Home page of the Nab experiment at the SNS

This is the home page for the Nab collaboration. The Nab experiment, currently at the Letter of Intent stage, is planned for the Fundamental Neutron Physics Beamline (FNPBL) at the Spallation Neutron Source (SNS), Oak Ridge, Tennessee.


The Nab collaboration has proposed to perform a precise measurement of a, the electron-neutrino correlation parameter, and b, the Fierz interference term in neutron beta decay, at the Fundamental Neutron Physics Beamline at the SNS, using a novel electric/magnetic field spectrometer and detector design. The experiment is aiming at the 10-3 accuracy level in a, and will provide an independent measurement of λ = GA/GV, the ratio of axial-vector to vector coupling constants of the nucleon. We will also perform the first ever measurement of b in neutron decay, which will provide an independent limit on the tensor weak coupling.

Collaborating institutions

  • Arizona State University
  • University of Kentucky
  • Los Alamos National Laboratory
  • University of Manitoba
  • University of Michigan
  • University of New Hampshire
  • North Carolina State University
  • Oak Ridge National Laboratory
  • RMKI, Budapest
  • University of South Carolina
  • University of Sussex
  • University of Tennessee
  • University of Virginia
  • University of Winnipeg

Documentation and Publications


Dinko Počanić, 29 Jul 2005.
Last updated: 03 July 2014.

This work has been supported by grants from the US National Science Foundation and the Department of Energy.