Chemical Composition and Energy Spectrum of Cosmic Rays Using the IceCube Neutrino Observatory

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Cosmic rays constantly bombard the atmosphere, yet key information regarding the processes of cosmic ray creation, acceleration, and propagation is lacking. However, candidate theoretical models have been developed to make testable predictions about cosmic ray parameters that are observable at Earth. In order to test these models, precise experimental measurements of multiple elemental spectra of cosmic rays are needed from a single experiment across the full energy range. Using the IceCube Neutrino Observatory (ICNO), the IceCube group at Marquette University will provide the cosmic ray community with the first measurement of the elemental spectra from four distinct mass groups from the 'knee' to the 'ankle' in the cosmic ray energy spectrum using six years of IceCube data, new post-LHC simulations, novel methods for event selection, reduced systematic errors, new software algorithms, and new composition-sensitive parameters. The group will share their research with the broader Milwaukee community to help bridge the racial and socio-economic divide in one of the most highly segregated cities in the United States. Under this award, they will go out into the community to inspire the diverse local high school student population with fun and interactive "household physics" projects and bring diverse high school students back to Marquette to expose them to "big science" job opportunities through an IceCube Master Class. In order to increase awareness among high school students of physics as a strong and viable career path for students from all backgrounds, this work will be framed by an intercultural competency program to train Marquette students to interact and connect with their local community empathetically, increase their own intercultural competency, and to build a culture of compassion within the physics department to sustain the participation of women and underrepresented minorities in physics.The ICNO is the only detector that can presently perform this highly sought measurement that includes an entire decade in energy where four elemental spectra have never been measured. This will provide a new and coherent picture across the entire transition region from galactic to extragalactic cosmic rays. Further, the Marquette IceCube group will simulate and fully optimize the detector response and array layout for a new prototype scintillator array being partially deployed at the South Pole this season (2018-19) to maximize its effectiveness for the cosmic ray analyses. This new array is designed to mitigate the problem of snow drift and accumulation that threatens the effectiveness of the current ICNO surface array (IceTop).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.