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The lifetimes of excited states in neutron-rich nuclei around the doubly-magic nucleus 48Ca have been measured using a novel technique that combines the Recoil Distance Doppler Shift method with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. The experimental method will be discussed and the results for Ca nuclei will be compared with realistic simulations of the CLARA and PRISMA spectrometers. [ABSTRACT FROM AUTHOR]

Excited states in the very neutron-deficient122La nucleus have been established for the first time using the92Mo(40Ca, 2α1 p1 n) reaction at beam energies of 190 and 200MeV. The observed transitions were grouped in three bands. Configurations have been assigned to the observed bands based on the properties extracted from the experimental data and on cranked shell model calculations. [ABSTRACT FROM AUTHOR]

The neutron-deficient nucleus68As was populated at high spin in two experiments using the reaction40Ca(32S, 3pn) at beam energies of 105 and 95 MeV. A self-supporting and a gold-backed, highly enriched40Ca target were used. Gamma rays were detected with the EUROBALL array, combined with the charged-particle detector array EUCLIDES and the Neutron Wall. The68As level scheme was considerably extended, especially at negative parity and many previous spin-parity assignments were confirmed or rejected. The total-Routhian-surface (TRS) calculations find shape coexistence and ? softness for the negative- and positive-parity states, respectively. [ABSTRACT FROM AUTHOR]

We have studied the emission of light unbound clusters,8Be and12C *(0+2), in the reactions18O +13C ?{31} Si ?{23} Ne +8Be and28Si +24Mg ?{52} Fe ?{40} Ca +12C *(0+2). The ?-ray spectra obtained in coincidence with8Be and12C *(0+2) emission have been studied relative to the statistical emission of two or three a-particles. The angular-momentum-to-energy balance of the cluster emission is compared with that of multiple-a emission. The properties of the energy spectra of the binary process and the population of the residual nuclei by cluster emission are discussed. It is observed that cluster emission carries away less excitation energy on average than the sequential emission of the individual components. [ABSTRACT FROM AUTHOR]

High-spin states in 160,161,162Ho have been populated in the reactions 158,160Gd(7Li, xn) at 56 MeV. In all three isotopes the known rotational bands have been extended to significantly higher spin. In 160Ho, the band crossing in the π7/2- [523] × v11/2- [505] band has been observed for the first time. The sequences built on the proton 7/2- [523], 7/2+[404], 1/2+[411} and 1/2- [541] states in 161Ho have been extended up to spin 51/2-, 35/2+, 51/2+ and 41/2-, respectively, leading to the first observation of upbends in all four cases. In addition, a new band most probably belonging to this nucleus has been identified. In the most neutron-rich isotope 162Ho, the only known rotational band, which is built on the π7/2 [523] ⊗ v5/2+ [642] configuration, has been extended up to the 28- state. The properties of all observed bands are discussed and compared to the neighbouring isotopes. [ABSTRACT FROM AUTHOR]

We have studied the reactions 28Si + 24Mg ¯→52Fe→40Ca* + 3α as well as the binary channel 52Fe→40Ca* + 12C*, in order to search for deformed states, which form rotational bands in 40Ca. We observe positive- and negative-parity bands. The negative-parity band is proposed to be a partner of an inversion doublet with the positive-parity states being based on 4p-4h configurations. The properties of the positive-parity states are discussed on the basis of the shell model and the parity doublet on the basis of a cluster model with intrinsic reflection asymmetric shapes. [ABSTRACT FROM AUTHOR]

: Lifetimes of excited states in 148Gd were measured using the recoil distance method with a plunger device coupled to the EUROBALL Ge detector array. The differential decay curve method in coincidence mode allowed the unambiguous determination of lifetimes of more than 20 excited states. The obtained transition strengths are in good agreement with the shell model calculations. The effect of the Z = 64 subshell closure on the B(E2 : 2+ → 0+) reduced strengths above the N = 82 magic number is discussed.-1 [ABSTRACT FROM AUTHOR]

Excited states in 59Zn were observed for the first time following the fusion-evaporation reaction 24Mg + 40Ca at a beam energy of 60 MeV. The GASP array in conjunction with the ISIS Silicon ball and the NeutronRing allowed for the detection of γ-rays in coincidence with evaporated light particles. The mirror symmetry of 59Zn and 59Cu is discussed. [ABSTRACT FROM AUTHOR]

