Search results for "ISOTOPES"
showing 10 items of 1216 documents
Precision measurements of the charge radii of potassium isotopes
2019
International audience; Precision nuclear charge radii measurements in the light-mass region are essential for understanding the evolution of nuclear structure, but their measurement represents a great challenge for experimental techniques. At the Collinear Resonance Ionization Spectroscopy (CRIS) setup at ISOLDE-CERN, a laser frequency calibration and monitoring system was installed and commissioned through the hyperfine spectra measurement of $^{38–47}$K. It allowed for the extraction of the hyperfine parameters and isotope shifts with better than 1 MHz precision. These results are in excellent agreement with available literature values and they demonstrate the suitability of the CRIS tec…
Laser spectroscopy measurement of isotope shifts and nuclear moments of short-lived neon isotopes
2003
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.
Nuclear Charge Radii ofMg21−32
2012
Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on (24)Mg and (32)Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.
Frequency-comb-based measurements of lithium and beryllium isotopes for nuclear structure studiesThis paper was presented at the International Confer…
2009
We report on the measurement of the 2s-3s transition frequencies in the stable lithium isotopes and 2s-2p isotope shift measurements of 7,9,10,11Be, using a femtosecond frequency comb. For the beryllium isotopes, we extract the changes in the mean-square nuclear charge radius along the isotope chain by comparison with high-precision atomic mass shift calculations. The 2s-3s transition frequency is compared with theoretical calculations, and possibilities to extract an absolute value for the nuclear charge radius of lithium isotopes are discussed.
New Short-Lived IsotopeU221and the Mass Surface NearN=126
2015
Two short-lived isotopes ^{221}U and ^{222}U were produced as evaporation residues in the fusion reaction ^{50}Ti+^{176}Yb at the gas-filled recoil separator TASCA. An α decay with an energy of E_{α}=9.31(5) MeV and half-life T_{1/2}=4.7(7) μs was attributed to ^{222}U. The new isotope ^{221}U was identified in α-decay chains starting with E_{α}=9.71(5) MeV and T_{1/2}=0.66(14) μs leading to known daughters. Synthesis and detection of these unstable heavy nuclei and their descendants were achieved thanks to a fast data readout system. The evolution of the N=126 shell closure and its influence on the stability of uranium isotopes are discussed within the framework of α-decay reduced widt…
Nuclear spin and moments of 73Kr and odd—even staggering in the radii of light krypton isotopes
2003
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/…
Isotope shifts and hyperfine structure in calcium 4snp and 4snf F Rydberg states
2000
Isotope shifts and hyperfine structure have been measured in 4snp 1 P1 and Rydberg states for all stable calcium isotopes and the radioisotope 41Ca using high-resolution laser spectroscopy. Triple-resonance excitation via Rydberg state was followed by photoionization with a CO2 laser and mass selective ion detection. Isotope shifts for the even-mass isotopes have been analyzed to derive specific mass shift and field shift factors. The apparent isotope shifts for 41Ca and 43Ca exhibit anomalous values that are n-dependent. This is interpreted in terms of hyperfine-induced fine-structure mixing, which becomes very pronounced when singlet-triplet fine-structure splitting is comparable to the h…
Isotope shifts from collinear laser spectroscopy of doubly charged yttrium isotopes
2018
Collinear laser spectroscopy has been performed on doubly charged ions of radioactive yttrium in order to study the isotope shifts of the 294.6-nm $5s\phantom{\rule{0.16em}{0ex}}^{2}S_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}$ line. The potential of such an alkali-metal-like transition to improve the reliability of atomic-field-shift and mass-shift factor calculations, and hence the extraction of nuclear mean-square radii, is discussed. Production of yttrium ion beams for such studies is available at the IGISOL IV Accelerator Laboratory, Jyv\"askyl\"a, Finland. This newly recommissioned facility is described here in relation to the on-line study of accelerator-p…
Beta Decay of68–74Niand Level Structure of Neutron-Rich Cu Isotopes
1998
The isotopes ${}^{68--74}\mathrm{Ni}$, of interest both for nuclear physics and astrophysics, have been produced in proton-induced fission of ${}^{238}\mathrm{U}$ and ionized in a laser ion guide coupled to an on-line mass separator. Their $\ensuremath{\beta}$ decay was studied by means of $\ensuremath{\beta}$- $\ensuremath{\gamma}$ and $\ensuremath{\gamma}$- $\ensuremath{\gamma}$ spectroscopy. Half-lives have been determined and production cross sections extracted. A partial level scheme is presented for ${}^{73}\mathrm{Cu}$ and additional levels for ${}^{71}\mathrm{Cu}$, providing evidence for a sharply lowered position of the $\ensuremath{\pi}{1f}_{5/2}$ orbital as occupancy of the $\ens…
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…