixel CCD (FPCCD) is one of the candidate sensor technologies for the ILC vertex detector. It will be located near interaction point and require high radiation tolerance. It will thus be operated at -40 degree C to improve radiation tolerance. In this paper, we report on the status of neutron radiation tests, on a cooling system using two-phase CO2 with a gas compressor for circulation, and on the mechanical structure of the FPCCD ladders.
Topics: High Energy Physics - Experiment, Physics, Instrumentation and Detectors
Source: http://arxiv.org/abs/1603.00009
54
54
Jul 20, 2013
07/13
by
R. Okazaki; T. Shibauchi; H. J. Shi; Y. Haga; T. D. Matsuda; E. Yamamoto; Y. Onuki; H. Ikeda; Y. Matsuda
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eye 54
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A second-order phase transition is characterized by spontaneous symmetry breaking. The nature of the broken symmetry in the so-called "hidden order" phase transition in the heavy fermion compound URu2Si2, at transition temperature T_h=17.5 K, has posed a long-standing mystery. We report the emergence of an in-plane anisotropy of the magnetic susceptibility below T_h, which breaks the four-fold rotational symmetry of the tetragonal URu2Si2. Two-fold oscillations in the magnetic torque...
Source: http://arxiv.org/abs/1107.5480v1
67
67
Jul 19, 2013
07/13
by
Y. Nakai; T. Iye; S. Kitagawa; K. Ishida; H. Ikeda; S. Kasahara; H. Shishido; T. Shibauchi; Y. Matsuda; T. Terashima
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eye 67
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Spin dynamics evolution of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ was probed as a function of P concentration via $^{31}$P NMR. Our NMR study reveals that two-dimensional antiferromagnetic (AF) fluctuations are notably enhanced with little change in static susceptibility on approaching the AF phase from the superconducting dome. Moreover, magnetically ordered temperature $\theta$ deduced from the relaxation rate vanishes at optimal doping. These results provide clear-cut evidence for a quantum-critical...
Source: http://arxiv.org/abs/1005.2853v2
101
101
Jul 20, 2013
07/13
by
K. Hashimoto; S. Kasahara; R. Katsumata; Y. Mizukami; M. Yamashita; H. Ikeda; T. Terashima; A. Carrington; Y. Matsuda; T. Shibauchi
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eye 101
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High-precision measurements of magnetic penetration depth $\lambda$ in clean single crystals of LiFeAs and LiFeP superconductors reveal contrasting low-energy quasiparticle excitations. In LiFeAs the low-temperature $\lambda(T)$ shows a flat dependence indicative of a fully gapped state, which is consistent with previous studies. In contrast, LiFeP exhibits a $T$-linear dependence of superfluid density $\propto \lambda^{-2}$, indicating a nodal superconducting order parameter. A systematic...
Source: http://arxiv.org/abs/1107.4505v1
47
47
Sep 18, 2013
09/13
by
Y. Ihara; H. Takeya; K. Ishida; H. Ikeda; C. Michioka; K. Yoshimura; K. Takada; T. Sasaki; H. Sakurai; E. Takaayama-Muromachi
texts
eye 47
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Co nuclear-quadrupole-resonance (NQR) measurements were performed on various bilayered hydrate cobaltate Na_x(H_3O)_zCoO_2\cdot yH_2O with different values of the superconducting and magnetic-ordering temperatures, T_c and T_M, respectively. From measurements of the temperature and sample dependence of the NQR frequency, it was revealed that the NQR frequency is changed by the change of the electric field gradient (EFG) along the c axis \nu_{zz} rather than the asymmetry of EFG within the...
Source: http://arxiv.org/abs/cond-mat/0606212v2
106
106
Sep 21, 2013
09/13
by
S. Kasahara; T. Shibauchi; K. Hashimoto; K. Ikada; S. Tonegawa; R. Okazaki; H. Ikeda; H. Takeya; K. Hirata; T. Terashima; Y. Matsuda
texts
eye 106
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The normal-state charge transport is studied systematically in high-quality single crystals of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ ($0 \leq x \leq 0.71$). By substituting isovalent P for As, the spin-density-wave (SDW) state is suppressed and the dome-shaped superconducting phase ($T_c \lesssim 31$ K) appears. Near the SDW end point ($x\approx0.3$), we observe striking linear temperature ($T$) dependence of resistivity in a wide $T$-range, and remarkable low-$T$ enhancement of Hall coefficient...
