Russell G Neilson

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop.

Very accurate measurements of the half‐life, 3.8755(12) s, and the branching ratio, 0.5315(12), are reported for the superallowed 0+ → 0+ β‐decay of 22Mg. The precision in the branching ratio was achieved by the efficiency calibration of an HPGe detector to 0.15% precision for γ‐ray energies between 50 and 1400 keV. The ft‐value extracted from the measurement, corrected for small calculated radiative effects is Ft=3071(9) s. With this measurement, we open up a new series of superallowed emitters with Tz = −1 to precision measurements. This series will permit direct tests of the calculated nuclear‐structure‐dependent correction terms essential to the determination of the vector coupling constant, GV, and of Vud, the up‐down quark‐mixing element of the Cabibbo‐Kobayashi‐Moskawa (CKM) matrix. As the top row of the CKM matrix currently fails the unitarity test by more than two standard deviations, measurements to improve the precision with which Vud is known are of paramount importance.