Cosmic Ray Muon Flux at the Sanford Underground Laboratory at Homestake

TL;DR

This paper reports measurements of the vertical cosmic ray muon flux at three different depths in the Sanford Underground Laboratory, providing data essential for low background experiments and confirming model predictions.

Contribution

First measurements of muon flux at multiple depths in the Sanford Underground Laboratory, aiding future low background physics experiments.

Findings

Muon flux decreases with depth as predicted by models.

Measured fluxes at three depths are consistent with theoretical predictions.

Data supports the design of low background experiments underground.

Abstract

Measuring the muon flux is important to the Sanford Underground Laboratory at Homestake, for which several low background experiments are being planned. The nearly-vertical cosmic ray muon flux was measured in three locations at this laboratory: on the surface (1.149 \pm 0.017 x 10^-2 cm^-2 s^-1 sr^-1), at the 800-ft (0.712 km w.e.) level (2.67 \pm 0.06 x 10^-6 cm^-2 s^-1 sr^-1), and at the 2000-ft (1.78 km w.e.) level (2.56 \pm 0.25 x 10^-7 cm^-2 s^-1 sr^-1). These fluxes agree well with model predictions.