Source: http://arxiv.org/abs/0905.4427v3
84
84
Sep 22, 2013
09/13
by
M. Yamashita; Y. Senshu; T. Shibauchi; S. Kasahara; K. Hashimoto; D. Watanabe; H. Ikeda; T. Terashima; I. Vekhter; A. B. Vorontsov; Y. Matsuda
texts
eye 84
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The structure of the superconducting order parameter in the iron-pnictide superconductor BaFe$_2$(As$_{0.67}$P$_{0.33}$)$_2$ ($T_c=31$\,K) with line nodes is studied by the angle-resolved thermal conductivity measurements in a magnetic field rotated within the basal plane. We find that the thermal conductivity displays distinct fourfold oscillations with minima when the field is directed at $\pm45^\circ$ with respect to the tetragonal a-axis. We discuss possible gap structures that can account...
Source: http://arxiv.org/abs/1103.0885v2
36
36
Sep 21, 2013
09/13
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T. Yoshida; I. Nishi; S. Ideta; A. Fujimori; M. Kubota; K. Ono; S. Kasahara; T. Shibauchi; T. Terashima; Y. Matsuda; H. Ikeda; R. Arita
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eye 36
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We have studied the three-dimensional shapes of the Fermi surfaces (FSs) of BaFe2(As1-xPx)2 (x=0.38), where superconductivity is induced by isovalent P substitution, by angle-resolved photoemission spectroscopy. Moderately strong electron mass enhancement has been identified for both the electron and hole FSs. Among two observed hole FSs, the nearly two-dimensional one shows good nesting with the outer two-dimensional electron FS, but its orbital character is different from the outer electron...
Source: http://arxiv.org/abs/1008.2080v1
4
4.0
Jun 30, 2018
06/18
by
K. Fushimi; Y. Awatani; H. Ejiri; R. Hazama; H. Ikeda; K. Imagawa; K. Inoue; A. Kozlov; R. Orito; T. Shima; R. Sugawaraand K. Yasuda
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eye 4
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KamLAND-PICO project aims to search for WIMPs dark matter by means of NaI(Tl) scintillator. To investigate the WIMPs candidate whose cross section is as small as $10^{-9}$ pb, a pure NaI(Tl) crystal was developed by chemical processing and taking care of surroundings. The concentration of U and Th chain was reduced to $5.4\pm0.9$ ppt and $3.3\pm2.2$ ppt, respectively. It should be remarked that the concentration of $^{210}$Pb which was difficult to reduce reached to the high purity as $58\pm26$...
Topics: Physics, Instrumentation and Methods for Astrophysics, Astrophysics, Instrumentation and Detectors
Source: http://arxiv.org/abs/1407.3542
5
5.0
Jun 28, 2018
06/18
by
Y. Mizukami; Y. Kawamoto; Y. Shimoyama; S. Kurata; H. Ikeda; T. Wolf; D. A. Zocco; K. Grube; H. v. Löhneysen; Y. Matsuda; T. Shibauchi
texts
eye 5
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In the heavily hole-doped iron-based superconductors $A$Fe$_2$As$_2$ ($A=$ K, Rb, and Cs), the electron effective mass increases rapidly with alkali-ion radius. To study how the mass enhancement affects the superconducting state, we measure the London penetration depth $\lambda(T)$ in clean crystals of $A$Fe$_2$As$_2$ down to low temperature $T\sim0.1$ K. In all systems, the superfluid stiffness $\rho_s(T)=\lambda^2(0)/\lambda^2(T)$ can be approximated by a power-law $T$ dependence at low...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1510.02273
3
3.0
Jun 30, 2018
06/18
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M. Shimozawa; S. K. Goh; R. Endo; R. Kobayashi; T. Watashige; Y. Mizukami; H. Ikeda; H. Shishido; Y. Yanase; T. Terashima; T. Shibauchi; Y. Matsuda
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eye 3
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By using a molecular beam epitaxy technique, we fabricate a new type of superconducting superlattices with controlled atomic layer thicknesses of alternating blocks between heavy fermion superconductor CeCoIn_5, which exhibits a strong Pauli pair-breaking effect, and nonmagnetic metal YbCoIn_5. The introduction of the thickness modulation of YbCoIn_5 block layers breaks the inversion symmetry centered at the superconducting block of CeCoIn_5. This configuration leads to dramatic changes in the...
