The photonuclear contribution to charged lepton energy loss has been reevaluated taking into account DESY HERA results on real and virtual photon interactions with nucleons. With large Q{sup 2} ...processes incorporated, the average muon range in rock for energies of 10{sup 9} GeV is reduced by only 5% compared with the standard treatment. We have calculated the tau energy loss for energies up to 10{sup 9} GeV taking into consideration the decay of tau. A Monte Carlo evaluation of tau survival probability and range shows that at energies below 10{sup 7}--10{sup 8} GeV, depending on the material, only tau decays are important. At higher energies the tau energy losses are significant, reducing the survival probability of the tau. We show that the average range for tau is shorter than its decay length and reduces to 17 km in water for an incident tau energy of 10{sup 9} GeV, as compared with its decay length of 49 km at that energy. In iron, the average tau range is 4.7 km for the same incident energy.
We examine the dependence of event rates at neutrino telescopes on the neutrino-nucleon cross section for neutrinos with energy above 1 PeV, and contrast the results with those for cosmic ray ...experiments. Scaling of the standard model cross sections leaves the rate of upward events essentially unchanged. Details, such as detector depth and cross section inelasticity, can influence rates. Numerical estimates of upward shower, muon, and tau event rates in the IceCube detector confirm these results.
We describe herein a measurement of the Antarctic surface “roughness” performed by the balloon‐borne ANITA (Antarctic Impulsive Transient Antenna) experiment. Originally purposed for cosmic ray ...astrophysics, the radio frequency (RF) receiver ANITA gondola, from its 38 km altitude vantage point, can scan a disk of snow surface 600 km in radius. The primary purpose of ANITA is to detect RF emissions from cosmic rays incident on Antarctica, such as neutrinos which penetrate through the atmosphere and interact within the ice, resulting in signal directed upward which then refracts at the ice‐air interface and up and out to ANITA, or high‐energy nuclei (most likely irons or protons), which interact in the upper atmosphere (at altitudes below ANITA) and produce a spray of down‐coming RF which reflects off the snow surface and back up to the gondola. The energy of such high‐energy nuclei can be inferred from the observed reflected signal only if the surface reflectivity is known. We describe herein an attempt to quantify the Antarctic surface reflectivity, using the Sun as a constant, unpolarized RF source. We find that the reflectivity of the surface generally follows the expectations from the Fresnel equations, lending support to the use of those equations to give an overall correction factor to calculate cosmic ray energies for all locations in Antarctica. The analysis described below is based on ANITA‐II data. After launching from McMurdo Station in December 2008, ANITA‐II was aloft for a period of 31 days with a typical instantaneous duty cycle exceeding 95%.
Key Points
Solar radio radiation is used to determine Antarctic albedo
Reflection coefficients agree with Fresnel predictions at high incidence angles
Reflection coefficients are lower than expected at glancing incidence angles
We set the first limits on the ultra-high energy (UHE) neutrino fluence at energies greater than 109 GeV from gamma-ray bursts (GRBs) based on data from the second flight of the Antarctic Impulsive ...Transient Antenna (ANITA). During the 31 day flight of ANITA-II, 26 GRBs were recorded by Swift or Fermi. Of these, we analyzed the 12 GRBs which occurred during quiet periods when the payload was away from anthropogenic activity. In a blind analysis, we observe 0 events on a total background of 0.0044 events in the combined prompt window for all 12 low-background bursts. We also observe 0 events from the remaining 14 bursts. We place a 90% confidence level limit on the E --4 prompt neutrino fluence between 108 GeV < E < 1012 GeV of E 4 Delta *Q = 2.5 X 1017 GeV3 cm--2 from GRB090107A. This is the first reported limit on the UHE neutrino fluence from GRBs above 109 GeV, and the strongest limit above 108 GeV.
The Radio Ice Cherenkov Experiment at the South Pole, co-deployed with the AMANDA experiment, seeks to detect ultra-high energy electron neutrinos interacting in cold polar ice. Such interactions ...produce electromagnetic showers, which emit radio-frequency Cherenkov radiation. We describe the experimental apparatus and the procedures used to measure the neutrino flux.
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