First direct mass-measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He

Understand

The first direct mass-measurement of $^{6}$He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility.

• In addition, the mass of $^{8}$He was determined with improved precision over our previous measurement.
• The obtained masses are $m$($^{6}$He) = 6.018 885 883(57) u and $m$($^{8}$He) = 8.033 934 44(11) u.
• The $^{6}$He value shows a deviation from the literature of 4$\sigma$.