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 = G_A/G_V, 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.

• The full text of the Nab Letter of Intent, submitted to the SNS Program Advisory Committee on 29 July 2005.

• For completeness, the abBA Letter of Intent, is included, as well.

• Nab Monte Carlo archive containing the source codes of GEANT4 Nab detector simulations.

• Technical note on the Nab spectrometer self-calibration (8 Nov 2007).

• The Nab experiment proposal (9 Nov 2007).

• and the abBA experiment proposal (9 Nov 2007).

• Transparencies of presentations relating to Nab at FnPB PRAC meetings, DoE reviews, as well as at workshops and conferences. Some photos of equipment in development are also given.

• "Nab: measurement principles, apparatus and uncertainties" paper presented at the International Workshop for Particle Physics with Slow Neutrons, ILL, Grenoble, held 29 - 31 May 2008; published in Nucl. Instrum. Meth. A611, 211-215 (2009).

• Summary and results of the Virginia GEANT4 Simulations for the Nab Spectrometer prepared by Pete Alonzi, 19 Feb 2009.

• Nab proposal update and funding request, 27 Jan 2010.

• Internal documents for use by collaborators.

Dinko Počanić, 29 Jul 2005.
Last updated: 25 Mar 2011.