New Experimental Techniques for Neutrino Physics

中微子是宇宙中最丰富的粒子之一，它们是许多天体物理过程的关键，它们可能是解释宇宙物质-反物质不对称的关键。众所周知，它们在自然界中有三种类型，或称“味道”。人们还观察到，中微子可以通过一种称为中微子振荡的过程来改变味道。从这样的振荡实验中发现，中微子一定有一个非零的质量。这是第一个已知的迹象，表明存在超越非常成功的粒子物理标准模型的物理学。中微子质量仍然是物理学中最重要的悬而未决的问题之一，实验正在寻找确定中微子质量的方法，因为它们的丰度可能会在我们的宇宙演化中发挥重要作用。在过去的80年里，由于日益强大的电子能谱技术，基于对β光谱的精确测量的直接实验室测定一直在扩大。2009年，PI提出了一种提取低能电子能谱的新技术。这项名为回旋辐射发射光谱(CRES)的技术依赖于对电子在磁场中回旋运动产生的相干辐射的探测和测量。中微子质量的知识对科学界具有广泛的影响，特别是在核物理、粒子物理和宇宙学领域。CRES技术是一种通用的低能电子光谱技术，具有广泛的适用性。金属超导测辐射热计用于反冲探测也有广泛的应用，在核反应堆监测和直接暗物质探测方面有潜在的应用。麻省理工学院的本科生研究机会计划(UROP)促进了与本科生的研究活动，该计划将学生和教职员工联系起来，允许学生在整个学年从事基础研究。2009年，PI提出了一种新技术，可以用来提取低能电子的能谱。CRES技术依赖于探测和测量电子在磁场中回旋运动产生的相干辐射。这种基于频率的技术有能力克服在直接使用氚的中微子质量实验中使用的传统光谱技术施加的许多限制。以PI为代言人的Project 8实验现在已经成功地展示了CRES技术如何有效地精确测量从放射性气体发射的电子的动能。在坚定的原则证明下，该奖项为下一阶段的S项目研发计划提供了持续的支持，该项目将朝着利用氚β衰变进行中微子质量测量的方向发展。特别是，下一阶段是对氚贝塔谱进行第一次测量，以确定该技术的可扩展性。研究还将继续确定这项技术的最终能力：探测倒置的中微子质量尺度。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Neutrinos are amongst the most abundant particles in the Universe, they are keys to many astrophysical processes, and they may hold the key to explaining the matter-antimatter asymmetry of the Universe. They are known to occur in nature in three types, or "flavors." It has also been observed that neutrinos could switch flavors through a process known as neutrino oscillation. From such oscillation experiments, it is found that neutrinos must have a non-zero mass. This is the first known indication that there is physics beyond the very successful Standard Model of Particle Physics. Neutrino mass remains one of the most important open questions in physics and experiments are searching for ways to determine it since with their abundance they could play an important role in the evolution of our Universe. Direct laboratory determinations based on the precise measurement of the beta spectrum have been expanding over the past 80 years due to increasingly powerful electron spectrometry techniques. In 2009, the PI proposed a new technique by which the energy spectrum of low energy electrons can be extracted. The technique, known as Cyclotron Radiation Emission Spectroscopy (CRES), relies on the detection and measurement of coherent radiation created from the cyclotron motion of electrons in a magnetic field. Knowledge of neutrino masses has broad implications for the scientific community, particularly in the fields of nuclear physics, particle physics, and cosmology. The CRES technique, being a general spectroscopic technique for low energy electrons, has broad applicability. The use of metallic superconducting bolometers for recoil detection also has broad reach, with potential applications in nuclear reactor monitoring and direct dark matter detection. Research engagement with undergraduate students is facilitated by MIT's Undergraduate Research Opportunity Program (UROP), which connects students and faculty and allows students to engage in basic research throughout the academic year.In 2009, the PI proposed a new technique by which the energy spectrum of low energy electrons can be extracted. The CRES technique relies on the detection and measurement of coherent radiation created from the cyclotron motion of electrons in a magnetic field. Such a frequency-based technique has the capability of overcoming many of the limitations imposed by traditional spectroscopic techniques used in direct neutrino mass experiments using tritium. The Project 8 experiment, of which the PI is the spokesperson, has now successfully demonstrated how the CRES technique is effective in precisely measuring the kinetic energy of electrons emitted from a radioactive gas. With the proof of principle firmly established, this award provides continued support of the next stage of Project 8's R&D program, moving toward a neutrino mass measurement from tritium beta decay. In particular, the next phase is to make a first measurement of a tritium beta spectrum in order to determine the scalability of the technique. Research will also continue to determine the technique's ultimate capability: to probe the inverted neutrino mass scale.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.