Progress Towards a Single Atom Microscope (SAM) for Nuclear Astrophysics

Development of a detector that is efficient, selective and sensitive at the single atom level is necessary for the measurement of low yield nuclear reactions that are relevant for nuclear astrophysics. These low yield reactions may be due to either very low cross- sections or low beam intensity. We are developing the single atom microscope (SAM) technique to study the 22Ne(a, n)25Mg reaction, which is an important source of neutrons for the s-process. The s-process in stars forms approximately half the atomic nuclei heavier than iron through neutron capture. This reaction is challenging to measure as it requires low background and high selectivity to distinguish the products from the unreacted beam. Therefore, as a proof-of-principle measurement, we are aiming to study the 84K(p, y)85Rb reaction first, which plays a role in the photodisintegration process in stars. The SAM technique works by first capturing reaction products in a cryogenically frozen noble gas film and then detecting product atoms by laser induced fluorescence via a CCD camera. We will report on our progress towards demonstrating single atom sensitivity, which is feasible due to the large shift between the excitation and emission wavelengths.