Search results for "ISOTOPES"
showing 10 items of 1216 documents
High-accuracy mass measurements of neutron-rich Kr isotopes
2006
The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.
Lithium isotopes beyond the drip line
2008
The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in th…
Fine structure in the alpha decays of 226U and 230Pu
1999
The nuclei 226U and 230Pu have been populated via reactions involving 208Pb targets bombarded by 22Ne and 26Mg projectiles. Fusion-evaporation residues were separated in-flight using a gas-filled recoil separator. A position-sensitive Si-strip detector was employed at the focal plane in order to identify correlated α-decay chains. Two fine structure α-decay lines have been observed. The first, with an energy of 7385(5) keV, is assigned as the α decay from 226U to the first excited 2+ state of 222Th. The second line, observed for the first time in this work, has an energy of 6961(30) keV and is assigned as the α decay from 230Pu to the first excited 2+ state of 226U. The excitation energy of…
β-Decay Studies Close to the N=82 r-process Path
2005
New half-lives for neutron-rich ruthenium, rhodium and palladium isotopes close to the r-process path along the N=82 closed shell have been measured at the National Superconducting Cyclotron Laboratory at Michigan State University. The studied isotopes are close to the critical A=118-126 mass region in the astrophysical r-process, where incorrect nuclear structure development towards the shell closure may have the most pronounced effect on the abundances of elements produced. Neutron-rich nuclei were produced by fragmentation of a 120-MeV per nucleon 136 Xe beam on Be and were separated by the A1900 fragment separator. The nuclei of interest were implanted into a double-sided Si strip detec…
Direct mass measurements of neutron-rich zirconium isotopes up toZr104
2004
Atomic masses of radioactive zirconium isotopes from {sup 96}Zr to {sup 104}Zr have been measured with a relative accuracy of {<=}5x10{sup -7} using a Penning trap coupled to the ion guide isotope separator on-line system. The obtained two-neutron separation energies show strong local correlation in relation to the shape change and shape coexistence between N=58 and 60.
New neutron-rich isotopes of astatine and bismuth
1989
Neutron-rich isotopes of astatine have been produced through spallation reactions with 600 MeV protons on a232Th target and identified by spectroscopic techniques combined with one-line mass separation at the ISOLDE facility. The half-lives of218At and219At have been remeasured to be 1.5(3) s and 57(4) s, respectively. Four new isotopes of astatine,220−223At, have been observed for the first time, and their half-lives were found to be 3.73(13) min, 2.3(2) min, 54(10) s, and 50(7) s, respectively. Another nuclide,216Bi, has been observed for the first time as the daughter product of the220At alpha decay, and its half-life has been measured to be 6.6(21) min.
Intense beams of mass-separated, neutron-deficient indium, tin, thallium and lead isotopes
1985
A discharge ion source of the FEBIAD-type that delivers intense beams of neutron-deficient isotopes of indium, tin, thallium and lead produced in heavy-ion-induced fusion reactions is described. After mass separation the isotopically pure beams with intensities of up to 3 × 107 ions/s were available for gamma and laser spectroscopy. This corresponds to an overall separation efficiency of about 30%.
Isotope shifts of neutron-deficient gold isotopes with 193?A?190
1985
The isotope shift between197Au (stable) and the radioactive Au isotopes190Au,191Au,192Au and193Au were determined by resonance fluorescence spectroscopy in the 6s2S1/2–6p2P1/2.λ=267.6nm line. The unstable Au isotopes were produced at the ISOLDE mass separator at CERN. The nuclei were investigated semi on-line in a resonance vessel, heated to 1,400°C. The results areδν190,197=−11.12(39) GHz,δν191,197=−9.67(12) GHz,δν192,197=−8.32(15) GHz,δν193,197=−6.29(11) GHz, corresponding to a change of the mean-square charge radius byδ〈r2〉190,197 =0.261(12) fm2,δ〈r2〉191,197=0.227(5) fm2,δ〈r2〉192,197=0.195(5) fm2,δ〈r2〉193,197 =0.148(4) fm2.
Nuclear charge radii of molybdenum fission fragments
2009
Abstract Radioisotopes of molybdenum have been studied using laser spectroscopy techniques at the IGISOL facility, University of Jyvaskyla. Differences in nuclear charge radii have been determined for neutron deficient isotopes 90,91Mo and neutron rich isotopes 102–106,108Mo (and all stable isotopes). A smooth transition in the mean square charge radii is observed as the neutron number increases with no sudden shape change observed in the region around N = 60 . As N increases, the nuclear deformation appears to go beyond a maximum and a fall off at N = 66 is observed. The magnetic moments of the odd isotopes 91,103,105Mo are also determined.
Resolution of nuclear ground and isomeric states by a Penning trap mass spectrometer.
1992
Ground and isomeric states of a nucleus have been resolved for the first time by mass spectrometry. Measurements on $^{78}\mathrm{Rb}^{\mathit{m},}$g and $^{84}\mathrm{Rb}^{\mathit{m},}$g were performed using a tandem Penning trap mass spectrometer on-line with the isotope separator ISOLDE/CERN. The effects of ion-ion interaction were investigated for two ion species differing in mass and stored simultaneously in the trap.