Atmospheric muon flux suppression at potential new low-radiation Underground Physics Laboratory in Israel

Abstract

The residual atmospheric muon flux was measured at a candidate site for a new underground, low-radiation physics laboratory beneath the Kokhav HaYarden national park in Israel. Located inside the tunnels of a hydroelectric pumped-storage facility, the proposed site benefits from a vertical rock overburden of 361 m, large potential floorspace, and easy access by road. A muon hodoscope of vertically stacked wide-area plastic scintillator plates was employed to measure the suppression in the integrated muon flux at the site as compared with above ground at sea level. The suppression factor is reported at \(4456 \pm 77\), expressed as \(3.75 \pm 0.2 \times 10^{-6}\) \(\text {cm}^{-2}\) s\(^{-1}\) in absolute terms, corresponding to an effective overburden of roughly 873 m.w.e.. Furthermore, the asymmetric topography of the mountain above and its muon shadow are clearly visible in the angular data. Finally, auxiliary environmental measurements recorded low background radon activity at \(28.3 \pm 14.0\) Bq \(\text {m}^{-3}\). The experimental campaign thus succeeded in demonstrating the viability of the site’s working conditions for future scientific research.