Limits on the spatial width of the electron-neutrino wave packet using 7-beryllium electron capture decay
ORAL
Abstract
The coherence length of a neutrino source is proportional to the spatial width of neutrino wave packets at production. A sufficiently small width of the wave packet could affect current and future neutrino oscillation data. Theoretical predictions for the spatial width of the neutrino wave packet vary by several orders of magnitude and are only loosely constrained by current oscillation data. The BeEST experiment uses superconducting sensors to measure the kinetic energy of the recoiling 7Li atom in 7Be electron capture decay final state which is entangled with the neutrino at its creation. The high energy resolution of the BeEST recoil spectrum combined with knowledge of the spatial localization within a single pixel are converted to lower-limit and upper-limits on the spatial width of the entangled electron-neutrino wave packets. In this talk, I will present this concept and our preliminary results to stimulate discussion within the community on this technique.
* The BeEST experiment is funded in part by the Gordon and Betty Moore Foundation (10.37807/GBMF11571), the DOE-SC Office of Nuclear Physics under Award Numbers DE-SC0021245 and DE-FG02-93ER40789, and the LLNL Laboratory Directed Research and Development program through Grants No. 19-FS-027 and No. 20-LW-006. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. The theoretical work was performed as part of the European Metrology Programme for Innovation and Research (EMPIR) Projects No. 17FUN02 MetroMMC and No. 20FUN09 PrimA-LTD. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344.
