SNO + expanded R&D

萨德伯里中微子天文台（Sudbury Neutrino Observatory，SNO）使用重水作为探测太阳中微子的介质。 在2007年完成目前对这种重水的测量之后，将有可能用液体闪烁体取代SNO中的重水--一种有机烃液体，当亚原子粒子在其中相互作用时会发光。液体闪烁体将使SNO中中微子相互作用产生的光比目前的配置增加50倍以上，从而可以研究低能量的中微子。 带有液体闪烁体的SNO（称为SNO+）将是一种具有独特物理能力的多用途中微子探测器。 这些能力包括精确测量低能量的“pep”太阳中微子，探测中微子与物质相互作用的细节。 中微子物质势的测试对新物理学很敏感，并提高了我们对SNO最近发现的新中微子性质的认识的精度。 还将加深对恒星核能产生机制的了解。 在较低的能量下，也有可能探测到地球中微子，即地球天然放射性释放的中微子。 通过研究地球中微子，人们可以一次测量整个地球，直接确定地球深处的放射性总量及其在地球生热中的作用，这是地球物理学的一个重要和基本方面，目前还没有很好地确定。 液体闪烁体探测器也可以作为探测和研究超新星中微子的一个很好的监测器。 这是一项扩大SNO+项目研发的建议，以便在2006年9月之前制定一项完整的建议。 明年提交一份完整的提案，旨在从2007年4月开始提供资金，以便在重水被移除后无缝过渡到SNO+探测器。

The Sudbury Neutrino Observatory (SNO) uses heavy water as the medium for detecting solar neutrinos.  After current measurements with this heavy water are completed in 2007, it would be possible to replace the heavy water in SNO with a liquid scintillator - an organic hydrocarbon liquid that emits light when subatomic particles interact in it.  A liquid scintillator would boost the light produced by neutrino interactions in SNO by more than a factor of fifty over the present configuration, allowing lower energy neutrinos to be studied.  SNO with liquid scintillator (called SNO+) would be a multipurpose neutrino detector with unique physics capabilities.  These include the ability to make precision measurements of the low energy "pep" solar neutrinos that probe the details of the neutrino-matter interaction.  Testing the neutrino-matter potential is sensitive to new physics and improves the precision of our knowledge of the new neutrino properties recently discovered by SNO.  A deeper understanding of the nuclear energy generation mechanisms in stars would also be achieved.  At lower energies it would also be possible to detect geo-neutrinos, the neutrinos emitted by natural radioactivity in the Earth.  By studying geo-neutrinos one can survey the whole Earth at once to directly determine the total amount of radioactivity deep in the Earth and its role in Earth's heat generation, an important and fundamental aspect of geophysics that is currently not well determined.  A liquid scintillator detector would also serve as an excellent monitor for detecting and studying supernova neutrinos.  This is a proposal to expand the R&D for the SNO+ project in order to develop a full proposal by September 2006.  The submission of a full proposal next year aims at a funding profile that would start in April 2007, allowing for a seamless transition to the SNO+ detector after the heavy water is removed.