T. Rzaca-Urban

The decay of theIπ=8+ isomer in100Cd-neutron particle and proton hole states

The γ-decay and half life of the t1/2=60(3) ns Iπ=8+ isomer in100Cd have been studied with a recoil catcher setup inside the multidetector π-array OSIRIS. Evaporation neutrons and charged particles from the reaction58Ni+46Ti were measured in coincidence with delayed γ-rays. Six new γ-ray transitions with intensities of 1–10% of the main γ-ray cascade were found, two new states established and firm spin-parity assignments were made to all states below the isomer. The new states were identified as the 4+ and 6+ members of the proton πg9/2−2 multiplet.

Recent developments of multi e-gamma spectrometers

A brief introductory survey of gamma-ray detector arrays and in-beam electron spectrometers developed during the last three lustra is followed by a broad discussion of the general requirements for single and multiple in-beam e-gamma spectrometers. A detailed analysis is made of a few important tools for reducing the low-energy electron background (i.e. simultaneous E-Bp selection, true and random coincidence rates, EM static fields around the target region). This survey and discussion are illustrated by the results of several in-beam e-gamma measurements dealing with nuclear spectroscogic investigations of a few medium and heavy nuclei

Shape changes in189Au at high spins

The level scheme of 189Au has been extended to high spins. Decoupled, strongly coupled as well as vibrational bands have been found indicating shape coexistence in this nucleus.

Shape changes in 189 Au at high spins

The level scheme of 189Au has been extended to high spins. Decoupled, strongly coupled as well as vibrational bands have been found indicating shape coexistence in this nucleus.

Nuclear targets, recoil ion catchers and reaction chambers

The main features of nuclear targets, recoil ion catchers and reaction chambers used in nuclear spectroscopic investigations involving in-beam multi-e-gamma spectrometers are discussed. The relative importance of the F-ray background due to the accelerated ion-target and the recoil-ion-target interaction is estimated. Its impact on the prompt low-energy electron measurements is stressed. Finally a few general features of the interplay between accelerated ion beams, targets and recoil ion catchers particularly relevant for these measurements are broadly discussed and illustrated with typical examples of in-beam e-gamma studies

Accelerated ion beams for in-beam e-gamma spectroscopy

A few accelerated ion beam requirements for in-beam e-gamma spectroscopy are briefly reviewed as well as several features of the MP Tandem accelerator of IPN-Orsay and the accelerated ion-beam transport devices leading to the experimental area of in-beam e-gamma spectroscopy. In particular, the main capabilities of the ion-sources, the ion pulsing system, the ion stripping and stabilizing devices as well as the versatility of the ion beam transport system are discussed from the point of view of the different kinds of in-beam e-gamma experiments performed in that area

Origin of the backbending in theπh9/2 band of185Ir

Highspin states of185Ir were excited in the187Re(α,6n) reaction and measured with the OSIRIS spectrometer. The first backbending in theπhx9/2 band was found at a rotational frequency of ħω=0.40 MeV. Blocking arguments suggest that this is due to the alignment of an h9/2 quasiproton pair.

Near-yrast excitations in nucleus 83As: tracing the deformation in the

Medium-spin, yrast excitations in nucleus 83As have been studied in neutron-induced fission of 235U. The experiment took place at the Institut Laue-Langevin in Grenoble where gamma rays were registered using the EXILL detector array. Recently, we proposed new tentative (9=2+) spin assignment for 2777 keV level in 83As, which is now discussed in the context of deformation showing up in 78Ni region.

^{78}

The medium-spin structure of the neutron-rich, odd-odd nucleus Rb-94 was studied by means of gamma-ray spectroscopy. Excited levels were populated in the neutron-induced fission of U-235 and in the spontaneous fission of Cf-252 and Cm-248. Two isomeric states were found at 1485.2 and 2074.8 keV with half-lives of 18 and 107 ns, respectively. The probable structures of the two isomers involve the fully aligned, proton-neutron configurations [pi(g(9/2))circle times nu(g(7/2))](8+) and [pi(g(9/2))circle times nu(h(11/2))](10-), respectively. These new data give information on the single-particle energies in the region.

Ni region

Excited states in 149 La, populated in the spontaneous fission of 248 Cm, were studied with the EUROGAM2 array. A new ΔI = 2 band found in 149 La is interpreted as the a = -1/2 branch of the π 3/2 - [402] configuration. The bandhead has spin 7/2- because the 3/2 and 5/2 - levels are pushed up by the Coriolis interaction. The 7/2 - level is located not higher than 30 keV above the ground state and may form a long-lived isomer if spin and parity of the g.s. is 3/2 + .