2,335 research outputs found
Magnetic properties and interlayer coupling in Co/V multilayers
The magnetic properties of evaporated Co/V multilayer films have been studied by superconducting quantum interference device magnetometer and ferromagnetic-resonance (FMR). FMR has been used to study the interlayer exchange coupling and the FMR linewidth in Co/V multilayers at room temperature. Spin-waves resonance modes were observed in some Co/V multilayers and the relation of resonant field Hres with the mode number n obeys the so-called n2 law. The interlayer coupling constant was determined. The FMR linewidth, in parallel geometry, of the uniform mode was found to increase with decreasing Co thickness (10Å £ tCo £ 45Å) indicating that it corresponds to an interfacial effect
Volvulus du grêle sur mésentère commun incomplet une redoutable complication rare chez l’adulte: à propos de 1 cas
Le mésentère commun résulte d'une anomalie de rotation du tube digestif. Il est caractérisé par la persistance d'une disposition anatomique embryonnaire secondaire à une anomalie de rotation de l'anse ombilicale primitive, constituant ainsi un méso commun à toute l'anse intestinale etune racine du mésentère extrêmement courte. Cette insuffisance de rotation est le plus souvent associée à un défaut d'accolement. Ces anomalies de rotation intestinale peuvent aboutir à des complications redoutables parfois mortelles, qui surviennent généralement au cours de la période néonatale où à l'âge pédiatrique. On estime que la prévalence de ces malformations congénitales à l'âge adulte est de l'ordre de 0,2% à 0,5% âge auquel elles demeurent très souvent asymptomatiques et donc non diagnostiquées. Le diagnostic de volvulus total du grêle peut se faire dans des circonstances très variées: en urgence devant un tableau d'occlusion intestinale aiguë, voire un état de choc pouvant conduire au décès, devant un tableau de douleurs abdominales répétées plus ou moins associées à des troubles du transit. Nous rapportons l'observation d'un patient de 18 ans admis pour volvulus total du grêle sur mésentère commun incomplet chez qui l'évolution était favorable
Time variations in the deep underground muon flux
More than 35 million high-energy muons collected with the MACRO detector at
the underground Gran Sasso Laboratory have been used to search for flux
variations of different nature. Two kinds of studies were carried out: a search
for the occurrence of clusters of events and a search for periodic variations.
Different analysis methods, including the Scan Statistics test and the
Lomb-Scargle spectral analysis have been applied to the data.Comment: 7 pages, 5 figures, accepted by EP
Confronting Spin Flavor Solutions of the Solar Neutrino Problem with current and future solar neutrino data
We show that spin flavor precession solutions to the solar neutrino problem,
although preferred by the latest solar data, are ruled out by the first results
from the KamLAND reactor experiment, at more than 3_sigma. An illustrative chi2
plot comparing these descriptions with oscillations is given.Comment: new appendix added discussing the impact of the KamLAND data. This
updates the one published in Phys.Rev.D66:093009,200
Experimental Bounds on Masses and Fluxes of Nontopological Solitons
We have re-analyzed the results of various experiments which were not
originally interested as searches for the Q-ball or the Fermi-ball. Based on
these analyses, in addition to the available data on Q-balls, we obtained
rather stringent bounds on flux, mass and typical energy scale of Q-balls as
well as Fermi-balls. In case these nontopological solitons are the main
component of the dark matter of the Galaxy, we found that only such solitons
with very large quantum numbers are allowed. We also estimate how sensitive
future experiments will be in the search for Q-balls and Fermi-balls.Comment: 19 pages, 7 eps figures, RevTeX, psfig.st
Search for massive rare particles with MACRO
Massive rare particles have been searched for in the penetrating cosmic
radiation using the MACRO apparatus at the Gran Sasso National Laboratories.
Liquid scintillators, streamer tubes and nuclear track detectors have been used
to search for magnetic monopoles (MMs).
Based on no observation of such signals, stringent flux limits are
established for MMs as slow as a few 10^(-5)c. The methods based on the
scintillator and on the nuclear track subdetectors were also applied to search
for nuclearites. Preliminary results of the searches for charged Q-balls are
also presented.Comment: 20 pages, 9 EPS figures included with epsfi
Search for Nucleon Decays induced by GUT Magnetic Monopoles with the MACRO Experiment
The interaction of a Grand Unification Magnetic Monopole with a nucleon can
lead to a barion-number violating process in which the nucleon decays into a
lepton and one or more mesons (catalysis of nucleon decay). In this paper we
report an experimental study of the effects of a catalysis process in the MACRO
detector. Using a dedicated analysis we obtain new magnetic monopole (MM) flux
upper limits at the level of for
, based on the search for
catalysis events in the MACRO data. We also analyze the dependence of the MM
flux limit on the catalysis cross section.Comment: 12 pages, Latex, 10 figures and 2 Table
Observation of the Shadowing of Cosmic Rays by the Moon using a Deep Underground Detector
Using data collected by the MACRO experiment during the years 1989-1996, we
show evidence for the shadow of the moon in the underground cosmic ray flux
with a significance of 3.6 sigma. This detection of the shadowing effect is the
first by an underground detector. A maximum-likelihood analysis is used to
determine that the angular resolution of the apparatus is 0.9+/-0.3 degrees.
These results demonstrate MACRO's capabilities as a muon telescope by
confirming its absolute pointing ability and quantifying its angular
resolution.Comment: 14 pages, 8 figures Submitted to Phys. Rev.
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