Cosmogenic Backgrounds in Borexino at 3800 m water-equivalent depth

Abstract

The solar neutrino experiment Borexino, which is located in the Gran Sasso\nunderground laboratories, is in a unique position to study muon-induced\nbackgrounds in an organic liquid scintillator. In this study, a large sample of\ncosmic muons is identified and tracked by a muon veto detector external to the\nliquid scintillator, and by the specific light patterns observed when muons\ncross the scintillator volume. The yield of muon-induced neutrons is found to\nbe Yn =(3.10+-0.11)10-4 n/({\\mu} (g/cm2)). The distance profile between the\nparent muon track and the neutron capture point has the average value {\\lambda}\n= (81.5 +- 2.7)cm. Additionally the yields of a number of cosmogenic\nradioisotopes are measured for 12N, 12B, 8He, 9C, 9Li, 8B, 6He, 8Li, 11Be, 10C\nand 11C. All results are compared with Monte Carlo simulation predictions using\nthe Fluka and Geant4 packages. General agreement between data and simulation is\nobserved for the cosmogenic production yields with a few exceptions, the most\nprominent case being 11C yield for which both codes return about 50% lower\nvalues. The predicted {\\mu}-n distance profile and the neutron multiplicity\ndistribution are found to be overall consistent with data.\n