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

20世纪最重要的智力成就之一是粒子物理学标准模型（SM）的发展。这个模型已经成功地将所有已知的基本粒子分类为具有相似量子特性的群体层次。到目前为止，这个模型的有效性已经被欧洲核子研究中心的大型强子对撞机发现的希格斯玻色子所证实。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多于反物质。寻找关于宇宙的开放性问题的答案的主要领域之一，它是如何形成的，为什么它是这样的，就是把重点放在中微子的特性研究上，并利用我们所知道的和可以学到的关于中微子的知识作为标准模型之外的科学探测器。中微子是一种基本粒子，几乎不与宇宙中的任何物质相互作用。它们不带电荷，一度被认为是无质量的。此外，标准模型预测，实际上有三种不同的中微子，通过它们与物质相互作用时所经历的不同相互作用，可以区分它们。但是最近的测量完全改变了我们对中微子的认识。我们现在知道中微子确实有质量，正因为如此，它们实际上可以从一种类型转变为另一种类型。对这些变化的详细测量，以及其他当前的中微子测量，形成了探索超越标准模型的新物理的最有希望的方法之一。在各种新型中微子（称为惰性中微子）的实验中也可能有线索，而建造关键仪器来澄清这些“线索”是该项目工作的主要重点之一。智力优势：本文提出的工作是开发一个用于LAr1-ND实验的液氩时间投影室（LAr TPC）。这种探测器技术的强大之处在于，它允许实验者区分电子和光子，这对于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，以及一个名为MicroBooNE的同伴实验，应该会大大增加物理学的范围，以回答假设的“无菌”中微子是否存在的重要问题，并解决最近中微子实验中的异常现象。更广泛的影响：该研究项目将成为LAr TPC技术以及重建和分析技术的宝贵试验场，这些技术将使未来的实验取得成功。耶鲁大学、锡拉丘兹大学和芝加哥大学这三所合作机构的建设工作将使每所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，这是培养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.