HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. X-ray energies of circular transitions and electrons screening in kaonic atoms J.P. Santos, F. Parente, Paul Indelicato, S. Boucard, J.P. Desclaux

A set of 14 high-accuracy x-ray transition energies in the 2.4-3.1 keV range is presented, which can be used as x-ray standards. They were measured in two-to four-electron sulfur, chlorine, and argon ions produced in an electron-cyclotron resonance ion source, using a single spherically bent crystal spectrometer. The results include the first measurement of six transitions and improve the accuracy of six other experimental values. These measurements considerably extend the set of high-accuracy x-ray energies reported for highly charged ions. Their relative uncertainties range from 1 to 10 ppm. Theory only reaches such a precision in one-and two-electron ions. Our results thus have two distinct applications. On the one hand, they test predictions in two-electron ions [Artemyev, Shabaev, Yerokhin, Plunien, and Soff, Phys. Rev. A 71, 062104 (2005)], at the precision level of some two-photon QED contributions. We observe an agreement with theory for most of the transitions. On the other hand, the three-and four-electron ion transitions provide new benchmark energies for the calculation of missing theoretical contributions, such as Auger shifts or electronic correlations. Spectra were analyzed with an x-ray tracing simulation that contains all the relevant physics of the spectrometer.

The experimental and spectrum analysis procedures that led to about 15 new, high-precision, relative x-ray line energy measurements are presented. The measured lines may be used as x-ray reference lines in the 2.4-3.1 keV range. Applications also include tests of the atomic theory, and in particular of quantum electrodynamics and of relativistic many-body theory calculations. The lines originate from 2- to 4-electron ions of sulfur (Z = 16), chlorine (Z = 17) and argon (Z = 18). The precision reached for their energy ranges from a few parts per million (ppm) to about 50 ppm. This places the new measurements among the most precise performed in mid-Z highly charged ions (Z is the nuclear charge number). The elements of the experimental setup are described: the ion source (an electron cyclotron resonance ion trap), the spectrometer (a single, spherically bent crystal spectrometer), as well as the spectrum acquisition camera (low-noise, high-efficiency CCD). The spectrum analysis procedure, which is based on a full simulation of the spectrometer response function, is also presented.

We demonstrate how combining highly-charged ions and exotic atoms measurements can provide high-accuracy information on particle properties, like the pion mass, on interactions, like the pion-proton strong interaction at low energy, and bound-state QED in strong fields. The use of highly-charged ion X-rays emitted by the plasma inside a super-conducting ion source provides a very detailed characterization of the response function of the X-ray spectrometer used to study exotic atoms, allowing for very accurate measurements. Conversely the use of the same high-resolution and high transmission spectrometer provides very accurate measurements of X-ray lines of few-electron ions.

Radiation from the highly charged ions contained in the plasma of Electron–Cyclotron Resonance Ion Sources (ECRISs) constitutes a very bright source of X-rays. Because the ions have a relatively low kinetic energy (≈1eV) transitions can be very narrow, containing only a small Doppler broadening. We describe preliminary accurate measurements of two and three-electron ions with Z=16–18. We show how these measurement can test sensitively many-body relativistic calculations or can be used as X-ray standards for precise measurements of X-ray transitions in exotic atoms.

We present a new measurement on X-ray spectroscopy of multicharged argon, chlorine and sulfur obtained with the Electron Cyclotron Resonance Ion Trap installed at the Paul Scherrer Institut (Villigen, Switzerland). For this purpose, we used a crystal spectrometer with a spherically bent crystal having an energy resolution of about 0.4 eV. High intensity Kα X-ray spectra were obtained from ions with one 1s hole ranging from almost neutral to heliumlike charge states. In particular we observed the 1s2s 3 S1 → 1s 21 S0 M1 and 1s2p 3 P2 → 1s 21 S0 M2 transitions in He-like argon, chlorine and sulfur with unprecedented statistics and resolution. The preliminary analysis presented here describes a new technique to measure precisely energy differences between transitions using a Johann-type Bragg spectrometer. A recent characterization of the spectrometer will allow for a drastic reduction of the systematic errors.

