First Penning-trap mass measurement in the millisecond half-life range: the exotic halo nucleus 11Li

In this letter, we report a new mass for $^{11}$Li using the trapping experiment TITAN at TRIUMF's ISAC facility. This is by far the shortest-lived nuclide, $t_{1/2} = 8.8 \rm{ms}$, for which a mass measurement has ever been performed with a Penning trap. Combined with our mass measurements of $^{8,9}$Li we derive a new two-neutron separation energy of 369.15(65) keV: a factor of seven more precise than the best previous value. This new value is a critical ingredient for the determination of the halo charge radius from isotope-shift measurements. We also report results from state-of-the-art atomic-physics calculations using the new mass and extract a new charge radius for $^{11}$Li. This result is a remarkable confluence of nuclear and atomic physics.Comment: Formatted for submission to PR

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

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.Comment: 4 pages, 2 figure

TITAN project status report and a proposal for a new cooling method of highly charged ions

The TITAN facility for precision mass measurements of short-lived isotopes is currently being constructed at the ISAC radioactive beam facility at TRIUMF, Vancouver, Canada. Current status and developments in the project are reported. A new method for cooling of highly charged ions (HCI) with singly charged ions in a Penning trap, critically needed for precision measurements, is presented. Estimates show that the technique is promising and can be applied to cooling of highly charged short-lived isotope ions without recombination losses

Precision mass measurements of neutron halo nuclei using the TITAN Penning trap

International audiencePrecise atomic mass determinations play a key role in various fields of physics, including nuclear physics, testing of fundamental symmetries and constants and atomic physics. Recently, the TITAN Penning trap measured the masses of several neutron halos. These exotic systems have an extended, diluted, matter distribution that can be modelled by considering a nuclear core surrounded by a halo formed by one or more of loosely bound neutrons. Combined with laser spectroscopy measurements of isotopic shifts precise masses can be used to obtain reliable charge radii and two-neutron-seperation energies for these halo nuclei. It is shown that these results can be used as stringent tests of nuclear models and potentials providing an important metric for our understanding of the interactions in all nuclei

Mass measurements on highly charged radioactive ions, a new approach to high precision with TITAN

TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) is a system of multiple ion traps installed at the radioactive ion beam facility ISAC. The uniqueness of the system lies in the combination of different kinds of ion traps nowhere else available, and the coupling of this system to ISAC as a source of the most intense radioactive beams of very exotic nuclei worldwide. ISAC is now been operational for more than 5 years, and has been proven to be able to deliver a broad variety of radioactive species with unsurpassed production yields, making it the facility of choice for a next generation ion trap facility, like TITAN. The physics goals of TITAN are manifold, but the emphasis lies on the test of the Standard Model via the determination of the Vud CKM matrix element, nuclear structure and halo-nuclei investigations, and nuclear astrophysics by providing precise and accurate mass measurements