CAREER: Particle Astrophysics with High-Resolution Cerenkov Imaging

University Of Chicago, Chicago IL

Investigators

Abstract

The nature and origin of cosmic rays remains one of the most elusive questions in high-energy astrophysics. After about a century of analysis, it is not known how and where they are produced, or exactly what mechanisms govern their propagation to earth. A major reason for the impasse lies in the steepness of the cosmic ray energy spectrum, which can be described by a rapidly-falling power-law. To push measurements one decade higher in energy, one requires increasing the instrument size by a factor of ~100. Therefore, relatively small (i.e., affordable) balloon or space-based missions become less practical for measurements above energies much higher than 1014 electron Volts (eV). As the cosmic ray flux decreases, ground-based observatories become the only viable option for providing the needed detector area. However, because the atmosphere prevents primary particles from propagating to the earth's surface, direct observation of these particles is not possible. Instead, ground-based instruments have, by necessity, been forced to make indirect observations of the extensive air showers produced by the interactions of the primaries in the atmosphere. Such observations are relatively low precision. Furthermore, they are hampered by large uncertainties in the interaction models used to interpret the observables. These weaknesses exist in even the most sophisticated air shower detector systems. The research goal of this proposal is to perform, for the first time, high-resolution measurements of cosmic ray composition from a ground-based observatory. This will be achieved by exploiting a new technique, proposed by the PI and others, which provides excellent charge resolution by targeting the direct light produced by the primary particle prior to its first interaction in the atmosphere though a new technology. The requested funding will augment and enable this research effort, ultimately culminating in the construction and operation of a prototype instrument called TRICE, for TRack-Imaging Cerenkov Experiment. The broader impacts of the proposed effort will be felt through the support of young female scientists in a hands-on, experimental small-group setting, through the development of instrumentation applicable to other fields, through the support of a fruitful cross-discipline collaboration with a National Laboratory, and through a dedicated education and outreach program designed to broaden the exposure of under-represented groups to research-based educational material.