Greg Keefer
University of Alabama
ABSTRACT
The KamLAND collaboration operates a 1 kton liquid scintillation detector in the Kamioka mine in Gifu, Japan. KamLAND's main scientific results are the precision measurement of the solar ∆m^2 utilizing reactor anti-neutrinos and a first indication of geologically produced anti-neutrinos.
The KamLAND collaboration has been working toward upgrading the detector for a low background phase. During the spring of 2007, we performed the first phase of purification by circulating 1.3 ktons of KamLAND liquid scintillator through a newly developed distillation and nitrogen purge system. In the spring of 2008 we made upgrades to the purification system and performed a second phase of purification from July of 2008 to February of 2009. The ultimate goal is to reduce internal radioactive backgrounds to a level that will facilitate a direct measurement of low-energy solar neutrinos.
An overview of solar neutrino theory and a description of the KamLAND detector with the on-going purification process, liquid scintillator quality control measures, and detector monitoring will be presented. The currently achieved background reduction after four full volume exchanges and planned future work will be discussed.