Direct mass measurements of A=80 isobars
S. Issmer1 - M. Fruneau2 - J.A. Pinston2 - M. Asghar2 - D. Barnéoud2 - J. Genevey2 - Th. Kerscher1 - K.E.G. Löbner1
1 Sektion Physik, Universität München, D-85748 Garching, Germany
2 Institut des Sciences Nucléaires, Université Joseph Fourier, CNRS-IN2P3, F-38026 Grenoble Cedex, France
Received: 22 Juli 1997 / Revised version: 3 February 1998 Communicated by P. Armbruster
Direct mass measurements of A=80 isobars were performed using the second cyclotron of SARA (Système Accélérateur Rhône-Alpes) of the ISN (Institut des Sciences Nucléaires) in Grenoble as a time-of-flight mass spectrometer. Using the 300 MeV Ni +Al reaction, the isobars Rb, Sr, Y, and Zr (only one event!) were measured. For Y we found a mass value of 79.934320(180) u, corresponding to a decay energy Q (Y Sr) of keV. Comparing this value to the former experiments of Lister et al. and Della Negra et al. results in a difference of about 2.2 MeV. However, it does agree with the recommended value of Audi and Wapstra, which is derived from systematic trends. For Zr the single event was identified with a probability of 0.999975 and a mass value of 79.940400(1600) u could be deduced from our experiment.