11C Background in Liquid Scintillator Detectors

Abstract

Cosmogenic 11C produced in muon showers is one of the main backgrounds for the detection of pep and CNO solar neutrinos in underground organic liquid scintillator detectors. Experimental data available for the effective cross section for 11C by muons indicate that 11C is in fact the dominant background for the observation of such neutrinos. 11C decays are expected to total a rate 2.5 (20) times higher than the combined rate of pep and CNO neutrinos in Borexino (KamLAND) in the energy window preferred for the pep measurement, between 0.8 and 1.3 MeV.Background from 11C in organic liquid scintillator detectors can be reduced if a neutron is emitted when the 11C nuclide is created. 11C decays can be tagged on a one‐by‐one basis using a three‐fold coincidence with the parent muon track and the subsequent neutron capture on protons. The efficiency of such background reduction critically relies on the emission of a free neutron associated with 11C production.In order to verify the hypothesis, first suggested by...