Figure 1
Credit: (Top) NASA/Dana Berry; (Bottom) Carin Cain

Figure 1: (Top) Artist’s conception of an accreting neutron star in a binary system. Highly unstable, proton-rich isotopes are produced in x-ray bursts from the star via the so-called rp process. These unstable isotopes subsequently decay to more stable isotopes and could be the source of some of the rare isotopes on Earth. (Bottom) Possible rp process in the region of the nuclear chart where the SHIPTRAP group performed its measurements. The balance between proton radiative capture (p,γ)—where energy is released—and photodissociation (γ,p)—where energy is absorbed and a proton emitted—that create and destroy technetium-87, respectively, is highly sensitive to the nuclear masses involved. SHIPTRAP’s newly measured masses of technetium-87 and molybdenum-86, in particular, show that photodissociation is relatively strong enough to impede the flow of the reaction “upwards” and strengthen the beta decay branch into A=86 nuclei.