The Next Breakthroughs in Neutrino Physics

Project Overview

The neutrino is an important fundamental particle, one of the building blocks of the universe. A better understanding of the neutrino will answer questions regarding the origin of mass, the matter and anti-matter asymmetry of the universe, and the nature of dark matter. The nation's research community has recognized that the answers to these and other questions are within reach and has assigned neutrino experiments the highest priority for both nuclear and particle physics programs. We investigated three aspects of neutrino experimentation: detection techniques, target materials, and data analysis. Our efforts targeted multiple applications including experiments to measure neutrinoless double-beta-decay, neutrino-oscillation, and neutrino mass. Our research objectives included (1) developing approaches that make detectors scalable to larger sizes and insensitive to background signals; (2) increasing the signal strength and reducing noise from targets; and (3) efficiently distinguishing background noise from signals during analysis. In this LDRD we have advanced all of these areas. We have demonstrated the scale up of a metal organic framework that can adsorb xenon directly from the air that will allow for large neutrino detectors made from xenon. We have studied the use of Cherenkov radiation to reduce the signal backgrounds. We demonstrated the cracking of hydrogen to make atomic tritium for neutrino mass measurements, and lastly we demonstrated the benefits of machine learning techniques to improve signal to noise during analysis.

Mission Impact

This project supports the NNSA's goal to reduce nuclear dangers by providing expert knowledge and operational capability for nuclear threat response. The measurement techniques we developed will find applications in many areas including antineutrino-based reactor monitoring projects, nuclear forensics detection technology, and nuclear cross section measurements of interest to the NNSA. Our research supports the Lawrence Livermore National Laboratory's nuclear, chemical, and isotopic science and technology core competency, as well as the Laboratory's nuclear threat reduction mission research challenge.

Publications, Presentations, and Patents

Brodsky, J.A., et al. 2019. "Background discrimination for neutrinoless double beta decay in liquid xenon using cherenkov light," Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 922:76-83, April 2019. https://doi.org/10.1016/j.nima.2018.12.057, LLNL-JRNL-761641.

Albert, J.B., et al. (nEXO collaboration) 2018. "Sensitivity and discovery potential of the proposed nEXO experiment to neutrinoless double beta decay," Phys. Rev. C 97, 065503. https://doi.org/10.1103/PhysRevC.97.065503, LLNL-JRNL-737682.

Alamre, A. et al. (nEXO collaboration) 2018, "nEXO Pre-Conceptual Design Report," arXiv:1805.11142v2, LLNL-TR-752007.

A.A. Esfahani et al., 2019, "Electron radiated power in cyclotron radiation emission spectroscopy experiments," Physical Review C 99, 055501 (2019).

Heffner, M. 2018, "The nEXO Experiment: A Tonne Scale Majorana Neutrino Search." Invited talk American Physical Society, Division of Nuclear Physics Oct 2018.

Stiegler, T. 2019, "Improved Sensitivity of nEXO to Neutrinoless Double Beta Decay." APS April Meeting, March 2019.

Stiegler, T. 2019, "The nEXO Experiment." Conference on Science at the Sanford Underground Research Facility, May 2019.

Stiegler, T. 2019, "Improved Modeling of the nEXO Detector for Neutrinoless Double Beta Decay." LLNL's 2019 Postdoc Symposium June 2019.

Kazkaz, K. 2018, "Project 8." American Physical Society, Division of Nuclear Physics, Oct 2018.