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Cross-sections of the main reaction channels for the collision Ne + Pb at 7.9MeV/u were studied using the radioactive ion beam delivered by the SPIRAL facility and the VAMOS-EXOGAM experimental set-up. Angular distributions for the elastic and inelastic channels were extracted, together with distributions for the +1 n and -1 p channels. A comprehensive description of the present data is made within the GRAZING model approach. [ABSTRACT FROM AUTHOR]

The odd-odd 88 37Rb51 and 86 35Br51 nuclei have been produced as fission fragments in the fusion reaction 18O$ + $208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the triple $ \gamma$ -ray coincidence data and $ \gamma$ - $ \gamma$ angular correlations have been analyzed in order to assign spin and parity values to many observed states. The proposed configurations involve proton excitations from three sub-shells located close to the Fermi levels, $ \pi$ p3/2 , $ \pi$ f5/2 , and $ \pi$ g9/2 , the $ \nu$ d5/2 neutron acting as a spectator. The residual $ \pi$ $ \nu$ interactions are extracted from the multiplets of states resulting from the $ \pi$ p3/2 $ \nu$ d5/2 and $ \pi$ f5/2 $ \nu$ d5/2 configurations. The empirical values of the latter are discussed and compared to those known in two similar configurations having jp = jn with lp = ln + 1 , where the role of the tensor force had been highlighted. [ABSTRACT FROM AUTHOR]

The 81, 82, 83, 85Se nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the triple $ \gamma$ -ray coincidence data and $ \gamma$ - $ \gamma$ angular correlations have been analyzed in order to assign spin and parity values to many observed states. The lowest-spin states of the two-neutron and three-neutron configurations are strongly mixed with two-proton excitations among the fp orbits. On the other hand, the highest-spin states of these neutron configurations are found to remain almost pure. Neutron excitation across the N = 50 gap is observed both in 83Se49 and in 85Se51 . [ABSTRACT FROM AUTHOR]

High-spin states in the 142Ce and 140Ba nuclei have been populated in the 12C + 238U and 18O + 208Pb fusion-fission reactions at 90MeV and 85MeV bombarding energy, respectively. The emitted γ -radiation was detected using the Euroball III and IV arrays. The high-spin yrast and near-to-yrast structures of 142Ce have been considerably extended. The level scheme of 140Ba has been extended by six new levels. The newly observed structures in these N = 84 isotones are discussed by analogy with the neighbouring nuclei. [ABSTRACT FROM AUTHOR]

Independent fission fragment yields have been obtained for the six fragment pairs ( Z L/ Z H = 44/46 , 42/48, 40/50, 38/52, 36/54 and 34/56) in 208Pb(18O, f ) at the beam energy E = 85 MeV. γ -ray spectroscopy technique was applied to analyze the experimental data. With use of these data the mass distribution of fission fragments was restored. Data on average fragment spin distribution and total neutron multiplicity are presented. The agreement of the obtained results with other experimental data proves the validity of the applied method to solve this kind of problems. [ABSTRACT FROM AUTHOR]

The 84, 85Br nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85MeV bombarding energy and studied with the Euroball IV array. The high-spin states of the odd-odd 84Br nucleus have been identified for the first time, the observed structure being built on the known 6- isomeric state. High-spin states of 85Br have been observed up to 5.4MeV excitation energy and spin I ∼ 21/2. From angular correlation analysis, spin values have been assigned to most of the 85Br excited states up to 4MeV. None of these excited states has been found to exhibit a delayed decay having T 1/2 > 10ns. All the observed states in 84, 85Br can be described by various proton excitations involving at least the two sub-shells ( π f 5/2 and π p 3/2) located just above the Z = 28 shell closure. [ABSTRACT FROM AUTHOR]

