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International audience; Target properties such as thickness and composition are essential ingredients in nuclear physics experiments, therefore, dedicated analyses to evaluate them before and/or after the measurement are often performed. In some experimental techniques, the exploited detectors allow for the evaluation of these properties on-line, i.e. directly during the experiment. In this paper, we report on the use of analysis methods coming from the Rutherford backscattering spectroscopy technique to obtain on-line information on the target used in a nuclear physics experiment. This measurement was performed at INFN LNL by exploiting the low-energy Coulomb excitation technique. The results have been compared with an independent Rutherford backscattering spectroscopy analysis of the same target performed at INFN LABEC in Florence.

The GALILEO array is a high-efficiency γ -ray spectrometer, resident at the Legnaro National Laboratory (LNL)in Italy, and it is currently used in combination with the Si-ball EUCLIDES for the detection of charged-particles. The combined setup was used in the 6 Li+89Y experiment with incident energies of 22 MeV and 34 MeV to investigate the influence of breakup and transfer of weakly bound projectile on the fusion process. Using the coincidence by the charged particles and γ -rays, the different reaction channels can be clearly identified and the different reaction mechanisms can be clearly studied. It is shown that this facility can be used well to explore the fusion reaction mechanisms induced by weakly bound nuclei.

L. Pellegri et al. ; 5 pags. ; 6 figs. ; open access article under the CC BY license. Funded by SCOAP3, © 2014 The Authors. The γ decay from the high-lying states of 124Sn was measured using the inelastic scattering of 17O at 340 MeV. The emitted γ rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented δE-E silicon telescopes. The angular distribution was measured both for the γ rays and the scattered 17O ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with (γ, γ') and (α, α'γ) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1- excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density., Grant No. 2011/03/B/ST2/01894; (iii) the National Superconducting Cyclotron Laboratory at MSU; (iv) the US NSF Grant PHY-1204486; and the German BMBF under Grant 06KY9136.

Position sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ - spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined.

The main objective of the Advanced GAmma Tracking Array (AGATA) is the investigation of the structure of exotic nuclei at the new generation of RIB facilities. As part of the preparatory phase for FAIR-NUSTAR, AGATA is going to be installed at the FRS fragmentation facility of the GSI centre for an experimental campaign to be performed in 2012 and 2013. Owing to its γ - ray tracking capabilities and the envisaged enhancement in resolving power, a series of in-flight γ - ray spectroscopy experiments are being planned. The present work describes the conceptual design of this first implementation of AGATA at GSI-FRS, and provides information about the expected performance figures. According to the characteristics of each particular experiment, it is foreseen that the target–array distance is adjusted in order to achieve the optimum compromise between detection efficiency and energy resolution, or to cover an specific angular range of the emitted electromagnetic radiation. Thus, a comprehensive Monte Carlo study of the detection sensitivity in terms of photopeak efficiency, resolution and peak-to-total ratio, as a function of the target–array distance is presented. Several configurations have been investigated, and MC-calculations indicate that a remarkable enhancement in resolving power can be achieved when double-cluster AGATA detectors are developed and implemented. Several experimental effects are also investigated. This concerns the impact of passive materials between the target and the array, the angular distribution of the detection efficiency and the influence of target thickness effects and transition lifetimes in the attainable detection sensitivity. A short overview on half-life measurements via lineshape effects utilizing AGATA is also presented.

The level structures of the N = 50 83As, 82Ge, and 81Ga isotones have been investigated by means of multi-nucleon transfer reactions. A first experiment was performed with the CLARA–PRISMA setup to identify these nuclei. A second experiment was carried out with the GASP array in order to deduce the γ-ray coincidence information. The results obtained on the high-spin states of such nuclei are used to test the stability of the N = 50 shell closure in the region of 78Ni ( Z = 28 ). The comparison of the experimental level schemes with the shell-model calculations yields an N = 50 energy gap value of 4.7(3) MeV at Z = 28 . This value, in a good agreement with the prediction of the finite-range liquid-drop model as well as with the recent large-scale shell model calculations, does not support a weakening of the N = 50 shell gap down to Z = 28 .