Topics: Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1404.0482
79
79
Sep 20, 2013
09/13
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S. Tonegawa; K. Hashimoto; K. Ikada; Y. -H. Lin; H. Shishido; Y. Haga; T. D. Matsuda; E. Yamamoto; Y. Onuki; H. Ikeda; Y. Matsuda; T. Shibauchi
texts
eye 79
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We report the first observation of cyclotron resonance in the hidden-order phase of ultra-clean URu$_2$Si$_2$ crystals, which allows the full determination of angle-dependent electron-mass structure of the main Fermi-surface sheets. We find an anomalous splitting of the sharpest resonance line under in-plane magnetic-field rotation. This is most naturally explained by the domain formation, which breaks the fourfold rotational symmetry of the underlying tetragonal lattice. The results reveal the...
Source: http://arxiv.org/abs/1207.3905v1
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45
Sep 22, 2013
09/13
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K. Hashimoto; Y. Mizukami; R. Katsumata; H. Shishido; M. Yamashita; H. Ikeda; Y. Matsuda; J. A. Schlueter; J. D. Fletcher; A. Carrington; D. Gnida; D. Kaczorowski; T. Shibauchi
texts
eye 45
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When a second-order magnetic phase transition is tuned to zero temperature by a non-thermal parameter, quantum fluctuations are critically enhanced, often leading to the emergence of unconventional superconductivity. In these `quantum critical' superconductors it has been widely reported that the normal-state properties above the superconducting transition temperature $T_c$ often exhibit anomalous non-Fermi liquid behaviors and enhanced electron correlations. However, the effect of these strong...
Source: http://arxiv.org/abs/1302.2945v1
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38
Sep 18, 2013
09/13
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P. J. White; Z. X. Shen; D. L. Feng; C. Kim; M. Z. Hasan; J. M. Harris; A. G. Loeser; H. Ikeda; R. Yoshizaki; G. D. Gu; N. Koshizuka
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eye 38
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An angle resolved photoelectron spectroscopy study was conducted on BiSrCaCuZnO. A small amount of Zn substitution for Cu almost completely suppresses the otherwise sharp spectral peak along the (0,0) to (pi,pi) direction in BiSrCaCuZnO, while superconductivity with Tc as high as 83K survives. This behavior contrasts markedly from that seen in cases where the impurities are located off the CuO plane, as well as when the CuO planes are underdoped. This effect is also accompanied by changes of...
Source: http://arxiv.org/abs/cond-mat/9901349v3
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50
Sep 21, 2013
09/13
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Jeffrey M. Harris; P. J. White; Z. -X. Shen; H. Ikeda; R. Yoshizaki; H. Eisaki; S. Uchida; W. D. Si; J. W. Xiong; Z. -X. Zhao; D. S. Dessau
texts
eye 50
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We report angle-resolved photoemission spectra both above and below T_c in the single-plane cuprate superconductor Bi_2Sr_{2-x}La_xCuO_{6+d}. The superconducting state measurements show a highly anisotropic excitation gap with a maximum magnitude smaller than that of the bilayer compound Bi_2Sr_2CaCu_2O_8 by a factor of 3. For a range of doping, the gap persists well above T_c, behavior previously associated with underdoped bilayer cuprates. The anisotropy and magnitude of the normal-state gap...
Source: http://arxiv.org/abs/cond-mat/9705304v1
4
4.0
Jun 28, 2018
06/18
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K. Fushimi; H. Ejiri; R. Hazama; H. Ikeda; K. Imagawa; K. Inoue; G. Kanzaki; A. Kozlov; R. Orito; T. Shima; Y. Takemoto; Y. Teraoka; S. Umehara; K. Yasuda; S. Yoshida
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eye 4
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The PICO-LON project aims at search for cold dark matter by means of highly radio-pure and large volume NaI(Tl) scintillator. The NaI powder was purifed by chemical processing to remove lead isotopes and selecting a high purity graphite crucible. The concentrations of radioactive impurities of $^{226}$Ra and $^{228}$Th were effectively reduced to 58$\pm$4 $\mu$Bq/kg and 1.5$\pm$1.9 $\mu$Bq/kg, respectively. It should be remarked that the concentration of $^{210}$Pb, which is crucial for the...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics, Instrumentation and Detectors, Physics
Source: http://arxiv.org/abs/1512.04645
3
3.0
Jun 30, 2018
06/18
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S. Tonegawa; S. Kasahara; T. Fukuda; K. Sugimoto; N. Yasuda; Y. Tsuruhara; D. Watanabe; Y. Mizukami; Y. Haga; T. D. Matsuda; E. Yamamoto; Y. Onuki; H. Ikeda; Y. Matsuda; T. Shibauchi
texts
eye 3
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Since the 1985 discovery of the phase transition at $T_{\rm HO}=17.5$ K in the heavy-fermion metal URu$_2$Si$_2$, neither symmetry change in the crystal structure nor magnetic ordering have been observed, which makes this "hidden order" enigmatic. Some high-field experiments have suggested electronic nematicity which breaks fourfold rotational symmetry, but direct evidence has been lacking for its ground state at zero magnetic field. Here we report on the observation of lattice...