The 87Kr nucleus has been produced as fission fragment in the fusion reaction 18O + 208Pb at 85MeV bombarding energy and studied with the Euroball IV array. High-spin states of this neutron-rich isotope have been identified for the first time. Its level scheme has been obtained up to 6.3MeV excitation energy and spin I ∼ 23/2ℏ. Its structure is interpreted by analogy with those of the heavier isotones. The proposed configurations involve both proton and neutron excitations from several sub-shells located close to the Fermi levels, particularly ν d 5/2, π p 3/2 f 5/2 and π g 9/2. Moreover, a revised spin value of 5/2- for the 87Br ground state is proposed. [ABSTRACT FROM AUTHOR]

High-spin states of the N = 87 nuclei, 147Nd and 145Ce, have been populated in the 12C + 238U and 18O + 208Pb fusion-fission reactions at 90 MeV and 85 MeV bombarding energy, respectively. The emitted γ-radiation was detected using the Euroball III and IV arrays. High-spin states of the 147Nd isotope have been identified for the first time. The high-spin yrast and near-to-yrast structures of the 145Ce nucleus have been considerably extended. The newly observed structures, discussed by analogy with the neighbouring isotones, show the coupling of an h 9/2 neutron to the quadrupole and octupole excitations of the core. [ABSTRACT FROM AUTHOR]

The84Se nucleus has been produced as fission fragment in the fusion reaction18O +208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Medium-spin states of this neutron-rich isotope have been identified for the first time. Its level scheme has been obtained up to 4.9MeV excitation energy and spinI~ 7?. Its structure is interpreted by analogy with those of the stable heavier isotones. The evolution of the energy of theN= 50 neutron-core excitation is discussed as a function of the proton number. [ABSTRACT FROM AUTHOR]

High-spin states from the three-quasiparticle (3qp) configuration &paig9/2vh211/2 in the neutronrich 49In isotopes have been studied in the framework of shell model calculation. The two-body residual interactions needed for such calculations have been extracted from the level schemes of neighbouring nuclei. In particular, the evolution of the proton-neutron &paig9/2vh211/2 interaction has been analyzed as a function of the neutron number. When the gradual filling of the vh211/2 sub-shell is taken into account, the results of the 3qp configuration calculations are found to be very close to the experimental positive-parity yrast states located above 2 MeV excitation energy in 113-121In. Moreover, several long-lived isomeric states with positive parity are predicted in 123, 125, 127In. [ABSTRACT FROM AUTHOR]

High-spin states in 108,110Pd isotopes are studied by γ-ray spectroscopy of heavy-ion-induced fission. The Pd isotopes are produced in the fission channel of the 31P + 176Yb reaction at beam energy 152 MeV. The prompt γ-rays are detected with the EUROBALL4 multidetector array. The yrast states of 108,110Pd have been observed above the region of the first backbend. The level scheme of 108Pd was extended with a new negative-parity band. The yrast sequence in 110Pd is observed up to spin I = 14+ and negative-parity bands have also been identified. The back bending in these even-mass Pd isotopes is associated with the alignment of the neutron (h11/2)² pair. The negative-parity states arise from two neutron configurations vh11/2 ⊗ vg7/2 and vh11/2 ⊗ vd5/2 and they are interpreted in the frame of two-quasiparticle + rotor model as semidecoupled bands. The observed experimental staggering in the γ-bands of 108,110Pd supports the theoretical predictions for γ-instability of their shapes. [ABSTRACT FROM AUTHOR]

The 110,112 Rh and 114',16Ag nuclei have been produced as fission fragments in the fusion reaction 18 + 208Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of these neutron-rich nuclei have been identified for the first time. The yrast structures consist of rotational bands in which the odd proton occupies the πg9/2 sub-shell and the odd neutron the vh11/2 sub-shell. The evolution of the πg9/2 ® vh11/2 band structure is analyzed as a function of the neutron number. [ABSTRACT FROM AUTHOR]

