First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap

Abstract

Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed β emitter 74Rb (T(1/2)=65 ms). The determination of its atomic mass and an improved Q(EC) value are presented.

The advanced trapping facility MATS at FAIR

“…It is important to note that all the masses Table 1 Relative mass uncertainty for short-lived isotopes measured with Penning-traps: 11 Li, 12 Be, 44 S, and 74 Rb, with the excitation times, and the production rates at different facilities including FAIR. The nuclide 74 Rb has been also measured recently at TITAN with ım/m = 8.7 × 10 −8 [38]. The production rate for 78 Ni and 100 Sn are indicated as possible candidates to be only measured at FAIR.…”

“…According to Eq. (2), decreasing T RF can be compensated by increasing the charge state of the ions, recently demonstrated [38,39]. Besides the measurement time, one has to take also into account the losses during the preparation of the ions due to radioactive decays and the efficiency of the apparatus.…”

“…After approval of the TDR, other important breakthroughs for MATS have been achieved by performing experiments to provide highly charged ions of short-lived nuclei for the first time [38,39], and by the successful demonstration of the MR-TOF-MS system [30,31].…”

Toward precision mass measurements of neutron-rich nuclei relevant to r-process nucleosynthesis

“…The first measurement with highly charged states was recently performed at TITAN on a neutrondeficient 74 Rb isotope (T 1/2 = 65 ms) [38], where Rb isotopes were successfully charge-bred in an electron beam ion trap to q = 8 − 12…”

Experiments with Highly-Ionized Atoms in Unitary Penning Traps

“…Some of the techniques were honed by generations of experiments studying trapped antiprotons [39], positrons [40] and antihydrogen (see [41] and the references therein). A high-field Penning trap at the TRIUMF TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) facility in Canada has been used recently to capture short-lived nuclides [42]; examples include experiments at the Max-Planck-Institut für Kernphysik (MPI-K) to capture highly-charged ions using Penning traps built with meter-long electrode structures and multi-tesla solenoid magnets [43,44].…”