J W Klimes

We have built and operated a cryogenic Penning trap arrangement that allows for the efficient production, selection, and long-term storage of highly charged atomic ions. In close similarity to an electron-beam ion trap (EBIT) it works by electron-impact ionisation of atoms inside a dedicated confinement region. The electrons are produced by field emission at liquid-helium temperature and are subsequently accelerated to the keV energy range. The electron beam is reflected through the trap multiple times to increase the ionisation efficiency. We show a characterisation of the system and measurements with argon and tungsten ions up to Ar$^{16+}$ and W$^{27+}$, respectively.

The electroweak interaction in the Standard Model (SM) is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this work, we present the most precise measurement of tensor currents in the low-energy regime by examining the $β$-$\barν$ correlation of trapped $^{8}$Li ions with the Beta-decay Paul Trap. We find $a_{βν} = -0.3325 \pm 0.0013_{stat} \pm 0.0019_{syst}$ at $1σ$ for the case of coupling to right-handed neutrinos $(C_T=-C_T')$, which is consistent with the SM prediction.