1,929 research outputs found
On the light-bending model of X-ray variability of MCG-6-30-15
We apply the light bending model of X-ray variability to Suzaku data of the
Seyfert 1 galaxy MCG-6-30-15. We analyze the energy dependence of the root mean
square (rms) variability, and discuss conditions necessary for the model to
explain the characteristic decrease of the source variability around 5-8 keV. A
model, where the X-ray source moves radially rather than vertically close to
the disk surface, can indeed reproduce the reduced variability near the energy
of the Fe Kalpha line, although the formal fit quality is poor. The model then
predicts the energy spectra, which can be compared to observational data. The
spectra are strongly reflection dominated, and do not provide a good fit to
Suzaku spectral data of the source. The inconsistency of this result with some
previous claims can be traced to our using data in a broader energy band, where
effects of warm absorber in the spectrum cannot be neglected.Comment: 6 pages, PASJ, accepte
Modal test of the Viking orbiter
A modal test of the Orbiter Development Test Modal (ODTM) has been conducted to verify, or update, the mathematical model used for load analysis. The approach used to assure the quality and validity of the experimental data is defined, the modal test is described, and test results are presented and compared with analysis results. Good correlation between the analyses and the test data assures an acceptable model for incorporation into the mathematical model of the launch system
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Upgrade to the SHARP EUV mask microscope
The Sharp High-NA Actinic Reticle review Project (SHARP) is a synchrotron-based, extreme ultraviolet (EUV) microscope dedicated to photomask research. A potential upgrade to the SHARP microscope is presented. The upgrade includes changing the light path in the instrument from its current off-Axis configuration to an on-Axis configuration. This change allows for an increased working distance of 2.5 mm or more. A central obscuration, added to the zoneplate aperture, blocks stray light from reaching the central part of the image, thus improving the image contrast. The imaging performance of the two configurations is evaluated by means of ray tracing
Probing the Phase Diagram of Bi2Sr2CaCu2O8+d with Tunneling Spectroscopy
Tunneling measurements are performed on Ca-rich single crystals of
Bi2Sr2CaCu2O8+d (Bi2212), with various oxygen doping levels, using a novel
point contact method. At 4.2 K, SIN and SIS tunnel junctions are obtained with
well-defined quasiparticle peaks, robust dip and hump features and in some
cases Josephson currents. The doping dependence of tunneling conductances of
Ca-rich Bi2212 are analyzed and compared to stoichiometric Bi2212. A similar
profile of energy gap vs. doping concentration is found although the Ca-rich
samples have a slighly smaller optimum Tc and therefore smaller gap values for
any doping level. The evolution of tunneling conductance peak height to
background ratios with hole concentration are compared. For a given doping
level, the Ca-rich spectra showed more broadened features compared to the
stoichiometric counterparts, most likely due to increased disorder from the
excess Ca. Comparison of the dip and hump features has provided some potential
insights into their origins.Comment: 4 pages, 4 figures; presented at the Applied Superconductivity
Conference (August 4-9, 2002) in Houston, TX; to be published in IEEE Trans.
Appl. Supercon
The Experimental plan of the 4m Resonant Sideband Extraction Prototype for The LCGT
The 4m Resonant Sideband Extraction (RSE) interferometer is a planned prototype of the LCGT interferometer. The aim of the experiment is to operate a powerrecycled Broadband RSE interferometer with suspended optics and to achieve diagonalization of length signals of the central part of the interferometer directly through the optical setup. Details of the 4m RSE interferometer control method as well as the design of the experimental setup will be presented
Single Junction and Intrinsic Josephson Junction Tunneling Spectroscopies of Bi2Sr2CaCu2O8+d
Tunneling spectroscopy measurements are reported on optimally-doped and
overdoped BiSrCaCuO single crystals. A novel
point contact method is used to obtain superconductor-insulator-normal metal
(SIN) and SIS break junctions as well as intrinsic Josephson junctions (IJJ)
from nanoscale crystals. Three junction types are obtained on the same crystal
to compare the quasiparticle peaks and higher bias dip/hump structures which
have also been found in other surface probes such as scanning tunneling
spectroscopy and angle-resolved photoemission spectroscopy. However, our IJJ
quasiparticle spectra consistently reveal very sharp conductance peaks and no
higher bias dip structures. The IJJ conductance peak voltage divided by the
number of junctions in the stack consistently leads to a significant
underestimate of when compared to the single junction values. The
comparison of the three methods suggests that the markedly different
characteristics of IJJ are a consequence of nonequilibrium effects and are not
intrinsic quasiparticle features.Comment: 4 pages, 4 figures; presented at the Applied Superconductivity
Conference (October 3-8, 2004) in Jacksonville, FL; to be published in IEEE
Trans. Appl. Supercon
Bose-Fermi Mixtures in One Dimension
We analyze the phase stability and the response of a mixture of bosons and
spin-polarized fermions in one dimension (1D). Unlike in 3D, phase separation
happens for low fermion densities. The dynamics of the mixture at low energy is
independent of the spin-statistics of the components, and zero-sound-like modes
exist that are essentially undamped.Comment: 5 pages; 1 figur
Control sideband generation for dual-recycled laser interferometric gravitational wave detectors
We present a discussion of the problems associated with generation of multiple control sidebands for length sensing and control of dual-recycled, cavity-enhanced Michelson interferometers and the motivation behind more complicated sideband generation methods. We focus on the Mach–Zehnder interferometer as a topological solution to the problem and present results from tests carried out at the Caltech 40 m prototype gravitational wave detector. The consequences for sensing and control for advanced interferometry are discussed, as are the implications for future interferometers such as Advanced LIGO
Two Sizes of Superconducting Gaps on an Under-doped Bi2.1Sr1.9Ca2Cu3O10+δ with TC ∼ 101K by Tunneling Spectroscopy
AbstractWe measured tunneling conductances on an under-doped trilayer cuprate Bi2.1Sr1.9Ca2Cu3O10+≏ (Bi2223) with TC ∼ 101K by a point contact method, which has three CuO2 planes in a unit cell. The tunneling conductances on Bi2223 exhibited two sizes of gaps originated from outer and inner CuO2 plane (OP and IP). The estimated size of superconducting gap from OP ΔOP is 34 ± 6 meV, and the ΔIP from IP is 51 ± 5 meV, respectively. We also observed tunneling conductances which simultaneously displayed two superconducting peaks of OP and IP. Moreover, we propose the model of two superconductor-insulator-normal metal junctions which exhibit two sizes gaps of OP and IP
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