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

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 (1) , A. Schwenk , J. Dilling

1 GANIL - Grand Accélérateur National d'Ions Lourds

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.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

A. T. Gallant, J.C. Bale, T. Brunner, U. Chowdhury, S. Ettenauer, et al.. New precision mass measurements of neutron-rich calcium and potassium isotopes and three-nucleon forces. Physical Review Letters, 2012, 109, pp.032506. ⟨10.1103/PhysRevLett.109.032506⟩. ⟨in2p3-00686713⟩