Type of Document Dissertation Author Hakmana Witharana, Sampath S URN etd-04232007-151331 Title DEVELOPMENT OF COSMIC RAY SIMULATION PROGRAM -- EARTH COSMIC RAY SHOWER (ECRS) Degree Ph.D. Department Physics and Astronomy Advisory Committee
Advisor Name Title Dr. Xiaochun He Committee Chair Dr. Brian Thoms Committee Member Dr. Richard Miller Committee Member Dr. Unil Perera Committee Member Dr. William Nelson Committee Member Keywords
- Geant4
- Air shower
- Geomagnetic Field
- Monte Carlo simulation
- Cosmic rays
Date of Defense 2007-04-03 Availability unrestricted Abstract ECRS is a program for the detailed simulation of extensive air shower initiated by high energy cosmic ray particles. In this dissertation work, a Geant4 based ECRS simulation was designed and developed to study secondary cosmic ray particle showers in the full range of Earth's atmosphere. A proper atmospheric air density and geomagnetic field are implemented in order to correctly simulate the charged particles interactions in the Earth's atmosphere.
The initial simulation was done for the Atlanta (33.460 N , 84.250 W) region. Four different types of primary proton energies (109, 1010, 1011 and 1012 eV) were considered to determine the secondary particle distribution at the Earth's surface. The geomagnetic field and atmospheric air density have considerable effects on the muon particle distribution at the Earth's surface.
The muon charge ratio at the Earth's surface was studied with ECRS simulation for two different geomagnetic locations: Atlanta, Georgia, USA and Lynn Lake, Manitoba, Canada. The simulation results are shown in excellent agreement with the data from NMSU-WIZARD/CAPRICE and BESS experiments at Lynn Lake. At low momentum, ground level muon charge ratios show latitude dependent geomagnetic effects for both Atlanta and Lynn Lake from the simulation. The simulated charge ratio is 1.20 ± 0.05 (without geomagnetic field), 1.12 ± 0.05 (with geomagnetic field) for Atlanta and 1.22 ± 0.04 (with geomagnetic field) for Lynn Lake. These types of studies are very important for analyzing secondary cosmic ray muon flux distribution at the Earth's surface and can be used to study the atmospheric neutrino oscillations.
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