The 106, 108Rh and 110, 112Ag nuclei have been produced as fission fragments following the fusion reaction 28Si + 176Yb at 145 MeV bombarding energy and studied with the Eurogam2 array. The yrast high-spin states of these four odd-odd nuclei, which are observed for the first time, consist of rotational bands in which the odd proton occupies the π g9/2 subshell and the odd neutron the ν h11/2 subshell. Their behaviour as a function of spin values does not vary with the number of neutrons: as observed in the odd- N neighbouring nuclei, the motion of the odd neutron remains decoupled from the motion of the core, from N = 61 to N = 65. Moreover, the staggering observed in the yrast bands of odd-odd isotopes is strongly reduced as compared to the large values displayed by the rotational bands built on the π g9/2 subshell in the odd- A Rh and Ag isotopes. The results of particle-rotor calculations indicate that this reduction is related to a change of the core deformation. [ABSTRACT FROM AUTHOR]

The 109,111,113Rh nuclei have been produced as fission fragments in the fusion reaction 18O + 208Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of the neutron-rich 111,113Rh nuclei have been identified for the first time. Several rotational bands with the odd proton occupying the π g9/2, π p1/2 and π( g7/2/ d5/2) sub-shells have been observed. A band of low-energy transitions has been identified at excitation energy around 2 MeV in 109,111Rh, which can be interpreted in terms of three-quasiparticle excitation, π g9/2ν h11/2ν g7/2/ d5/2. In addition another structure built on states located at low excitation energy (608 keV in 111Rh, 570 keV in 113Rh) points out that, as already observed in the lighter isotopes 107,109Rh, triaxial deformation plays a role in the neutron-rich Rh isotopes well beyond the mid-shell. [ABSTRACT FROM AUTHOR]

High-spin states of 103 43Tc have been identified for the first time, this nucleus being produced as fission fragment following the fusion reaction 37Cl + 176Yb at 170 MeV bombarding energy. The high-spin level scheme has been built from the prompt gamma rays detected using the Euroball III array. It exhibits similarities with those of the neighbouring isotopes and isotones. All the band head configurations observed in the 97-105Tc isotopes are identified from the behaviour of the rotational bands built on them. The single-proton states located around the Fermi level are discussed as a function of deformation of these nuclei. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This work has established eight cross-talk transitions between the two signature partner superdeformed (SD) bands in 197Pb with the EUROBALL IV spectrometer. Directional correlations from oriented states measurements confirm the Δ I = 1 character of these transitions. The flat behaviour of the dynamical moment of inertia and the agreement between the experimental and microscopic HF+BCS values of ( gK - gR) K/ Q0 suggest that the configuration of the SD bands is based upon the υ[752]5/2- neutron intruder orbital. The derived effective spin gyromagnetic factor gs eff is found to be not quenched, and is close to the theoretical gs free value. [ABSTRACT FROM AUTHOR]

High-spin states in 113-116Cd have been investigated with the fusion-fission reaction 28Si +176Yb at 145 > MeV. The experiment has been performed with the Eurogam2 array. New rotational bands based on two quasi-particle states have been observed for even-even cadmium isotopes. A new level scheme based on the 11/2− isomeric state is proposed for 115Cd and the one of 113Cd has been extended to spin (31/2−). The decoupled bands identified in both odd-A nuclei are interpreted as being built upon a low-Ωh11/2 quasi-neutron configuration. Microscopic Hartree-Fock + BCS calculations confirm the prolate deformation in this mass region especially for the odd cadmium isotopes. [ABSTRACT FROM AUTHOR]

New band structures have been observed in 112Pd, 113Pd, 115Pd and 118Pd produced via the fusion-fission reaction 12C+238U at a bombarding energy of 90 MeV. γ-γ-γ coincidence measurements have been performed with the Euroball III array. The first crossings observed in even-mass palladium up to A=118 are interpreted as the alignment of a ν h11/2 pair. This interpretation is supported by the rotational behavior of odd-mass palladium. Hartree-Fock-Bogoliubov calculations using D1S-Gogny force suggest a similar interpretation consistent with a prolate deformation. [ABSTRACT FROM AUTHOR]

By using the IGISOL technique, adapted for the study of products of heavy ion induced fusion-evaporation reactions, it has been possible to identify a new isomer in the mass chain A=125. [ABSTRACT FROM AUTHOR]

