The muon flux in the Felsenkeller shallow underground laboratory


The muon flux in the Felsenkeller shallow underground laboratory

Ludwig, F.; Wagner, L.; Al-Abdullah, T.; Barnaföldi, G. G.; Bemmerer, D.; Degering, D.; Surányi, G.; Zuber, K.

The muon intensity and angular distribution in the shallow-underground laboratory Felsenkeller in Dresden, Germany
have been studied using a portable muon detector based on the closed cathode chamber design. Data has been taken at
four positions in Felsenkeller tunnels VIII and IX, where a new 5 MV underground ion accelerator is being installed, and
in addition at four positions in Felsenkeller tunnel IV, which hosts a low-radioactivity counting facility. At each of the
eight positions studied, seven different orientations of the detector were used to compile a map of the upper hemisphere
with 0.85 ◦ angular resolution. The muon intensity is found to be suppressed by a factor of 40 due to the 45 m thick rock
overburden, corresponding to 140 meters water equivalent.
The angular data are matched by two different simulations taking into account the known geodetic features of the
terrain: First, simply by determining the cutoff energy using the projected slant depth in rock and the known muon
energy spectrum, and second, in a GEANT4 simulation propagating the muons through a column of rock equal to the
known slant depth. The present data are instrumental for studying muon-induced effects at these depths and also in the
planning of an active veto for accelerator-based underground nuclear astrophysics experiments.

Keywords: Muon intensity; Underground laboratories; GEANT4; nuclear astrophysics; wire chambers; muon tomography; muon radiography

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Publ.-Id: 28281