2,786 research outputs found
On the Magnetic Field Strength of Active Region Filaments
We study the vector magnetic field of a filament observed over a compact
Active Region Neutral Line. Spectropolarimetric data acquired with TIP-II (VTT,
Tenerife, Spain) of the 10830 \AA spectral region provide full Stokes vectors
which were analyzed using three different methods: magnetograph analysis,
Milne-Eddington inversions and PCA-based atomic polarization inversions. The
inferred magnetic field strengths in the filament are of the order of 600 - 700
G by all these three methods. Longitudinal fields are found in the range of 100
- 200 G whereas the transverse components become dominant, with fields as large
as 500 - 600 G. We find strong transverse fields near the Neutral Line also at
photospheric levels. Our analysis indicates that strong (higher than 500 G, but
below kG) transverse magnetic fields are present in Active Region filaments.
This corresponds to the highest field strengths reliably measured in these
structures. The profiles of the Helium 10830 \AA lines observed in this Active
Region filament are dominated by the Zeeman effect.Comment: Accepted for publication in Astronomy and Astrophysics, 9 pages, 4
figure
Scattering polarization of hydrogen lines from electric-induced atomic alignment
We consider a gas of hydrogen atoms illuminated by a broadband, unpolarized
radiation with zero anisotropy. In the absence of external fields, the atomic
J-levels are thus isotropically populated. While this condition persists in the
presence of a magnetic field, we show instead that electric fields can induce
the alignment of those levels. We also show that this electric alignment cannot
occur in a two-term model of hydrogen (e.g., if only the Ly-alpha transition is
excited), or if the level populations are distributed according to Boltzmann's
law.Comment: 10 pages, 4 figures. Accepted by J.Phys.B: At.Mol.Opt.Phy
Promoção do consumo de frutas, legumes e verduras em Unidades de Educação Infantil: diagnóstico inicial.
Seleção do público-alvo e coleta de dados nas unidades de educação infantil; Diagnóstico do ambiente nas unidades de educação infantil; Consumo de frutas, legumes e verduras das crianças das unidades de educação infantil, segundo os pais/responsáveis; Consumo de frutas, legumes e verduras das crianças das unidades de educação infantil, segundo os recreadores/professores; Informações sobre os recreadores/professores nas unidades de educação infantil; Consumo de frutas, legumes e verduras das crianças das unidades de educação infantil, segundo as merendeiras; Informações sobre as merendeiras nas unidades de educação infantil; Aceitação de frutas, legumes e verduras pelas crianças nas unidades de educação infantil, segundo observação.bitstream/item/84158/1/2008-DOC-0088.pd
Promoção do consumo de frutas, legumes e verduras junto a comunidades atendidas pelo Programa Saúde da Família (PSF) e Programa de Agentes Comunitários de Saúde (PACS): diagnóstico inicial.
bitstream/item/84147/1/2008-DOC-0091.pd
On the Magnetic Field Strength of Active Region Filaments
We study the vector magnetic field of a filament observed over a compact
Active Region Neutral Line. Spectropolarimetric data acquired with TIP-II (VTT,
Tenerife, Spain) of the 10830 \AA spectral region provide full Stokes vectors
which were analyzed using three different methods: magnetograph analysis,
Milne-Eddington inversions and PCA-based atomic polarization inversions. The
inferred magnetic field strengths in the filament are of the order of 600 - 700
G by all these three methods. Longitudinal fields are found in the range of 100
- 200 G whereas the transverse components become dominant, with fields as large
as 500 - 600 G. We find strong transverse fields near the Neutral Line also at
photospheric levels. Our analysis indicates that strong (higher than 500 G, but
below kG) transverse magnetic fields are present in Active Region filaments.
This corresponds to the highest field strengths reliably measured in these
structures. The profiles of the Helium 10830 \AA lines observed in this Active
Region filament are dominated by the Zeeman effect.Comment: Accepted for publication in Astronomy and Astrophysics, 9 pages, 4
figure
A Measurement of the Correlation of Galaxy Surveys with CMB Lensing Convergence Maps from the South Pole Telescope
We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg^2 of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4σ, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg^2 SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe
Evidence for radial flow of thermal dileptons in high-energy nuclear collisions
The NA60 experiment at the CERN SPS has studied low-mass dimuon production in
158 AGeV In-In collisions. An excess of pairs above the known meson decays has
been reported before. We now present precision results on the associated
transverse momentum spectra. The slope parameter Teff extracted from the
spectra rises with dimuon mass up to the rho, followed by a sudden decline
above. While the initial rise is consistent with the expectations for radial
flow of a hadronic decay source, the decline signals a transition to an
emission source with much smaller flow. This may well represent the first
direct evidence for thermal radiation of partonic origin in nuclear collisions.Comment: Accepted for publication in Physical Review Letter
Dielectron Cross Section Measurements in Nucleus-Nucleus Reactions at 1.0 A GeV
We present measured dielectron production cross sections for Ca+Ca, C+C,
He+Ca, and d+Ca reactions at 1.0 A GeV. Statistical uncertainties and
systematic effects are smaller than in previous DLS nucleus-nucleus data. For
pair mass < 0.35 GeV/c2 : 1) the Ca+Ca cross section is larger than the
previous DLS measurement and current model results, 2) the mass spectra suggest
large contributions from pi0 and eta Dalitz decays, and 3) dsigma/dM is
proportional to ApAt. For M > 0.5 GeV/c2 the Ca+Ca to C+C cross section ratio
is significantly larger than the ratio of ApAt values.Comment: Submitted to Physical Review Letters. Further analysis information
will be posted on our web pages -- http://macdls.lbl.gov Figure 1 has been
redrawn to make more legible. Text modified to support redrawn figur
Measurement of an excess in the yield of J/ at very low in Pb-Pb collisions at = 2.76 TeV
We report on the first measurement of an excess in the yield of J/ at
very low transverse momentum ( GeV/) in peripheral hadronic
Pb-Pb collisions at = 2.76 TeV, performed by ALICE at the
CERN LHC. Remarkably, the measured nuclear modification factor of J/ in
the rapidity range reaches about 7 (2) in the range 0-0.3
GeV/ in the 70-90% (50-70%) centrality class. The J/ production cross
section associated with the observed excess is obtained under the hypothesis
that coherent photoproduction of J/ is the underlying physics mechanism.
If confirmed, the observation of J/ coherent photoproduction in Pb-Pb
collisions at impact parameters smaller than twice the nuclear radius opens new
theoretical and experimental challenges and opportunities. In particular,
coherent photoproduction accompanying hadronic collisions may provide insight
into the dynamics of photoproduction and nuclear reactions, as well as become a
novel probe of the Quark-Gluon Plasma.Comment: 18 pages, 3 captioned figures, 1 table, authors from page 13,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/191
Inclusive Dielectron Cross Sections in p+p and p+d Interactions at Beam Energies from 1.04 to 4.88 GeV
Measurements of dielectron production in p+p and p+d collisions with beam
kinetic energies from 1.04 to 4.88 GeV are presented. The differential cross
section is presented as a function of invariant pair mass, transverse momentum,
and rapidity. The shapes of the mass spectra and their evolution with beam
energy provide information about the relative importance of the various
dielectron production mechanisms in this energy regime. The p+d to p+p ratio of
the dielectron yield is also presented as a function of invariant pair mass,
transverse momentum, and rapidity. The shapes of the transverse momentum and
rapidity spectra from the p+d and p+p systems are found to be similar to one
another for each of the beam energies studied. The beam energy dependence of
the integrated cross sections is also presented.Comment: 15 pages and 16 figure
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