Volume 82, Number 9                         Physical Review Letters                                                  1999

    Precise Atomic Mass Values near 132Sn: The Resolution of a Puzzle

    B. Fogelberg1, K. A. Mezilev2, H. Mach1, V. I. Isakov2, and J. Slivova3
1 Department of Neutron Research, Uppsala University, S-62182 Nykoping, Sweden
2St. Petersburg Nuclear Physics Institute, 188350 Gatchina, Russia
3Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 18000 Prague 8, Czech Republic
(Received 29 October 1998)

The total Qβ-decay energies of 14 nuclides in the vicinity of 132Sn have been measured using high resolution spectroscopic methods. The present results derived for the atomic masses in this region are significantly more precise than the previously accepted values, and differ significantly from these in some cases. The precision of the new mass values surpasses that expected from the systems currently proposed for direct mass measurements of nuclei far from stability. The present results resolve a recently observed and highly puzzling discrepancy between    the experimental mass values in the 132Sn region and theoretical systematics.

                    PACS numbers: 21.10.Dr. 21.60.Cs, 23.20.Lv, 27.60.+j