Observation in the MINOS far detector of the shadowing of cosmic rays by the sun and moon

TL;DR

This paper reports the detection of the moon and sun shadows in cosmic ray muons by the MINOS detector, providing insights into detector pointing accuracy and magnetic field effects.

Contribution

First observation of solar and lunar shadows in cosmic rays by MINOS, demonstrating detector pointing precision and magnetic field influences.

Findings

Moon shadow detected at 5.6σ significance

Sun shadow detected at 3.8σ significance

Detector pointing accuracy of 0.17±0.12°

Abstract

The shadowing of cosmic ray primaries by the the moon and sun was observed by the MINOS far detector at a depth of \unit[2070]{mwe} using 83.54 million cosmic ray muons accumulated over 1857.91 live-days. The shadow of the moon was detected at the \unit[5.6]{$\sigma$} level and the shadow of the sun at the \unit[3.8]{$\sigma$} level using a log-likelihood search in celestial coordinates. The moon shadow was used to quantify the absolute astrophysical pointing of the detector to be 0.17\pm 0.12^\circ. Hints of Interplanetary Magnetic Field effects were observed in both the sun and moon shadow.