The level scheme of133Sb

Nuclear spectroscopy studies of ₅₁ ¹³³ Sb₈₂ have been performed at the recoil fission product separators JOSEF and LOHENGRIN. A tentative level scheme has been established for this nucleus with one proton in addition to the doubly closed shell core¹³²Sn. Two isomeric states with half-lives of 3 and 16 μs have been found at excitation energies of >4300 keV and 4526 keV, respectively. Lower limits of 15/2 are deduced for the spins of these levels. The h_11/2 proton state is suggested at 2792 keV in agreement with the systematics of the lighter Z=51 isotopes and the heavier N=82 isotones. Several states have been observed between 4300 and 4600 keV which are probably due to the coupling of the single proton to core-excited states which have energies between 4000 and 4800 keV.     

Prompt fission induced by antiproton annihilation at rest on heavy nuclei

Antiproton induced fission probabilities of U²³⁸, Bi²⁰⁹, Pb²⁰⁸ and Au¹⁷⁷ are reported together with the mass distribution of the fission fragments in the U²³⁸ and Bi²⁰⁹ cases. The charged particles multiplicities observed in co-incidence with fission have, also, been measured for U and Bi and are presented.Dedicated to Peter Armbruster on the occasion of his 60th birthday in recognition of his important contribution to modern Nuclear Physics     

Evidence for a 10+ state in132Te

A new isomeric state witht _1/2=3.9±0.3μs has been observed in the nucleus ₅₂ ¹³² Te₈₀ which has two protons more and two neutrons less than the doubly magic isobar ₅₀ ¹³² Sn₈₂. The deexcitation pattern suggests spin and parity 10⁺ for this level near 2,700 keV which is populated in fission. The energy and the half-life of the isomer can be understood with the assumption that it is the 10⁺ level based on theh ₁₁ ^2/?2 neutron hole configuration.     

The19F(n, γ)20F reaction

The gamma-ray spectrum emitted following thermal neutron capture in¹⁹F has been studied with curved crystal and Ge(Li) spectrometers. From the 109 transitions assigned to²⁰F, 85 have been placed in a level scheme containing 26 levels. An average gammaray multiplicity of 2.8 gammas per neutron capture was observed. The neutron binding energy was found to be 6601.33(14) keV. The experimental level scheme is compared to rotational model predictions. In addition it is shown that the decay of the capture state is non-statistical and that there is a strong correlation between the strengths of excitation of levels by the (n, γ) and (d, p) reactions. Calculations of the partial cross-sections using the direct capture theory of Lane and Lynn give order of magnitude agreement with experiment.     

Theβ-decays of99Y and99Zr and the level schemes of99Zr and99Nb

Theβ-decays of⁹⁹Y and⁹⁹Zr have been investigated with the two recoil fission product separators JOSEF and LOHENGRIN. Half-lives of 1.51±0.08s and 2.1±0.1s respectively, have been determined. Aβ-decaying isomeric state has been observed in⁹⁹Y. The level schemes of ₄₀ ⁹⁹ Zr₅₉ and ₄₁ ⁹⁹ Nb₅₈ have been established fromγ-ray spectroscopy. Absoluteγ-intensities have been obtained by means of two independent techniques. Halflives of 293±10 ns for the 251.9 keV state and 10.2±1.5 ns for the 614.0 or 667.2 keV level in⁹⁹Zr have been measured through delayedβ,γ- andγ,γ-coincidence experiments. Values for the spins and parities of the low lying levels in⁹⁹Zr are proposed in accordance with the systematics of lighter odd Zr isotopes. Spins and partities are assigned to some levels in⁹⁹Nb fromγ,γ-angular correlation measurements. In this nucleus there is evidence for three-particle configurations of some excited states, where the odd proton is coupled to two neutrons which are in different orbits.     

Elastic and inelastic scattering of 1.03 GeV 12C projectiles

Elastic scattering cross sections of 86 MeV/N ¹²C ions on ¹²C, ^NATCa, ⁸⁹Y and ²⁰⁸Pb targets has been measured together with inelastic scattering to the 4.4 MeV state of ¹²C. There is some indication for giant (quadrupole) resonance excitation in ⁴⁰Ca. Optical model and DWBA analyses are reported. Nuclear transparency effect is discussed.     

Nuclear spectroscopy of neutron-richA=145 nuclei

A study of theβ-decay of neutron-richA=145 fission products was undertaken by the use of the two recoil separators LOHENGRIN and JOSEF and the ISOL-type separator OSTIS. Theβ-decaying isotopes¹⁴⁵Ba,¹⁴⁵La and¹⁴⁵Ce were extensively studied. Level schemes for¹⁴⁵La,¹⁴⁵Ce and¹⁴⁵Pr were deduced fromγ and conversion electron spectra,γγ, X γ delayed andβγ coincidences. TheQ _β -values have been measured for the¹⁴⁵Ba,¹⁴⁵La and¹⁴⁵Ce decays.     

Experimental beta-decay energies of several neutron-rich nuclides with mass number 131≦A≦146

With sources obtained from the on-line mass separator LOHENGRIN the beta-decay energies of¹³¹Sn,¹³⁴Sb,^135,136Te,^143,146Ba and¹⁴⁶La have been determined from measuredβ-endpoint energies. The experimental values are compared with the predictions of several mass formulae.