20,520 research outputs found
Charged-Current Disappearance Measurements in the NuMI Off-Axis Beam
This article studies the potential of combining charged-current disappearance
measurements of \nu_{\mu} to \nu_{\tau} from MINOS and an off-axis beam. I find
that the error on \Delta m^2 from a 100 kt-yr off-axis measurement is a few
percent of itself. Further, I find little improvement to an off-axis
measurement by combining it with MINOS.Comment: Presented at NuFact'02. Four pages, three figure
Analytical and experimental investigation of a 1/8-scale dynamic model of the shuttle orbiter. Volume 3A: Supporting data
For abstract, see N75-15681
Analytical and experimental investigation of a 1/8-scale dynamic model of the shuttle orbiter. Volume 1: Summary report
A 1/8-scale structural dynamics model of the space shuttle orbiter was analyzed using the NASA Structural Analysis System (NASTRAN). Comparison of the calculated eigenvalues with preliminary test data for the unrestrained condition indicate that the analytical model was consistently stiffer, being about 20% higher in the first mode. The eigenvectors show reasonably good agreement with test data. A series of analytical and experimental investigations undertaken to resolve the discrepancy are described. Modifications in the NASTRAN model based upon these investigations resulted in close agreement for both eigenvalues and eigenvectors
A note on compactly generated co-t-structures
The idea of a co-t-structure is almost "dual" to that of a t-structure, but
with some important differences. This note establishes co-t-structure analogues
of Beligiannis and Reiten's corresponding results on compactly generated
t-structures.Comment: 10 pages; details added to proofs, small correction in the main
resul
High resolution spectroscopy of single NV defects coupled with nearby C nuclear spins in diamond
We report a systematic study of the hyperfine interaction between the
electron spin of a single nitrogen-vacancy (NV) defect in diamond and nearby
C nuclear spins, by using pulsed electron spin resonance spectroscopy.
We isolate a set of discrete values of the hyperfine coupling strength ranging
from 14 MHz to 400 kHz and corresponding to C nuclear spins placed at
different lattice sites of the diamond matrix. For each lattice site, the
hyperfine interaction is further investigated through nuclear spin polarization
measurements and by studying the magnetic field dependence of the hyperfine
splitting. This work provides informations that are relevant for the
development of nuclear-spin based quantum register in diamond.Comment: 8 pages, 5 figure
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Development Of Third Harmonic Generation As A Short Pulse Probe Of Shock Heated Material
We are studying high-pressure laser produced shock waves in silicon (100). To examine the material dynamics, we are performing pump-probe style experiments utilizing 600 ps and 40 fs laser pulses from a Ti:sapphire laser. Two-dimensional interferometry reveals information about the shock breakout, while third harmonic light generated at the rear surface is used to infer the crystalline state of the material as a function of time. Sustained third harmonic generation (THG) during a similar to 100 kbar shock breakout indicate that the rear surface remains crystalline for at least 3 ns. However, a decrease in THG during a similar to 300 kbar shock breakout suggests a different behavior, which could include a change in crystalline structure.Mechanical Engineerin
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Optimization of the neutron yield in fusion plasmas produced by Coulomb explosions of deuterium clusters irradiated by a petawatt laser
The kinetic energy of hot (multi-keV) ions from the laser-driven Coulomb explosion of deuterium clusters and the resulting fusion yield in plasmas formed from these exploding clusters has been investigated under a variety of conditions using the Texas Petawatt laser. An optimum laser intensity was found for producing neutrons in these cluster fusion plasmas with corresponding average ion energies of 14 keV. The substantial volume (1-10 mm(3)) of the laser-cluster interaction produced by the petawatt peak power laser pulse led to a fusion yield of 1.6x10(7) neutrons in a single shot with a 120 J, 170 fs laser pulse. Possible effects of prepulses are discussed. DOI: 10.1103/PhysRevE.87.023106Glenn Focht Memorial FellowshipNNSA DE-FC52-08NA28512DOE Office of Basic Energy SciencesPhysic
Third-order cosmological perturbations of zero-pressure multi-component fluids: Pure general relativistic nonlinear effects
Present expansion stage of the universe is believed to be mainly governed by
the cosmological constant, collisionless dark matter and baryonic matter. The
latter two components are often modeled as zero-pressure fluids. In our
previous work we have shown that to the second-order cosmological
perturbations, the relativistic equations of the zero-pressure, irrotational,
multi-component fluids in a spatially near flat background effectively coincide
with the Newtonian equations. As the Newtonian equations only have quadratic
order nonlinearity, it is practically interesting to derive the potential
third-order perturbation terms in general relativistic treatment which
correspond to pure general relativistic corrections. Here, we present pure
general relativistic correction terms appearing in the third-order
perturbations of the multi-component zero-pressure fluids. We show that, as in
a single component situation, the third-order correction terms are quite small
(~ 5 x10^{-5} smaller compared with the relativistic/Newtonian second-order
terms) due to the weak level anisotropy of the cosmic microwave background
radiation. Still, there do exist pure general relativistic correction terms in
third-order perturbations which could potentially become important in future
development of precision cosmology. We include the cosmological constant in all
our analyses.Comment: 20 pages, no figur
Anti-Proton Evolution in Little Bangs and Big Bang
The abundances of anti-protons and protons are considered within
momentum-integrated Boltzmann equations describing Little Bangs, i.e.,
fireballs created in relativistic heavy-ion collisions. Despite of a large
anti-proton annihilation cross section we find a small drop of the ratio of
anti-protons to protons from 170 MeV (chemical freeze-out temperature) till 100
MeV (kinetic freeze-out temperature) for CERN-SPS and BNL-RHIC energies thus
corroborating the solution of the previously exposed "ani-proton puzzle". In
contrast, the Big Bang evolves so slowly that the anti-baryons are kept for a
long time in equilibrium resulting in an exceedingly small fraction. The
adiabatic path of cosmic matter in the phase diagram of strongly interacting
matter is mapped out
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