Residual activities produced viaCl orS beams in thinSn andCd 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 asEu (12 s),Gd (22 s),Tb (12 s and <17 s),Dy (9 s) and possiblyGd (11 s) have been derived. New informations have also been provided forSm (45 s),Eu (24 s) andTb (5 s). Data have been presented through systematics. The shapes of these nuclei and their trends versus N and Z have been analysed. [ABSTRACT FROM AUTHOR]

The nucleusPb was populated via theEr(Si,5n) reaction at a beam energy of 159 MeV and studied with the EUROGAM II spectrometer. Five new dipole ΔI=1 cascades have been found. These structures have been connected to the level scheme which has been considerably extended up to a spin of 61/2 ℏ and an excitation energy of about 8 MeV. Angular distribution coefficients, α , have been measured and confirm the dipole character of the in-band transitions. B(M1)/B(E2) ratios have been extracted for the two most intense cascades. ThePb dipole bands are discussed in comparison with those known in odd lead isotopic series and the structure of the band heads is analyzed in terms of microscopic HF-BCS calculations. The proposed configurations are based on a high- K two quasiproton excitation, π([505]9/2⊗[606]13/2)=11, coupled to one or three rotation aligned quasineutrons involving the i , p , f and/or h subshells. The main difference, compared with the heavier lead isotopes, is the presence of large Ω orbitals from the ν ( i ) shell near the Fermi surface which are responsible for the increasing band-head spin as A decreases. [ABSTRACT FROM AUTHOR]

Lifetimes of ten states with spins between 23 and 32 have been measured in a cascade of dipole transitions inHg using the Doppler-shift recoil-distance method. Average reduced transition probabilities, deduced from the lifetimes, are B(M1)≈0.01 and 1.1 µ in the lower and higher spin region of the cascade, respectively, and B(E2)≈0.13 (eb). The jump in the B(M1) values can be explained by different multi-quasiparticle configurations in the lower and higher spin regions of the band. [ABSTRACT FROM AUTHOR]

TheHg nucleus was populated in theGd(S, 4n) reaction at a beam energy of E=159 MeV. Emitted γ-rays were detected with the EUROGAM array comprising 43 Compton-suppressed large volume Ge detectors. The level scheme ofHg has been extended up to an excitation energy of E=10.4 MeV and spin I=34 ħ. Two new structures, made of competing ΔI=1 and ΔI=2 transitions have been observed and their connexions with the low-lying levels established. Their lowest levels are located at 6.304 MeV and 6.879 MeV excitation energy. The experimental results are compared with mean-field HF+BCS calculations. It is proposed that the new structures originate from deformation-aligned quasi-proton excitations π(i * h) and π (h), coupled to rotation-aligned quasi-neutron ν(i) and quasi-proton π(h) excitations. [ABSTRACT FROM AUTHOR]

The β-decays ofIr have been studied using a Hejet system throughS induced reactions, β half-lives have been measured and compared with those given from α decays. The level schemes of osmium nuclei are deduced and forOs andOs, the 2 level is possibly located. The observed β-decay half-lives clearly indicate an isomerism phenomenon occuring in light Ir isotopes. [ABSTRACT FROM AUTHOR]

Three high energy γ rays have been observed to connect the two yrast signature-partners superdeformed bands in 193Tl to the normal deformed states. Thereby, both excitation energy and spin of these bands are proposed for the first time in an odd-proton nucleus. [ABSTRACT FROM AUTHOR]

Isomeric states have been observed in fission-fragments produced by spontaneous fission of 252Cf. These states are found in neutron rich nuclei of different structure and deformations. About 50 isomeric nuclei have been observed using coincidences between γ-rays identified in EUROGAM II and fission fragments detected in photovoltaic cells (SAPhIR). Lifetimes in the range from 20 ns to 2μs have been measured. Presented calculations based on HFB +D1S force on new measured isomeric states in the 152,154,156Nd show evidence for K-isomers. [ABSTRACT FROM AUTHOR]

The 99−105Tc isotopes have been produced at high spin as fission fragments following the fusion reaction 37Cl(170 MeV) + 176Yb and studied with the Euroball3 array. The high-spin structures of 103Tc have been identified for the first time. From the systematics of the yrast states of 97−105Tc, the location of individual proton states can be analyzed as a function of the neutron number. [ABSTRACT FROM AUTHOR]

