Collaborative Research: Estimating the mantle contribution to the Geo-neutrino flux at the Sudbury Neutrino Observatory

研究人员将在加拿大南部-美国中北部1000公里宽的区域内确定大陆地壳和下地幔中钍(Th)和铀(U)的丰度和分布，在那里将建造一个地下实验室，以测量地球内部的地球中微子的通量。地球中微子是在地球内部自然产生的放射性元素的贝塔衰变过程中产生的电子反中微子。这些粒子是我们星球上放射性元素丰度和分布的信使，并提供了约束地球所有地球化学和地球物理模型的直接信息。利用两个亚千吨液体闪烁体探测器成功地进行了地中微子探测。SnO+探测器(加拿大安大略省萨德伯里)是一个千吨探测器，将是第一个液体闪烁中微子探测器，具有足够的基准体积和足够低的反应堆背景，以便在大约3年内探测到足够的地球中微子计数，将地球上的Th和U含量限制在~±25%(1西格玛)或更好的范围内。所有这些探测器还能够探测动力核反应堆的电子反中微子发射。通过将地球核动力限制在区域大陆地壳约12%的不确定度内，研究人员将能够关键地评估地幔中的Th和U含量。他们的目标是对照实时中微子数据测试解释性的成分地球模型。这两个独立的数据集的整合将为地球如何工作提供变革性的见解，并限制能源驱动板块构造。反过来，这些数据将提供关于地壳和地幔的独特的整体成分信息。该团队将联合地球科学和物理学的科学家，在反中微子探测研究及其应用方面有着共同的目标。本科生和研究生将参与这项研究。结果将传达给普通公众、K-12教育工作者和美国情报界成员。为了防止核扩散，探测反中微子对美国国家安全机构具有重大意义。

The investigators will identify the abundance and distribution of thorium (Th) and uranium (U) in the continental crust and underlying mantle beneath a 1000-km wide area in southern Canada - northern central US where there will be an underground laboratory constructed to measure the flux of geoneutrinos from inside the Earth. Geoneutrinos are electron antineutrinos produced inside the Earth during beta-decays of naturally occurring radioactive elements. These particles are messengers of the abundances and distribution of radioactive elements within our planet, and provide direct information that constrains all geochemical and geophysical models of the planet. Geoneutrino detection was successfully performed by two sub-kiloton, liquid scintillator detectors. The SNO+ detector (Sudbury, Ontario, Canada), a kiloton detector, will be the first liquid scintillation neutrino detector with ample fiducial volume and low enough reactor background to allow detection of sufficient geoneutrino counts in approximately 3 years to constrain the Th and U content of the Earth to within ~±25% (1 sigma) or better. All of these detectors are also capable of detecting the electron antineutrino emissions of power nuclear reactors. By constraining the Earth's nuclear power to uncertainties of about 12% for the regional continental crust the investigators will be able to assess critically the Th and U content of the mantle. Their goals are to test interpretive compositional Earth models against real time neutrino data. The integration of these two independent data sets will provide transformative insights into how the Earth works and constrain the energy source driving Plate Tectonics. In turn, these data will provide unique bulk compositional information about the crust and mantle. The team will unite scientists from earth sciences and physics with shared goals in antineutrino detection research and its applications. Undergraduate and graduate students will be involved in this research. Results will be communicated to the general public, K-12 educators and members of the US intelligence community. The detection of antineutrinos for nuclear nonproliferation purposes is of significant interest to US national security agencies.