共查询到20条相似文献,搜索用时 296 毫秒
1.
Rodolfo Sánchez Wilfried Nörtershäuser Andreas Dax Guido Ewald Stefan Götte Reinhard Kirchner H.-Jürgen Kluge Thomas Kühl Agnieszka Wojtaszek Bruce A. Bushaw Gordon W. F. Drake Zong-Chao Yan Claus Zimmermann Daniel Albers John Behr Pierre Bricault Jens Dilling Marik Dombsky Jens Lassen C. D. Phil Levy Matthew R. Pearson Erika J. Prime Vladimir Ryjkov 《Hyperfine Interactions》2006,171(1-3):181-188
We have determined the nuclear charge radius of 11Li by high-precision laser spectroscopy. The experiment was performed at the TRIUMF-ISAC facility where the 7Li-11Li isotope shift (IS) was measured in the 2s→3s electronic transition using Doppler-free two-photon spectroscopy with a relative accuracy better than 10−5. The accuracy for the IS of the other lithium isotopes was also improved. IS’s are mainly caused by differences in nuclear
mass, but changes in proton distribution also give small contributions. Comparing experimentally measured IS with advanced
atomic calculation of purely mass-based shifts, including QED and relativistic effects, allows derivation of the nuclear charge
radii. The radii are found to decrease monotonically from 6Li to 9Li, and then increase with 11Li about 11% larger than 9Li. These results are a benchmark for the open question as to whether nuclear core excitation by halo neutrons is necessary
to explain the large nuclear matter radius of 11Li; thus, the results are compared with a number of nuclear structure models. 相似文献
2.
V. S. Pokatilov 《Physics of the Solid State》2007,49(12):2217-2222
Amorphous and microcrystalline Fe-B alloys (4–25 at % B) obtained by rapid quenching of the melt were studied using the pulsed nuclear magnetic resonance (NMR) of 11B nuclei at 4.2 K. Alloy samples were prepared from both a natural isotope mixture and a mixture of the 56Fe and 11B isotopes. The NMR spectra were measured as a function of the boron content. The maximum hyperfine fields at the 11B nuclei sites are 25–29 kOe and overlap the values of the hyperfine fields at the 11B nuclei sites in the tetragonal and orthorhombic Fe3B phases and also in the α-Fe phase containing boron as a substitutional impurity. The short-range order and local atomic structure of the amorphous Fe-B alloys were determined. The amorphous alloys are found to consist of microregions (clusters) with a short-range order similar to that in the tetragonal or orthorhombic Fe3B phase or the α-Fe phase. 相似文献
3.
We present a comprehensive analysis of the structure of Hamiltonian matrices based on visualization of the matrices in three
dimensions as well as in terms of measures for GOE, banded and two-body random matrix ensembles (TBRE). We have considered
two nuclear shell model examples, 22Na with Jp T = 2+0\ensuremath J^{\pi} T = 2^+0 and 24Mg with Jp T = 0+0\ensuremath J^{\pi} T = 0^+0 and, for comparison we have also considered the SmI atomic example. It is clearly established that the matrices are neither
GOE nor banded. For the TBRE structure we have examined the correlations between diagonal elements and eigenvalues, fluctuations
in the basis states variances and structure of the two-body part of the Hamiltonian in the eigenvalue basis. Unlike the atomic
example, nuclear examples show that the nuclear shell model Hamiltonians can be well represented by TBRE. 相似文献
4.
B. Bleaney 《Hyperfine Interactions》1991,63(1-4):3-11
The history of hyperfine interactions is outlined from the first observations by optical spectroscopy, through magnetic resonance
in the solid state and in atomic beams, to the use of lasers. For lanthanide atoms and ions, a number of hyperfine structure
corrections are discussed, with particular reference to the problem of <r
−3>. The various contributions to the nuclear electric quadrupole interaction are reviewed, including shielding effects. Results
deduced from electronic spectra are compared with those involving the use of negative muons. 相似文献
5.
135Ba and137Ba Fourier transform nuclear magnetic resonance and nuclear quadrupole resonance investigations are reported in liquids resp. solids. From these measurements ratios of g1-factors, hyperfine structure anomalies, magnetic moments, atomic shielding constants and the ratio of the quadrupole moments are evaluated using also data from literature. 相似文献
6.