We report the results of an experiment, realized with the EUROBALL IV spectrometer, in which superdeformed (SD) states have been populated in 197,198Pb nuclei. Crosstalk transitions between two signature partner SD bands in 197Pb have been observed with an established Mi character, giving access to the magnetic properties of the v[752]5/2 intruder orbital. Six new SD bands have been identified in 197,198Pb. The results are interpreted in the framework of cranked Hartree-Fock calculations. A mixing between quasi-particle excitations and an octupole vibration is suggested in the two SD isotopes. [ABSTRACT FROM AUTHOR]

Levels in 125La have been studied via β+/EC decay of on-line mass-separated 125Ce using the HIGISOL technique. A new (390 ± 40) ms isomer is definitely attributed to 125La by conversion electron measurements of the 107 keV E3 isomeric transition. [ABSTRACT FROM AUTHOR]

Even-A praseodymium activities have been produced and identified in theCa +Mo reactions at 5.8 MeV/u:Pr[T=(3.0 ±0.4)s]Pr[T=(3.1 ±0.3)s],Pr[T =(40.0 ±0.4)s]Pr[T=1.6 min]. Several new low-energy levels have been populated in even-even cerium nuclei. [ABSTRACT FROM AUTHOR]

The nucleus Pb was populated via the Er(Si, 5n) reaction at a beam energy of 159 MeV and studied with the EUROGAM II spectrometer. Five new dipole ΔI = 1 cascades have been found. The Pb dipole bands are discussed in terms of microscopic HF+BCS calculations. The proposed configurations are based on a high-K two-quasiproton excitation coupled to rotation aligned quasineutrons. Parallel to the dipole bands the six superdeformed bands have been discussed in the framework of microscopic mean-field calculations. The bands are interpreted as three pairs of signature partners based on quasineutron excitations. Cross-talk transitions linking two signature partner superdeformed bands have been observed and, for the first time in lead isotopes, a mean B(M1)/B(E2) ratio value of 0.15±0.04 μ/e has been extracted. [ABSTRACT FROM AUTHOR]

We have carried out an experiment using the reactionEr (Si, 5n)Pb at a beam energy of 159MeV with EUROGAM 2 to study the superdeformed (SD) bands inPb. We have observed some discrete γ rays which are possible candidates for links between the yrast SD band and the low-lying levels in this odd lead isotope. These data suggest for the lowest state of the SD band 1 an excitation energy of 4217±2 keV and a spin of (23/2). [ABSTRACT FROM AUTHOR]

A discrete γ-ray transition with an energy of 3360.6 keV deexciting the second lowest SD state inEu has been discovered. It carries 3.2% of the full intensity of the band and feeds into a nearly spherical state which is above the I=35/2, E=4947 keV level. The exact placement of the single-step link is, however, not established due to the specially complicated level scheme in the region of interest. The energy of the single-step link agrees well with the previously determined two-step links. [ABSTRACT FROM AUTHOR]

A controversy has arisen over the existence, or not, of a superdeformed rotational band inPb. We have carried out an experiment using theEr(Si, 6n)Pb reaction at 159 MeV and have observed the coincident γ rays in the EUROGAM 2 spectrometer. We confirm the original result of Henry et al. that a superdeformed band exists inPb. [ABSTRACT FROM AUTHOR]

Internal conversion coefficients have been determined from online measurement of electron- and y- ray emission related to the dipole transitions in the so-called oblate collective bands inPb. The results strongly support the M1 (or M1+E2) character of these transitions. [ABSTRACT FROM AUTHOR]

The nucleus Pb was populated via the W( O,6n) Pb reaction at beam energies of 98 and 110 MeV. Two regular Δ I=1 bands of magnetic dipole transitions have been found. Possible interpretations in terms of collective oblate configurations involving high-K proton orbitals coupled to three i neutrons are discussed. The similarities between several of the bands discovered inpb nuclei are emphasized. [ABSTRACT FROM AUTHOR]