Topics: Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1406.5040
62
62
Sep 20, 2013
09/13
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H. Ikeda; T. Nagao; K. Matsuoka; Y. Taniguchi; Y. Shioya; M. Kajisawa; M. Enoki; P. Capak; F. Civano; A. M. Koekemoer; D. Masters; T. Morokuma; M. Salvato; E. Schinnerer; N. Z. Scoville
texts
eye 62
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We present the result of our low-luminosity quasar survey in the redshift range of 4.5 < z < 5.5 in the COSMOS field. Using the COSMOS photometric catalog, we selected 15 quasar candidates with 22 < i' < 24 at z~5, that are ~ 3 mag fainter than the SDSS quasars in the same redshift range. We obtained optical spectra for 14 of the 15 candidates using FOCAS on the Subaru Telescope and did not identify any low-luminosity type-1 quasars at z~5 while a low-luminosity type-2 quasar at...
Source: http://arxiv.org/abs/1207.1515v1
5
5.0
Jun 30, 2018
06/18
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S. Kasahara; T. Watashige; T. Hanaguri; Y. Kohsaka; T. Yamashita; Y. Shimoyama; Y. Mizukami; R. Endo; H. Ikeda; K. Aoyama; T. Terashima; S. Uji; T. Wolf; H. v. Löhneysenn; T. Shibauchi; Y. Matsuda
texts
eye 5
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Fermi systems in the crossover regime between weakly coupled Bardeen-Cooper-Schrieffer (BCS) and strongly coupled Bose-Einstein-condensate (BEC) limits are among the most fascinating objects to study the behavior of an assembly of strongly interacting particles. The physics of this crossover has been of considerable interest both in the fields of condensed matter and ultracold atoms. One of the most challenging issue in this regime is the effect of large spin imbalance on a Fermi system under...
Topics: Quantum Gases, Superconductivity, Strongly Correlated Electrons, Condensed Matter
Source: http://arxiv.org/abs/1411.1232
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39
Sep 17, 2013
09/13
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K. Hashimoto; A. Serafin; S. Tonegawa; R. Katsumata; R. Okazaki; T. Saito; H. Fukazawa; Y. Kohori; K. Kihou; C. H. Lee; A. Iyo; H. Eisaki; H. Ikeda; Y. Matsuda; A. Carrington; T. Shibauchi
texts
eye 39
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Among the iron-based pnictide superconductors the material KFe$_2$As$_2$ is unusual in that its Fermi surface does not consist of quasi-nested electron and hole pockets. Here we report measurements of the temperature dependent London penetration depth of very clean crystals of this compound with residual resistivity ratio $>1200$. We show that the superfluid density at low temperatures exhibits a strong linear-in-temperature dependence which implies that there are line nodes in the energy...
Source: http://arxiv.org/abs/1003.6022v2
50
50
Sep 23, 2013
09/13
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K. Hashimoto; K. Cho; T. Shibauchi; S. Kasahara; Y. Mizukami; R. Katsumata; Y. Tsuruhara; T. Terashima; H. Ikeda; M. A. Tanatar; H. Kitano; N. Salovich; R. W. Giannetta; P. Walmsley; A. Carrington; R. Prozorov; Y. Matsuda
texts
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In a superconductor, the ratio of the carrier density, $n$, to their effective mass, $m^*$, is a fundamental property directly reflecting the length scale of the superfluid flow, the London penetration depth, $\lambda_L$. In two dimensional systems, this ratio $n/m^*$ ($\sim 1/\lambda_L^2$) determines the effective Fermi temperature, $T_F$. We report a sharp peak in the $x$-dependence of $\lambda_L$ at zero temperature in clean samples of BaFe$_2$(As$_{1-x}$P$_x$)$_2$ at the optimum composition...
Source: http://arxiv.org/abs/1212.5632v1
12
12
Jun 29, 2018
06/18
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S. Iwata; I. Adachi; K. Hara; T. Iijima; H. Ikeda; H. Kakuno; H. Kawai; T. Kawasaki; S. Korpar; P. Krizan; T. Kumita; S. Nishida; S. Ogawa; R. Pestotnik; L. Šantelj; A. Seljak; M. Tabata; E. Tahirović; Y. Yusa
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eye 12
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We have developed a new type of particle identification device, called an Aerogel Ring Imaging Cherenkov (ARICH) counter, for the Belle II experiment. It uses silica aerogel tiles as Cherenkov radiators. For detection of Cherenkov photons, Hybrid Avalanche Photo-Detectors (HAPDs) are used. The designed HAPD has a high sensitivity to single photons under a strong magnetic field. We have confirmed that the HAPD provides high efficiency for single-photon detection even after exposure to neutron...