V. S. Pokatilov V. V. Pokatilov N. B. D’yakonova 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(11):1589-1591
Amorphous and microcrystalline Fe-B alloys in the composition range (4–25) at % B, fabricated by melt spinning, were investigated by pulse nuclear magnetic resonance (NMR) on 11B nuclei at 4.2 K. Alloy samples were prepared both from a natural mixture of isotopes and an isotope mixture 56Fe-11B. The NMR spectra were measured at different boron contents. The local atomic structure of amorphous Fe-B alloys has been determined. The amorphous alloys consist of microregions (clusters) with short-range order of the tetragonal and orthorhombic Fe3B-phase types, as well as of the α-Fe type. 相似文献
7.
F. Zolfagharpour 《Few-Body Systems》2008,44(1-4):175-178
To extract the nuclear structure function of light nuclei like 3He and 3H, the convolution of proton and neutron structure functions in the conventional approach could not explain the modification of nuclear structure functions of these nuclei because of some nuclear medium effects. There are some models that have some success to explain the modification of nuclear structure functions in limited x range. So in this investigation the quark exchange model is considered to extract the nuclear medium effect of this phenomenon (quark exchange effect) for nuclear structure functions of 3He and 3H nuclei. The Fermi motion part of the nuclear structure functions for these nuclei is extracted by taking the GRV’s neutron and proton structure functions in the conventional approach. So the nuclear structure functions and the EMC ratios of 3He and 3H nuclei are calculated by considering both Fermi motion and the nuclear medium effect of quark exchange. Finally the extracted results are compared with available data. 相似文献
8.
From hyperfine structure measurements in the ground multiplet 3F of 179Hf performed with the atomic beam magnetic resonance method effective radial parameters have been determined and new spectroscopic values of the nuclear quadrupole moments of 177Hf and 179Hf are evaluated. 相似文献
9.
Through the nuclear binding energy, the atomic mass gives us important information about nuclear structure. Viewing the ensemble
of mass data over the nuclear chart, we can examine the hills and valleys that form this surface and make hypotheses about
the effects of certain nuclear configurations. To unveil these effects, mass measurements of very high precision (<10−6) are required. Two experiments at ISOLDE pursue this effort of nuclear cartography: the tandem Penning trap spectrometer
ISOLTRAP and the radiofrequency transmission spectrometer MISTRAL. Between them, the masses of almost 150 nuclides have been
measured from stable isotopes to those with half-lives as short as 30 ms. Both experiments rely on good optical properties
of a low energy ion beam and are thus well suited to the ISOLDE facility.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
We determine nuclear structure functions and quark distributions for 7Li, 11B, 15N and 27Al. For the nucleon bound state we solve the covariant quark–diquark equations in a confining Nambu–Jona-Lasinio model, which yields excellent results for the free nucleon structure functions. The nucleus is described using a relativistic shell model, including mean scalar and vector fields that couple to the quarks in the nucleon. The nuclear structure functions are then obtained as a convolution of the structure function of the bound nucleon with the light-cone nucleon distributions. We find that we are readily able to reproduce the EMC effect in finite nuclei and confirm earlier nuclear matter studies that found a large polarized EMC effect. 相似文献
11.
We considered the kaon absorption from atomic states into the nucleus. We found that the nuclear density probed by the atomic
kaon significantly depends on the kaon orbit. Then, we re-examined the meanings of the observed strengths of one-body and
two-body kaon absorption, and investigated the effects to the formation spectra of kaon bound states by in-flight (K
-, p) reactions. As a natural consequence, if the atomic kaon probes a smaller nuclear density, the ratio of the two-body absorption
at nuclear center is larger than the observed value in kaonic atoms, and the depth of the imaginary potential is deeper even
at smaller kaon energies as in kaonic nuclear states because of the large phase space for the two-body processes. This deeper
imaginary potential makes the signals of kaonic nucleus formation more unclear in the (K
-, p) spectra. 相似文献
12.
Recent advances in atomic theory make possible the determination of nuclear charge radii for light isotopes from their isotope
shift relative to other known isotopes. This method provides a unique measurement tool for the halo nuclei such as 6He and 11Li. The theoretical techniques are reviewed and applied to recent measurements performed at Argonne, GSI, and TRIUMF. 相似文献
13.
