260 research outputs found

    User's manual for Axisymmetric Diffuser Duct (ADD) code. Volume 1: General ADD code description

    Get PDF
    This User's Manual contains a complete description of the computer codes known as the AXISYMMETRIC DIFFUSER DUCT code or ADD code. It includes a list of references which describe the formulation of the ADD code and comparisons of calculation with experimental flows. The input/output and general use of the code is described in the first volume. The second volume contains a detailed description of the code including the global structure of the code, list of FORTRAN variables, and descriptions of the subroutines. The third volume contains a detailed description of the CODUCT code which generates coordinate systems for arbitrary axisymmetric ducts

    User's manual for Axisymmetric Diffuser Duct (ADD) code. Volume 3: ADD code coordinate generator

    Get PDF
    This User's Manual contains a complete description of the computer codes known as the Axisymmetric Diffuser Duct (ADD) code. It includes a list of references which describe the formulation of the ADD code and comparisons of calculation with experimental flows. The input/output and general use of the code is described in the first volume. The second volume contains a detailed description of the code including the global structure of the code, list of FORTRAN variables, and descriptions of the subroutines. The third volume contains a detailed description of the CODUCT code which generates coordinate systems for arbitrary axisymmetric ducts

    Improved flux limits for neutrinos with energies above 1022^{22} eV from observations with the Westerbork Synthesis Radio Telescope

    Get PDF
    Particle cascades initiated by ultra-high energy (UHE) neutrinos in the lunar regolith will emit an electromagnetic pulse with a time duration of the order of nano seconds through a process known as the Askaryan effect. It has been shown that in an observing window around 150 MHz there is a maximum chance for detecting this radiation with radio telescopes commonly used in astronomy. In 50 hours of observation time with the Westerbork Synthesis Radio Telescope array we have set a new limit on the flux of neutrinos, summed over all flavors, with energies in excess of 4×10224\times10^{22} eV.Comment: Submitted to Phys. Rev. Let

    Prospects for Lunar Satellite Detection of Radio Pulses from Ultrahigh Energy Neutrinos Interacting with the Moon

    Full text link
    The Moon provides a huge effective detector volume for ultrahigh energy cosmic neutrinos, which generate coherent radio pulses in the lunar surface layer due to the Askaryan effect. In light of presently considered lunar missions, we propose radio measurements from a Moon-orbiting satellite. First systematic Monte Carlo simulations demonstrate the detectability of Askaryan pulses from neutrinos with energies above 10^{20} eV, i.e. near and above the interesting GZK limit, at the very low fluxes predicted in different scenarios.Comment: RevTeX (4 pages, 2 figures). v2 includes updated results and extended discussio

    Determining neutrino absorption spectra at Ultra-High Energies

    Full text link
    A very efficient method to measure the flux of Ultra-high energy (UHE) neutrinos is through the detection of radio waves which are emitted by the particle shower in the lunar regolith. The highest acceptance is reached for radio waves in the frequency band of 100-200 MHz which can be measured with modern radio telescopes. In this work we investigate the sensitivity of this detection method to structures in the UHE neutrino spectrum caused by their absorption on the low-energy relic anti-neutrino background through the Z-boson resonance. The position of the absorption peak is sensitive to the neutrino mass and the redshift of the source. A new generation of low-frequency digital radio telescopes will provide excellent detection capabilities for measuring these radio pulses, thus making our consideration here very timely.Comment: 7 figures, submitted to JCAP revision: References updated and minor changes in tex

    On defining the Hamiltonian beyond quantum theory

    Full text link
    Energy is a crucial concept within classical and quantum physics. An essential tool to quantify energy is the Hamiltonian. Here, we consider how to define a Hamiltonian in general probabilistic theories, a framework in which quantum theory is a special case. We list desiderata which the definition should meet. For 3-dimensional systems, we provide a fully-defined recipe which satisfies these desiderata. We discuss the higher dimensional case where some freedom of choice is left remaining. We apply the definition to example toy theories, and discuss how the quantum notion of time evolution as a phase between energy eigenstates generalises to other theories.Comment: Authors' accepted manuscript for inclusion in the Foundations of Physics topical collection on Foundational Aspects of Quantum Informatio

    The Parallax, Mass and Age of the PSR J2145-0750 binary system

    Full text link
    We present results of timing measurements of the binary millisecond pulsar PSR J2145-0750. Combining timing data obtained with the Effelsberg and Lovell radio telescopes we measure a significant timing parallax of 2.0(6) mas placing the system at 500 pc distance to the solar system. The detected secular change of the projected semi-major axis of the orbit x˙=1.8(6)×1014\dot x=1.8(6)\times 10^{-14} lt-s s1^{-1}, where x=(apsini)/cx=(a_{\rm p}\sin i)/c, is caused by the proper motion of the system. With this measurement we can constrain the orbital inclination angle to i<61\degr, with a median likelihood value of 46\degr which is consistent with results from polarimetric studies of the pulsar magnetosphere. This constraint together with the non-detection of Shapiro delay rules out certain combinations of the companion mass, m2m_2, and the inclination, ii. For typical neutron star masses and using optical observations of the carbon/oxygen-core white dwarf we derive a mass range for the companion of 0.7Mm21.0M0.7 M_\odot\leq m_2\leq 1.0 M_\odot. We apply evolutionary white dwarf cooling models to revisit the cooling age of the companion. Our analysis reveals that the companion has an effective temperature of Teff=5750±600T_{\rm eff}=5750\pm600 K and a cooling age of τcool=3.6(2)\tau_{\rm cool}=3.6(2) Gyr, which is roughly a factor of three lower than the pulsar's characteristic age of 10.4 Gyr. The cooling age implies an initial spin period of P0=13.0(5)P_0=13.0(5) ms, which is very close to the current period.Comment: 11 pages, 5 figures, accepted for publication in A&
    corecore