Topics: High Energy Physics - Experiment, Physics, Instrumentation and Detectors
Source: http://arxiv.org/abs/1603.02503
15
15
Jun 28, 2018
06/18
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H. Ikeda; T. Nagao; Y. Taniguchi; K. Matsuoka; M. Kajisawa; M. Akiyama; T. Miyaji; N. Kashikawa; T. Morokuma; Y. Shioya; M. Enoki; P. Capak; A. M. Koekemoer; D. Masters; M. Salvato; D. B. Sanders; E. Schinnerer; N. Z. Scoville
texts
eye 15
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In order to investigate the origin of quasars, we estimate the bias factor for low-luminosity quasars at high redshift for the first time. In this study, we use the two-point angular cross-correlation function (CCF) for both low-luminosity quasars at $-24
Topics: Astrophysics, Astrophysics of Galaxies
Source: http://arxiv.org/abs/1507.05292
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44
Sep 19, 2013
09/13
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H. Shishido; A. F. Bangura; A. I. Coldea; S. Tonegawa; K. Hashimoto; S. Kasahara; P. M. C. Rourke; H. Ikeda; T. Terashima; R. Settai; Y. Onuki; D. Vignolles; C. Proust; B. Vignolle; A. McCollam; Y. Matsuda; T. Shibauchi; A. Carrington
texts
eye 44
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Using the de Haas-van Alphen effect we have measured the evolution of the Fermi surface of BaFe_2(As_{1-x}P_x)_2 as function of isoelectric substitution (As/P) for 0.41
Source: http://arxiv.org/abs/0910.3634v1
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51
Sep 21, 2013
09/13
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H. Ikeda; T. Nagao; K. Matsuoka; Y. Taniguchi; Y. Shioya; J. R. Trump; P. Capak; A. Comastri; M. Enoki; Y. Ideue; Y. Kakazu; A. M. Koekemoer; T. Morokuma; T. Murayama; T. Saito; M. Salvato; E. Schinnerer; N. Z. Scoville; J. D. Silverman
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We searched for quasars that are ~ 3 mag fainter than the SDSS quasars in the redshift range 3.7 < z < 4.7 in the COSMOS field to constrain the faint end of the quasar luminosity function. Using optical photometric data, we selected 31 quasar candidates with 22 < i' < 24 at z ~ 4. We obtained optical spectra for most of these candidates using FOCAS on the Subaru telescope, and identified 8 low-luminosity quasars at z ~ 4. In order to derive the quasar luminosity function (QLF) based...
Source: http://arxiv.org/abs/1011.2280v2
59
59
Sep 21, 2013
09/13
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W. Malaeb; T. Shimojima; Y. Ishida; K. Okazaki; Y. Ota; K. Ohgushi; K. Kihou; T. Saito; C. H. Lee; S. Ishida; M. Nakajima; S. Uchida; H. Fukazawa; Y. Kohori; A. Iyo; H. Eisaki; C. -T. Chen; S. Watanabe; H. Ikeda; S. Shin
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We performed a Laser angle-resolved photoemission spectroscopy (ARPES) study on a wide doping range of Ba1-xKxFe2As2 (BaK) and precisely determined the doping evolution of the superconducting (SC) gaps in this compound. The gap size of the outer hole Fermi surface (FS) sheet around the Brillioun zone (BZ) center shows an abrupt drop with overdoping (for x > 0.6) while the inner and middle FS gaps roughly scale with Tc. This is accompanied by the simultaneous disappearance of the electron FS...
Source: http://arxiv.org/abs/1204.0326v1
40
40
Sep 22, 2013
09/13
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F. Civano; M. Brusa; A. Comastri; M. Elvis; M. Salvato; G. Zamorani; P. Capak; F. Fiore; R. Gilli; H. Hao; H. Ikeda; Y. Kakazu; J. S. Kartaltepe; D. Masters; T. Miyaji; M. Mignoli; S. Puccetti; F. Shankar; J. Silverman; C. Vignali; A. Zezas; A. M. Koekemoer
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We present the high redshift (33. 81 sources are selected in the 0.5-2 keV band, 14 are selected in the 2-10 keV and 6 in the 0.5-10 keV bands. We sample the high luminosity (log L_(2-10 keV)>44.15 erg/s) space density up to z~5 and a fainter luminosity range (43.53. We find that the space density of high-luminosity AGNs declines exponentially at all the redshifts, confirming the trend observed for optically selected quasars. At lower luminosity, the measured space density is not conclusive,...
