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PRISMA is a magnetic spectrometer installed at Laboratori Nazionali di Legnaro (Italy) and designed for A=100–200, E=5–10 MeV-per-nucleon beams, and for possible use with the proposed radioactive beam facility SPES. The foremost features of the instrument are presented, along with the outline of two data analyses exemplifying the effectiveness of PRISMA-CLARA in studies of reaction dynamics.

Abstract.: The CLARA-PRISMA experimental set-up combines the large acceptance magnetic spectrometer for heavy ions PRISMA with the highly efficient CLARA array of 25 Clover detectors. Selected results on the structure of neutron-rich nuclei, populated in multinucleon transfer and deep-inelastic reactions, are presented here. Some technical developments of the setup are also discussed.

The CLARA-PRISMA experimental set-up combines the large acceptance magnetic spectrometer for heavy ions PRISMA with the highly efficient CLARA array of 25 Clover detectors. Selected results on the structure of neutron-rich nuclei, populated in multinucleon transfer and deep-inelastic reactions, are presented here. Some technical developments of the setup are also discussed.

Neutron-rich sdf-shell nuclei have attracted a great deal of international interest, both theoretically and experimentally. There is an increasing interest in using deep-inelastic reactions to obtain spectroscopic information about these exotic nuclei. New results obtained from two such experiments are presented here. The highly sensitive GASP array was used to measure the γ decays of previously unobserved yrast and near yrast states of 34P which were populated when 230 MeV 36S ions were incident on a thick target of 176Yb. In addition, a recent investigation of the spectroscopy of neutron-rich P and S isotopes has been undertaken with 215 MeV 36S ions incident on a thin target of 208Pb using the CLARA Ge detector array in conjunction with the PRISMA magnetic spectrometer. Preliminary results from this experiment are presented here.

Several nuclei in the A ∼ 190 region have been studied following deep-inelastic reactions using a 460 MeV 82Se projectile impinging upon a thick 192Os target. The GASP array (at the Legnaro National Laboratory in Italy) was used to measure the resulting γ-decays. The previously reported near-yrast structure of 191Os is extended to a isomer, at an energy of 2640 keV. Branching ratios for ΔI = 1 and ΔI = 2 transitions in the band have been measured, giving |(gK − gR)/Q0| = 0.022(3) and 0.024(7) for transitions from the and states respectively. These are consistent with the theoretical calculation for the proposed ν11/2+[615] configuration of the band. Nilsson plus BCS calculations reveal that the isomer is likely to have a {ν11/2+[615] ⊗ π11/2−[505] ⊗ π9/2−[514]} configuration with . This yields an implied reduced hindrance of fν= 1.9, in accordance with empirical systematics of K isomers in the A ∼ 180–190 region.

Fusion and incomplete fusion evaporation channels were studied in the 7Li +164Dy reaction at the INFN Laboratory, Legnaro, Italy. The Tandem-XTU accelerator was used to accelerate a beam of 7Li ions to 55 MeV. The highly sensitive GASP γ-detector array coupled with the selectivity of the ISIS charged particle ΔE–E telescope array provided a powerful tool for studies of high spin states in the fusion and incomplete fusion reaction products. Rotational sequences in the Er and Tm isotopes around A = 166 have been observed and extended to higher spin states. Comparisons of the experimental data with the results of the cranked shell model give some insight into the configuration dependence of the crossing of the ground-state band with the aligned i13/2 two quasineutron configuration.

CLARA is an array of 25 Clover (EUROBALL type) Ge detectors, placed at the target position of the large acceptance magnetic spectrometer PRISMA. Due to the granularity of the CLARA Ge array (100 crystals), the photopeak efficiency (≈3%) and the PRISMA large acceptance (≈80 msr, and 20% Δp/p), the setup is an excellent tool to investigate the structure of neutron-rich nuclei, populated in multinucleon transfer reactions and deep inelastic collisions with stable beams. Since March 2004 the setup is fully operational, and since then several experiments have been performed, with beams delivered by the LNL XTU-Tandem and the ALPI linac. In this contribution the preliminary outcome of the first experiments is shown.

Based on the energy spectra and relative transition probabilities 176,178,180Os turned out to be very promising candidates for testing the features of the critical point symmetry X(5). In order to also test absolute transition probabilities predicted in the framework of the X(5) symmetry lifetime measurements were performed at the Cologne FN tandem accelerator. The lifetimes of the first 2+ states in 176,178,180Os were measured using electronic timing and in the case of 178Os with the recoil distance Doppler shift (RDDS) technique using an 16O-induced fusion evaporation reaction. In addition, a coincidence RDDS measurement was performed at the Laboratori Nazionali di Legnaro with the GASP spectrometer using the 154Sm(29Si,5n)178Os reaction. The deduced transition quadrupole moments agree well with the X(5) predictions, thus further supporting an X(5) structure for 178Os. The experimental data for 178Os are compared to calculations in the framework of the interaction boson model (IBM) and of the general collective model (GCM).

High-spin states in the doubly odd N = 77 nucleus ¹³²Cs have been studied. Gamma-ray linear polarization and angular correlation measurements have been performed to determine the spin and parity of the states. A rotational sequence of enhanced dipole transitions was established. This band can be described within the framework of the the tilted axis cranking (TAC) model as a band based on a weakly deformed structure in which the total angular momentum vector does not coincide with any of the principal axes of the triaxial nucleus but still is in the plane defined by the short and long axes. The theoretical description of the previously proposed chiral bands in ¹³²Cs was extended in the framework of the core–particle coupling model (CPCM) confirming that the total angular momentum for the πh_11/2 ⊗ νh_11/2 configuration is well outside any planes defined by the principal axes of the nucleus and revealing the important role of the residual proton–neutron interaction between the valence particles.

Abstract:: 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:: The first evidence for excited states in 95Ag is presented. 95Ag is the heaviest T z = 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:: 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/10MeV -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:: 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:: 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.: 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:: 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 πi 13/2⊗νi 13/2 structure has been identified up to spin 36 ?. This band exhibits an anomalous signature splitting and a signature inversion around spin 25 ?.

Abstract:: The lifetime and the -decay to the 0+ ground state 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 state is also reported.

Abstract.: PRISMA is a magnetic spectrometer installed at Laboratori Nazionali di Legnaro (Italy) and designed for A=100–200, E=5–10 MeV-per-nucleon beams, and for possible use with the proposed radioactive beam facility SPES. The foremost features of the instrument are presented, along with the outline of two data analyses exemplifying the effectiveness of PRISMA-CLARA in studies of reaction dynamics.

PRISMA is a magnetic spectrometer installed at Laboratori Nazionali di Legnaro (Italy) and designed for A=100?200, E=5?10?MeV-per-nucleon beams, and for possible use with the proposed radioactive beam facility SPES. The foremost features of the instrument are presented, along with the outline of two data analyses exemplifying the effectiveness of PRISMA-CLARA in studies of reaction dynamics.

Abstract:: 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:: 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:: 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.: 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:: 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.

The structure of 105Sn has been investigated through the 50Cr(58Ni,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.