Observation of the moon shadow in deep underground muon flux

摘要

A shadow of the moon, with a statistical significance of 5(sigma), has been211u001eobserved in the underground muon flux at a depth of 2090 mwe using the Soudan 2 211u001edetector. The angular resolution of the detector is well described by a Gaussian 211u001ewith (sigma) (le)0.3(degree). The position of the shadow confirms the alignment 211u001eof the detector to better than 0.15(degree). This alignment has remained stable 211u001eduring 10 years of data taking from 1989 through 1998.