By Jon Cartwright
The Fundamental Neutron Physics Beamline (FNPB) has just become operational at the SNS, which is based at Oak Ridge National Laboratory. Although just one of 25 instruments that will eventually power up at the SNS, the FNBP will not be using neutrons to study other materials. Rather, scientists will use it to perform studies of the neutron itself.
Neutrons are, of course, neutral. But the FNBP will be able to examine whether, for example, the charged quarks inside neutrons give the particle a slight dipole. Such a dipole could help explain why the universe is almost solely made from matter and not antimatter. The FNBP will also look into the decay of free neutrons — which bound in nuclei are normally quite stable — to clarify the distribution of elements shortly after the Big Bang. Finally, the the FNBP will measure the interactions between neutrons and nuclei, hopefully to shed light on so-called symmetry violation — a concept that was first outlined theoretically by Yoichiro Nambu, joint winner of this year’s Nobel Prize for Physics.