Half-life measurement for the rp-process waiting point nuclide Zr-80

X-ray bursts have been suggested as a possible site for the astrophysical r p-process. The time scale for the process is governed by beta-decay half-li ves of several even-even N = Z waiting point nuclei, in particular, N = Z = 40 Zr-80. A 4.1((+0.8)(-0.6))-s beta(+)/EC half-life for Zr-80 was determi ned by observing delayed 84-keV gamma rays depopulating a T-1/2 = 4-mu s is omer at 312 keV in the laughter Y-80. As this half-life is lower than many previously predicted values, the calculated excessive production of A = 80 nuclides in astrophysical x-ray burst scenarios is reduced, and less extrem e conditions are necessary for the production of heavier nuclides.