193 research outputs found
Evidence of resonant surface wave excitation in the relativistic regime through measurements of proton acceleration from grating targets
The interaction of laser pulses with thin grating targets, having a periodic
groove at the irradiated surface, has been experimentally investigated.
Ultrahigh contrast () pulses allowed to demonstrate an enhanced
laser-target coupling for the first time in the relativistic regime of
ultra-high intensity >10^{19} \mbox{W/cm}^{2}. A maximum increase by a factor
of 2.5 of the cut-off energy of protons produced by Target Normal Sheath
Acceleration has been observed with respect to plane targets, around the
incidence angle expected for resonant excitation of surface waves. A
significant enhancement is also observed for small angles of incidence, out of
resonance.Comment: 5 pages, 5 figures, 2nd version implements final correction
A violência contra mulheres: demandas espontâneas e busca ativa em unidade básica de saúde
Acolher demandas e assistir mulheres que sofrem violência é parte dos direitos em saúde, embora a assistência não esteja estruturada e ocorra pouca detecção de casos. Buscou-se um diagnóstico de situação em serviços, avaliando-se a emergência de demandas referidas à violência por parte das usuárias de uma unidade básica da rede pública, contrastando-se a demanda espontânea com a busca ativa de casos. Realizou-se um primeiro estudo por técnicas de observação participante, seguida de estudo de prontuário, com 142 mulheres sendo acompanhadas; num segundo estudo, em uma amostra de 322 usuárias, aplicou-se entrevista. Em atividades grupais observou-se relatos espontâneos e nos prontuários médicos registros de demandas espontâneas; o mesmo não ocorreu em consultas individuais. A entrevista detectou uma prevalência de casos muito maior. Então, a possibilidade de detecção de casos, seu acolhimento e algumas respostas do serviço, requer especificidade de abordagem e cuidados próprios para que a violência contra mulheres possa emergir como parte da demanda usual na saúde
Search for the Flavor-Changing Neutral-Current Decays and
We report the results of a search for the flavor-changing neutral-current
decays and in
data from Fermilab charm hadroproduction experiment E791. No signal above
background is found, and we obtain upper limits on branching fractions,
and
, at the 90\% confidence
level.Comment: nine pages with figures; compressed, uuencoded postscrip
Non-adiabatic cluster expansion after ultrashort laser interaction
AbstractWe used X-ray spectroscopy as a diagnostic tool for investigating the properties of laser-cluster interactions at the stage in which non-adiabatic cluster expansion takes place and a quasi-homogeneous plasma is produced. The experiment was carried out with a 10 TW, 65 fs Ti:Sa laser focused on CO2 cluster jets. The effect of different laser-pulse contrast ratios and cluster concentrations was investigated. The X-ray emission associated to the Rydberg transitions allowed us to retrieve, through the density and temperature of the emitting plasma, the time after the beginning of the interaction at which the emission occurred. The comparison of this value with the estimated time for the "homogeneous" plasma formation shows that the degree of adiabaticity depends on both the cluster concentration and the pulse contrast. Interferometric measurements support the X-ray data concerning the plasma electron density
Measurement of the Ds Lifetime
We report the results of a precise measurement of the Ds meson lifetime based
on 1662 +/- 56 fully reconstructed Ds -> phi pi decays, from the charm
hadroproduction experiment E791 at Fermilab. Using an unbinned maximum
likelihood fit, we measure the Ds lifetime to be 0.518 +/- 0.014 +/- 0.007 ps.
The ratio of the measured Ds lifetime to the world average D0 lifetime is 1.25
+/- 0.04. This result differs from unity by six standard deviations, indicating
significantly different lifetimes for the Ds and the D0.Comment: 12 pages, 3 figures, 2 table. LaTe
Experimental evidence for a light and broad scalar resonance in decay
From a sample of decay, we find
. Using a coherent amplitude analysis
to fit the Dalitz plot of this decays, we find strong evidence that a scalar
resonance of mass MeV/ and width MeV/ accounts for approximately half of all decays.Comment: 10 pages, 3 eps figure
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