5,576 research outputs found
Mechanical quality factor of a sapphire fiber at cryogenic temperatures
A mechanical quality factor of was obtained for the 199
Hz bending vibrational mode in a monocrystalline sapphire fiber at 6 K.
Consequently, we confirm that pendulum thermal noise of cryogenic mirrors used
for gravitational wave detectors can be reduced by the sapphire fiber
suspension.Comment: To be published to Physiscs Letters A. Number of pages: 10 Number of
figures: 5 Number of tables:
Probing the Cosmic X-ray and MeV Gamma-ray Background Radiation through the Anisotropy
While the cosmic soft X-ray background is very likely to originate from
individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV
gamma-ray background is not fully understood. It is expected that Seyferts
including Compton thick population may explain the cosmic hard X-ray
background. At MeV energy range, Seyferts having non-thermal electrons in
coronae above accretion disks or MeV blazars may explain the background
radiation. We propose that future measurements of the angular power spectra of
anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to
deciphering these backgrounds and the evolution of active galactic nuclei
(AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of
AGNs exists. We show that e-ROSITA will clearly detect the correlation signal
of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to
measure the bias parameter of AGNs at both bands. Once the future hard X-ray
all sky satellites achieve the sensitivity better than 10^{-12} erg/cm^2/s at
10-30 keV or 30-50 keV - although this is beyond the sensitivities of current
hard X-ray all sky monitors - angular power spectra will allow us to
independently investigate the fraction of Compton-thick AGNs in all Seyferts.
We also find that the expected angular power spectra of Seyferts and blazars in
the MeV range are different by about an order of magnitude, where the Poisson
term, so-called shot noise, is dominant. Current and future MeV instruments
will clearly disentangle the origin of the MeV gamma-ray background through the
angular power spectrum.Comment: 14 pages, 8 figures, accepted for publication in Ap
Force measurements of a superconducting-film actuator for a cryogenic interferometric gravitational-wave detector
We measured forces applied by an actuator with a YBCO film at near 77 K for
the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An
actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81
square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on
a test mass. The presented actuator system can be used to displace the mirror
of LCGT for fringe lock of the interferometer.Comment: 9 pages, 3 figure
Crystals for Demazure Modules of Classical Affine Lie Algebras
We study, in the path realization, crystals for Demazure modules of affine
Lie algebras of types . We find a special sequence of
affine Weyl group elements for the selected perfect crystal, and show if the
highest weight is l\La_0, the Demazure crystal has a remarkably simple
structure.Comment: Latex, 28 page
Nongassing NiCd battery cell
Method of constructing nickel cadmium batteries prevents excessive gas buildup and allows hermetic sealing of battery for increased service life and reduced maintenance cost
Dynamic analysis of parallel-link manipulators under the singularity-consistent formulation
科研費報告書収録論文(課題番号:08555062・基盤研究(A)(2)・H8~H10/研究代表者:内山, 勝/6自由度超高速パラレルロボットの試作研究
The Timing Counter of the MEG experiment: calibration and performance
The MEG detector is designed to test Lepton Flavor Violation in the
decay down to a Branching Ratio of a few
. The decay topology consists in the coincident emission of a
monochromatic photon in direction opposite to a monochromatic positron. A
precise measurement of the relative time is crucial to suppress
the background. The Timing Counter (TC) is designed to precisely measure the
time of arrival of the and to provide information to the trigger system.
It consists of two sectors up and down stream the decay target, each consisting
of two layers. The outer one made of scintillating bars and the inner one of
scintillating fibers. Their design criteria and performances are described.Comment: Presented at the 12th Topical Seminar on Innovative Particle and
Radiation Detectors (IPRD10) 7 - 10 June 2010, Siena. Accepted by Nuclear
Physics B (Proceedings Supplements) (2011)tal
Constraints on cosmic-ray efficiency in the supernova remnant RCW 86 using multi-wavelength observations
Several young supernova remnants (SNRs) have recently been detected in the
high-energy and very-high-energy gamma-ray domains. As exemplified by RX
J1713.7-3946, the nature of this emission has been hotly debated, and direct
evidence for the efficient acceleration of cosmic-ray protons at the SNR shocks
still remains elusive. We analyzed more than 40 months of data acquired by the
Large Area Telescope (LAT) on-board the Fermi Gamma-Ray Space Telescope in the
HE domain, and gathered all of the relevant multi-wavelength (from radio to VHE
gamma-rays) information about the broadband nonthermal emission from RCW 86.
For this purpose, we re-analyzed the archival X-ray data from the ASCA/Gas
Imaging Spectrometer (GIS), the XMM-Newton/EPIC-MOS, and the RXTE/Proportional
Counter Array (PCA). Beyond the expected Galactic diffuse background, no
significant gamma-ray emission in the direction of RCW 86 is detected in any of
the 0.1-1, 1-10 and 10-100 GeV Fermi-LAT maps. In the hadronic scenario, the
derived HE upper limits together with the HESS measurements in the VHE domain
can only be accommodated by a spectral index Gamma <= 1.8, i.e. a value
in-between the standard (test-particle) index and the asymptotic limit of
theoretical particle spectra in the case of strongly modified shocks. The
interpretation of the gamma-ray emission by inverse Compton scattering of high
energy electrons reproduces the multi-wavelength data using a reasonable value
for the average magnetic field of 15-25 muG. For these two scenarios, we
assessed the level of acceleration efficiency. We discuss these results in the
light of existing estimates of the magnetic field strength, the effective
density and the acceleration efficiency in RCW 86.Comment: Accepted for publication in A&A; 10 pages and 4 figure
Design and test of an extremely high resolution Timing Counter for the MEG II experiment: preliminary results
The design and tests of Timing Counter elements for the upgrade of the MEG
experiment, MEG II,is presented. The detector is based on several small plates
of scintillator with a Silicon PhotoMultipliers dual-side readout. The
optimisation of the single counter elements (SiPMs, scintillators, geometry) is
described. Moreover, the results obtained with a first prototype tested at the
Beam Test Facility (BTF) of the INFN Laboratori Nazionali di Frascati (LNF) are
presented.Comment: 10 pages, 7 figures. Presented at the 13th Topical Seminar on
Innovative Particle and Radiation Detectors (IPRD13) 7-10 October 2013 Siena,
Ital
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