Experimental Measurements of Atmospheric Neutrinos

TL;DR

This paper discusses recent experimental evidence of an anomaly in atmospheric neutrino measurements, suggesting neutrino oscillations as a possible explanation, based on data from Soudan-2 and Super-Kamiokande.

Contribution

It presents new experimental results indicating a neutrino flavor ratio anomaly and supports neutrino oscillations as the underlying cause.

Findings

Evidence of a deficit of upward-going muon neutrinos.

The ratio of muon to electron neutrino interactions is inconsistent with expectations.

Zenith angle dependence supports neutrino oscillation hypothesis.

Abstract

This talk reports the latest indications of an anomaly in the measurements of atmospheric neutrinos. New results from Soudan-2 and Super-Kamiokande provide evidence that the ratio of nu_mu to nu_e interactions is not as expected. High energy Super-Kamiokande data indicates the cause is a deficit of upward-going nu_mu, and the zenith angle dependence of the effect is consistent with neutrino oscillations. Upward-going muon measurements by several detectors are discussed, but in total they provide inconclusive evidence for the anomaly.