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Abstract

The investigation of neutrinos has become a powerfull approach to test the particle physics standard model. All results of solar neutrino measurements point to a nonvanishing neutrino rest mass, with flavor conversion of propagating neutrinos. The scintillation detector BOREXINO is specially built to spectroscopically measure the flux of the monoenergetic 7Be neutrinos from the solar pp fusion chain. An experimental challenge is the required reduction of radioactive background, in peculiar the prevention of the radioactive noble gas nuclides 222Rn, 85Kr and 39Ar, which are present in ambient air. Special requirements are set to nitrogen, used as the purification gas. New approaches for gas chromatography in purification and measurement are applied. Furthermore 222Rn is emanated from all detector components by means of emanation from 226Ra. Numerous emanation measurements were performed, applying existing techniques and devices, to understand the background sources, thus allowing to optimize the detector operations