. In this paper we review the different relativistic and QED contributions to energies, ionic radii, transition probabilities and Landé g-factors in super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method (MCDF). The effects of taking into account the Breit interaction to all orders by including it in the self-consistent field process are demonstrated. State of the art radiative corrections are included in the calculation and discussed. We also study the non-relativistic limit of MCDF calculation and find that the non-relativistic offset can be unexpectedly large.

Energies of the circular (n, ℓ = n − 1) 1 ⩽ n ⩽ 20 levels have been calculated for hydrogenlike sigmonic atoms with 1 ⩽ Z ⩽ 92, using the current world average sigma mass, as well as the electronic shift in Σ− + Ne e− + nucleus systems, where Ne stands for the number of electrons. The electronic influence on sigmonic orbitals has also been investigated through the computation of the hyperfine structure and the anomalous Σ− magnetic moment effects in sigmonic Be 2p states.

We present new results on the X‐ray spectroscopy of multicharged argon, sulfur and chlorine obtained with the Electron Cyclotron Resonance Ion Trap (ECRIT) in operation at the Paul Scherrer Institut (Villigen, Switzerland). We used a Johann‐type Bragg spectrometer with a spherically‐bent crystal, with an energy resolution of about 0.4 eV. The ECRIT itself is of a hybrid type, with a superconducting split coil magnet, special iron inserts which provides the mirror field, and a permanent magnetic hexapole. The high frequency was provided by a 6.4 GHz microwave emitter.We obtained high intensity X‐ray spectra of multicharged F‐like to He‐like argon, sulfur and chlorine with one 1s hole. In particular, we observed the 1s2s 3S1 → 1s2 1S0 M1 and 1s2p 3P2 → 1s2 1S0 M2 transitions in He‐like argon, sulfur and chlorine with unprecedented statistics and resolution. The energies of the observed lines are being determined with good accuracy using the He‐like M1 line as a reference.We surveyed the He‐like M1 transitio...

The QED contribution to the energies of the circular (n,l=n-1), 2 <= n <= 13, transitions have been calculated for several kaonic atoms throughout the periodic table, using the current world-average kaon mass. Calculations were done in the framework of the Klein-Gordon equation, with finite nuclear size, finite particle size, and all-order Uelhing vacuum polarization corrections, as well as Kallen and Sabry and Wichmann and Kroll corrections. These energy level values are compared with other computed values. The circular transition energies are compared with available measured and theoretical transition energies. Electron screening is evaluated using a Dirac-Fock model for the electronic part of the wave function. The effect of electronic wave-function correlation is evaluated.

Energies of the [(n,ℓ=n−1),1≤n≤20] and the [(n,ℓ=n−2),2≤n≤20] levels have been calculated for several hydrogenlike kaonic atoms throughout the periodic table, using the current world average kaon mass. Calculations were done in the framework of the Klein–Gordon equation, with finite nuclear size and all-order vacuum polarization corrections.

The hyperfine splitting of the ground state of three-electron ions is studied in detail with the help of the multi-configuration Dirac-Fock method. We study the role of the magnetic electron-electron interaction and of the negative energy continuum. An all-order evaluation of some vacuum polarization corrections is performed. The Bohr-Weisskopf effect is evaluated in a simple model.

Structure and QED effects for \(\) and \(\) levels are calculated for lithiumlike U89+ trough neonlike U82+, lithiumlike Th87+ trough neonlike Th80+ and lithiumlike Bi80+ trough neonlike Bi73+. The results of the first two sets are compared with recent measurements of the \(\)transition energy in 3 to 10-electron ions. Good agreement with experiment is found for most of the observed lines. Forty-one possible transitions are calculated for each ion in the eight ionization states, in the experimental energy range. Twenty-eight of these transitions have not been observed, nor calculated previously. We also calculate transition rates, branching ratios, excitation and ionization cross sections and confirm that the thirteen experimental o bserved transitions correspond to the ones with highest relative intensities. However, we find nineteen more transitions that could be measured in a more sensitive experiment.

