34,181 research outputs found
Differential pressure cell Patent
Differential pressure cell insensitive to changes in ambient temperature and extreme overloa
Short-range Magnetic interactions in the Spin-Ice compound HoTiO
Magnetization and susceptibility studies on single crystals of the pyrochlore
HoTiO are reported for the first time. Magnetization
isotherms are shown to be qualitatively similar to that predicted by the
nearest neighbor spin-ice model. Below the lock-in temperature, K, magnetization is consistent with the locking of spins along
[111] directions in a specific two-spins-in, two-spins-out arrangement. Below
the magnetization for displays a two step behavior
signalling the breaking of the ice rules.Comment: 4 pages, 3 figure
Isospin-breaking effects on alpha extracted in B --> pi pi, rho rho, rho pi
Isospin-breaking in B --> pi pi caused by pi^0-eta-eta' mixing is studied in
a model-independent way using flavor SU(3). Measured branching ratios for B^+
--> pi^+ pi^0, B^+ --> pi^+ eta^(') and B^0 --> pi^0 eta^(') imply an
uncertainty in alpha smaller than 1.4 degree. We find a negligible effect of
pi^0-eta-eta' mixing on alpha in B --> rho pi. Characterizing the effect of
rho^0-omega mixing in B --> rho rho and in B --> rho pi by the two-pion
invariant mass dependence, we point out a way of constraining this effect
experimentally or eliminating it altogether. We show that a model-independent
shift in alpha caused by electroweak penguin amplitudes in B --> pi pi and B
--> rho rho, \Delta alpha_{EWP}=1.5+- 0.3 degree, may be slightly different in
B --> rho pi. Other sources of isospin-breaking in these processes are briefly
discussed.Comment: 21 pages, very slight changes, same version as in Physical Review
New Prospects in Fixed Target Searches for Dark Forces with the SeaQuest Experiment at Fermilab
An intense, 120 GeV proton beam incident on an extremely long, iron target
generates enormous numbers of light-mass particles that also decay within that
target. If one of these particles decays to a final state with a hidden gauge
boson, or if such a particle is produced as a result of the initial collision,
then that weakly interacting, hidden-sector particle may traverse the remainder
of the target and be detected downstream through its possible decay to an
, , or final state. These conditions can be
realized through an extension of the SeaQuest experiment at Fermilab, and in
this initial investigation we consider how it can serve as an ultrasensitive
probe of hidden vector gauge forces, both Abelian and non-Abelian. A light,
weakly coupled hidden sector may well explain the dark matter established
through astrophysical observations, and the proposed search can provide
tangible evidence for its existence --- or, alternatively, constrain a "sea" of
possibilities.Comment: 14 pages, 8 figures; improved sensitivity analysis and cross-checks;
small shifts in the expected limits; conclusions unchanged; refs. adde
Loads and aeroelasticity division research and technology accomplishments for FY 1985 and plans for FY 1986
The Langley Research Center Loads and Aeroelasticity Division's research accomplishments for FY85 and research plans for FY86 are presented. The rk under each branch (technical area) will be described in terms of highlights of accomplishments during the past year and highlights of plans for the current year as they relate to five year plans for each technical area. This information will be useful in program coordination with other government organizations and industry in areas of mutual interest
Loads and Aeroelasticity Division research and technology accomplishments for FY 1984 and plans for FY 1985
The loads and aeroelasticity divisions research accomplishments are presented. The work under each branch or technical area, described in terms of highlights of accomplishments during the past year and highlights of plans for the current year as they relate to 5 year plans for each technical area. This information will be useful in program coordination with other government organizations and industry in areas of mutual interest
Theoretical and lidar studies of the density response of the mesospheric sodium layer to gravity wave perturbations
The density response of atmospheric layers to gravity waves is developed in two forms, an exact solution and a perturbation series solution. The degree of nonlinearity in the layer density response is described by the series solution whereas the exact solution gives insight into the nature of the responses. Density perturbation in an atmospheric layer are shown to be substantially greater than the atmospheric density perturbation associated with the propagation of a gravity wave. Because of the density gradients present in atmospheric layers, interesting effects were observed such as a phase reversal in the linear layer response which occurs near the layer peak. Once the layer response is understood, the sodium layer can be used as a tracer of atmospheric wave motions. A two dimensional digital signal processing technique was developed. Both spatial and temporal filtering are utilized to enhance the resolution by decreasing shot noise by more han 10 dB. Many of the features associated with a layer density response to gravity waves were observed in high resolution density profiles of the mesospheric sodium layer. These include nonlinearities as well as the phase reversal in the linear layer response
Operating manual for the RRL 8 channel data logger
A data collection device which takes measurements from external sensors at user specified time intervals is described. Three sensor ports are dedicated to temperature, air pressure, and dew point. Five general purpose sensor ports are provided. The user specifies when the measurements are recorded as well as when the information is read or stored in a minicomputer or a paper tape
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