7,073 research outputs found
Thermal noise in half infinite mirrors with non-uniform loss: a slab of excess loss in a half infinite mirror
We calculate the thermal noise in half-infinite mirrors containing a layer of
arbitrary thickness and depth made of excessively lossy material but with the
same elastic material properties as the substrate. For the special case of a
thin lossy layer on the surface of the mirror, the excess noise scales as the
ratio of the coating loss to the substrate loss and as the ratio of the coating
thickness to the laser beam spot size. Assuming a silica substrate with a loss
function of 3x10-8 the coating loss must be less than 3x10-5 for a 6 cm spot
size and a 7 micrometers thick coating to avoid increasing the spectral density
of displacement noise by more than 10%. A similar number is obtained for
sapphire test masses.Comment: Passed LSC (internal) review. Submitted to Phys. Rev. D. (5/2001)
Replacement: Minor typo in Eq. 17 correcte
Charge-stripe order in the electronic ferroelectric LuFe2O4
The structural features of the charge ordering states in LuFe2O4 are
characterized by in-situ cooling TEM observations from 300K down to 20K. Two
distinctive structural modulations, a major q1= (1/3, 1/3, 2) and a weak
q2=q1/10 + (0, 0, 3/2), have been well determined at the temperature of 20K.
Systematic analysis demonstrates that the charges at low temperatures are well
crystallized in a charge stripe phase, in which the charge density wave
behaviors in a non-sinusoidal fashion resulting in elemental electric dipoles
for ferroelectricity. It is also noted that the charge ordering and
ferroelectric domains often change markedly with lowering temperatures and
yields a rich variety of structural phenomena.Comment: 15 pages, 4 figure
Far-infrared all sky diffuse mapping with AKARI
We discuss the capability of AKARI in recovering diffuse far-infrared
emission, and examine the achieved reliability. Critical issues in making
images of diffuse emission are the transient response and long-term stability
of the far-infrared detectors. Quantitative evaluation of these characteristics
are the key to achieving sensitivity comparable to or better than that for
point sources (< 20 -- 95 MJy sr-1). We describe current activity and progress
toward the production of high quality images of the diffuse far-infrared
emission using the AKARI all-sky survey data.Comment: 4 pages, 8 figures, to appear in the Proceedings of the Conference
"AKARI, a light to illuminate the misty Universe", Fukutake Hall, The
University of Tokyo, Japan, 16-19 February 200
AKARI Far-Infrared All Sky Survey
We demonstrate the capability of AKARI for mapping diffuse far-infrared
emission and achieved reliability of all-sky diffuse map. We have conducted an
all-sky survey for more than 94 % of the whole sky during cold phase of AKARI
observation in 2006 Feb. -- 2007 Aug. The survey in far-infrared waveband
covers 50 um -- 180 um with four bands centered at 65 um, 90 um, 140 um, and
160 um and spatial resolution of 3000 -- 4000 (FWHM).This survey has allowed us
to make a revolutionary improvement compared to the IRAS survey that was
conducted in 1983 in both spatial resolution and sensitivity after more than a
quarter of a century. Additionally, it will provide us the first all-sky survey
data with high-spatial resolution beyond 100 um. Considering its extreme
importance of the AKARI far-infrared diffuse emission map, we are now
investigating carefully the quality of the data for possible release of the
archival data. Critical subjects in making image of diffuse emission from
detected signal are the transient response and long-term stability of the
far-infrared detectors. Quantitative evaluation of these characteristics is the
key to achieve sensitivity comparable to or better than that for point sources
(< 20 -- 95 [MJy/sr]). We describe current activities and progress that are
focused on making high quality all-sky survey images of the diffuse
far-infrared emission.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for
Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies".
Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche
A search for non-random cosmic-ray time series by a cluster analysis
Non-random time series of cosmic rays were searched for in air shower data of mean energy 1:1 x 1015 eV, collected by the air shower array atMitsuishi, Japan, during the period from January 1989 to October 1996. By clustering the arrival time of air showers, five occasions of rate elevation phenomena were found with an expected probability 0:05 (varying from 0:18 x 1
Design and Performance of the Wide-Field X-Ray Monitor on Board the High-Energy Transient Explorer 2
The Wide-field X-ray Monitor (WXM) is one of the scientific instruments
carried on the High Energy Transient Explorer 2 (HETE-2) satellite launched on
2000 October 9. HETE-2 is an international mission consisting of a small
satellite dedicated to provide broad-band observations and accurate
localizations of gamma-ray bursts (GRBs). A unique feature of this mission is
its capability to determine and transmit GRB coordinates in almost real-time
through the burst alert network. The WXM consists of three elements: four
identical Xe-filled one-dimensional position-sensitive proportional counters,
two sets of one-dimensional coded apertures, and the main electronics. The WXM
counters are sensitive to X-rays between 2 keV and 25 keV within a
field-of-view of about 1.5 sr, with a total detector area of about 350 cm.
The in-flight triggering and localization capability can produce a real-time
GRB location of several to 30 arcmin accuracy, with a limiting sensitivity of
erg cm. In this report, the details of the mechanical
structure, electronics, on-board software, ground and in-flight calibration,
and in-flight performance of the WXM are discussed.Comment: 28 pages, 24 figure
Effect of short range order on electronic and magnetic properties of disordered Co based alloys
We here study electronic structure and magnetic properties of disordered CoPd
and CoPt alloys using Augmented Space Recursion technique coupled with the
tight-binding linearized muffin tin orbital (TB-LMTO) method. Effect of short
range ordering present in disordered phase of alloys on electronic and magnetic
properties has been discussed. We present results for magnetic moments, Curie
temperatures and electronic band energies with varying degrees of short range
order for different concentrations of Co and try to understand and compare the
magnetic properties and ordering phenomena in these systems.Comment: 15 pages,17 postscript figures,uses own style file
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