Nicholas D. Guise

Experimental efforts at NIST towards one-electron ions in circular Rydberg states

Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

Penning traps with unitary architecture for storage of highly charged ions

Penning traps are made extremely compact by embedding rare-earth permanent magnets in the electrode structure. Axially-oriented NdFeB magnets are used in unitary architectures that couple the electric and magnetic components into an integrated structure. We have constructed a two-magnet Penning trap with radial access to enable the use of laser or atomic beams, as well as the collection of light. An experimental apparatus equipped with ion optics is installed at the NIST electron beam ion trap (EBIT) facility, constrained to fit within 1 meter at the end of a horizontal beamline for transporting highly charged ions. Highly charged ions of neon and argon, extracted with initial energies up to 4000 eV per unit charge, are captured and stored to study the confinement properties of a one-magnet trap and a two-magnet trap. Design considerations and some test results are discussed.

Capture and isolation of highly-charged ions in a unitary Penning trap

(Dated: December 3, 2013)We recently used a compact Penning trap to capture and isolate highly-charged ions extractedfrom an electron beam ion trap (EBIT) at the National Institute of Standards and Technology(NIST). Isolated charge states of highly-stripped argon and neon ions with total charge Q ≥ 10,extracted at energies of up to 4×10

Measurement of the Kr XVIII 3d 2D5/2 lifetime in a unitary Penning Trap

A different technique is used to study the radiative decay of a metastable state in multiply ionized atoms.With use of a unitary Penning trap to selectively capture Kr17+ ions from an ion source at ...

Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

A newly constructed apparatus at the United States National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.

Multiply-ionized atoms isolated at low energy in a unitary Penning trap

Ions extracted from the EBIT at NIST are slowed and captured in a Penning trap that is made very compact (< 150 cm3) by a unitary architecture [1]. Measurements after 1 ms of ion storage indicate that the isolated ions are distributed with 5.5(5) eV of energy spread, which is roughly 2 orders of magnitude lower than expected in the ion source, without implementing any active cooling [2]. Some experiments are discussed. One goal is to produce one-electron ions in high angular momentum states for studying optical transitions between Rydberg states that could potentially enable new tests of quantum electrodynamics (QED) and determinations of fundamental constants [3].

Towards one-electron ions in Rydberg states for laser spectroscopy

Simple quantum systems play important roles in the determination of fundamental constants. Very recently at NIST, bare nuclei created in an EBIT were extracted and captured in a novel compact Penning trap. This is a step towards production of one-electron ions isolated in an ion trap designed to facilitate recombination experiments and laser spectroscopy. Our goal is to form Rydberg states that can be probed accurately using optical frequency metrology, which could provide a new determination of the Rydberg constant that is independent of the proton radius.