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.
- 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
- The full text of the Nab Letter of
Intent, submitted to the SNS Program Advisory Committee on 29 July
- 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
Dinko Počanić, 29 Jul 2005.
Last updated: 25 Mar 2011.
This work has been supported by grants from the US National Science