Observation of the cosmic-ray shadow of the Moon with IceCube

TL;DR

This paper reports the detection of the Moon's cosmic-ray shadow using IceCube, confirming the detector's angular resolution and pointing accuracy through high-significance observations in two configurations.

Contribution

First observation of the Moon shadow with IceCube, demonstrating its angular resolution and pointing accuracy in partial detector configurations.

Findings

Moon shadow observed with >6 sigma significance

Shadow location within 0.2 degrees of expected position

Validates IceCube's directional reconstruction capabilities

Abstract

We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector. The study of this "Moon shadow" is used to characterize the angular resolution and absolute pointing capabilities of the detector. The detection is based on data taken in two periods before the completion of the detector: between April 2008 and May 2009, when IceCube operated in a partial configuration with 40 detector strings deployed in the South Pole ice, and between May 2009 and May 2010 when the detector operated with 59 strings. Using two independent analysis methods, the Moon shadow has been observed to high significance (> 6 sigma) in both detector configurations. The observed location of the shadow center is within 0.2 degrees of its expected position when geomagnetic deflection effects are taken into account. This measurement validates the directional reconstruction capabilities of IceCube.