Cosmogenic neutrinos and quasi-stable supersymmetric particle production

We study the signal for the detection of quasi-stable supersymmetric particles produced in interactions of cosmogenic neutrinos. We consider energy loss of high energy staus due to photonuclear and weak interactions. We show that there are optimal nadir angles for which the stau signal is a factor of several hundred larager than muons. We discuss how one could potentially eliminate the muon background by considering the energy loss of muons in the detector. We also show results for the showers produced by weak interactions of staus that reach the detector.Comment: 11 pages, 18 figures; minor changes in the conclusion, version to be published in Phys. Rev.

Production of muon pairs in annihilation of high-energy positrons with resting electrons

A Monte Carlo generator for the electromagnetic production of muon pairs by annihilation of high-energy positrons with atomic electrons is described. The computer code is designed as a standard electromagnetic process for GEANT4. The formulas and algorithms are described and illustrated in detail. The code has been applied to study muon production by high energy positrons in a spoiler. The results are presented and compared to muon pair production by gamma conversion

Results of a search for monopoles and tachyons in horizontal cosmic ray flux

A search for monopoles and tachyons at ground level was carried out using an arrangement consisting of an ionization calorimeter and two hodoscope detectors. No clear evidence for these particles was obtained. The flux of monopoles with velocities beta approximately 0.01 is found to be less than 5.1 x 10 to the minus 13th power square centimeters s(-1) sr(-1) (95% cl.). The upper limit on the tachyon flux density is set as a 6 x 10 the minus 9th power particle/square centimeter event

Weak interactions of supersymmetric staus at high energies

Neutrino telescopes may have the potential to detect the quasi-stable staus predicted by supersymmetric models. Detection depends on stau electromagnetic energy loss and weak interactions. We present results for the weak interaction contribution to the energy loss of high energy staus as they pass through rock. We show that the neutral current weak interaction contribution to the energy loss increases with energy, but it is much smaller than the photonuclear energy loss, however, the charged current contribution may become the dominant process above the energy of $\sim 10^9$ GeV, depending on the parameters of the model. As a consequence, the stau range may be reduced above $\sim 10^9$ GeV as compared to the range neglecting weak interactions. We contrast this with the tau range which is barely changed with the inclusion of charged current interactions.Comment: 7 pages, 8 figures, version to be publishe

Energy spectrum of cascade showers induced by cosmic ray muons in the range from 50 GeV to 5 TeV

The energy spectrum of cascade showers induced by electromagnetic interactions of high energy muons of horizontal cosmic ray flux in iron absorber was measured. The total observation time exceeded 22,000 hours. Both the energy spectrum and angular distributions of cascade showers are fairly described in terms of the usual muon generation processes, with a single power index of the parent meson spectrum over the muon energy range from 150 GeV to 5 TeV

High energy leptons from muons in transit

The differential energy distribution for electrons and taus produced from lepton pair production from muons in transit through materials is numerically evaluated. We use the differential cross section to calculate underground lepton fluxes from an incident atmospheric muon flux, considering contributions from both conventional and prompt fluxes. An approximate form for the charged current differential neutrino cross section is provided and used to calculate single lepton production from atmospheric neutrinos. We compare the fluxes of underground leptons produced from incident muons with those produced from incident neutrinos and photons from muon bremsstrahlung. We discuss their relevance for underground detectors.Comment: 11 pages, 9 figures v2: Revised to include the calculation of muon bremsstrahlung events in comparison to pair production events. 1 new figur

Tau energy losses at ultra-high energy: continuous versus stochastic treatment

We study the energy losses of the tau lepton in matter through electromagnetic processes at ultra-high energy (UHE). We use both a stochastic and a continuous framework to treat these interactions and compare the flux of tau leptons propagated after some amount of matter. We discuss the accuracy of the approximation of continuous energy losses by studying the propagation in standard rock of taus with both mono-energetic and power law injection spectra.Comment: 7 pages, 8 figure

Geant4 simulation of production and interaction of muons

A set of models for Monte Carlo simulation of production and interaction of high energy muons is developed in the framework of the Geant4 toolkit. It describes the following physics processes: ionization of high energy muons with radiative corrections, bremsstrahlung, electron-positron pair production, muon induced nuclear reactions, gamma annihilation into muon pair, positron annihilation into muon pair, and into pion pair. These processes are essential for the LHC experiments, for the understanding of the background in underground detectors, for the simulation of effects related with high-energy muons in cosmic ray experiments and for the estimation of backgrounds in future colliders. The applicability area of the models extends to 1 PeV. The major use-cases are discussed

Measurements of integral muon intensity at large zenith angles

High-statistics data on near-horizontal muons collected with Russian-Italian coordinate detector DECOR are analyzed. Precise measurements of muon angular distributions in zenith angle interval from 60 to 90 degrees have been performed. In total, more than 20 million muons are selected. Dependences of the absolute integral muon intensity on zenith angle for several threshold energies ranging from 1.7 GeV to 7.2 GeV are derived. Results for this region of zenith angles and threshold energies have been obtained for the first time. The dependence of integral intensity on zenith angle and threshold energy is well fitted by a simple analytical formula.Comment: 4 pages, 4 figures, 1 tabl