This award provides support for the continued operation of the Homestake chlorine solar electron neutrino detector. This detector was the first detector to provide experimental evidence for nuclear fusion reaction in the solar core and simultaneously established that the observed solar electron neutrino flux is much smaller than that predicted by the standard solar model. The result obtained by experiment is about 27% that predicted by the theory of stellar evolution.
In the light of this pioneering work, other groups around the world have built their own detectors, and all have confirmed this initial result. The consequences have been of high significance. Many now believe that these results can only be explained if the neutrino has mass. Recent work at another solar neutrino detector in Japan seems to have provided the first evidence for massive neutrinos.
The support provided in this award will phase out NSF support of the Homestake Mine experiment. This experiment is going to be superceded by other experiments currently under construction in Italy and in other countries. Until such time as these experiments are in operation, it of great importance that the measurements at Homestake continue.
This project is being jointly supported by the Department of Energy and the National Science Foundation. DOE will be providing partial support of the first year of operational costs. NSF will provide the costs of equipment and the remaining costs for operations of the first year. The final two years of support of operations will be provided by NSF. NSF support is provided through participation by the Division of Astronomical Sciences, the Division of Physics, and the Office of Multidisciplinary Activities in the Directorate for Mathematical and Physical Sciences.
