0000000000023728
AUTHOR
J. Verdú
The g Factor of Hydrogenic Ions: A Test of Bound State QED
We present a new experimental value for the magnetic moment of the electron bound in hydrogenlike carbon (12C5+): g exp = 2.001 041 596 (5). The experiment was carried out on a single 12C5+ ion stored in a Penning trap. The high accuracy was made possible by spatially separating the induction of spin flips and the analysis of the spin direction. Experiment and theory test the bound-state QED contributions to the gJ factor of a bound electron to a precision of 1%. We discuss also implications of the experiment on the knowledge of the electron mass.
Determination of the g-Factor of Single Hydrogen-Like Ions by Mode Coupling in a Penning Trap
A method has been developed and applied for the determination of the electronic g-factor of single hydrogen-like ions stored in a Penning trap. The method is based on mode coupling of the ion trapping motions and is conceptionally advantageous as compared to previously used methods. It has been applied to hydrogen-like oxygen 16O7+ and yields a value for the gJ-factor which is in agreement with previously determined values. Experimental requirements and possibilities of the new method are discussed.
New determination of the electron's mass.
A new independent value for the electron's mass in units of the atomic mass unit is presented, ${m}_{e}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.0005485799092(4)\mathrm{u}$. The value is obtained from our recent measurement of the $g$ factor of the electron in ${}^{12}{\mathrm{C}}^{5+}$ in combination with the most recent quantum electrodynamical (QED) predictions. In the QED corrections, terms of order ${\ensuremath{\alpha}}^{2}$ were included by a perturbation expansion in $Z\ensuremath{\alpha}$. Our total precision is three times better than that of the accepted value for the electron's mass.
High-accuracy measurement of the magnetic moment anomaly of the electron bound in hydrogenlike carbon.
We present a new experimental value for the magnetic moment of the electron bound in hydrogenlike carbon (12C5+): g(exp) = 2.001 041 596 (5). This is the most precise determination of an atomic g(J) factor so far. The experiment was carried out on a single 12C5+ ion stored in a Penning trap. The high accuracy was made possible by spatially separating the induction of spin flips and the analysis of the spin direction. The current theoretical value amounts to g(th) = 2.001 041 591 (7). Together experiment and theory test the bound-state QED contributions to the g(J) factor of a bound electron to a precision of 1%.
The magnetic moment anomaly of the electron bound in hydrogen-like oxygen16O7
The measurement of the g-factor of the electron bound in a hydrogen-like ion is a high-accuracy test of the theory of quantum electrodynamics (QED) in strong fields. Here we report on the measurement of the g-factor of the bound electron in hydrogen-like oxygen (16O7+). In our experiment a single highly charged ion is stored in a Penning trap. The electronic spin state of the ion is monitored via the continuous Stern?Gerlach effect in a quantum non-demolition measurement. Quantum jumps between the two spin states (spin up and spin down) are induced by a microwave field at the spin precession frequency of the bound electron. The g-factor of the bound electron is obtained by varying the micro…
Phase-sensitive measurement of trapped particle motions
We have developed and applied a novel method for the precise determination of small frequency differences of particle motions inside a Penning trap. In the present case, the frequency differences on the order of 100 mHz at motional frequencies on the order of 1 MHz are used to determine the spin state of an electron bound in a hydrogen-like ion. This novel technique measures the integrated phase difference of the particles' motions relative to an excitation with a well-defined phase. Thereby, the Fourier-limit for frequency measurements based on Fourier-analyses of detection signals can be overcome.
Highly charged ions, quantum-electrodynamics, and the electron mass
Abstract High precision experiments on the magnetic moment of hydrogen-like ions confined in a Penning trap have provided the most stringent test of bound-state quantum-electrodynamic calculations. Experiments have been performed on single C 5+ and O 7+ ions. These experiments are briefly reviewed and prospects for future improvements and extension to other systems are discussed.
Double Penning trap technique for precise g factor determinations in highly charged ions
We present a detailed description of an experiment to determine the magnetic moment of an electron bound in hydrogen-like carbon. This forms a high-accuracy test of bound-state quantum electrodynamics. Special emphasis is given to the discussion of systematic uncertainties which limit our present accuracy. The described experimental setup may also be used for the determination of g factors in other highly charged ions.
HITRAP: A Facility for Experiments with Trapped Highly Charged Ions
HITRAP is a planned ion trap facility for capturing and cooling of highly charged ions produced at GSI in the heavy-ion complex of the UNILAC-SIS accelerators and the ESR storage ring. In this facility heavy highly charged ions up to uranium will be available as bare nuclei, hydrogenlike ions or few-electron systems at low temperatures. The trap for receiving and studying these ions is designed for operation at extremely high vacuum by cooling to cryogenic temperatures. The stored highly charged ions can be investigated in the trap itself or can be extracted from the trap at energies up to about 10 keV/q. The proposed physics experiments are collision studies with highly charged ions at wel…
A Possible New Value for the Electron Mass from g-Factor Measurements on Hydrogen-Like Ions
The mass of the electron in atomic units (m e) represents the largest error contribution in an experiment to determine the g-factor of the electron bound in hydrogen-like carbon. Recent progress in the calculation reduces the uncertainty of the theoretical value to such a low value that m e can be determined from a comparison of experimental and theoretical g-factors. The present preliminary value of the electron mass agrees with the accepted value but reduces the uncertainty by about a factor 2.
