The neutron is a unique probe for the investigation of fundamental questions in particle physics and cosmology. With high measurement precision at extremely low energies, neutrons can be used to search for diluted traces of physics that dominated the early Universe, some of them well beyond the reach of accelerators. In the next few years, a boost in the statistical quality of experiments by more than two orders of magnitude is expected, using super-thermal sources of ultra-cold neutrons (UCN) at various facilities. A prominent UCN experiment is the search for the neutron’s electric dipole moment (EDM) using spin-clock comparisons combined with Ramsey’s method of separated oscillatory fields. A non-zero neutron EDM would be a manifestation of yet unknown, broken symmetries above the TeV scale, and, in most theories beyond the standard model, an important ingredient in the explanation of the matter-antimatter asymmetry of the Universe. The reach of this experiment will be compared to other scientific highlights in the field and crazy ideas. One scientific highlight is the demonstration of a gravity-resonance spectroscopy technique, a first step toward a Ramsey-like experiment without electromagnetic interactions. This type of measurement benefits from the absence of an electron shell surrounding the neutron for the investigation of short distances interactions probing both new gravity-like forces, as well as possible spin-matter couplings. An example of the technological developments necessary for these precise measurements is an experimental environment with the smallest magnetic fields on earth. I will also discuss selected recent developments and proposals with potentially large impact as new facilities allowing high statistics experiments become available.

Argonne Physics Division Colloquium Schedule