10,086 research outputs found
Detecting atmospheric neutrino oscillations in the ATLAS detector at CERN
We discuss the possibility to study oscillations of atmospheric neutrinos in
the ATLAS experiment at CERN. Due to the large total detector mass, a
significant number of events is expected, and during the shutdown phases of the
LHC, reconstruction of these events will be possible with very good energy and
angular resolutions, and with charge identification. We argue that 500 live
days of neutrino running could be achieved, and that a total of ~160 contained
\nu_\mu events and ~360 upward going muons could be collected during this time.
Despite the low statistics, the excellent detector resolution will allow for an
unambiguous confirmation of atmospheric neutrino oscillations and for
measurements of the leading oscillation parameters. Though our detailed
simulations show that the sensitivity of ATLAS is worse than that of dedicated
neutrino experiments, we demonstrate that more sophisticated detectors, e.g. at
the ILC, could be highly competitive with upcoming superbeam experiments, and
might even give indications for the mass hierarchy and for the value of
theta-13.Comment: 8 pages, 4 figures, 2 tables, RevTeX 4; modified treatment of upward
going muons, results unchanged; matches published versio
ATS-6 flight accelerometers
Five accelerometers mounted near the adapter base of the Titan 3-C launch vehicle and three on the hub of the ATS-F spacecraft provided (1) data for verifying basic spacecraft mode shapes and frequencies during powered flight while attached to the launch vehicle; (2) failure mode detection and diagnostic information on in-flight anomalies; and (3) data to be used in the design of future spacecraft to be flown on the Titan 3-C. Because data from the instruments mounted on the spacecraft hub passed through an in-flight disconnect at the separation plane between the transtage and ATS-F, the moment this connector was broken, the signal to the telemetry system showed a step function change. By monitoring these telemetry traces on the ground at appropriate times during flight sequences, a positive indication of spacecraft separation was obtained. Flight data showing dynamic response at spacecraft launch vehicle interface and at the top of ATS spacecraft during significant launch events are presented in tables
W(h)ither the Fed’s balance sheet?
Federal Reserve policymakers have expressed their support for ultimately shrinking the Fed’s balance sheet and returning the composition of its portfolio to only Treasury securities. Policymakers also favor returning to a fed-funds-rate-targeting procedure or something quite similar. While Fed holdings of some asset classes have been diminishing naturally, the orderly reduction of others could involve special tools that the Fed has been putting in place for a while. An ongoing issue will be to determine an optimal sequence of appropriate actions.Monetary policy - United States ; Federal Reserve System ; Financial crises
Exploiting the directional sensitivity of the Double Chooz near detector
In scintillator detectors, the forward displacement of the neutron in the
reaction provides neutrino directional information as
demonstrated by the CHOOZ reactor experiment with 2,500 events. The near
detector of the forthcoming Double Chooz experiment will collect
events per year, enough to determine the average neutrino
direction with a half-cone aperture of in one year. It
is more difficult to separate the two Chooz reactors that are viewed at a
separation angle . If their strengths are known and
approximately equal, the azimuthal location of each reactor is obtained with
() and the probability of confusing them with a single
source is less than 11%. Five year's data reduce this ``confusion probability''
to less than 0.3%, i.e., a separation is possible. All of these
numbers improve rapidly with increasing angular separation of the sources. For
a setup with and one year's data, the azimuthal
uncertainty for each source decreases to . Of course, for Double
Chooz the two reactor locations are known, allowing one instead to measure
their individual one-year integrated power output to (), and
their five-year integrated output to ().Comment: 7 pages, 10 figure
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Condition number estimates for combined potential boundary integral operators in acoustic scattering
We study the classical combined field integral equation formulations for time-harmonic acoustic scattering by a sound soft bounded obstacle, namely the indirect formulation due to Brakhage-Werner/Leis/Panic, and the direct formulation associated with the names of Burton and Miller. We obtain lower and upper bounds on the condition numbers for these formulations, emphasising dependence on the frequency, the geometry of the scatterer, and the coupling parameter. Of independent interest we also obtain upper and lower bounds on the norms of two oscillatory integral operators, namely the classical acoustic single- and double-layer potential operators
Signatures of axion-like particles in the spectra of TeV gamma-ray sources
One interpretation of the unexplained signature observed in the PVLAS
experiment invokes a new axion-like particle (ALP) with a two-photon vertex,
allowing for photon-ALP oscillations in the presence of magnetic fields. In the
range of masses and couplings suggested by PVLAS, the same effect would lead to
a peculiar dimming of high-energy photon sources. For typical parameters of the
turbulent magnetic field in the galaxy, the effect sets in at E_gamma >~ 10
TeV, providing an ALP signature in the spectra of TeV gamma sources that can be
probed with Cherenkov telescopes. A dedicated search will be strongly motivated
if the ongoing photon regeneration experiments confirm the PVLAS particle
interpretation.Comment: 8 pages, 1 eps figure; typos corrected, matches published versio
Störungen des Natriumhaushalts beim Notfallpatienten: Salz in der Suppe der Notfallmedizin
Zusammenfassung: Elektrolytstörungen sind beim Notfallpatienten häufig und können potenziell lebensbedrohlich sein. So weisen z.B. knapp 20 % aller Notfallpatienten eine Hypo- oder Hypernatriämie auf. In den letzten Jahren konnte gezeigt werden, dass Störungen des Natriumhaushalts nicht nur Ausdruck der Schwere der Grunderkrankung, sondern unabhängige Prädiktoren für das Outcome des Patienten darstellen. Die Patienten berichten häufig unspezifische Symptome wie Gang- und Konzentrationsstörungen oder werden nach Sturz bei erhöhter Falltendenz der zentralen Notaufnahme zugeführt. Umso wichtiger ist es, Dysnatriämien beim Notfallpatienten rechtzeitig zu erkennen und eine adäquate Korrektur einzuleiten. Hierfür ist die Kenntnis der Mechanismen der Entstehung von Hypo- [Diuretikatherapie, Syndrom der inadäquaten Vasopressin(ADH)-Sekretion (SIADH), Herzinsuffizienz, Leberzirrhose etc.] und Hypernatriämien (Dehydration, Infusionen, Diuretikatherapie, osmotische Diurese etc.) zu berücksichtigen. Akute, symptomatische Dysnatriämien sind rasch mithilfe der Gabe von 3 %iger Kochsalz(NaCl)-Lösung im Fall einer Hyponatriämie und mithilfe der Gabe von 5 %iger Glucoselösung im Fall einer Hypernatriämie zu therapieren. Unter allen Umständen ist während der Korrektur einer Hypo- oder Hypernatriämie das engmaschige Monitoring der Serumnatriumkonzentration essenziell, um eine zu rasche Korrektur und daraus resultierende Folgeschäden zu vermeiden. Der vorliegende Beitrag erläutert Epidemiologie und Ätiologie der Hypo- sowie Hypernatriämie auf Basis der aktuellen Studienlage unter spezieller Berücksichtigung notfallmedizinischer Aspekte und gibt Empfehlungen zur Therapie der Elektrolytstörunge
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