SNO + expanded R&D

萨德伯里中微子天文台（SNO）使用重水作为探测太阳中微子的介质。在2007年完成对重水的当前测量后，有可能用液体闪烁体取代SNO中的重水。液体闪烁体是一种有机碳氢化合物液体，当亚原子粒子在其中相互作用时，它会发光。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，从而允许对低能量中微子进行研究。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。其中包括对低能太阳中微子进行精确测量的能力，从而探测中微子与物质相互作用的细节。测试中微子物质势对新物理学很敏感，并提高了我们对SNO最近发现的新中微子性质的认识的准确性。对恒星中的核能产生机制也将有更深入的了解。在能量较低的情况下，也有可能探测到地球中微子，即地球自然放射性释放的中微子。通过研究地球中微子，人们可以一次调查整个地球，直接确定地球深处的放射性总量及其在地球热生成中的作用，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优秀监测器。这是为了在2006年9月之前制定出完整的提案，扩大SNO+项目的研究开发（R&D）规模的提案。明年将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.