New Experiment Techniques For Neutrino Physics

在过去的20年里，中微子物理学和宇宙学发生了两次显著的范式转变。 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，该领域已经从发现转向精确。 从太阳、大气和反应堆收集的中微子的测量结果确凿地表明，中微子会改变味道，因此具有非常小但不为零的质量。这些振荡参数的测量现在正在百分之几的水平上进行探索。 几乎与此同时，观测宇宙学也经历了类似的相变，进入了精确测量阶段，提供了一个出色的宇宙观。 对能量和物质含量以及宇宙演化的精确测量现在允许对宇宙学模型进行详细的测试，即使在十年前也是不可用的。 研究人员终于达到了这样一个阶段，即直接比较宇宙学确定的中微子质量和核实验确定的中微子质量是可能的。 这些新的进展迫使该领域开发技术，推动中微子质量灵敏度的界限。 麻省理工学院的中微子小组正在领导一个名为Project 8的下一代中微子质量实验，该实验利用了一种全新的中微子质量测量方法。通过使用频率来测量能量，人们可以提取精细的光谱信息。合作表明，回旋辐射发射光谱（克雷斯）技术提取了放射性气体产生的电子能量，并表明该技术也适用于氚β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。克雷斯技术是低能电子的通用光谱技术，具有广泛的适用性。使用金属超导测辐射热计进行反冲探测也具有广泛的应用范围，在核反应堆监测和直接暗物质探测中具有潜在的应用。这些课题已经并将继续得到物理学本科生的广泛支持和参与。该合作目前正在扩展克雷斯技术，以建立一个新的β衰变实验，提高中微子质量尺度的灵敏度。Project 8实验的目标是将中微子质量灵敏度降低到40 meV/c^2，置信限为90%。 麻省理工学院的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测辐射热计，其阈值足够低，以便能够检测反应堆中微子的相干散射。新的实验努力，跳弹，有潜在的应用在寻找新的物理，甚至核反应堆监测。该实验最近被批准部署在法国格勒诺布尔的ILL反应堆上。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.