Search results for "Hyperfine structure"
showing 10 items of 423 documents
Determination of accurate rest frequencies and hyperfine structure parameters of cyanobutadiyne, HC5N
2020
Very accurate transition frequencies of HC$_5$N were determined between 5.3 and 21.4 GHz with a Fourier transform microwave spectrometer. The molecules were generated by passing a mixture of HC$_3$N and C$_2$H$_2$ highly diluted in neon through a discharge valve followed by supersonic expansion into the Fabry-Perot cavity of the spectrometer. The accuracies of the data permitted us to improve the experimental $^{14}$N nuclear quadrupole coupling parameter considerably and the first experimental determination of the $^{14}$N nuclear spin-rotation parameter. The transition frequencies are also well suited to determine in astronomical observations the local speed of rest velocities in molecula…
Physics at CERN's Antiproton Decelerator
2013
The Antiproton Decelerator of CERN began operation in 1999 to serve experiments for studies of CPT invariance by precision laser and microwave spectroscopy of antihydrogen ($\bar{\rm H}$) and antiprotonic helium ($\bar{p}{\rm He}^+$). The first 12 years of operation saw cold $\bar{\rm H}$ synthesized by overlapping clouds of positrons ($e^+$) and antiprotons ($\bar{p}$) confined in magnetic Penning traps. Cold $\bar{\rm H}$ was also produced in collisions between Rydberg positronium atoms and $\bar{p}$. Ground-state $\bar{\rm H}$ was later trapped for up to $\sim 1000$ s in a magnetic bottle trap, and microwave transitions excited between its hyperfine levels. In the $\bar{p}{\rm He}^+$ ato…
Nuclear moments and laser spectroscopy
1990
Laser spectroscopy measurements have yielded a wealth of new information about the moments and charge radii of unstable isotopes. The procedures of evaluating these moments from the magnetic dipole and electric quadrupole terms of the hyperfine structure arew discussed. Examples are presented, with emphasis on the isotopic chains of odd-proton nuclei, and their essential features are put into the context of current theoretical model descriptions for spherical and deformed nuclei. Finally, new developments of extremely sensitive experimental techniques are discussed with regard to an application to nuclei very far from stability.
How to measure nuclear ground-state properties in simple systems such as 11Li or U91+?
2008
Abstract Atomic spectroscopy yields key information on properties of ground and isomeric states via a determination of the hyperfine structure and isotope shift. In order to deduce precise nuclear moments and charge radii, the electromagnetic fields produced by the electrons at the site of the nucleus must be known with high accuracy. This is presently possible only for simple systems with very few electrons. This contribution describes two scenarios for such experiments: the determination of the charge radius of the neutron-rich isotopes 8,9Li and of the halo nucleus 11Li at the on-line isotope separators at GSI and TRIUMF and the Highly charged Ion TRAP (HITRAP) facility which is under co…
LASER SPECTROSCOPY WITH A COOLER RING AT THE ESR (GSI) AND THE TSR (MPI HEIDELBERG)
1992
At the TSR cooler ring at Heidelberg, laser studies were carried out using singly charged lithium and beryllium ions. Laser spectroscopy of relativistic lithium ions (v=0.04c) yielded signals with a narrow linewidth, suitable for an experimental test of special relativity. A dramatic reduction of the beam temperature, as defined by the longitudinal velocity spread, was achieved via laser cooling in both cases. At the ion energies available at ESR it will become possible to prepare and store bare ions up to U92+. Electron cooling was succesfully demonstrated for hydrogen-like Bi82+ ions, where a laser experiment is scheduled to study the ground-state hyperfine splitting.
The state of iron in andalusite
1990
Iron in andalusite (Al2SiO5) with concentrations of 1.5 … 4.3 wt-% has been reported in the literature to occupy mainly Al1 sites as Fe3+, and only small portions occupy Al2 sites as Fe3+ and Fe2+. In no case a magnetic hyperfine splitting has been found at temperatures above 77 K.
First observation of a resonance ionization signal on242mAm fission isomers
1992
The feasibility of a hyperfine spectroscopy on242mAm fission isomers has been demonstrated at the low target production rate of 10/s. The experimental method employed is based on resonance ionization spectroscopy in a buffer gas cell with detection of the ionization process by means of the fission decay of the isomers. The resonance ionization has been performed in two steps, utilizing an excimer dye laser combination with a repetition rate of 300 Hz. The first resonant step proceeds through theJ=7/2 term at 21440.35 cm−1, which has been excited with the tuncable dye laser beam of a wavelength of 466.28 nm, the second non-resonant step is achieved with the 351 nm radiation of the excimer la…
Isomer separation of Cu and Cu with a resonance ionization laser ion source
2000
Abstract Radioactive copper isotopes were ionized with the resonance ionization laser ion source (RILIS) at the on-line isotope separator ISOLDE (CERN). Using the different hyperfine structure in the 3d10 4s 2 S1/2 – 3d10 4p 2 P01/2 transition the low- and high-spin isomers of 70 Cu were selectively enhanced by tuning the laser wavelength. The light was provided by a narrow-bandwidth dye laser pumped by copper vapor lasers (CVL) and frequency doubled in a BBO crystal. The ground state to isomeric state intensity ratio could be varied by a factor of 30, allowing to assign gamma transitions unambiguously to the decay of the individual isomers. It is shown that the method can also be used to…
Changes in nuclear structure along the Mn isotopic chain studied via charge radii
2016
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…
New developments of the in-source spectroscopy method at RILIS/ISOLDE
2013
At the CERN ISOLDE facility, long isotope chains of many elements are produced by proton-induced reactions in target materials such as uranium carbide. The Resonance Ionization Laser Ion Source (RILIS) is an efficient and selective means of ionizing the reaction products to produce an ion beam of a chosen isotope. Coupling the RILIS with modern ion detection techniques enables highly sensitive studies of nuclear properties (spins, electromagnetic moments and charge radii) along an isotope chain, provided that the isotope shifts and hyperfine structure splitting of the atomic transitions can be resolved. At ISOLDE the campaign to measure the systematics of isotopes in the lead region (Pb, Bi…