Experimental Physics Research Program at Columbia University/Nevis Laboratories

现代粒子物理实验的一个主要目标是发现和阐明超越标准模型的新物理。可能的方法包括在加速器上研究最高可用碰撞能量的物理过程，或通过研究非常罕见的中微子相互作用。哥伦比亚大学的粒子物理小组从事这两种方法，这两种方法都与在宇宙大爆炸后的极短时间内对宇宙最基本层面的理解有关，也与我们为什么会看到现在的宇宙有关。在最高的可用碰撞能量下，瑞士日内瓦欧洲核子研究中心的大型强子对撞机(LHC)的实验目标是了解最近发现的希格斯玻色子的性质，并发现标准模型以外的新物理。在接下来的三年里，通过越来越高的相互作用速率和越来越多的数据集，在13-14TeV的碰撞能量下，LHC物理计划将会增长。哥伦比亚团队是参与欧洲核子研究中心ATLAS实验的领导小组之一。他们的贡献包括广泛参与实验的科学和技术管理、对能量测量的关键探测器的维护和操作以及升级作出重大贡献，特别是液体氩热量计。在寻找新物理的过程中，该小组专注于在广泛的产生和衰变过程中寻找超对称性的证据，以及寻找质量非常高的奇异粒子，涉及矢量玻色子和希格斯玻色子，并依赖于对带电轻子、喷流和丢失能量的识别。另一个主要问题是宇宙中所有反物质发生了什么。基本的对称性论证表明，物质和反物质在早期宇宙中应该是同等丰度的，但现在我们所看到的只有物质。解开这一谜团的关键可能在于被称为中微子的难以捉摸的粒子，中微子在宇宙中大量存在，但几乎不与物质相互作用。已知的此类粒子有三种。为什么是三个？这些粒子的质量是多少？还有别的吗？为了了解这些现象并查看是否存在三个以上的中微子，实验正在进行中。哥伦比亚大学的团队参与了MicroBooNE实验，该实验目前在伊利诺伊州巴达维亚的费米国家加速器实验室上线，以及一种名为SBND的新探测器正在准备中。该计划将解决中微子物理中的几个关键问题，包括寻找额外的中微子，以及该领域一项重要的新技术--液态Ar时间投影室的进展。哥伦比亚小组主要负责时间投影室和触发系统的读出电子设备、探测器模拟、数据采集软件和MicroBooNE的物理分析，并正在将这些工作推进到未来的深层地下中微子实验(DUNE)。广泛的影响：哥伦比亚小组多年来的主要重点是通过非常成功的本科生研究经验(REU)暑期项目对本科生进行培训。这项计划表明了对纳入代表性不足群体的承诺，包括许多来自仅限本科生院校的学生。后续跟踪显示，他们项目的毕业生在STEM领域攻读高级学位的成功率令人印象深刻。

A principal goal of experiments in modern particle physics is to uncover and elucidate new physics beyond the Standard Model. Possible approaches include the study of physics processes at the highest available collision energies at accelerators or through studies of the very rare interactions of neutrinos. The Columbia Particle Physics group is engaged in both approaches, which are relevant to the understanding of the Universe at its most fundamental level in the fleeting fraction of a second just after the Big Bang, and to why we see the Universe as we do now. At the highest available collision energies, the objectives of the experiments at the Large Hadron Collider (the LHC) at CERN, Geneva, Switzerland is to understand the nature of the recently discovered Higgs Boson, and to uncover new physics beyond the Standard Model.   The next three years will witness the growth of the LHC physics program through ever higher interaction rates and ever increasing data sets at collision energies of 13-14 TeV. The Columbia team is one of the leading groups participating in the ATLAS experiment at CERN. Their contributions include extensive involvement in the scientific and technical management of the experiment, substantial contributions to the maintenance and operations and upgrades of the key detectors for energy measurement, in particular the Liquid Argon Calorimetry. In the search for new physics, the group is focusing on searches for evidence of supersymmetry and for exotic particles of very high masses in a broad range of production and decay processes, involving vector bosons and the Higgs boson, and relying on the recognition of charged leptons, jets and missing energy.  Another major question is what happened to all the antimatter in the universe. Fundamental symmetry arguments suggest that matter and antimatter should have been produced in equal abundance in the early universe, but now all we see is matter. A key to unraveling this mystery may lie with elusive particles called neutrinos, which are abundant in the universe, but which barely interact with matter. There are three of these particles known. Why three? And what are the masses of these particles? Are there more? Experiments are underway to understand these phenomena and to see if more than three neutrinos exist. The Columbia group is involved with the experiment MicroBooNE, which is now online at Fermi National Accelerator Laboratory in Batavia, Illinois, and a new detector in preparation, called SBND. This program will address several of the key questions in neutrino physics, including the search of additional neutrinos as well as advancement of an important new technology for the field, the Liquid Argon Time Projection Chamber. The Columbia group has major responsibilities for the readout electronics of the Time Projection Chamber and triggering system, detector simulation, data acquisition software, and physics analysis for MicroBooNE, and is advancing these efforts to the future Deep Underground Neutrino Experiment (DUNE).Broader Impacts: A principal focus of the Columbia group over many years and strengthened with this award is the training of undergraduate students through their highly successful Research Experiences for Undergraduates (REU) summer program. This program has demonstrated a commitment to the inclusion of under-represented groups, including many students from undergraduate-only institutions. And follow-up tracking has shown an impressive rate of success for graduates of their programs to pursue advanced degrees in STEM fields.