0000000000004491
AUTHOR
W. Geithner
Laser spectroscopy of the ground-state hyperfine structure in H-like and Li-like bismuth
The LIBELLE experiment performed at the experimental storage ring (ESR) at the GSI Helmholtz Center in Darmstadt aims for the determination of the ground state hyperfine (HFS) transitions and lifetimes in hydrogen-like (209Bi82+) and lithium-like (209Bi80+) bismuth. The study of HFS transitions in highly charged ions enables precision tests of QED in extreme electric and magnetic fields otherwise not attainable in laboratory experiments. While the HFS transition in H-like bismuth was already observed in earlier experiments at the ESR, the LIBELLE experiment succeeded for the first time to measure the HFS transition in Li-like bismuth in a laser spectroscopy experiment.
Nuclear moments of neon isotopes in the range fromNe17at the proton drip line to neutron-richNe25
Nuclear moments of odd-A neon isotopes in the range 17 ≤ A ≤ 25 have been determined from optical hyperfine structures measured by collinear fast-beam laser spectroscopy. The magnetic dipole moments of 17 Ne, 23 Ne and 25 Ne, as well as the electric quadrupole moment of 23 Ne are either reported for the first time or improved considerably. The measurements also decide for a 1/2 + ground state of 25 Ne. The behavior of the magnetic moments of the proton drip-line nucleus 17 Ne and its mirror partner 17 N suggests isospin symmetry. Thus, no clear indication of an anomalous nuclear structure is found for 17 Ne. The magnetic moments of the investigated nuclei are discussed in a shell-model appr…
Lifetimes and g-factors of the HFS states in H-like and Li-like bismuth
The LIBELLE experiment performed at the experimental storage ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany, has successfully determined the ground state hyperfine (HFS) splittings in hydrogen-like ($^{209}\rm{Bi}^{82+}$) and lithium-like ($^{209}\rm{Bi}^{80+}$) bismuth. The study of HFS transitions in highly charged ions enables precision tests of QED in extreme electric and magnetic fields otherwise not attainable in laboratory experiments. Besides the transition wavelengths the time resolved detection of fluorescence photons following the excitation of the ions by a pulsed laser system also allows to extract lifetimes of the upper HFS levels and g-fac…
Laser spectroscopy measurement of isotope shifts and nuclear moments of short-lived neon isotopes
Within the scope of a laser spectroscopy study of nuclear structure in the sd shell we are measuring nuclear moments and isotope shifts of neon isotopes. An ultra-sensitive variant of collinear laser spectroscopy [1, 2] is applied to a neutralized fast beam from ISOLDE (CERN). The non-optical detection is based on optical pumping, state selective collisional ionization and β-activity counting. This method gives access in particular to the short-lived isotopes in the extended chain of 17–26,28Ne.
An improved value for the hyperfine splitting of hydrogen-like209Bi82+
We report an improved measurement of the hyperfine splitting in hydrogen-like bismuth (209Bi82+) at the experimental storage ring ESR at GSI by laser spectroscopy on a coasting beam. Accuracy was improved by about an order of magnitude compared to the first observation in 1994. The most important improvement is an in situ high voltage measurement at the electron cooler (EC) platform with an accuracy at the 10 ppm level. Furthermore, the space charge effect of the EC current on the ion velocity was determined with two independent techniques that provided consistent results. The result of nm provides an important reference value for experiments testing bound-state quantum electrodynamics in t…
Transient collisionally excited X-ray laser in nickel-like zirconium pumped with the PHELIX laser facility
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium.
Hyperfine transition in209Bi80+—one step forward
The hyperfine transitions in lithium-like and hydrogen-like bismuth were remeasured by direct laser spectroscopy at the experimental storage ring. For this we have now employed a voltage divider which enabled us to monitor the electron cooler voltage in situ. This will improve the experimental accuracy by about one order of magnitude with respect to our previous measurement using the same technique.
Nuclear spin and moments of 73Kr and odd—even staggering in the radii of light krypton isotopes
Nuclear spectroscopy measurements in the region of neutron-deficient krypton isotopes have indicated that pronounced shape changes and instabilities occur when the nuclei approach the N = Z line. This is confirmed by isotope shift measurements on krypton [1] yielding an increasing inverted odd—even staggering of the radii [2] from 82Kr (N = 46) to 74Kr (N = 38). We have now completed the published data by measuring the hyperfine structure and isotope shift of 73Kr. This is also interesting in context with a recent β-decay study [3]. The feeding of excited states in 73Br gave strong arguments for the ground-state spin and parity of 73Kr to be 3/2−, in contrast to the adopted assignment of 5/…
Defect reactions of implanted Li in ZnSe observed by β-NMR
Abstract Using β-radiation detected nuclear magnetic resonance (β-NMR), we investigated the microscopic behavior of implanted 8 Li in nominally undoped ZnSe crystals. From the temperature-dependent amplitudes of high-resolution NMR spectra we conclude a gradual interstitial-to-substitutional site change between 200 and 350 K . This is in accordance with earlier emission channeling results. We argue that this conversion proceeds via Lii++VZn2−→LiZn− and involves implantation related Zn vacancies.
