Toward a New Era in Particle Astrophysics: Search for Antinuclei and Reduction of Critical Uncertainties in Antinuclei Production and Propagation

In recent years, the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station has reported detecting several antideuteron and antihelium nucleus candidates. The existence of cosmic antideuterons in the reported energy range might be the first sign of dark matter annihilation or decay, or of physics beyond the standard model of particle physics.

However, it could be explained by astrophysical background effects. This project will profoundly advance the understanding of cosmic antinuclei by analyzing an extended AMS-02 data set with state-of-the-art machine-learning analysis techniques and complementing their interpretation with data from the fixed-target SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) at the Super Proton Synchrotron (SPS) at the European Laboratory for Particle Research (CERN).

The group will provide a hands-on computer programming outreach program for underrepresented high school students from economically disadvantaged backgrounds in cooperation with the University of Hawaiʻi at Mānoa's Office of Student Equity, Excellence, and Diversity. They are also developing strategies for increasing Science, Technology, Engineering, and Mathematics (STEM) education efforts for mature adults.

The AMS-02 collaboration reported detecting several antideuteron and antihelium nucleus candidate events in approximately equal amounts in the energy region of a few GeV/n. However, no coherent theory exists that can explain a) the existence of any detectable antihelium flux in the Galaxy and b) that the number of antideuterons is comparable to the number of antihelium nuclei.

AMS-02’s antideuteron candidates in the few-GeV/n region will be studied with new reconstruction and analysis methods, and systematic Galactic propagation uncertainties will be addressed by interpreting AMS-02’s nuclei measurements, and systematic uncertainties in the astrophysical antideuteron background production will be reduced with new and existing proton-proton collision data from NA61/SHINE in the energy range most relevant to cosmic rays.

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.