MRI Consortium: Development of a Time Projection Chamber to Measure Neutrino Interactions in the LAr1 Near Detector

20世纪的主要智力成就之一是粒子物理标准模型(SM)的发展。这个模型已经成功地将所有已知的基本粒子归入具有相似量子性质的群组的层次中。最近在欧洲核子研究中心的大型强子对撞机上发现的希格斯玻色子证实了这个模型到目前为止的有效性。然而，目前存在的标准模型留下了许多悬而未决的问题，例如，为什么宇宙中物质比反物质占优势。要寻找关于宇宙的这些悬而未决的问题的答案，它是如何形成的，为什么它是这样的，主要领域之一是专注于中微子的性质研究，并将我们所知道和可以了解的中微子用作超越标准模型的科学探测器。中微子是基本粒子，几乎不与宇宙中的其他任何东西相互作用。它们没有电荷，曾经被认为是无质量的。此外，标准模型预测，实际上有三种不同类型的中微子，可以通过它们与物质相互作用时所经历的不同相互作用来区分。但最近的测量完全改变了我们对中微子的看法。我们现在知道中微子确实有质量，因为它们有质量，所以它们实际上可以从一种类型变成另一种类型。对这些变化的详细测量，以及目前的其他中微子测量，形成了探索标准模型以外的新物理的最有前途的方法之一。在各种新型中微子(称为稀有中微子)的实验中也出现了可能的线索，而建造关键仪器来澄清这种“线索”是这一项目工作的主要推动力之一。智能价值：本文提出的工作是为LAr1-ND实验研制一台液体Ar时间投影室(LAR TPC)。这种探测器技术很强大，因为它允许实验者区分电子和光子，这对理解中微子相互作用和中微子振荡的特征很重要。在费米实验室，LAr1-ND实验，以及一项名为MicroBooNE的配套实验，应该会极大地扩大物理学领域的覆盖面，回答假设的“不育”中微子是否存在，并解决最近中微子实验中的反常问题。更广泛的影响：这项研究计划将成为LAR TPC技术以及使未来实验成功所需的重建和分析技术的宝贵试验场。耶鲁大学、锡拉丘兹大学和芝加哥大学这三个合作机构的建设工作将使每个机构的学生和博士后能够参与并获得先进探测器技术的宝贵实践经验，这是培训高能物理领域科学家的重要组成部分。

One of the major intellectual achievements of the 20th century was the development of the Standard Model (SM) of particle physics. This model has succeeded in classifying all of the elementary particles known into a hierarchy of groups having similar quantum properties. The validity of this model to date has been recently confirmed by the discovery of the Higgs boson at the Large Hadron Collider at CERN. However, the Standard Model as it currently exists leaves open many questions, for example why there is a preponderance of matter over antimatter in the universe. One of the primary areas to search for answers to such open questions about the universe, how it came to be and why it is the way it is, is to focus on a study of the properties of neutrinos and to use what we know and can learn about neutrinos as probes of science beyond the Standard Model. Neutrinos are elementary particles that barely interact with anything else in the universe. They have no electric charge and were once thought to be massless. Moreover, the Standard Model predicted that there were actually three different kinds of neutrinos that were distinguishable through the different interactions that they would undergo whenever they would interact with matter. But recent measurements have totally changed our picture of neutrinos. We now know that neutrinos do have a mass and because they do, they can actually change from one type to another. Detailed measurements of these changes, along with other current neutrino measurements, form one of the most promising ways to probe for new physics beyond the Standard Model. There have also been possible hints in various experiments of new types of neutrinos (called sterile neutrinos), and building the critical instruments to clarify such "hints" is one of the main thrusts of the work in this project. Intellectual Merit: The work proposed here is to develop a Liquid Argon Time Projection Chamber (LAr TPC) for the LAr1-ND Experiment. This detector technique is powerful in that it allows the experimenter to distinguish between electrons and photons, important for the understanding of the character of neutrino interactions and neutrino oscillations. At Fermilab, the LAr1-ND experiment, along with a companion experiment called MicroBooNE, should significantly increase the physics reach toward answering the important question of whether hypothesized "sterile" neutrinos exist and resolving the anomalies in recent neutrino experiments. Broader Impact: This research program will serve as an invaluable proving ground for LAr TPC technology and in the reconstruction and analysis techniques that will be needed to make future experiments a success. The construction effort at the three collaborating institutions Yale, Syracuse and Chicago will enable students and postdocs at each institution to participate and acquire invaluable hands-on experience with advanced detector technology that is a vital component of training scientists in the field of high-energy physics.