An Experiment to Measure the Elemental Abundances of Ultra-Heavy Cosmic Rays

Abstract

Measurements of the elemental abundances of galactic cosmic ray nuclei with charge 26≤z≤92 can provide important information that should help to resolve the question of cosmic-ray origin; i.e. whether cosmic rays originate from the acceleration of interstellar grain material or from preferential selection and acceleration of nuclei from stellar photosphere-chromosphere regions with T-10^4 based on first ionization potential. They will also refine tests of whether freshly synthesized rprocess material is a significant component in cosmic rays. The detector concept described utilizes an array of silicon detectors for dF/dx measurements, two Cherenkov counters with radiators of different refractive index for velocity determination (one using aerogel and one using a novel waveshifter readout approach), and scintillating fibers for a hodoscope/time-of-flight detector. The numbers of particles which can be collected with this approach and the expected charge resolution are discussed.