Shape of Big Rockets
Recent publications discuss the size of chemical rockets for long-distance travel, to be launched from a planet. Here I point out that such a rocket cannot be tall and slim but will be short and fat.
physics.pop-ph↗
arXiv subjects
Thomas Hebbeker
Publications and source records attributed to Thomas Hebbeker.
Study of muon pairs in hadronic events with bottom tag using L3 data recorded near the Z resonance
A recent publication based on ALEPH $\mathrm{e}^+\mathrm{e}^-$ data taken near the Z resonance reports an excess, near 30 GeV, in the di-muon mass spectrum for events containing b quarks. In this paper we measure the di-muon mass spectrum for L3 data with a bottom tag, recorded in the years 1994 and 1995 at the LEP collider at CERN, and compare it to Monte Carlo predictions.
hep-ex↗
Status of the Silicon Photomultiplier Telescope FAMOUS for the Fluorescence Detection of UHECRs
An established technique for the measurement of ultra-high-energy-cosmic-rays is the detection of the fluorescence light induced in the atmosphere of the Earth, by means of telescopes equipped with photomultiplier tubes. Silicon photomultipliers (SiPMs) promise an increase in the photon detection efficiency which outperforms conventional photomultiplier tubes. In combination with their compact package, a moderate bias voltage of several ten volt and single photon resolution, the use of SiPMs can improve the energy and spatial resolution of air fluorescence measurements, and lead to a gain in information on the primary particle. Though, drawbacks like a high dark-noise-rate and a strong temperature dependency have to be managed. FAMOUS is a refracting telescope prototype instrumented with 64 SiPMs of which the main optical element is a Fresnel lens of 549.7 mm diameter and 502.1 mm focal length. The sensitive area of the SiPMs is increased by a special light collection system consisting of Winston cones. The total field of view of the telescope is approximately 12 $^\circ$. The frontend electronics automatically compensates for the temperature dependency of the SiPMs and will provide trigger information for the readout. Already for this prototype, the Geant4 detector simulation indicates full detection efficiency of extensive air showers of $E=10^{18}\,\text{eV}$ up to a distance of 6 km. We present the first working version of FAMOUS with a focal plane prototype providing seven active pixels.
astro-ph.IM↗
Model Unspecific Search in CMS
We present the results of a model independent analysis, which systematically scans the data taken by CMS for deviations from the Standard Model predictions. Due to the minimal theoretical bias this approach is sensitive to a variety of models for new physics. Events with at least one electron or muon are classified according to their content of reconstructed objects (muons, electrons, photons, jets and missing transverse energy). A broad scan of three kinematic distributions in those classes is performed by identifying deviations from Standard Model expectations, accounting for systematic uncertainties.
hep-ex↗
A phenomenological model of the muon density profile on the ground of very inclined air showers
Ultra-high energy cosmic rays generate extensive air showers in Earth's atmosphere. A standard approach to reconstruct the energy of an ultra-high energy cosmic rays is to sample the lateral profile of the particle density on the ground of the air shower with an array of surface detectors. For cosmic rays with large inclinations, this reconstruction is based on a model of the lateral profile of the muon density observed on the ground, which is fitted to the observed muon densities in individual surface detectors. The best models for this task are derived from detailed Monte-Carlo simulations of the air shower development. We present a phenomenological parametrization scheme which allows to derive a model of the average lateral profile of the muon density directly from a fit to a set of individual Monte-Carlo simulated air showers. The model reproduces the detailed simulations with a high precision. As an example, we generate a muon density model which is valid in the energy range 1e18 eV < E < 1e20 eV and the zenith angle range 60 deg < theta < 90 deg. We will further demonstrate a way to speed up the simulation of such muon profiles by three orders of magnitude, if only the muons in the shower are of interest.
astro-ph.IM↗
Parametrization of the Cosmic Muon Flux for the Generator CMSCGEN
The cosmic muon generator CMSCGEN is based on a parametrization of the differential muon flux at ground level, as obtained from the air shower simulation program CORSIKA. We present the underlying ansatz for this parameterization and provide an approximation of the momentum and angular distributions in terms of simple polynomials, in the momentum range 3 to 3000 GeV.
astro-ph.IM↗
A Compilation of High Energy Atmospheric Muon Data at Sea Level
We collect and combine all published data on the vertical atmospheric muon flux and the muon charge ratio for muon momenta above 10 GeV. At sea level the world average of the momentum spectra agrees with the flux calculated by E.V. Bugaev et al. within 15%. The observed shape of the differential flux versus momentum is slightly flatter than predicted in this calculation. The experimental accuracy varies from 7% at 10 GeV to 17% at 1 TeV. The ratio of fluxes of positive to negative muons is found to be constant, at a value of 1.268, with relative uncertainties increasing from approximately 1% at low momenta to about 6% at 300 GeV.
hep-ph↗
Can the sneutrino be the lightest supersymmetric particle ?
Within the framework of the constrained Minimal Supersymmetric extension of the Standard Model we show that recent LEP I limits on the invisible Z width exclude the possibility that the lightest sparticle is the sneutrino.
hep-ph↗