T. Bloxham

7Be Solar Neutrino Measurement with KamLAND

We report a measurement of the neutrino-electron elastic scattering rate of 862 keV ^7Be solar neutrinos based on a 165.4 kt d exposure of KamLAND. The observed rate is 582±94(kt d)^(−1), which corresponds to an 862-keV Be7 solar neutrino flux of (3.26±0.52)×10^9cm^(−2)s^(−1), assuming a pure electron-flavor flux. Comparing this flux with the standard solar model prediction and further assuming three-flavor mixing, a ν_e survival probability of 0.66±0.15 is determined from the KamLAND data. Utilizing a global three-flavor oscillation analysis, we obtain a total ^7Be solar neutrino flux of (5.82±1.02)×10^9cm^(−2)s^(−1), which is consistent with the standard solar model predictions.

A compact ultra-clean system for deploying radioactive sources inside the KamLAND detector

We describe a compact, ultra-clean device used to deploy radioactive sources along the vertical axis of the KamLAND liquid-scintillator neutrino detector for purposes of calibration. The device worked by paying out and reeling in precise lengths of a hanging, small-gauge wire rope (cable); an assortment of interchangeable radioactive sources could be attached to a weight at the end of the cable. All components exposed to the radiopure liquid scintillator were made of chemically compatible UHV-cleaned materials, primarily stainless steel, in order to avoid contaminating or degrading the scintillator. To prevent radon intrusion, the apparatus was enclosed in a hermetically sealed housing inside a glove box, and both volumes were regularly flushed with purified nitrogen gas. An infrared camera attached to the side of the housing permitted real-time visual monitoring of the cable׳s motion, and the system was controlled via a graphical user interface.