a Study of Hadrons Near the Cores of Extensive Air Showers Observed at Sea Level
Abstract
The subject of this dissertation is an experiment designed to study the hadronic structure of extensive air showers initiated by cosmic ray particles of energy 10('13) to 10('16) eV. It employed four 1.5 m('2) ionization calorimeters and a twelve-counter air shower array. Cuts were applied to hadron energy and electron density to restrict events to the vicinity of the shower core. Results were interpreted through the use of a very detailed simulation of the experiment and Monte Carlo simulations of air showers using three different models of high-energy particle interactions. Simulations using two of these models were repeated with the average elasticity of an nucleon-nucleus interaction lowered from .5 to .31 and the total inelastic cross-section decreased by 10%. Several forms of primary spectrum were assumed. A particular spectrum is determined completely by two parameters, one specifying slope and one the location of the spectral bend. The experimental event rate and published all-particle flux data were used to constrain the values of these parameters for each interaction model. All three interaction models are consistent with the event rate and the all-particle flux only if the fluxes of protons and (alpha) particles remain significantly steeper than those of the heavier nuclei, leading to a primary flux in which the heavier nuclei dominate at energies greater than 2 x 10('13) eV, regardless of whether the bend seen in the all-particle flux is dependent on rigidity or energy. The two high-inelasticity versions of interaction model are acceptable if the fluxes of protons and (alpha) particles flatten to assume a common slope with the fluxes of heavier nuclei at a rigidity of 5 TV/u. These interaction models, however, are in poor agreement with data from the SPS. Events themselves were examined for sensitivity to the primary spectrum. The quantities analyzed include spectra of the calorimeter signals, the shower density and the root-mean-square distribution of hadronic energy per event, a measure of hadronic density that does not require knowledge of the position of the shower core. There was good agreement between Monte Carlo and data in most areas, but little sensitivity to primary composition.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1986
- Bibcode:
- 1986PhDT........42F
- Keywords:
-
- COSMIC RAY;
- Physics: Elementary Particles and High Energy