Possible candidates for discrete gamma rays linking superdeformed and yrast states in an odd nucleus:193Pb

The francium isotopes^200–202Fr were produced in the reaction³⁵Cl+¹⁷⁰Yb using bombarding energies of 4.9–5.3 MeV/nucleon. Fusion products were separated in-flight from the primary beam using a gas-filled recoil separator. An alpha line with the alpha particle energy and half-life of (7468±9) keV and (19 ₋₆ ⁺¹³ ) ms, respectively, was assigned to²⁰⁰Fr. Previously reported decay properties of^201,202Fr were confirmed. Communicated by V. Metag     

Identification and decay of182Tl

A new activity with a 3s half-life at mass 182 was produced via proton spoliation reaction on thorium carbide target and mass separation. From the observation of known rays observed in¹⁸²Hg, it was assigned to the (⁺+ EC) decay of¹⁸²Tl, the spin and parity of which is very likely 7⁺.     

Energy levels of80,82Br from (p,nγ) reactions

The levels of odd-odd^{80, 82}Br nuclei have been investigated via^{80, 82}Se(p, nγ)^{80, 82}Br reactions. Excitation functions and angular distributions were analysed with the Hauser-Feshbach compound nucleus theory. 27 and 29 levels have been identified. The transitions connecting the first 1⁺ and 2^?levels have been studied by the delayed coincidence method and their half-lives are 7.8±0.5 ns and 7.2±0.8 ns for⁸⁰Br and⁸²Br respectively. The experimental results are discussed in the framework of thej- j coupling.     

New excited superdeformed bands in heavy Pb nuclei: Clue for an octupole softness near the N = 118 gap at large deformation

We report the identification of six new superdeformed (SD) bands in ^197,198Pb observed with the EUROBALL IV spectrometer. The results are interpreted in the framework of cranked Hartree-Fock calculations with approximate projection on the particle number by means of the Lipkin-Nogami method. A mixing between quasi-particle excitations and an octupole vibration is suggested in the two SD isotopes. We have estimated the ordering of the neutron valence orbitals and confirm indirectly a N = 118 SD gap. Received: 20 December 2000 / Accepted: 24 January 2001     

On-line γ-ray investigation of the14N+27Al reaction at 30 MeV/u

The cross-sections of target-like residues following the¹⁴N+²⁷Al reaction at 30 MeV/u have been measured from in-beam and radioactiveγ-ray spectra. The recoil velocities of some fragments have been estimated from theγ-ray Doppler broadening.     

The decays of 5.5 min Lu and 6.7 min Lu

In order to clear up important discrepancies amongst previous investigations, the decay of ¹⁶⁸Lu, produced through the ¹⁶⁹Tm (α, 5n) reaction, has been re-investigated. Instead of the well-known 7 min activity, evidence has been obtained for two distinct decays with half-lives of 5.5 min and 6.7 min. The corresponding Q-values have been determined to be respectively 4470±80 keV and 4690±100 keV. The decay schemes are given for each isomeric state. The assignments 6⁻(p404↓+n523↓) and 3⁺(p541↓+n523↓) are proposed for ^168gLu (5.5 ruin) and ^168mLu (6.7 min), respectively. The structure of the levels are discussed in the framework of current nuclear models.     

High spin states in103Rh

High spin states in¹⁰³Rh have been studied using the¹⁰⁰Mo(⁷Li, 4n) reaction. Standard in-beam measurements involving singlesγ-ray,γ-γ-t coincidences, angular distribution and linear polarization measurements have been performed. A perturbed band based on a 9/2⁺ state is interpreted as ag _9/2 coupled band. A sequence built on a 1/2^? state is related to thep _1/2 state. At higher excitation energy, in the range 2.2–3.7 MeV, the strongΔI=1 cascade observed, connecting negative parity levels, probably arises from states including three quasi-particle configurations.     

Dipole bands in the oblate-shaped195Pb

The nucleus¹⁹⁵Pb has been populated with the¹⁸⁴W+¹⁶O reaction at 113 MeV. Two dipole γ-ray cascades have been observed using the EUROGAM spectrometer. A comprehensive level scheme related to these structures has been established. Multiparticle configurations are attributed to these high-spin structures from detailed comparison with the neighbouring nuclei,¹⁹³Hg,¹⁹⁴Pb and¹⁹⁵Tl. Band crossings due to i13/2 neutron pair breaking are observed in¹⁹⁵Pb at about the same frequencies as in the isotone¹⁹³Hg.

     

New exotic neutron-deficient nuclei nearN=82

Residual activities produced via³⁵Cl or³²S beams in thin¹¹²Sn and¹⁰⁶Cd targets have been studied by γ-ray and X-ray spectroscopy techniques behind a He-jet system. Mass identification of the products has been performed by coupling the He-jet to the medium current ion source of an isotope separator. Neutron-deficient nuclei with 137≦A≦144 have been identified. Decay schemes of several new isotopes as¹³⁸Eu (12s),¹⁴¹Gd (22s),¹⁴³Tb (12s and <17s),¹⁴⁴Dy (9s) and possibly¹⁴⁰Gd (11s) have been derived. New informations have also been provided for¹³⁷Sm (45s),¹³⁹Eu (24s) and¹⁴⁴Tb (5s). Data have been presented through systematics. The shapes of these nuclei and their trends versusN andZ have been analysed.     

Spin and parity of isomeric and ground states of the doubly-odd nucleus184Au

Low-spin states in doubly-odd¹⁸⁴Au have been populated in the ⁺/EC decay of¹⁸⁴Hg produced by bombarding¹⁸⁴Sm targets with an 185 MeV⁴⁰Ar beam. Radioactive Hg nuclei were transported by a He jet system. A new level scheme has been established from --t and X--t coincidence measurements. Spin and parity values I=5⁺, I =2⁺ and I=3^– were assigned to the ground state and the two isomeric states of¹⁸⁴Au, respectively. The structure of these states is discussed using B(E1) values.