Source: http://arxiv.org/abs/1103.2570v2
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35
Sep 20, 2013
09/13
by
KamLAND-Zen Collaboration; :; A. Gando; Y. Gando; H. Hanakago; H. Ikeda; K. Inoue; R. Kato; M. Koga; S. Matsuda; T. Mitsui; T. Nakada; K. Nakamura; A. Obata; A. Oki; Y. Ono; I. Shimizu; J. Shirai; A. Suzuki; Y. Takemoto; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; S. Yamada; H. Yoshida; A. Kozlov; S. Yoshida; T. I. Banks; J. A. Detwiler; S. J. Freedman; B. K. Fujikawa; K. Han; T. O'Donnell; B. E. Berger; Y. Efremenko; H. J. Karwowski; D. M. Markoff; W. Tornow; S. Enomoto; M. P. Decowski
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We present limits on Majoron-emitting neutrinoless double-beta decay modes based on an exposure of 112.3 days with 125 kg of Xe-136. In particular, a lower limit on the ordinary (spectral index n = 1) Majoron-emitting decay half-life of Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at 90% C.L., a factor of five more stringent than previous limits. The corresponding upper limit on the effective Majoron-neutrino coupling, using a range of available nuclear matrix...
Source: http://arxiv.org/abs/1205.6372v2
14
14
Jun 28, 2018
06/18
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KamLAND-Zen Collaboration; :; K. Asakura; A. Gando; Y. Gando; T. Hachiya; S. Hayashida; H. Ikeda; K. Inoue; K. Ishidoshiro; T. Ishikawa; S. Ishio; M. Koga; S. Matsuda; T. Mitsui; D. Motoki; K. Nakamura; S. Obara; M. Otani; T. Oura; I. Shimizu; Y. Shirahata; J. Shirai; A. Suzuki; H. Tachibana; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; H. Yoshida; A. Kozlov; Y. Takemoto; S. Yoshida; K. Fushimi; T. I. Banks; B. E. Berger; B. K. Fujikawa; T. O'Donnell; L. A. Winslow; Y. Efremenko; H. J....
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A search for double-beta decays of 136Xe to excited states of 136Ba has been performed with the first phase data set of the KamLAND-Zen experiment. The 0+1, 2+1 and 2+2 transitions of 0{\nu}\{beta}\{beta} decay were evaluated in an exposure of 89.5kg-yr of 136Xe, while the same transitions of 2{\nu}\{beta}\{beta} decay were evaluated in an exposure of 61.8kg-yr. No excess over background was found for all decay modes. The lower half-life limits of the 2+1 state transitions of...
Topics: Instrumentation and Detectors, Physics, High Energy Physics - Experiment
Source: http://arxiv.org/abs/1509.03724
6
6.0
Jun 29, 2018
06/18
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KamLAND Collaboration; A. Gando; Y. Gando; T. Hachiya; A. Hayashi; S. Hayashida; H. Ikeda; K. Inoue; K. Ishidoshiro; Y. Karino; M. Koga; S. Matsuda; T. Mitsui; K. Nakamura; S. Obara; T. Oura; H. Ozaki; I. Shimizu; Y. Shirahata; J. Shirai; A. Suzuki; T. Takai; K. Tamae; Y. Teraoka; K. Ueshima; H. Watanabe; A. Kozolov; Y. Takemoto; S. Yoshida; K. Fushimi; A. Piepke; T. I. Banks; B. E. Berger; B. K. Fujikawa; T. O'Donnell; J. G. Learned; J. Maricic; M. Sakai; L. A. Winslow; E. Krupczak; J....
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eye 6
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We present a search for low energy antineutrino events coincident with the gravitational wave events GW150914 and GW151226, and the candidate event LVT151012 using KamLAND, a kiloton-scale antineutrino detector. We find no inverse beta-decay neutrino events within $\pm 500$ seconds of either gravitational wave signal. This non-detection is used to constrain the electron antineutrino fluence and the luminosity of the astrophysical sources.
Topics: Astrophysics, High Energy Astrophysical Phenomena, Nuclear Experiment, High Energy Physics -...
