Probing the Earth’s Interior with Neutrinos

Sanjib Kumar Agarwalla, PhD; Institute of Physics, Bhubaneswar / University of Wisconsin, Madison

Neutrinos produced in cosmic ray interactions in the atmosphere provide a unique and independent probe to explore the internal structure and composition of the deep Earth, which is complementary to traditional seismic and gravitational measurements and pave the way for multi-messenger tomography of Earth. I will discuss the two different approaches to perform Earth tomography with neutrinos: (i) neutrino absorption tomography, based on partial absorption of a high-energy TeV-PeV neutrino flux as it propagates through Earth and (ii) neutrino oscillation tomography, based on Earth matter effects due to the coherent forward scattering of multi-GeV neutrinos with the ambient electrons modifying neutrino oscillation patterns. I will subsequently show how well the DeepCore detector, a densely instrumented sub-array of the IceCube neutrino observatory at the South Pole, can observe these Earth matter effects in atmospheric neutrino oscillations using 9.3 years of data. We will further demonstrate that these matter effects in oscillations of atmospheric neutrinos can be used to establish the layered structure inside Earth and measure the mass of Earth and mass of core. I will conclude my talk discussing the remarkable physics reach of a new extension of DeepCore to be deployed in the Antarctic summer of 2025/26, called the IceCube Upgrade.