2,843 research outputs found
Observation of Gemini 6 - Gemini 7 rendezvous
Gemini 6-Gemini 7 rendezvous photographs taken by Baker-Nunn camer
On the degeneracies of the mass-squared differences for three-neutrino oscillations
Using an algebraic formulation, we explore two well-known degeneracies
involving the mass-squared differences for three-neutrino oscillations assuming
CP symmetry is conserved. For vacuum oscillation, we derive the expression for
the mixing angles that permit invariance under the interchange of two
mass-squared differences. This symmetry is most easily expressed in terms of an
ascending mass order. This can be used to reduce the parameter space by one
half in the absence of the MSW effect. For oscillations in matter, we derive
within our formalism the known approximate degeneracy between the standard and
inverted mass hierarchies in the limit of vanishing . This is done
with a mass ordering that permits the map .
Our techniques allow us to translate mixing angles in this mass order
convention into their values for the ascending order convention. Using this
dictionary, we demonstrate that the vacuum symmetry and the approximate
symmetry invoked for oscillations in matter are distinctly different.Comment: 5 pages, revised manuscrip
Station coordinates in the standard earth 3 system and radiation-pressure perturbations from ISAGEX camera data
Simultaneous and individual camera observations of GEOS 1, GEOS 2, Pageos, and Midas 4 obtained during the International Satellite Geodesy Experiment are utilized to determine station coordinates. The Smithsonian Astrophysical Observatory Standard Earth III system of coordinates is used to tie the geometrical network to a geocentric system and as a reference for calculating satellite orbits. A solution for coordinates combining geometrical and dynamical methods is obtained, and a comparison between the solutions and terrestrial data is made. The radiation-pressure and earth-albedo perturbations for Pageos are very large, and Pageos' orbits are used to evaluate the analytical treatment of these perturbations. Residual effects, which are probably of interest to aeronomists, remain in the Pageos orbits
Vacuum-UV negative photoion spectroscopy of CH3F, CH3Cl and CH3Br
Using tunable vacuum-UV radiation from a synchrotron, negative ions are detected by quadrupolar mass spectrometry following photoexcitation of three gaseous halogenated methanes CHX (X = F,Cl,Br). The anions X, H, CX, CHX and CHX are observed, and their ion yields recorded in the range 8-35 eV. The anions show a linear dependence of signal with pressure, showing that they arise from unimolecular ion-pair dissociation, generically described as AB + h A + B (+ neutrals). Absolute cross sections for ion-pair formation are obtained by calibrating the signal intensities with those of F from both SF and CF. The cross sections for formation of X + CH are much greater than for formation of CHX + H. In common with many quadrupoles, the spectra of / 1 (H) anions show contributions from all anions, and only for CHBr is it possible to perform the necessary subtraction to obtain the true H spectrum. The anion cross sections are normalised to vacuum-UV absorption cross sections to obtain quantum yields for their production. The appearance energies of X and CHX are used to calculate upper limits to 298 K bond dissociation energies for D (HC-X) and D (XHC-H) which are consistent with literature values. The spectra suggest that most of the anions are formed indirectly by crossing of Rydberg states of the parent molecule onto an ion-pair continuum. The one exception is the lowest-energy peak of F from CHF at 13.4 eV, where its width and lack of structure suggest it may correspond to a direct ion-pair transition
On detecting CP violation in a single neutrino oscillation channel at very long baselines
We propose a way of detecting CP violation in a single neutrino oscillation
channel at very long baselines (on the order of several thousands of
kilometers), given precise knowledge of the smallest mass-squared difference.
It is shown that CP violation can be characterized by a shift in of the
peak oscillation in the -- appearance channel, both in vacuum
and in matter. In fact, matter effects enhance the shift at a fixed energy. We
consider the case in which sub-GeV neutrinos are measured with varying baseline
and also the case of a fixed baseline. For the varied baseline, accurate
knowledge of the absolute neutrino flux would not be necessary; however,
neutrinos must be distinguishable from antineutrinos. For the fixed baseline,
it is shown that CP violation can be distinguished if the mixing angle
were known.Comment: 8 pages, 9 figures; minor typos correcte
- …