Source: http://arxiv.org/abs/1606.07155
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19
Jun 27, 2018
06/18
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K. Asakura; A. Gando; Y. Gando; T. Hachiya; S. Hayashida; H. Ikeda; K. Inoue; K. Ishidoshiro; T. Ishikawa; S. Ishio; M. Koga; S. Matsuda; T. Mitsui; D. Motoki; K. Nakamura; S. Obara; T. Oura; I. Shimizu; Y. Shirahata; J. Shirai; A. Suzuki; H. Tachibana; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; A. Kozlov; Y. Takemoto; S. Yoshida; K. Fushimi; A. Piepke; T. I. Banks; B. E. Berger; B. K. Fujikawa; T. O'Donnell; J. G. Learned; J. Maricic; S. Matsuno; M. Sakai; L. A. Winslow; Y. Efremenko; H. J....
texts
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In the late stages of nuclear burning for massive stars ($M>8~M_{\sun}$), the production of neutrino-antineutrino pairs through various processes becomes the dominant stellar cooling mechanism. As the star evolves, the energy of these neutrinos increases and in the days preceding the supernova a significant fraction of emitted electron anti-neutrinos exceeds the energy threshold for inverse beta decay on free hydrogen. This is the golden channel for liquid scintillator detectors because the...
Topics: Instrumentation and Detectors, High Energy Astrophysical Phenomena, Astrophysics, Physics, High...
Source: http://arxiv.org/abs/1506.01175
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21
Jun 27, 2018
06/18
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K. Asakura; A. Gando; Y. Gando; T. Hachiya; S. Hayashida; H. Ikeda; K. Inoue; K. Ishidoshiro; T. Ishikawa; S. Ishio; M. Koga; S. Matsuda; T. Mitsui; D. Motoki; K. Nakamura; S. Obara; Y. Oki; T. Oura; I. Shimizu; Y. Shirahata; J. Shirai; A. Suzuki; H. Tachibana; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; H. Yoshida; A. Kozlov; Y. Takemoto; S. Yoshida; K. Fushimi; A. Piepke; T. I. Banks; B. E. Berger; T. O'Donnell; B. K. Fujikawa; J. Maricic; J. G. Learned; M. Sakai; L. A. Winslow; Y....
texts
eye 21
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We search for electron anti-neutrinos ($\overline{\nu}_e$) from long and short-duration gamma-ray bursts~(GRBs) using data taken by the KamLAND detector from August 2002 to June 2013. No statistically significant excess over the background level is found. We place the tightest upper limits on $\overline{\nu}_e$ fluence from GRBs below 7 MeV and place first constraints on the relation between $\overline{\nu}_e$ luminosity and effective temperature.
Topics: High Energy Physics - Experiment, High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1503.02137
7
7.0
Jun 30, 2018
06/18
by
T. I. Banks; S. J. Freedman; J. Wallig; N. Ybarrolaza; A. Gando; Y. Gando; H. Ikeda; K. Inoue; Y. Kishimoto; M. Koga; T. Mitsui; K. Nakamura; I. Shimizu; J. Shirai; A. Suzuki; Y. Takemoto; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; H. Yoshida; S. Yoshida; A. Kozlov; C. Grant; G. Keefer; A. Piepke; T. Bloxham; B. K. Fujikawa; K. Han; K. Ichimura; H. Murayama; T. O'Donnell; H. M. Steiner; L. A. Winslow; D. A. Dwyer; R. D. McKeown; C. Zhang; B. E. Berger; C. E. Lane; J. Maricic; T. Miletic; M....
texts
eye 7
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We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible...
Topics: Physics, High Energy Physics - Experiment, Nuclear Experiment, Instrumentation and Detectors
Source: http://arxiv.org/abs/1407.0413
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40
Sep 21, 2013
09/13
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M. Salvato; O. Ilbert; G. Hasinger; A. Rau; F. Civano; G. Zamorani; M. Brusa; M. Elvis; C. Vignali; H. Aussel; A. Comastri; F. Fiore; E. Le Floc'h; V. Mainieri; S. Bardelli; M. Bolzonella; A. Bongiorno; P. Capak; K. Caputi; N. Cappelluti; C. M. Carollo; T. Contini; B. Garilli; A. Iovino; S. Fotopoulou; A. Fruscione; R. Gilli; C. Halliday; J-P. Kneib; Y. Kakazu; J. S. Kartaltepe; A. M. Koekemoer; K. Kovac; Y. Ideue; H. Ikeda; C. D. Impey; O. Le Fevre; F. Lamareille; G. Lanzuisi; J-F. Le Borgne;...
texts
eye 40
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With this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the COSMOS field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a...
