Crossing of shears bands in196Pb

High-spin states in¹⁹⁶Pb have been populated using the reaction¹⁷⁰Er(³⁰Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin.     

Search for a transient electric field gradient in the system90Zr→148Nd with the crystal ball spectrometer

The particle- angular correlation of the 2⁺0⁺ transition in¹⁴⁸Nd, Coulomb excited by⁹⁰Zr projectiles, was investigated to search for a transient electric field gradient expected to be present during the stopping of the recoils in²⁰⁸Pb. An upper limit of V_zz <>¹⁹V/cm² was obtained for¹⁴⁸Nd recoiling with initial velocities of 0.05 c.     

Superdeformed bands in195Tl

Two superdeformed (SD) bands have been found and assigned to¹⁹⁵Tl on the basis of excitation function and cross bombardment results. The two bands are almost identical in transition energies to those observed in¹⁹³Tl. They are signature partners with a splitting, presumably due to the proton i_13/2 (=5/2) orbital, characteristic of all known SD bands in the thallium isotopes. Their alignments relative to the¹⁹³Tl bands were found to be zero.On leave from Comision National de Energia Atomica 1429 Buenos Aires, Argentina.     

In-beam spectroscopy of 253, 254No

In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei ^{253, 254}No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyv?skyl?. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of ²⁵³No are discussed. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: rdh@ns.ph.liv.ac.uk RID="b" ID="b"Present address: GANIL, F-14021 Caen, France. RID="c" ID="c"Permanent address: IReS Strasbourg, IN2P3-CNRS, F-67037-Strasbourg, France. RID="d" ID="d"Present address: CEA/DIF DCRE/SDE/LDN F-91680 Bruyeres-le-Chatel. RID="e" ID="e"Present address: Daresbury Laboratory, Daresbury WA4 4AD, UK. RID="f" ID="f"Permanent address: IPN Lyon, IN2P3-CNRS, F-69037 Lyon, France.     

Entry distribution, fission barrier, and formation mechanism of 254102No

The entry distribution in angular momentum and excitation energy for the formation of 254No has been measured after the 208Pb(48Ca,2n) reaction at 215 and 219 MeV. This nucleus is populated up to spin 22Planck's over 2pi and excitation energy greater, similar6 MeV above the yrast line, with the half-maximum points of the energy distributions at approximately 5 MeV for spins between 12Planck's over 2pi and 22Planck's over 2pi. This suggests that the fission barrier is greater, similar5 MeV and that the shell-correction energy persists to high spin.     

Über eine Verbesserung beim Gebrauch des Goochtiegels

Analytical and Bioanalytical Chemistry -     

Superdeformed bands and ‘shears’ bands in 197Pb and 198Pb

Excited states in ¹⁹⁷Pb and ¹⁹⁸Pb, produced in the ¹⁸⁶W (¹⁸O,xn) reaction, were studied using the EUROGAM phase 2 γ ray spectrometer array. Two new superdeformed bands have been observed in ¹⁹⁷Pb, and the existence of a superdeformed band in ¹⁹⁸Pb has been confirmed. The increased statistics provided by the latest generation of arrays has resulted in the reordering of some of the previous known cascades of magnetic dipole transitions, with the first observation of the extremely weak E2 crossover transitions.     

Transition quadrupole moments of superdeformed states in194Pb

Lifetimes of superdeformed states in¹⁹⁴Pb were measured by the Doppler-shift attenuation method. Quadrupole moments around 20 eb, that are constant over the observed frequency range, are derived. The results rule out large centrifugal stretching effects.     

Crossing of shears bands in 196Pb

High-spin states in 196Pb have been populated using the reaction ¹⁷⁰Er(³⁰Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin.