First direct mass measurement of the two-neutron halo nucleus He6 and improved mass for the four-neutron halo He8

The first direct mass measurement of He6 has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of He8 was determined with improved precision over our previous measurement. The obtained masses are m(He6)=6.018885883(57)u and m(He8)=8.03393444(11)u. The He6 value shows a deviation from the literature of 4σ. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16)fm for He6 and He8, respectively. We present a detailed comparison to nuclear theory for He6, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces. © 2012 American Physical Society.

Duke Scholars

Author Jens Dilling Physics