Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion

Abstract

A special ion trap was initially built up to perform β-ν correlation experiments with radioactive ions. The trap geometry is also well suited to perform experiments with laser-cooled ions, serving for the development of a new type of Penning trap, in the framework of the project TRAPSENSOR at the University of Granada. The goal of this project is to use a single (40)Ca(+) ion as detector for single-ion mass spectrometry. Within this project and without any modification to the initial electrode configuration, it was possible to perform Doppler cooling on (40)Ca(+) ions, starting from large clouds and reaching single ion sensitivity. This new feature of the trap might be important also for other experiments with ions produced at radioactive ion beam facilities. In this publication, the trap and the laser system will be described, together with their performance with respect to laser cooling applied to large ion clouds down to a single ion.

A Single-Ion Reservoir as a High-Sensitive Sensor of Electric Signals

“…The experiments have been carried out using the open-ring Paul trap described in ref. 22 , but now driving the trapping field with a radiofrequency ω RF = 2 π × 1.47 MHz and applying a compensation DC voltage ( U DC ) to some of the trap electrodes. The 40 Ca + ion is created by photoionization at a background pressure of ≈10 −10 mbar.…”

The TRAPSENSOR facility: an open-ring 7 tesla Penning trap for laser-based precision experiments

“…This geometry (figure 5) has never been used before in a Penning trap configuration. It was used previously in [21], introducing this trap for laser cooling experiments. The device was similar to the one built at GANIL (LPCTRAP) [46] for β-ν correlation experiments [47,48] and in both cases operated as a Paul trap.…”

“…The width of the Lorentzian distribution is fixed to the cooling transition's width (see table 5). The temperature of the cooled ion cloud (T) is obtained from the width of the Gaussian distribution n D ( ) G (in turn from the Voigt fit) using the equation [21,49]…”

“…Besides the on-going developments of a variant of the induced-image current technique for SHEs [5,18], a novel method for mass spectrometry was proposed based on the use of a single laser-cooled 40 Ca + ion as detector [19], following a scheme based on two traps described earlier [20]. In the first ever attempt to experimentally realize this concept, the sensitivity of a single 40 Ca + ion laser-cooled to the Doppler limit (T 1 limit mK) has been characterized by studying its axial motion in an open-ring Paul trap [21,22]. The analytical method and a first approach of using just one trap to store the ion of interest and the laser-cooled ion simultaneously has been recently presented [23], following a former idea described in [24].…”

“…The analytical method and a first approach of using just one trap to store the ion of interest and the laser-cooled ion simultaneously has been recently presented [23], following a former idea described in [24]. Such scheme might allow identifying SHEs elements, after thermalization, transport and capture in a Penning trap with open-ring geometry [21], through the fluorescence photons emitted by the 40 Ca + ion. The identification relies on the determination of motional frequencies, limiting the relative mass uncertainty δm/m in the ion of interest to how precisely one can determine those frequencies from the fluorescence photons.…”