722 research outputs found
Radiative Proton Capture: Recent Results
Supported by the National Science Foundation and Indiana Universit
The (d,6-Li) Reaction Studies
Supported by the National Science Foundation and Indiana Universit
Radiative Capture Reactions at Intermediate Energies
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
flatIGW - an inverse algorithm to compute the Density of States of lattice Self Avoiding Walks
We show that the Density of States (DoS) for lattice Self Avoiding Walks can
be estimated by using an inverse algorithm, called flatIGW, whose step-growth
rules are dynamically adjusted by requiring the energy histogram to be locally
flat. Here, the (attractive) energy associated with a configuration is taken to
be proportional to the number of non-bonded nearest neighbor pairs (contacts).
The energy histogram is able to explicitly direct the growth of a walk because
the step-growth rule of the Interacting Growth Walk \cite{IGW} samples the
available nearest neighbor sites according to the number of contacts they would
make. We have obtained the complex Fisher zeros corresponding to the DoS,
estimated for square lattice walks of various lengths, and located the
temperature by extrapolating the finite size values of the real zeros to their
asymptotic value, (reasonably close to the known value,
\cite{barkema}).Comment: 18 pages, 7 eps figures; parts of the manuscript are rewritten so as
to improve clarity of presentation; an extra reference adde
Measurements of S and P-A Using the 12-C(p,p'y) Reaction at 150 MeV
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Neutron and hard X-ray measurements during pellet deposition in TFTR
Measurements of neutrons and hard x rays are made with a pair of plastic scintillators during injection of deuterium pellets into deuterium TFTR plasmas. Three cases are investigated. During ohmic heating in plasmas with few runaway electrons, the neutron emission does not increase when a pellet is injected, indicating that strong acceleration of the pellet ions does not occur. In ohmic plasmas with low but detectable levels of runaway electrons, an x-ray burst is observed on a detector near the pellet injector as the pellet ablates, while a detector displaced 126/sup 0/ toroidally from the injector does not measure a synchronous burst. Reduced pellet penetration correlates with the presence of x-ray emission, suggesting that the origin of the burst is bremsstrahlung from runaway electrons that strike the solid pellet. In deuterium beam-heated discharges, an increase in the d-d neutron emission is observed when the pellet ablates. In this case, the increase is due to fusion reactions between beam ions and the high density neutral and plasma cloud produced by ablation of the pellet; this localized density perturbation equilibrates in about 700 ..mu..sec. Analysis of the data indicates that the density propagates without forming a sharp shock front with a rapid initial propagation velocity (greater than or equal to 2 x 10/sup 7/ cm/sec) that subsequently decreases to around 3 x 10/sup 6/ cm/sec. Modelling suggests that the electron heat flux into the pellet cloud is much less than the classical Spitzer value
Anthropogenic Space Weather
Anthropogenic effects on the space environment started in the late 19th
century and reached their peak in the 1960s when high-altitude nuclear
explosions were carried out by the USA and the Soviet Union. These explosions
created artificial radiation belts near Earth that resulted in major damages to
several satellites. Another, unexpected impact of the high-altitude nuclear
tests was the electromagnetic pulse (EMP) that can have devastating effects
over a large geographic area (as large as the continental United States). Other
anthropogenic impacts on the space environment include chemical release ex-
periments, high-frequency wave heating of the ionosphere and the interaction of
VLF waves with the radiation belts. This paper reviews the fundamental physical
process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure
Esforço percebido, estresse e inflamação do trato respiratório superior em atletas de elite de canoagem
Toward an internally consistent astronomical distance scale
Accurate astronomical distance determination is crucial for all fields in
astrophysics, from Galactic to cosmological scales. Despite, or perhaps because
of, significant efforts to determine accurate distances, using a wide range of
methods, tracers, and techniques, an internally consistent astronomical
distance framework has not yet been established. We review current efforts to
homogenize the Local Group's distance framework, with particular emphasis on
the potential of RR Lyrae stars as distance indicators, and attempt to extend
this in an internally consistent manner to cosmological distances. Calibration
based on Type Ia supernovae and distance determinations based on gravitational
lensing represent particularly promising approaches. We provide a positive
outlook to improvements to the status quo expected from future surveys,
missions, and facilities. Astronomical distance determination has clearly
reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press
(chapter 8 of a special collection resulting from the May 2016 ISSI-BJ
workshop on Astronomical Distance Determination in the Space Age
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
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