Determination of the Ge-76 double beta decay Q value

The Q value of the Ge-76 double beta decay has been determined by measuring the masses of Ge-76 and Se-76 in a Penning trap using neon- and fluorineli ke ions. The obtained masses are 75.921 402 758(96) u and 75.919213795(81) u, respectively. The systematic errors of these two determinations are near ly equal, and therefore, the remaining systematic uncertainty of the D valu e is drastically reduced. A Q value of 2039.006(50) keV was obtained improv ing the accuracy of the accepted value by a factor of 6.