Dans ce memoire, nous presentons des calculs d'energie de transition dans les ions lithiumoides et les atomes exotiques : 1) Les nouvelles sources rendent possible la fabrication d'ions lourds fortement charges. Nous nous sommes interesses a l'etude de la structure hyperfine des ions lithiumoides. Cela nous permet d'examiner les problemes relativistes a plusieurs corps et la partie magnetique des corrections d'Electrodynamique Quantique (QED). Dans les ions lourds, ces dernieres sont de l'ordre de quelques pour-cents par rapport a l'energie totale de la transition hyperfine. Nous avons egalement evalue l'effet de Bohr-Weisskopf lie a la distribution du moment magnetique dans le noyau. Nous avons calcule puis compare ces differentes contributions en incluant les corrections radiatives (polarisation du vide et self-energie) ainsi que l'influence du continuum negatif. 2) Un atome exotique est un atome dans lequel un electron du cortege est remplace par une particule de meme charge : $\mu^(-)$, $\pi^(-)$, $\bar(p)$\ldots Des experiences recentes ont permis de gagner trois ordres de grandeur en precision et en resolution. Nous avons voulu ameliorer la precision des calculs d'energies de transitions necessaires a la calibration et a l'interpretation dans deux cas : la mesure de parametres de l'interaction forte dans l'hydrogene anti-protonique ($\bar(p)$H) et la determination de la masse du pion grâce a l'azote pionique ($\pi$N). Nos calculs prennent en compte la structure hyperfine et le volume de la distribution de charge de la particule. Nous avons ameliore le calcul de la polarisation du vide qui ne peut plus etre traitee au premier ordre de la theorie des perturbations dans le cas des atomes exotiques. Pour les atomes anti-protoniques, nous avons egalement ajoute la correction du g-2. Elle provient du caractere composite de l'anti-proton qui de ce fait possede un rapport gyromagnetique g $\approx$ -5.5856 .

We report on a calculation of K, L and M inner-shell ionization energy in atoms with atomic numbers in the range \(\). Many-body effects are evaluated for all n=1, 2, and 3 hole states. Those include correlation and effects due to the auto-ionizing nature of the hole states (Auger shift). For high Z we add recent corrected nuclear polarization, and several second-order vacuum polarization corrections. K and L ionization energies are compared with experimental X-ray absorption edges measurements. Excellent agreement with rare gazes and metal vapor measurements is found. We also compare our calculations with X-ray transition energies for all K and L lines that involve K, L and M holes. Finally we use K X-ray lines to deduce an hydrogenlike 1s Lamb shift for several heavy elements, with far better accuracy than has been obtained by direct measurements of hydrogenlike ions.

Structure and QED effects for 2s(1/2) and 2p(3/2) levels are calculated for lithiumlike U89+ trough neonlike U82+, lithiumlike Th87+ trough neonlike Th80+ and lithiumlike Bi80+ trough neonlike Bi73+ The results of the first two sets are compared with recent measurements of the 2s(1/2) - 2p(3/2) transition energy in 3 to 10-electron ions. Good agreement with experiment is found for most of the observed lines. Forty-one possible transitions are calculated for each ion in the eight ionization states, in the experimental energy range. Twenty-eight of these transitions have not been observed, nor calculated previously. We also calculate transition rates, branching ratios, excitation and ionization cross sections and confirm that the thirteen experimental observed transitions correspond to the ones with highest relative intensities. However, we find nineteen more transitions that could be measured in a more sensitive experiment.

We review the status of Quantum-Electrodynamic (QED) calculations in a number of exotic hydrogen atoms. These calculations are necessary to extract from spectroscopic measurements nuclei properties like charge radius or strong interaction shifts. Different theoretical results concerning antiprotonic, pionic and muonic atoms are compared to experiments. The limitation in precision of the calculations are emphasized.