443 research outputs found
No Pulsar Kicks from Deformed Neutrinospheres
In a supernova core, magnetic fields cause a directional variation of the
neutrino refractive index so that resonant flavor oscillations would lead to a
deformation of the "neutrinosphere" for, say, tau neutrinos. The associated
anisotropic neutrino emission was proposed as a possible origin of the observed
pulsar proper motions. We argue that this effect was vastly overestimated
because the variation of the temperature over the deformed neutrinosphere is
not an adequate measure for the anisotropy of neutrino emission. The neutrino
flux is generated inside the neutron star core and is transported through the
atmosphere at a constant luminosity, forcing the temperature gradient in the
atmosphere to adjust to the inflow of energy from below. Therefore, no emission
anisotropy is caused by a deformation of the neutrinosphere to lowest order. An
estimate of the higher-order corrections must take into account the modified
atmospheric temperature profile in response to the deformation of the
neutrinosphere and the corresponding feedback on the core. We go through this
exercise in the framework of a simplified model which can be solved
analytically.Comment: Final version with minor corrections, to be published in PRD.
Includes a "Note Added" in response to astro-ph/981114
Leptoquark pair production at e"+e"- linear colliders: signals and background
We study pair production of leptoquarks in e"+e"- annihilation at linear colliders. A detailed simulation including beamstrahlung and initial state radiation, leptoquark decay and hadronization, as well as detector smearing, is performed. Discovery limits are estimated for center-of-mass energies of 500 and 800 GeV. The prospects for determining masses and couplings of leptoquarks are also investigated. (orig.)Available from TIB Hannover: RR 2916(97-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Deep level defects in semiconductor detectors
Initiated by the application of semiconductors in the very high radiation environment of future high energy accelerators a formalism has been developed which, based on first principles, allows a quantitative prediction of macroscopic detector behaviour from microscopic defect properties and concentrations. It thus can be applied also for a systematic study of defect properties by means of measurements of macroscopic material properties. The relation between macroscopic and microscopic properties is developed sucessively for thermal equilibrium conditions, the fully depleted space charge region, the stationary situation and the general time dependent case. A one dimensional numerical simulation program provides several illustrative results. (orig.)3 refs.Available from TIB Hannover: RR 2916(95-27) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
A simplistic model for reverse annealing in irradiated silicon
Based on the experimental results of systematic studies on radiation damage by several groups, a model is presented which is able to explain some puzzles as the apparent absence of type inversion near the silicon surface of strongly irradiated detectors and the continuing functioning of n-type silicon detectors after type inversion. As a consequence of this model a new method for suppressing reverse annealing is proposed. This method at the same time would strongly reduce doping changes due to irradiation and also diminish the reverse bias current. It thus could significantly increase the radiation hardness of silicon detectors. (orig.)Available from TIB Hannover: RR 2916(94-10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
#alpha#_s 2002
An update of measurements of the strong coupling constant #alpha#_s is given, representing the status of September 2002. The results convincingly prove the energy dependence of #alpha#_s and are in excellent agreement with the expectations of Quantum Chromodynamics, QCD. Evolving all results to the rest energy of the Z"0 boson, the new world average of #alpha#_s(M_Z) is determined from measurements which are based on QCD calculations in complete NNLO perturbation theory, giving #alpha#_s(M_Z)=0.1183#+-#0.0027. (orig.)SIGLEAvailable from TIB Hannover: RR 2916(02-17) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Beobachtung von TeV-Photonen aus der Richtung des Krebsnebels mit dem 5 m"2-Tscherenkovteleskop des HEGRA-Detektors
Structure and initial operation of the first and second Cerenkov telescope for observation of point sources with very high energetic gamma emissions in the frame of the HEGRA project are described. Using Monte-Carlo-Simulations, the most important detector properties have been calculated including the energy threshold and the effective detection area for gamma-induced air showers. By the developed air shower image processing method the hadronically induced air showers are suppressed, and sensitivities for point sources are improved. Within 75 h of observation of TeV-photons from the Crab nebula a surplus of 544 events has been measured and identified as photon-induced air showers. The surplus is in line with the assumption of a point source. The calculated integral VHE gamma radiation flow, F(E#>=#2.4 TeV)=(0.8#+-#0.21#+-#0.16).10"-"1"1/cm"2 s, can be attributed to the generation by inverse Compton scattering of high-relativistic electrons on low-energetic photons in the Crab nebula. No TeV-photons have been found analyzing observation results on the BL-Lacertae object Markarian 421. (WEN)SIGLEAvailable from TIB Hannover: RR 2916(96-3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Properties of tau lepton
This note cover the new results obtained by LEP experiments in tau-physics. (orig.)Available from TIB Hannover: RR 2916(03-19) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Max-Planck-Institut fuer Physik. Werner-Heisenberg-Institut. Jahresbericht 1998
Available from TIB Hannover: ZB 3650(1998) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Contributions from the HEGRA Collaboration to the 24th international cosmic ray conference
The following topics were dealt with: Cosmic rays, its composition and energy spectrum, search for emission, new methods, gamma ray sources, TeV counterparts, status of the HEGRA experiment, search for gamma radiation, observations, instrumentationAvailable from TIB Hannover: RR 2916(95-14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Max-Planck-Institut fuer Physik. Werner-Heisenberg-Institut. Jahresbericht 1996
Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
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