31 research outputs found
Observation of Parity Violation in the Omega-minus -> Lambda + K-minus Decay
The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has
been measured from a sample of 4.50 million unpolarized Omega-minus decays
recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/-
0.19(stat) +/- 0.16(syst)]{\times}10^{-2}. This is the first unambiguous
evidence for a nonzero alpha decay parameter, and hence parity violation, in
the Omega-minus -> Lambda + K-minus decay.Comment: 10 pages, 7 figure
HyperCP: A high-rate spectrometer for the study of charged hyperon and kaon decays
The HyperCP experiment (Fermilab E871) was designed to search for rare
phenomena in the decays of charged strange particles, in particular CP
violation in and hyperon decays with a sensitivity of
. Intense charged secondary beams were produced by 800 GeV/c protons
and momentum-selected by a magnetic channel. Decay products were detected in a
large-acceptance, high-rate magnetic spectrometer using multiwire proportional
chambers, trigger hodoscopes, a hadronic calorimeter, and a muon-detection
system. Nearly identical acceptances and efficiencies for hyperons and
antihyperons decaying within an evacuated volume were achieved by reversing the
polarities of the channel and spectrometer magnets. A high-rate
data-acquisition system enabled 231 billion events to be recorded in twelve
months of data-taking.Comment: 107 pages, 45 Postscript figures, 14 tables, Elsevier LaTeX,
submitted to Nucl. Instrum. Meth.
Desempenho, variáveis fisiológicas e comportamento de bezerros mantidos em diferentes instalações: época chuvosa
Supernova neutrino detection in NOvA
The NOvA long-baseline neutrino experiment uses a pair of large, segmented, liquid-scintillator calorimeters to study neutrino oscillations, using GeV-scale neutrinos from the Fermilab NuMI beam. These detectors are also sensitive to the flux of neutrinos which are emitted during a core-collapse supernova through inverse beta decay interactions on carbon at energies of O(10 MeV). This signature provides a means to study the dominant mode of energy release for a core-collapse supernova occurring in our galaxy. We describe the data-driven software trigger system developed and employed by the NOvA experiment to identify and record neutrino data from nearby galactic supernovae. This technique has been used by NOvA to self-trigger on potential core-collapse supernovae in our galaxy, with an estimated sensitivity reaching out to 10 kpc distance while achieving a detection efficiency of 23% to 49% for supernovae from progenitor stars with masses of 9.6 M☉ to 27 M☉, respectively
Blood Plasma Constituents in 14-Week Old Hypertensive and Hypotensive Strains of Turkeys
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Study of the Rare Hyperon Decay {\boldmath \Omega^\mp \to \Xi^\mp \: \pi^+\pi^-}
The authors report a new measurement of the decay {Omega}{sup -} {yields} {Xi}{sup -} {pi}{sup +}{pi}{sup -} with 76 events and a first observation of the decay {bar {Omega}}{sup +} {yields} {bar {Xi}}{sup +} {pi}{sup +}{pi}{sup -} with 24 events, yielding a combined branching ratio (3.74{sub -0.56}{sup +0.67}) x 10{sup -4}. This represents a factor 25 increase in statistics over the best previous measurement. No evidence is seen for CP violation, with {Beta}({Omega}{sup -} {yields} {Xi}{sup -} {pi}{sup +}{pi}{sup -}) = 4.04{sub -0.71}{sup +0.83} x 10{sup -4} and {Beta}({bar {Omega}}{sup +} {yields} {bar {Xi}}{sup +} {pi}{sup +}{pi}{sup -}) = 3.15{sub -0.89}{sup +1.12} x 10{sup -4}. Contrary to theoretical expectation, they see little evidence for the decays {Omega}{sup -} {yields} {Xi}*{sub 1530}{sup 0} {pi}{sup -} and {bar {Omega}}{sup +} {yields} {bar {Xi}}*{sub 1530}{sup 0} {pi}{sup +} and place a 90% C.L. upper limit on the combined branching ratio {Beta}({Omega}{sup -}({bar {Omega}}{sup +}) {yields} {Xi}*{sub 1530}{sup 0} ({bar {Xi}}*{sub 1530}{sup 0}){pi}{sup {-+}}) < 7.0 x 10{sup -5}
The prevalence, prognostic significance and hormonal content of endocrine cells in gastric cancer
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Forward Neutron Production at the Fermilab Main Injector
We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as A{sup a} where a is 0.46 {+-} 0.06 for a beam momentum of 58 GeV/c and 0.54 {+-} 0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo. The MIPP (Main Injector Particle Production) experiment (FNAL E907) [1] acquired data in the Meson Center beam line at Fermilab. The primary purposes of the experiment were to investigate scaling laws in hadron fragmentation [2], to obtain hadron production data for the NuMI (Neutrinos at the Main Injector [3]) target to be used for calculating neutrino fluxes, and to obtain inclusive pion, neutron, and photon production data to facilitate proton radiography [4]. While there is considerable data available on inclusive charged particle production [5], there is little data on neutron production. In this article we present results for forward neutron production using proton beams of 58 GeV/c, 84 GeV/c, and 120 GeV/c on hydrogen, beryllium, carbon, bismuth, and uranium targets, and compare these data with predictions from Monte Carlo simulations