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(α, 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 particular reaction is challenging to measure as it requires low background and high selectivity to distinguish the products from the intense unreacted beam. Therefore, as a proof-of-principle measurement, we are aiming to study the ⁸⁴Kr(p, γ)⁸⁵Rb reaction first, which plays a role in the p-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. This work is supported by U.S. National Science Foundation under grant number #1654610 and is based upon wok supported by the Department of Energy National Nuclear Security Administration through the Nuclear Science and Security Consortium under Award Number DE-NA0003996.