The first evidence for excited states in 95Ag is presented. 95Ag is the heaviest Tz = 1/2 nucleus for which gamma-rays have been identified. The reaction 40Ca(58Ni, 1p2n)95Ag was used in the experiment, which resulted in the assignment of three gamma-rays to 95Ag. A detector system consisting of the detector arrays Euroball, Neutron Wall and Euclides was used to detect gamma-rays, neutrons and charged particles, respectively. [ABSTRACT FROM AUTHOR]

The reactions 11B + 198Pt →209Bi* and 10B + 198Pt →208Bi* have been investigated by measuring low- and high-energy γ-rays and proton-γ coincidences. The nuclear temperature of the 208Pb populated by first-chance proton emission from 209Bi has been determined by using an unfolding technique. The extracted value, T = 1.6±0.2 MeV, is compared with predictions from various level density parametrisations in which the shell effects play different roles. The comparison shows that, as expected in this excitation energy range, the shell effects in 208Pb are substantially washed out. Proton and high-energy γ-ray spectra as well as neutron average multiplicities have been also compared with predictions from Statistical Model calculations making use of a constant ( a = A/10 MeV-1) or an excitation-energy-dependent level density parameter. The obtained results demonstrate that the high-energy γ-rays are more sensitive than protons to the level density variation with the excitation energy. However, Statistical Model calculations fail in reproducing satisfactorily the line-shape of the experimental γ-ray spectra, suggesting that the actual knowledge of the level densities in the 208Pb region is not sufficiently accurate. [ABSTRACT FROM AUTHOR]

High-spin states in 142Gd have been populated by means of the 99Ru(48Ti, 2p3n) reaction at 240 MeV and investigated with the γ-spectrometer EUROBALL III and the charged-particle detector array ISIS. The features of four dipole bands have been determined and compared with tilted-axis cranking model calculations indicating that they are magnetic rotational bands. A transition from regular to irregular bands has been found approaching N = 82 demonstrating that this is a general phenomenon in nuclei near a double-shell closure. [ABSTRACT FROM AUTHOR]

By using the fusion-evaporation reaction 28Si(36Ar,p3n) and spectroscopy of β-delayed γ-rays and charged particles on mass-separated sources, β-decay properties of the neutron-deficient isotope 60Ga were studied for the first time. The half-life of 60Ga was determined to be 70(15) ms, and, based on βγγ coincidences, the isobaric-analogue state in 60Zn was identified at 4851.9(7) keV. A semiempirical proton separation energy value of 40(70) keV was deduced for 60Ga. The experimental results on half-life, mass excess, proton separation energy, and structure of the 60Zn daughter states are discussed in comparison with various model predictions, including large-scale shell model calculations. [ABSTRACT FROM AUTHOR]

Gamma ray transitions de-exciting states in the N = Z nucleus 70Br have been identified for the first time using the GASP and EUROBALL arrays coupled with ancillary detectors. The level scheme of 70Br has been established by means of particle-gated γ-γ and γ-γ-γ coincidences. The Coulomb energy differences between isobaric analogue states in 70Br and 70Se show a deviation from the expected behaviour which could be related to dripline effects. [ABSTRACT FROM AUTHOR]

High-spin states in 178Ir were investigated by means of in-beam γ-ray spectroscopy techniques using the multidetector array GASP. Excited states of 178Ir were populated through the 159Tb(24Mg, 5n) fusion-evaporation reaction at E(24 Mg) = 131-141 MeV. Several rotational bands were observed. Among them, the π i13/2⊗ν i13/2 structure has been identified up to spin 36 ?. This band exhibits an anomalous signature splitting and a signature inversion around spin 25 ?. [ABSTRACT FROM AUTHOR]

The lifetime andthe γ-decay to the 0+ groundstate of the lowest 3− state in 148Gd has been determined. The reduced strength B(E3, 3− → 0+)=41 (6) W.u. agrees well with the theoretical value from empirical shell model calculations and can be directly compared with the 12+ → 9− two-octupole-phonon → one-octupole-phonon strength obtained in the same Recoil Distance Method lifetime measurement. The results of our search for a three octupole-phonon state built on the ( νf 7/2) state is also reported. [ABSTRACT FROM AUTHOR]