Continuous Stern–Gerlach effect and the magnetic moment of the antiproton
Abstract The measurement of the magnetic moment (or g-factor ) of the antiproton and of the proton is a sensitive test of CPT invariance. We discuss the possibility of applying the continuous Stern–Gerlach effect to detect quantum jumps between the two spin states (spin up and spin down) of the antiproton. The measurement will be performed on a single antiproton stored in a Penning trap. The g -factor of the antiproton is determined by measuring its cyclotron frequency and its spin precession frequency in the magnetic field of the trap. With the double Penning trap method the g -factor of the antiproton can be determined with an accuracy of 1 ppb.
Electron and positron cooling of highly charged ions in a cooler Penning trap
Abstract Electron cooling is a well-established technique to increase the phase space density of particle beams in storage rings. In this paper, we discuss the feasibility of electron and positron cooling of ions in a Penning trap. We calculate the cooling times for the cases of trapped bare ions with nuclear charge Z =1 (protons), Z =36 (krypton) and Z =92 (uranium) with the Spitzer formula. Our calculations show that for typical experimental conditions the time for cooling from initial energies of 10 keV per charge down to rest is in the order of a second. We investigate the dependence of the cooling time on the number of ions and electrons, and their charge and mass.
Observation of the Continuous Stern-Gerlach Effect on an Electron Bound in an Atomic Ion
We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus.
The g-factor of the Electron Bound in Hydrogen-like Ions
The experimental determination of the magnetic moment (g-factor) of the electron bound in hydrogen-like ions represents a clean test of Quantum Electrodynamics, because it is not very sensitive to nuclear structure effects. Experimental data on the g-factor of the bound electron are available only for the hydrogen atom and the 4He+-ion. In this paper we present the first result for the g-factor of hydrogen-like carbon (12C5+). The experimental accuracy is high enough to verify the relativistic contribution to the g-factor on the 10-3 level.
Measurement of the g Factor of the Bound Electron in Hydrogen-like Oxygen 16O7+
The measurement of the g factor of the electron bound in a hydrogen-like ion is a high- accuracy test of the theory of Quantum Electrodynamics (QED) in strong fields. Here we report on the measurement of the g factor of the bound electron in hydrogen-like oxygen 16O7+. In our experiment a single 16O7+ ion is stored in a Penning trap. Quantum jumps between the two spin states (spin up and spin down) are induced by a microwave field at the spin precession frequency of the bound electron. The g factor of the bound electron is obtained by varying the microwave frequency and counting the number of spin flips. Our experimental value for the g factor of the bound electron is gexp(16O7+) = 2.000 04…
Precision studies in traps: Measurement of fundamental constants and tests of fundamental theories
Experiments on single atomic particles confined in Penning ion traps have contributed significantly to the improvements of fundamental constants and to tests of the theory of Quantum Electrodynamics for free and bound electrons. The most precise value of the fine structure constant as well as the electron mass have been derived from trap experiments. Numerous atomic masses of interest for fundamental questions have been determined with precisions of 10 � 9 or below. Further progress is envisaged in the near future.
Towards electronic g-factor measurements in medium-heavy hydrogen-like and lithium-like ions
Abstract Measurements of the anomalous magnetic moment of the electron bound in hydrogen-like ions with spinless nuclei have proven to be highly sensitive tests of corresponding calculations based on bound-state quantum electrodynamics. Measurements performed on H-like carbon 12C5+ and oxygen 16O7+ together with bound-state QED calculations on the same level of accuracy have achieved sensitivities around 0.25% of the QED bound state contributions to the calculated electronic g-factors of these ions. Currently, a similar experiment on hydrogen-like calcium 40Ca19+, lithium-like calcium 40Ca17+ and other medium-heavy ions is being prepared, which is capable of increasing this sensitivity on t…
ElectronicgFactor of Hydrogenlike OxygenO7+16
We present an experimental value for the $g$ factor of the electron bound in hydrogenlike oxygen, which is found to be ${g}_{\mathrm{e}\mathrm{x}\mathrm{p}\mathrm{t}}=2.000\text{ }047\text{ }025\text{ }4\text{ }(15)(44)$. The experiment was performed on a single $^{16}\mathrm{O}^{7+}$ ion stored in a Penning trap. For the first time, the expected line shape of the $g$-factor resonance is calculated which is essential for minimizing the systematic uncertainties. The measurement agrees within $1.1\text{ }\ensuremath{\sigma}$ with the predicted theoretical value ${g}_{\mathrm{t}\mathrm{h}\mathrm{e}\mathrm{o}\mathrm{r}\mathrm{y}}=2.000\text{ }047\text{ }020\text{ }2\text{ }(6)$. It represents a…
Determination of the electron’s mass from g -factor experiments on 12 C 5+ and 16 O 7+
Abstract We present a derivation of the electron’s mass from our experiment on the electronic g factor in 12C5+ and 16O7+ together with the most recent quantum electrodynamical predictions. The value obtained from 12C5+ is me=0.0005485799093(3) u, that from oxygen is me=0.0005485799092(5) u. Both values agree with the currently accepted one within 1.5 standard deviations but are four respectively two-and-a-half times more precise. The contributions to the uncertainties of our values and perspectives for the determination of the fine-structure constant α by an experiment on the bound-electron g factor are discussed.