Progress Towards a Single Atom Microscope for Nuclear Astrophysics

We are developing the technique of optically detecting individual atoms embedded in thin films of cryogenically frozen solids. Noble gas solids such as frozen neon or kypton are an attractive medium because they are optically transparent and provide efficient, pure, stable, & chemically inert confinement for a wide variety of atomic and molecular species. The excitation and emission spectra of atoms embedded in solids can be separated by up to hundreds of nanometers making optical single atom detection feasible. We propose to couple a single atom microscope (SAM) detector to an electromagnetic recoil separator with the goal of measuring rare nuclear reactions relevant for nuclear astrophysics. The electromagnetic recoil separator would minimize the heat load on SAM while allowing for isotope discrimination. This technique has the potential to capture and detect every product atom with near unity efficiency. Because of the additional selectivity provided by resonantly exciting the atomic transitions of the captured product atom, SAM would have a negligible false positive rate which would help loosen the often demanding beam rejection requirements imposed on electromagnetic recoil separators. Our current goal is to calibrate the brighness of Rb atoms in solid Kr. We will describe the SAM concept in more detail, summarize our findings regarding the growth of transparent noble gas films, and our current efforts towards spectroscopy of Rb in solid Kr. This work is supported by the U.S. National Science Foundation under grant number #1654610.