P odd effects caused by the nuclear spin dependent electron-nucleon interaction are considered. P-odd amplitudes are calculated
for 1S0 → 3D1,2 transitions in atomic ytterbium.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
Shamil Latypov Nataly Epifanova Elena Popova Sergey Vasilevsky Svetlana Solovieva Igor Antipin Alexander Konovalov 《Applied magnetic resonance》2011,41(2-4):467-475
The combined application of two-dimensional nuclear magnetic resonance (2-D NMR) correlation experiments and gauge-including atomic orbital (GIAO) 13C NMR chemical shift calculations allowed reliable and simple determination of regioisomeric structure of heterocyclic substituents on the calix[4]arene lower rim. Moreover, the 1-D double pulsed field gradient nuclear Overhauser effect technique allows quick and efficient measurement of small nuclear Overhauser effects and, in doing so, establishes a 3-D structure of calix[4]arene simply and unequivocally. In general, these methods may find application in the regio- and stereoisomeric structure determination of complicated macrocyclic compounds. 相似文献
15.
The ratio of theg I -factors of99Ru and101Ru has been measured accurately by the nuclear magnetic resonance method. Using hyperfine interaction constants from literature, the hyperfine structure anomalies of some atomic states of ruthenium are obtained. 相似文献
16.
S. Rahaman U. Hager V. -V. Elomaa T. Eronen J. Hakala A. Jokinen A. Kankainen P. Karvonen I. D. Moore H. Penttilä S. Rinta-Antila J. Rissanen A. Saastamoinen T. Sonoda J. Äystö 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):87-96
The Penning trap mass spectrometer JYFLTRAP, coupled to the Ion-Guide Isotope Separator On-Line (IGISOL) facility at Jyv?skyl?,
was employed to measure the atomic masses of neutron-rich 85-92Br and 94-97Rb isotopes with a typical accuracy less than 10keV. Discrepancies with the older data are discussed. Comparison to different
mass models is presented. Details of nuclear structure, shell and subshell closures are investigated by studying the two-neutron
separation energy and the shell gap energy. 相似文献
17.
K. H. Bürger S. Büttgenbach R. Dicke H. Gebauer R. Kuhnen F. Träber 《Zeitschrift für Physik A Hadrons and Nuclei》1980,298(3):159-165
The hyperfine structure of the atomic levels 5d 3 6s 2 4 F 7/2, 9/2 and4 P 1/2 in181Ta has been studied by atomic-beam magnetic-resonance. Using intermediate coupling wave functions derived for the configurations (5d+6s)5 the hyperfine structure data of six low-lying metastable states have been analyzed with respect to the effective operator formalism. The effective radial parameters for the magnetic dipole and electric quadrupole interactions are determined from these measurements and compared with relativistic calculations. The value obtained for the spectroscopic quadrupole moment of the181Ta nuclear ground state is Qhfs=3.44(17) barn (uncorrected for configuration interaction effects). 相似文献
18.
《Optics Communications》1987,61(6):383-386
The 141g and 141m samarium and 164g and 164m thulium nuclear isomers have been separated for the first time by the laser selective atomic photoionization technique in on-line experiments with a proton accelerator and a mass separator. The hyperfine structure of the 141Sm isomer lines has been studied and the nuclear parameters μ, Q, and δ 〈r2〉 of the isomers determined. 相似文献
19.
J.F. Chemin S. Andriamonje J. Roturier B. Saboya J.P. Thibaud S. Joly S. Plattard J. Uzureau H. Laurent J.M. Maison J.P. Shapira 《Nuclear Physics A》1979,331(2):407-428
A new method for measuring compound-nucleus lifetimes in the range of 10?18–10?16 s is presented. The method is based on the comparison between the known lifetime of an atomic excited state used as a reference and the nuclear delay time to be measured. On-line coincidences performed between the nuclear reaction products and the emitted X-rays enable the selection of the atomic vacancies decaying during the compound stage of the nuclear interaction. The main characteristics of this technique are illustrated by measurements of lifetimes of the 107In compound nucleus excited at 13.6 and 15.6 MeV in the 106Cd(p, p')106Cd reaction. They are found in agreement with statistical model calculations. The spurious effect associated with decay by internal conversion of final states populated by the competitive (p, n) reaction is emphasized. 相似文献
20.
A new method is proposed to measure multiaxis nuclear spin structures using γ-ray emission from oriented radioactive nuclei. This method, which depends only on angular momentum theory, is presented for helical spin structures. The atomic magnetic structure can also be obtained when the nuclear magnetism is produced by hyperfine interaction. Measurements on 166mHo in a single crystal of 165Ho metal show that the spin axes form a single cone with a half-angle of 80.4±0.4°. 相似文献