514 research outputs found
Performance of the AMS-02 Transition Radiation Detector
For cosmic particle spectroscopy on the International Space Station the AMS
experiment will be equipped with a Transition Radiation Detector (TRD) to
improve particle identification. The TRD has 20 layers of fleece radiator with
Xe/CO2 proportional mode straw tube chambers. They are supported in a conically
shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA
analog multiplexers are used as front-end readout. A 20 layer prototype built
from final design components has achieved proton rejections from 100 to 2000 at
90% electron efficiency for proton beam energies up to 250 GeV with cluster
counting, likelihood and neural net selection algorithms.Comment: 11 pages, 25 figures, espcrc2.sty (elsevier 2-column
Do Two Symmetry Breaking Transitions in Photosynthetic Light Harvesting Complexes Form One, Two or More Kibble Zurek Model Topological Defects?
Kibble and Zurek proposed that rapid symmetry breaking transitions in the
hot, early universe could result in causally disconnected topological defects
such as cosmic strings. This type of first order transition has analogues in
certain second order transitions present in condensed matter such as liquid
crystals, super fluids, and charge density waves in terms of flux tubes or
vortices. Recently, we discovered that Rhodopseudomonas acidophilus
photosynthetic light harvesting complex might have different types of coherent
ground and excited states, suggesting that there are two different symmetry
breaking transitions. The B 850 ground states comprise eight identical rings
each containing 18 bacteriochlorophyll components, and each ring has undergone
a Bose Einstein phase transition to a charge density wave that lowers the
energy. The excited state coherence results from polariton formation from the
non-crossing of bosons, here an extension of exciton theory. The result is
short-lived quasi-particles with very low mass that can form an unusual BEC. We
suggest the oriented, circular B 850 and enclosed singlet B 875 compounds
create a new cavity structure with some attributes of a nano pillar. Since both
the ground and excited states should contain solitons, we envisage three fast
light pulse experiments could be able to map both the Kibble Zurek Model phase
transitions and energy transfers as a function of light intensity and time in
this complex at room temperature
Differences in the epidemiology of out-of-hospital and in-hospital trauma deaths
BACKGROUND: Trauma is a leading cause of mortality. Holistic views of trauma systems consider injury as a public health problem that requires efforts in primary, secondary and tertiary prevention. However, the performance of trauma systems is commonly judged on the in-hospital mortality rate. Such a focus misses opportunities to consider all deaths within a population, to understand differences in in-hospital and out-of-hospital trauma deaths and to inform population-level injury prevention efforts. The aim of this study was to provide an epidemiological overview of out-of-hospital and in-hospital trauma deaths in a geographically-defined area over a 10-year period. METHODS: We performed a population-based review of out-of-hospital and in-hospital trauma deaths over the period of 01 July 2006 to 30 June 2016 in Victoria, Australia, using data from the National Coronial Information System and the Victorian State Trauma Registry. Temporal trends in population-based incidence rates were evaluated. RESULTS: Over the study period, there were 11,246 trauma deaths, of which 71% were out-of-hospital deaths. Out-of-hospital trauma deaths commonly resulted from intentional self-harm events (50%) and transport events (35%), while in-hospital trauma deaths commonly resulted from low falls (≤1 metre) (50%). The incidence of overall trauma deaths did not change over the study period (incidence rate ratio 0.998; 95%CI: 0.991, 1.004; P = 0.56). CONCLUSIONS: Out-of-hospital deaths accounted for most trauma deaths. Given the notable differences between out-of-hospital and in-hospital trauma deaths, monitoring of all trauma deaths is necessary to inform injury prevention activities and to reduce trauma mortality. The absence of a change in the incidence of both out-of-hospital and in-hospital trauma deaths demonstrates the need for enhanced activities across all aspects of injury prevention
ISOTOPIC COMPOSITION OF LIGHT NUCLEI IN COSMIC RAYS: RESULTS FROM AMS-01
The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper, we present measurements of the isotopic ratios [superscript 2]H/[superscript 4]He, [superscript 3]He/[superscript 4]He, [superscript 6]Li/[superscript 7]Li, [superscript 7]Be/([superscript 9]Be+[superscript 10]Be), and [superscript 10]B/[superscript 11]B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.United States. Dept. of EnergyMassachusetts Institute of Technolog
Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01
The variety of isotopes in cosmic rays allows us to study different aspects
of the processes that cosmic rays undergo between the time they are produced
and the time of their arrival in the heliosphere. In this paper we present
measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be)
and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The
measurements are based on the data collected by the Alpha Magnetic
Spectrometer, AMS-01, during the STS-91 flight in 1998 June.Comment: To appear in ApJ. 12 pages, 11 figures, 6 table
Formation of the in Two-Photon Collisions at LEP
The two-photon width of the meson has been
measured with the L3 detector at LEP. The is studied in the decay
modes , KK, KK,
KK, , , and
using an integrated luminosity of 140 pb at GeV and
of 52 pb at GeV. The result is
(BR) keV. The dependence of the cross section is studied for
GeV. It is found to be better described by a Vector Meson
Dominance model form factor with a J-pole than with a -pole. In addition,
a signal of events is observed at the mass. Upper limits
for the two-photon widths of the , , and are also
given
Search for Heavy Isosinglet Neutrino in e+e- Annihilation at LEP
We report on a search for the first generation heavy neutrino that is an
isosinglet under the standard SU(2)_L gauge group. The data collected with the
L3 detector at center-of-mass energies between 130 GeV and 208 GeV are used.The
decay channel N_e --> eW is investigated and no evidence is found for a heavy
neutrino, N_e, in a mass range between 80 GeV and 205 GeV. Upper limits on the
mixing parameter between the heavy and light neutrino are derived
Search for a Higgs Boson Decaying into Two Photons at LEP
A Higgs particle produced in association with a Z boson and decaying into two
photons is searched for in the data collected by the L3 experiment at LEP. All
possible decay modes of the Z boson are investigated. No signal is observed in
447.5 pb^-1 of data recorded at centre-of-mass energies up to 209 GeV. Limits
on the branching fraction of the Higgs boson decay into two photons as a
function of the Higgs mass are derived. A lower limit on the mass of a
fermiophobic Higgs boson is set at 105.4 GeV at 95% confidence level
Study of Z Boson Pair Production in e+e- Collisions at LEP at \sqrt{s}=189 GeV
The pair production of Z bosons is studied using the data collected by the L3
detector at LEP in 1998 in e+e- collisions at a centre-of-mass energy of 189
GeV. All the visible final states are considered and the cross section of this
process is measured to be 0.74 +0.15 -0.14 (stat.) +/- 0.04 (syst.) pb. Final
states containing b quarks are enhanced by a dedicated selection and their
production cross section is found to be 0.18 +0.09 -0.07 (stat.) +/- 0.02
(syst.) pb. Both results are in agreement with the Standard Model predictions.
Limits on anomalous couplings between neutral gauge bosons are derived from
these measurements
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