The structure of the N=Z nuclei60Zn,62Ga,64Ge, and72Kr has been investigated at GASP. Total Routhian surface (TRS) calculations have been performed for the N=36, 38 and 40 Kr isotones. In the case of72Kr the four quasi-particle g 9/2 alignment is observed to be significantly delayed in rotational frequency with respect to the heavier Kr isotopes. Such a delay contradicts the predictions of mean field calculations and may be viewed as the first sign of additional correlations in the T=0 pairing channel. [ABSTRACT FROM AUTHOR]

Very exotic shapes can be assumed for the nuclei at high angular momenta. Their study has become possible with the advent of the last generation high-resolution γ-ray spectrometers. In this talk results are presented on superdeformed nuclei of the A=140 mass region where a detailed spectroscopy in the second minimum is now possible. Hyperdeformed rotational bands, expected in the third minimum, lie at even higher spins where their observation is very difficult from the experimental point of view. We have up to now only weak signals of their presence. The status of the search for hyperdeformation in152Dy is reported. [ABSTRACT FROM AUTHOR]

Experimental data collected so far demonstrate that the population of superdeformed (SD) structures in nuclei with mass A∼150 is influenced by the asymmetry in the entrance channel of the reaction. Furthermore, evidences for the population of hyperdeformed (HD) structures in the same mass region have been obtained only when charged particles are emitted in the evaporation chain. Dynamical model calculations show that in the reactions used to populate SD bands the equilibration times of the compound nuclei are not very sensitive on the mass asymmetry of the entrance channel. A qualitative understanding of both phenomena (SD and HD) is obtained assuming a link between the population of evaporation residues at very high spin and the dynamical hindrance of fission. Recent experimental results obtained in this field at the GASP spectrometer are presented for the case of theDy nucleus populated in theCl+Sn reaction. Proton and alpha particle spectra in coincidence with SD structures have been obtained. A sizeable difference is evidenced between alpha particle spectra in coincidence with SD and normally deformed structures. [ABSTRACT FROM AUTHOR]

We have measured the high-energy γ-ray spectra from the fusion reactions 130 MeVO +Mo and 240 MeVTi +Ni, populating theSn andSn compound nuclei at the excitation energy of 110 MeV. The comparison of the spectra shows a ~36% enhancement of the α-ray yield in the Giant Dipole Resonance region ( E > 8 MeV) when the O-induced reaction is considered. This enhancement is interpreted as due to entrance channel effects related to the N/ Z asymmetry between the target and the projectile. [ABSTRACT FROM AUTHOR]

TheLi-induced incomplete fusion reactionGd(Li,p(d,t)xn) (beam energy 56 MeV) has been used to investigate in detail the first backbending region of the heavy stable Dy nucleiDy. InDy, the measured low interaction strength between the ground band and the Stockholm band of | V | ≈ 17 keV confirms the predicted existence of a node in the interaction strength for nuclei with neutron number between N = 96 and N = 98, which has not been accessed earlier. The crossing frequency between the ground band and the Stockholm band inDy was measured to be hw = 320 keV, which is about 40 keV higher than the expected value of hw = 280 keV known from other nuclei in this mass region. InDy, an yrare band could be established for the first time in a nucleus with a very large interaction strength. From fits to level energies as well as from branching ratios, an interaction strength of | V | ≈ 220 keV was extracted. [ABSTRACT FROM AUTHOR]

The quadrupole moments of highly deformed bands inNd andCe have been determined using the Doppler-shift attenuation method. The obtained Q0 values show no clear dependence on the number of occupied vi13/2 intruder orbitals. Cranked shell model calculations indicate that the charge-quadrupole moments of the highly deformed bands decrease with increasing spin. The expected increase in deformation induced by the vi13/2 orbital in the two bands ofNd is attenuated by a rotation-induced shrinking effect driving the nucleus towards smaller deformation. [ABSTRACT FROM AUTHOR]

The high-spin structure of deformed N = Z nuclei in f7/2 shell is presented. The experimental data obtained with the 4π γ-ray spectrometer is compared with large-scale shell model calculations. In odd-odd self-conjugate nuclei, both T = 0 and T = 1 band-like structures have been observed. [ABSTRACT FROM AUTHOR]

