Nuclear Volume Effect Research Articles

Isotope shift of calcium isotopes withA=40, 42, 43, 44, 46 and 48 by laser spectroscopy

Isotope shifts of all the stable Ca isotopes in the intercombination lineλ=6573A have been studied by laser spectroscopy. The nuclear volume effect for43Ca and46Ca could be evaluated from the measurements and the quadrupole moment of43Ca was obtained.

Observability of Hyperfine Structure and Lamb, Nuclear-Volume Shifts in1snl−1snl′Transitions of Heliumlike Ions

The hyperfine-structure widths of $1snl\ensuremath{-}1sn{l}^{\ensuremath{'}}$ transitions in heliumlike ions are estimated for $n=2, 3 \mathrm{and} Z$ up to 30. Relevant parameters such as spin-orbit and electrostatic parameters are also calculated on the basis of screened hydrogenic functions. It is found that the hyperfine-structure widths are greater than 10 \AA{} at accessible visible wavelengths in some cases. Also, absolute wavelength shifts due to Lamb and nuclear-volume effects are of the order of several angstroms.

Effects of chronic gamma irradiation on plant communities.

Three plant communities or assemblages of plants-the vascular plants of an oakpine forest, the lichens of that forest, and herbs of an old field-have been studied after being exposed experimentally to chronic gamma irradiation. Several kinds of changes in the communities have resulted, including: (1) in all three communities irradiation reduced community structure toward the lowest strata or growth-forms of the community; (2) dominant species replaced one another along the gradient of radiation intensity producing population curves similar to those found along natural environmental gradients; (3) significant changes in productivity occurred; (4) species-diversity decreased with increased exposure to radiation; (5) in respect to various tests used in the study, increasing community sensitivity to irradiation was in the sequence: forest lichens, old-field-herbs, forest vascular plants. Radiation effects on communities relate to evolutionary and ecological phenomena of broad interest, including nuclear volume effects on radiation sensitivity, stature and evolutionary level of plants, population processes determining community composition, and relations of communities to succession and natural environmental gradients.

Isotope shift in the arc spectrum of ruthenium

With the use of enriched isotopes of ruthenium, the isotope shifts in six lines of the arc spectrum of 44 Ru were studied. A Fabry-Perot etalon, with multiple dielectric coatings, provided the high resolution required. Shifts between all the stable isotopes were measured accurately in the line λ4372 Å, and several shifts were measured in the other five lines. A treatment of the combined results made it possible to derive a relation between the various specific mass shifts. From this, all the specific mass shifts could be determined if one were known. An estimate was made of the proportion of the shift due to mass effects and that due to nuclear volume effects in the different lines. The estimated nuclear volume shifts in λ4372 Å were: 96-98 39.6 mK, 98-99 11.3 mK , 99-100 23.7 mK , 100-101 7.1 mK, 101-102 24.9 mK, and 102-104 35.2 mK. The order of magnitude of the configuration mixing in some odd levels was also found.

Isotopieverschiebung im Zirkon I-Spektrum

Using highly enriched samples of the zirconium isotopes 90, 92, 94, and 96 the isotope shift in the Zr-I spectrum has been measured with the aid of a photoelectrically recording Fabry-Perot spectrometer. Both mass-dependent and nuclear-volume effects were found to contribute to the observed shifts. The nuclear-volume dependent part of the measured shifts has been determined; the relative position of the isotopes caused by this part isΔνV(90−92):ΔνV(92−94):ΔνV(94−96)=1:(0.70±0.08):(0.54±0.06). The experimental isotope-shift constantsβCexp are (90–92)∶44·1±5·1; (92–94)∶30·9±5·4; (94–96)∶23·8±5·0 mK.

Electric Quadrupole Splitting and the Nuclear Volume Effect in the Ions ofFe57

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Isotope Shift in the X-Ray Spectra of Heavy Elements

Isotope shifts in the x-ray levels due to the nuclear volume effect have been calculated for three different nuclear potentials by using first-order perturbation theory with the relativistic wave functions in a Coulomb field. In order to correct for the error made in using first-order perturbation theory, the exact relativistic wave function was obtained for one of the potentials. The screening effects of the atomic electrons are taken into account by comparing the value of the wave function at the nuclear radius in a Fermi-Thomas field with that in a Coulomb field. An upper limit is obtained on contributions to the isotope shift due to the change in screening of the other atomic electrons when a $K$ or $L$ shell electron is removed or replaced. The results for isotope shift in Mo and U are one-half and one-twentieth, respectively, of the experimental resolution of Rogosa and Schwarz.