New Experiment Techniques For Neutrino Physics

在过去的二十年里，中微子物理学和宇宙学发生了两个显著的范式转变。关于中微子物理学，或者更准确地说，关于中微子质量的问题，研究领域已经从发现转向了精确。从太阳中微子、大气中微子和反应堆中微子收集的测量结果已经确凿地表明，中微子会改变味道，因此具有非常小但非零的质量。对这些振荡参数的测量目前正在几个百分点的水平上进行探索。几乎与此同时，观测宇宙学也经历了类似的阶段转变，进入了精确的测量阶段，为我们提供了一幅出色的宇宙图景。对能量和物质含量以及宇宙演化的精确测量，现在可以对宇宙模型进行详细的测试，而这在十年前是根本无法实现的。研究人员终于达到了这样一个阶段：直接比较由宇宙学和核实验确定的中微子质量是可能的。这些新进展迫使该领域开发出突破中微子质量灵敏度极限的技术。麻省理工学院的中微子小组正在领导下一代中微子质量实验，称为8号项目，该实验利用了一种全新的中微子质量测量方法。利用频率测量能量，可以提取精细的光谱信息。这项合作证明了回旋辐射发射光谱（CRES）技术可以从放射性气体中提取电子的能量，并表明该技术也适用于氚衰变。中微子质量的知识对科学界有着广泛的影响，特别是在核物理、粒子物理和宇宙学领域。CRES技术作为低能电子光谱的一种通用技术，具有广泛的适用性。金属超导辐射热计用于后坐力探测也具有广泛的应用前景，在核反应堆监测和直接探测暗物质方面具有潜在的应用前景。这些课题已经并将继续得到物理系本科生的广泛支持和参与。该合作现在正在扩展CRES技术，以建立一个新的β衰变实验，提高对中微子质量尺度的灵敏度。项目8实验的目标是在90%的置信限下将中微子的质量灵敏度降低到40 meV/c^2。麻省理工学院中微子小组也在推动一项新技术，旨在探测由相干弹性中微子核散射产生的中微子相互作用中产生的低能反冲。具体来说，他们正在开发金属超导辐射热计，其阈值足够低，可以探测到反应堆中微子的相干散射。新的实验成果，弹跳，在寻找新的物理甚至核反应堆监测方面有潜在的应用。这项实验最近被批准在法国格勒诺布尔的ILL反应堆进行。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Two remarkable paradigm shifts have taken place over the past twenty years in neutrino physics and cosmology. With regard to neutrino physics, or more precisely on the question of neutrino mass, the field has shifted from discovery to precision. Measurements gathered from solar, atmospheric, and reactor neutrinos have shown conclusively that neutrinos change flavor and, as a consequence, have a very small but nonzero mass. The measurements on these oscillation parameters are now being probed at the few percent level. Almost concurrently, observational cosmology has made a similar phase transition into precision measurements, providing an outstanding view of the cosmos. Precision measurements on the energy and matter content and evolution of the universe now allow detailed tests of cosmological models that were simply unavailable even a decade ago. Investigators are finally reaching the stage in which direct comparisons between neutrino masses as determined by cosmology and as determined by nuclear experiments are possible. These new advances compel the field to develop techniques that push the boundaries of neutrino mass sensitivity. The Neutrino group at MIT is leading a next-generation neutrino mass experiment called Project 8 that utilizes an entirely new approach in neutrino mass measurements. By using frequency to measure energy, one can extract exquisite spectroscopic information. The collaboration has demonstrated that the Cyclotron Radiation Emission Spectroscopy (CRES) technique extracts the energy of electrons created from a radioactive gas and has shown that the technique also works on tritium beta decay. 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, having potential applications in nuclear reactor monitoring and direct dark matter detection. These topics have and continue to draw broad support and engagement from undergraduate students in physics.The collaboration is now expanding the CRES technique to build a new beta decay experiment with improved sensitivity for the neutrino mass scale. The goal of the Project 8 experiment is to push the neutrino mass sensitivity down to 40 meV/c^2 at 90% confidence limit. The MIT Neutrino Group is also pushing a novel technology designed to detect low energy recoils created in neutrino interactions from coherent elastic neutrino nucleus scattering. Specifically, they are developing metallic superconducting bolometers with thresholds sufficiently low as to enable detection of coherent scattering from reactor neutrinos. The new experimental effort, Ricochet, has potential applications in searching for new physics and even nuclear reactor monitoring. The experiment has recently been approved to be deployed at the ILL reactor in Grenoble, France.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.