Mass measurements of very neutron-deficient Mo and Tc isotopes and their impact on rp process nucleosynthesis

Phys Rev Lett. 2011 Mar 25;106(12):122501. doi: 10.1103/PhysRevLett.106.122501. Epub 2011 Mar 21.

Abstract

The masses of ten proton-rich nuclides, including the N=Z+1 nuclides ⁸⁵Mo and ⁸⁷Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical x-ray bursts. Surprisingly low α separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process.