The even-even nucleus 128Nd was studied via in-beam γ-ray spectroscopy using the 40Ca + 82Mo reaction at 190 MeV. Two new bands were observed besides the yrast one, that has been extended up to spin 34+. Configurations were assigned to the three bands by analysing their rotational properties and by comparison with the neighboring even-even nuclei. [ABSTRACT FROM AUTHOR]

The even-even nucleus 122Ba was studied via in-beam γ-ray spectroscopy using the 40Ca + 92Mo reaction at 190 MeV. Five bands were observed, four more that can be found in the literature. Configurations were assigned to the various bands from the comparison with the neighboring even-even nuclei. [ABSTRACT FROM AUTHOR]

The ridge structure with ΔEγ=±30 keV, observed in the past in coincidence with protons emitted in the reaction 187 MeV 37Cl +120Sn and attributed to an hyperdeformed nuclear shape in 152Dy, has been studied in a new experiment performed with the EUROBALL III array. The ridge is now observed in coincidence with transitions in the yrast superdeformed band of 152Dy but no discrete rotational bands have been identified. [ABSTRACT FROM AUTHOR]

The 178Pt and 181Au nuclei have been studied with the (230 MeV) 46Ti +142Nd fusion-evaporation reaction; γ-rays, evaporated particles and recoiling nuclei have been detected by the γ-array GASP + the Si ball ISIS + the recoil mass spectrometer RMS. The newly observed structures in 178Pt and 181Au are most probably built on the proton and quasi-proton h9/2 and i13/2 configurations. [ABSTRACT FROM AUTHOR]

Recent inclusive measurements on multinucleon transfer reactions reveal important information on the interplay between single-particle and nucleon pair degrees of freedom. More detailed studies are being performed with the new magnetic spectrometer PRISMA, coupled to the CLARA γ-array. [ABSTRACT FROM AUTHOR]

The highly sensitive GASP array at the INFN Legnaro Laboratory was used to study the γ-ray de-excitation of neutron-rich nuclei produced in the deep-inelastic processes which occur when 230 MeV 36S ions interact with a target of 176Yb. Yrast decay schemes were identified in over forty target-like fragments and in over twenty projectile-like fragments. Analysis of the data has resulted in extensions to the yrast decay sequences of the target-like species, 176Hf, 166Er, 172Yb, and 152Sm. New transitions have also been observed in a number of projectile-like species including 34P and 41Cl. Experimental results are compared with the results of shell model calculations. [ABSTRACT FROM AUTHOR]

The feasibility of the entire process of γ-ray tracking is demonstrated experimentally for the first time. The accuracy of the results is tested by the capability for Doppler correction of γ-rays emitted in flight. The resolution of the 847.8 keV (2+ → 0+) transition detected with the MARS detector after Coulomb excitation of a 56Fe beam could be improved from 15 KeV to below 5 KeV (FWHM). [ABSTRACT FROM AUTHOR]

To study basic properties of the fusion reaction dynamics for heavy compound systems the partial-wave distribution σell can be employed as an alternative to the classically used fusion/fission excitation functions. A variety of reactions leading to compound nuclei (CN) in the Pb region can be used to investigate features like the fusion-fission competition, the role of deformation in the fusion of heavy systems and a possible effect of the Z 82 shell on the enhancement of evaporation residue (ER) production. [ABSTRACT FROM AUTHOR]

The nucleus 84Nb has been studied with the 58Ni(28Si,pnγ) reaction at 90 MeV. Several rotational structures are established and connected to an irregular low-energy level scheme which includes one isomeric level whose decay was observed before. [ABSTRACT FROM AUTHOR]

Two-phonon γ-vibrational states in166Er have been populated using Coulomb excitation. The Kπ=4+ component of the vibration appears to be fragmented over several states, whereas only one Kπ=0+ state is observed. [ABSTRACT FROM AUTHOR]

The structure of Sn has been investigated through the Cr(Ni,2pn) reaction at a beam energy of 210 MeV. In addition to an extension of the spherical level scheme, a regular sequence of dipole transitions has been found. The experimental results are in agreement with the prediction of Tilted Axis Cranking calculations, which satisfactorily explain the properties of the band. [ABSTRACT FROM AUTHOR]