Source: http://arxiv.org/abs/1108.6061v1
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11
Jun 30, 2018
06/18
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A. Gando; Y. Gando; H. Hanakago; H. Ikeda; K. Inoue; K. Ishidoshiro; H. Ishikawa; Y. Kishimoto; M. Koga; R. Matsuda; S. Matsuda; T. Mitsui; D. Motoki; K. Nakajima; K. Nakamura; A. Obata; A. Oki; Y. Oki; M. Otani; I. Shimizu; J. Shirai; A. Suzuki; K. Tamae; K. Ueshima; H. Watanabe; B. D. Xu; S. Yamada; Y. Yamauchi; H. Yoshida; A. Kozlov; Y. Takemoto; S. Yoshida; C. Grant; G. Keefer; D. W. McKee; A. Piepke; T. I. Banks; T. Bloxham; S. J. Freedman; B. K. Fujikawa; K. Han; L. Hsu; K. Ichimura; H....
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We report a measurement of the neutrino-electron elastic scattering rate of 862 keV 7Be solar neutrinos based on a 165.4 kton-day exposure of KamLAND. The observed rate is 582 +/- 90 (kton-day)^-1, which corresponds to a 862 keV 7Be solar neutrino flux of (3.26 +/- 0.50) x 10^9 cm^-2s^-1, assuming a pure electron flavor flux. Comparing this flux with the standard solar model prediction and further assuming three flavor mixing, a nu_e survival probability of 0.66 +/- 0.14 is determined from the...
Topics: Nuclear Experiment, Astrophysics, Solar and Stellar Astrophysics, High Energy Physics - Experiment
Source: http://arxiv.org/abs/1405.6190
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56
Sep 21, 2013
09/13
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KamLAND Collaboration; S. Abe; K. Furuno; A. Gando; Y. Gando; K. Ichimura; H. Ikeda; K. Inoue; Y. Kibe; W. Kimura; Y. Kishimoto; M. Koga; Y. Minekawa; T. Mitsui; T. Morikawa; N. Nagai; K. Nakajima; K. Nakamura; M. Nakamura; K. Narita; I. Shimizu; Y. Shimizu; J. Shirai; F. Suekane; A. Suzuki; H. Takahashi; N. Takahashi; Y. Takemoto; K. Tamae; H. Watanabe; B. D. Xu; H. Yabumoto; E. Yonezawa; H. Yoshida; S. Yoshida; S. Enomoto; A. Kozlov; H. Murayama; C. Grant; G. Keefer; D. McKee; A. Piepke; T....
texts
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We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl...
Source: http://arxiv.org/abs/1106.0861v3
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58
Sep 21, 2013
09/13
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T. Abe; K. Akai; M. Akemoto; A. Akiyama; M. Arinaga; K. Ebihara; K. Egawa; A. Enomoto; J. Flanagan; S. Fukuda; H. Fukuma; Y. Funakoshi; K. Furukawa; T. Furuya; K. Hara; T. Higo; S. Hiramatsu; H. Hisamatsu; H. Honma; T. Honma; K. Hosoyama; T. Ieiri; N. Iida; H. Ikeda; M. Ikeda; S. Inagaki; S. Isagawa; H. Ishii; A. Kabe; E. Kadokura; T. Kageyama; K. Kakihara; E. Kako; S. Kamada; T. Kamitani; K. Kanazawa; H. Katagiri; S. Kato; T. Kawamoto; S. Kazakov; M. Kikuchi; E. Kikutani; K. Kitagawa; H....
texts
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Crab cavities have been installed in the KEKB B--Factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the...
Source: http://arxiv.org/abs/0706.3248v1
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169
Sep 21, 2013
09/13
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The JEM-EUSO Collaboration; :; J. H. Adams Jr; S. Ahmad; J. -N. Albert; D. Allard; M. Ambrosio; L. Anchordoqui; A. Anzalone; Y. Arai; C. Aramo; K. Asano; P. Barrillon; T. Batsch; J. Bayer; T. Belenguer; R. Bellotti; A. A. Berlind; M. Bertaina; P. L. Biermann; S. Biktemerova; C. Blaksley; J. Blecki; S. Blin-Bondil; J. Bluemer; P. Bobik; M. Bogomilov; M. Bonamente; M. S. Briggs; S. Briz; A. Bruno; F. Cafagna; D. Campana; J-N. Capdevielle; R. Caruso; M. Casolino; C. Cassardo; G. Castellini; O....
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Contributions of the JEM-EUSO Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011.
Source: http://arxiv.org/abs/1204.5065v1
