Search results for "nuclear fusion"
showing 10 items of 437 documents
The deformedN=60 nucleus 41 101 Nb
1991
The β− decay of101Zr has been investigated at the fission-product separators JOSEF and LOHENGRIN. The half-life of101Zr has been determined to 2.5(1) s and a level scheme for101Nb has been established fromγ ray singles as well as X/3-γ and γ—γ coincidence measurements. Conversion coefficients for transitions in101Nb and level half-lives between 10 ps and 2 ns have been determined. Three rotational bands are identified among the low-lying levels with band heads at 0 keV, 206 keV and 208 keV. The bands are probably based on the Nilsson configurations [422 5/2+], [301 3/2−] and [303 5/2−], respectively. The deformation has been determined to βq=0.40(4) and 0.41(8) for the ground state band and…
Shape coexistence near the double-midshell nucleus 111Rh
1998
The decay of 111Ru obtained from fast on-line chemical and mass separation has been investigated by β-γ-t and γ-γ coincidence techniques. Earlier spin and parity assignments of 111Rh levels based on extrapolations of level systematics are confirmed. In particular, the K=1/2 intruder band is supported by the hindrance of E2 transitions between deformed and spherical states and enhancement of intraband E2 transitions. The excitation energies of intruder band members in Rh isotopes show a minimum at 109Rh64, with two neutrons less than 111Rh at the N=66 midshell. This trend, which differs from the one in the higher-Z neighbouring elements Ag and Cd with minima at N=66, follows the evolution of…
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…
Ground-state properties of neutron-deficient platinum isotopes
1992
The hyperfine structure splitting and the isotope shift in the λ=266 nm transition of Pt isotopes within the mass range 183 ≦A≦ 198 have been determined by Resonance Ionization Mass Spectroscopy (RIMS) in combination with Pulsed-Laser Induced Desorption (PLID). The Pt isotopes were obtained at the on-line isotope separator ISOLDE-3/CERN as daugthers of the primarily produced Hg isotopes. Magnetic moments, quadrupole moments, and changes in the mean-square charge radii are deduced and compared with results of a particle-triaxial rotor model and mean field calculations. Good agreement with experimental data (including nuclear level schemes and transition probabilities) can only be obtained if…
New states in heavy Cd isotopes and evidence for weakening of the N = 82 shell structure
2000
A chemically selective laser ion source has been used in a β-decay study of heavy Ag isotopes into even-even Cd nuclides. Gamma-spectroscopic techniques in time-resolving event-by-event and multiscaling modes have permitted the identification of the first 2+ and 4+ levels in 126Cd78, 128Cd80, and tentatively the 2+ state in 130Cd82. From a comparison of these new states in 48Cd with the E(2+) and E(4+)/E(2+) level systematics of 46Pd and 52Te isotopes and several recent model predictions, possible evidence for a weakening of the spherical N = 82 neutron-shell below double-magic 132Sn is obtained.
Decay of 0 2 + states in88,92,94Zr andE0 systematics of Zr isotopes
1981
Branching ratios ofE0 andE2 transitions depopulating the 0 2 + states of88, 92, 94Zr have been determined using conversion-electron and γ-ray spectroscopy. Two different lifetime-measurement methods were applied in the remeasurement of the half-lives of the 0 2 + states in92, 94Zr, yielding consistent results ofT 1/2(0 2 + ,92Zr)=85(15) ps andT 1/2(0 2 + ,94Zr)=280(40) ps. The monopole strengths extracted areρ 2(92Zr)=8.4(17) ×10−3 andρ 2(94Zr)=11.9(20)×10−3. The proton configurations of the 0 2 + states are discussed in view of these values and proton transfer data.
Half-life and configuration of the 1/2+ intruder state in203Bi
1984
The decay properties of theJπ=1/2+,Eexc=1,098 keV state in203Bi were studied. The state was populated via the204Pb(p, 2n) reaction and the activity was studied with the ion guide isotope separator on-line system IGISOL. The half-life of the 1/2+ state was measured to beT1/2=303 ±5 ms. From this value the partial half-lives of the three depopulating branches 1/2+ →7/2− (E3), 1/2+→5/2− (E3 +M2) and 1/2+→9/2 g.s. − (M4) were deduced. Since all the transitions are configuration forbidden in first order, a detailed study of second-order shell-model configuration mixing could be performed.
The new element 111
1995
The new element 111 was produced and unambiguously identified in an experiment at SHIP, GSI Darmstadt. Three nuclei of the isotope272111 were observed in irradiations of209Bi targets with64Ni projectiles of 318 MeV and 320 MeV energy. The cross-sections are (1.7 −1.4 +3.3 ) pb and (3.5 −2.3 +4.6 ) pb, respectively. The nuclei decay by a emission into the new and so far the heaviest isotopes of the elements 109 and 107 with mass numbers A=268 and A=264. Theα-decay chains were followed down to the known nuclei260105 and256Lr.
The new element 112
1996
The new element 112 was produced and identified unambiguously in an experiment at SHIP, GSI Darmstadt. Two decay chains of the isotope277112 were observed in irradiations of208Pb targets with70Zn projectiles of 344 MeV kinetic energy. The isotope decays by emission of α particles with a half-life of (240 −90 +430 )µs. Two different α energies of (11,649±20) keV and (11,454±20) keV were measured for the two observed decays. The cross-section measured in three weeks of irradiations is (1.0 −0.4 +1.8 ) pb.
On the correspondence between rotational bands in the mass regionsA ? 100 andA ? 150
1987
A refined technique is presented to project rotational bands observed in the well studiedZ≧60 rare-earth region into the region of stable ground-state deformation atA ∼-100 with corresponding neutron numbers ofN ≧60. With this procedure, estimates of properties of so far unknown nuclei in the A∼-100 region can be obtained. As an illustration, isotopes aroundN=64 are discussed within this projection method and within the frame-work of the recent quartet model.