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

Abstract : 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$\sigma$. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) fm and 1.959(16) fm for $^{6}$He and $^{8}$He respectively. We present a detailed comparison to nuclear theory for $^6$He, 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.
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Journal articles
Physical Review Letters, American Physical Society, 2012, 108, pp.052504. <10.1103/PhysRevLett.108.052504>


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Submitted on : Tuesday, February 28, 2012 - 2:00:23 PM
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M. Brodeur, T. Brunner, C. Champagne, S. Ettenauer, M. J. Smith, et al.. First direct mass-measurement of the two-neutron halo nucleus 6He and improved mass for the four-neutron halo 8He. Physical Review Letters, American Physical Society, 2012, 108, pp.052504. <10.1103/PhysRevLett.108.052504>. <in2p3-00674911>

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