EXAM: A search for extragalactic antimatter.

Abstract

This thesis presents results from a search for extragalactic antimatter in the cosmic rays (the EXAM experiment). The reasons for undertaking a search for antimatter are given, along with various arguments that indicate that a antimatter fraction of 10$\sp{-6}$ $-$ 10$\sp{-7}$ in the cosmic ray flux at earth would not be inconsistent with current antimatter limits obtained from cosmic ray experiments or with limits set by gamma-ray observations. An experimental technique sensitive to antinuclei with charge $Z$ near iron ($Z$ = 26) is reviewed. This technique uses a combination of active detectors (scintillators, Cerenkov counters) and CR-39 track etch detectors to provide a unique signature for antimatter detection at a level consistent with the flux estimates given above. This is followed by description of the implementation of this technique (the EXAM detector), along with a summary of the data analysis to date. Directions for future work are described. A detailed description of the microscope system used in the automated analysis of the CR-39 plastic is presented.