1204.1987 (A. T. Gallant et al.)

New precision mass measurements of neutron-rich calcium and potassium
isotopes and three-nucleon forces    [PDF]

A. T. Gallant, J. C. Bale, T. Brunner, U. Chowdhury, S. Ettenauer, A. Lennarz, D. Robertson, V. V. Simon, A. Chaudhuri, J. D. Holt, A. A. Kwiatkowski, E. Mané, J. Menéndez, B. E. Schultz, M. C. Simon, C. Andreoiu, P. Delheij, M. R. Pearson, H. Savajols, A. Schwenk, J. Dilling

We present precision Penning-trap mass measurements of neutron-rich calcium and potassium isotopes in the vicinity of neutron number N=32. Using the TITAN system the mass of $^{51}$K was measured for the first time, and the precision of the $^{51,52}$Ca mass values were improved significantly. The new mass values show a dramatic increase of the binding energy compared to those reported in the atomic mass evaluation. In particular, $^{52}$Ca is more bound by 1.74 MeV, and the behavior with neutron number deviates substantially from the tabulated values. An increased binding was predicted recently based on calculations that include three-nucleon (3N) forces. We present a comparison to improved calculations, which agree remarkably with the evolution of masses with neutron number, making neutron-rich calcium isotopes an exciting region to probe 3N forces at neutron-rich extremes.

View original: http://arxiv.org/abs/1204.1987