Search results for "Isotopes of lithium"
showing 7 items of 17 documents
Isotope-shift measurements of stable and short-lived lithium isotopes for nuclear-charge-radii determination
2010
Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound iso…
Absolute frequency measurements on the 2S→3S transition of lithium-6,7
2009
The frequencies of the 2S–3S two-photon transition for the stable lithium isotopes were measured by cavity-enhanced Doppler-free laser excitation that was controlled by a femtosecond frequency comb. The resulting values of 815 618 181.57(18) and 815 606 727.59(18) MHz, respectively, for 7Li and 6Li are in agreement with previous measurements but are more accurate by an order of magnitude. There is still a discrepancy of about 11.6 and 10.6 MHz from the latest theoretical values. This is comparable to the uncertainty in the theoretical calculations, while uncertainty in our experimental values is more than a hundred-fold smaller. More accurate theoretical calculation of the transition freque…
On total muon capture rates and the average neutrino energy
1973
A method of avoiding the uncertainty associated with the average neutrino energy nu in the usual closure approach to muon capture rates is discussed. Instead of neglecting the kinematic dependence on each particular channel, the partial capture rate is approximated by a first-order expansion around nu . After the sum over the final states is performed, the result is quite independent of the specific value of nu . Application to /sup 3/He, /sup 6/Li and closed-shell nuclei is given, as an effective test of the nuclear models used. (17 refs).
The quadrupole moment of the neutron-halo nucleus 11Li
1995
The quadrupole moment ratio of 9Li and 11Li was measured by a combination of in-beam laser induced nuclear polarization and β-NMR in LiNbO3. The result |Q(11Li)/Q(9Li)| = 1.14(16) is consistent with cluster models describing 11Li as composed of a 9Li core and a far extended halo of two loosely bound neutrons.
New Mass Value forLi7
2006
A high-accuracy mass measurement of $^{7}\mathrm{Li}$ was performed with the SMILETRAP Penning-trap mass spectrometer via a cyclotron frequency comparison of $^{7}\mathrm{Li}^{3+}$ and $\mathrm{H}_{2}{}^{+}$. A new atomic-mass value of $^{7}\mathrm{Li}$ has been determined to be $7.016\text{ }003\text{ }425\text{ }6(45)\text{ }\text{ }\mathrm{u}$ with a relative uncertainty of 0.63 ppb. It has uncovered a discrepancy as large as $14\ensuremath{\sigma}$ ($1.1\text{ }\text{ }\ensuremath{\mu}\mathrm{u}$) deviation relative to the literature value given in the Atomic-Mass Evaluation AME 2003. The importance of the improved and revised $^{7}\mathrm{Li}$ mass value, for calibration purposes in nu…
Experimental study of the halo nucleusHe6using theLi6(γ,π+)He6reaction
2007
The reaction $^{6}\mathrm{Li}$($\ensuremath{\gamma},{\ensuremath{\pi}}^{+})$$^{6}\mathrm{He}$ was studied over the angular range ${\ensuremath{\theta}}_{\ensuremath{\pi}}=40$--150$\ifmmode^\circ\else\textdegree\fi{}$ with the aim of investigating the halo structure of $^{6}\mathrm{He}$. Photons from a bremsstrahlung beam were tagged in the energy range ${E}_{\ensuremath{\gamma}}=170$--220 MeV at a resolution of $\ensuremath{\Delta}{E}_{\ensuremath{\gamma}}=630$ keV, and positively charged pions detected using high resolution stacked HpGe detectors. The measured angular distributions for the resolved $^{6}\mathrm{He}$ ground and 1.80 MeV excited states are compared to previous measurements a…
The conductance of lithium-7 fluoride in dioxane-water mixtures at 25�C
1990
Conductance data for lithium-7 fluoride in dioxane-water mixtures covering the range 78.35>D>36 in dielectric constant are presented. These data and other previous data on lithium-7 chloride and lithium-7 iodide were analyzed by the Fuoss 1980 conductance equation in order to find the limiting conductance Δo, the pairing distance R and the conductometric association constant Kλ. Setting Ka=Kλ/VM (where VM is the molar volume of the solvent), the thermodynamic pairing constant and the corresponding change of the free energy Δg were calculated. Correlation among the values found for R and Δg=Δh−TΔs and the properties characteristic of the ions and solvents are discussed.