Cosmic Ray Results from the CosmoALEPH Experiment

Abstract

CosmoALEPH is an experiment operated in conjunction with the ALEPH detector. The ALEPH experiment took data from 1989 until the year 2000 at the Large Electron Positron Collider (LEP) at CERN. It provides, among others, high resolution tracking and calorimetry. CosmoALEPH used this e + e − detector for cosmic ray studies. In addition, six scintillator telescopes were installed in the ALEPH pit and the LEP tunnel. The whole experiment operated underground at a vertical depth of 320 meter water equivalent. Data from ALEPH and the scintillator telescopes provide informaton on the lateral distribution of energetic cosmic ray muons in extensive air showers. The decoherence curve of these remnant air shower muons is sensitive to the chemical composition of primary cosmic rays and to the interaction characteristics of energetic hadrons in the atmosphere. An attempt is made to extract the various interdependencies in describing the propagation of primary and secondary cosmic rays through the atmosphere and the rock overburden, and comparing the data with results from Monte Carlo (MC) calculations. Results on the multiplicity distributions of remnant air shower muons in ALEPH are also compared with expectations based on MC simulations. Data on the cosmic ray muon spectrum and charge ratio up to momenta of 3 TeV/c as obtained with the time projection chamber in ALEPH's strong magnetic field are presented. The large number of events also allowed to unambiguously observe muon tridents and to estimate the cross section for this process.