Quadrupole moments of odd-A 53−63Mn: Onset of collectivity towards N=40
Physics letters / B 760, 387 - 392 (2016). doi:10.1016/j.physletb.2016.07.016
Changes in nuclear structure along the Mn isotopic chain studied via charge radii
The hyperfine spectra of $^{51,53-64}$Mn were measured in two experimental runs using collinear laser spectroscopy at ISOLDE, CERN. Laser spectroscopy was performed on the atomic $3d^5\ 4s^2\ ^{6}\text{S}_{5/2}\rightarrow 3d^5\ 4s4p\ ^{6}\text{P}_{3/2}$ and ionic $3d^5\ 4s\ ^{5}\text{S}_2 \rightarrow 3d^5\ 4p\ ^{5}\text{P}_3$ transitions, yielding two sets of isotope shifts. The mass and field shift factors for both transitions have been calculated in the multiconfiguration Dirac-Fock framework and were combined with a King plot analysis in order to obtain a consistent set of mean-square charge radii which, together with earlier work on neutron-deficient Mn, allow the study of nuclear struc…
Nuclear moments and charge radii of argon isotopes between the neutron-shell closures and
We report the measurement of optical isotope shifts for 40−44 Ar relative to 38 Ar from which changes in the mean square nuclear charge radii across the 1f7/2 neutron shell are deduced. In addition, the hyperfine structure of 41 Ar and 43 Ar yields the spins, magnetic dipole and electric quadrupole moments, in particular the spin I = 5/2 for 43 Ar. The investigations were carried out by fast-beam collinear laser spectroscopy using highly sensitive detection based on optical pumping and state-selective collisional ionization. Mean square charge radii are now known from 32 Ar to 46 Ar, covering sd-shell as well as f7/2-shell nuclei. They are discussed in the framework of spherical SGII Skyrme…
High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED
Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron–nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improve…
Charge radii of neon isotopes across the sd neutron shell
We report on the changes in mean square charge radii of unstable neon nuclei relative to the stable Ne-20, based on the measurement of optical isotope shifts. The studies were carried out using collinear laser spectroscopy on a fast beam of neutral neon atoms. High sensitivity on short-lived isotopes was achieved thanks to nonoptical detection based on optical pumping and state-selective collisional ionization, which was complemented by an accurate determination of the beam kinetic energy. The new results provide information on the structural changes in the sequence of neon isotopes all across the neutron sd shell, ranging from the proton drip line nucleus and halo candidate Ne-17 up to the…
Charge radius change in the heavy tin isotopes until A = 132 from laser spectroscopy
Laser spectroscopy measurements have been carried out on the very neutron-rich tin isotopes with the COMPLIS experimental setup. Using the 5s 25p 23P 0 → 5s 25p6s 3P 1 optical transition, hyperfine spectra of 126-132Sn and 125m, 127m, 129m-131mSn where recorded for the first time. The variation of the mean-square charge radius ( δ〈r 2〉) between these nuclei and nuclear moments of the isomers and the odd isotopes were thus measured. An odd-even staggering which inverts at A = 130 is clearly observed. This indicates a small appearance of a plateau on the δ〈r 2〉 which has to be confirmed by measuring the isotope shift beyond A = 132.
Measurement of the Magnetic Moment of the One-Neutron Halo NucleusB11e
The magnetic moment of ${}^{11}\mathrm{Be}$ ( ${T}_{1/2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}13.8\phantom{\rule{0ex}{0ex}}\mathrm{s}$) was measured by detecting nuclear magnetic resonance signals in a beryllium crystal lattice. The experimental technique applied to a ${}^{11}{\mathrm{Be}}^{+}$ ion beam from a laser ion source includes in-beam optical polarization, implantation into a metallic single crystal, and observation of rf resonances in the asymmetric angular distribution of the $\ensuremath{\beta}$ decay ( $\ensuremath{\beta}$-NMR). The nuclear magnetic moment $\ensuremath{\mu}{(}^{11}\mathrm{Be})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}1.6816(8…