the Fundamental Neutron Physics Beam Line at SNS

FNPB user Elise Martin

Users conduct experiments on the most basic of physics questions at the SNS Fundamental Neutron Physics Beam Line.

FNPB exploits the special characteristics of a pulsed spallation source to study the detailed nature of the interactions of elementary particles. Of particular interest is the study of fundamental symmetries such as parity and time reversal invariance and the manner in which they are violated in elementary particle interactions.

Experiments conducted on this beam line address important questions in nuclear and particle physics, as well as astrophysics and cosmology. These experiments include precise measurements of the parameters describing neutron beta decay, studies of the quark-quark weak interaction, and the search for a neutron electric dipole moment.


The FNPB is designed to address questions of interest in cosmology, nuclear and particle physics, and astrophysics. Among the questions that will be addressed are the origin of the light elements (big bang nuclear synthesis), the source of the cosmic matter-antimatter asymmetry, and the origin of parity violation.

For more information about research that can be conducted on FNPB, see Capabilities.

FNPB is funded and operated by the Oak Ridge National Laboratory Physics Division.