Nuclear charge radius of $^8$He

P. Mueller (1) , I.A. Sulai (1, 2) , A.C.C. Villari (3) , J.A. Alcantara-Nunez (3) , R. Alves Condé (3) , K. Bailey (1) , G.W.F. Drake (4) , M. Dubois (3) , C. Eléon (3) , G. Gaubert (3) , R. J. Holt (1) , R. V. F. Janssens (1) , N. Lecesne (3) , Z.T. Lu (1, 2) , T.P. O'Connor (1) , M.G. Saint-Laurent (3) , J.C. Thomas (3) , L.B. Wang (5)

1 Physics Division, Argonne National Laboratory
2 Department of Physics and Enrico Fermi Institute
3 GANIL - Grand Accélérateur National d'Ions Lourds
4 Physics Department
5 LANL - Los Alamos National Laboratory

The root-mean-square (rms) nuclear charge radius of ^8He, the most neutron-rich of all particle-stable nuclei, has been determined for the first time to be 1.93(3) fm. In addition, the rms charge radius of ^6He was measured to be 2.068(11) fm, in excellent agreement with a previous result. The significant reduction in charge radius from ^6He to ^8He is an indication of the change in the correlations of the excess neutrons and is consistent with the ^8He neutron halo structure. The experiment was based on laser spectroscopy of individual helium atoms cooled and confined in a magneto-optical trap. Charge radii were extracted from the measured isotope shifts with the help of precision atomic theory calculations.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

P. Mueller, I.A. Sulai, A.C.C. Villari, J.A. Alcantara-Nunez, R. Alves Condé, et al.. Nuclear charge radius of $^8$He. Physical Review Letters, 2007, 99, pp.252501. ⟨10.1103/PhysRevLett.99.252501⟩. ⟨in2p3-00202461⟩