The differential Recoil Distance Doppler Shift (RDDS) method after multinucleon transfer (MNT) reactions to measure lifetimes of excited states in neutron-rich nuclei requires the use of a thick energy degrader for the recoiling ejectiles that are then detected in a spectrometer. This type of measurements greatly benefits from the use of the new generation segmented γ-ray detectors, such as the AGATA demonstrator which offers unprecedented energy and angular resolutions. In order to make an optimized choice of the material and the thickness of the degrader for lifetime measurements using the RDDS method after MNT, an experiment has been performed with the AGATA demonstrator. Counting rate measurements for different degraders are presented.

WOS: 000269865500014, Crosstalk effects of 36-fold segmented, large volume AGATA HPGe detectors cause shifts in the gamma-ray energy measured by the inner core and outer segments as function of segment multiplicity. The positions of the segment sum energy peaks vary approximately linearly with increasing segment multiplicity. The resolution of these peaks deteriorates also linearly as a function of segment multiplicity. Based on single event treatment, two methods were developed in the AGATA Collaboration to correct for the crosstalk induced effects by employing a linear transformation. The matrix elements are deduced from coincidence measurements of gamma-rays of various energies as recorded with digital electronics. A very efficient way to determine the matrix elements is obtained by measuring the base line shifts of untriggered segments using gamma-ray detection events in which energy is deposited in a single segment. A second approach is based on measuring segment energy values for gamma-ray interaction events in which energy is deposited in only two segments. After performing crosstalk corrections, the investigated detector shows a good fit between the core energy and the segment sum energy at all multiplicities and an improved energy resolution of the segment sum energy peaks. The corrected core energy resolution equals the segment sum energy resolution which is superior at all folds compared to the individual uncorrected energy resolutions. This is achieved by combining the two independent energy measurements with the core contact on the one hand and the segment contacts on the other hand., German BMBF [06KY2051]; European funding bodies; EU [R113-CF-2004-506065], This research was supported by the German BMBF under Grant 06KY2051. AGATA was supported by the European funding bodies and the EU Contract R113-CF-2004-506065.

The Pulse Shape Analysis algorithm “Recursive Subtraction” has been applied to data acquired during the in-beam tests of two different highly segmented HPGe detectors. This algorithm processes the net charge signal, determining the number of interactions per segment and their radial coordinates. The RS algorithm performances are evaluated by comparing the results obtained following its application to experimental pulse shapes with those obtained with specific GEANT simulations. Excellent agreement is found between the experimental distribution of the number of interactions per segment and the simulated one. Deviations between experimental radial distribution and the calculated ones are discussed.

A crucial step in the process of γ -ray tracking is the determination of the interaction points of the γ -rays within the detectors. This can be achieved by pulse shape analysis of the signals from highly segmented HPGe detectors. We present an approach for this task based on a genetic algorithm. Our algorithm makes no a priori assumption on the distribution of interaction points and hit segments in the detector but addresses the decomposition problem in full generality. In the analysis of simulated signals the number of interactions can be determined at a success rate of up to 83% and the interaction points can be localised within an average positional error in the order of 2.5–5.4 mm. Similar positional errors have been obtained also in the analysis of measured signals, demonstrating the capability of our approach to decompose measured multiple hit events using a base system of calculated signals.

Excited states up to I π = 8 + in the neutron-rich nucleus 58Cr have been identified by using a new experimental setup composed of the large acceptance magnetic spectrometer PRISMA and the highly efficient γ-detector array CLARA. Interestingly, the excitation energy sequence of the ground-state band follows the one expected by the E ( 5 ) dynamical symmetry for a nucleus at the critical point of the shape phase transition from a spherical vibrator ( U ( 5 ) ) to a γ-soft rotor ( O ( 6 ) ). For the first time, in the same physical system, large scale shell-model calculations in the full fp shell are compared to the E ( 5 ) analytical model results and to the Interacting Boson Model. The theoretical results are in excellent agreement with the present data.

New accelerator facilities for radioactive–ion beams will enter into operation in the next few years, providing the opportunity to explore unknown territories of the nuclear landscape. The foreseen harsh experimental conditions require the construction of a new generation of γ–ray detector arrays based on the emerging technique of γ–ray tracking. The “Advanced GAmma Tracking Array” (AGATA), proposed in Europe, will be built out of 120 or 180 highly segmented Ge crystals operated in position sensitive mode by means of digital data techniques and pulse shape analysis of the segment signals. AGATA will be capable of measuring γ radiation in a large energy range (from ∼ 10 keV to ∼ 10 MeV), with the largest possible photopeak efficiency (25% at M γ = 30 ) and with good spectral response. The very good Doppler correction and background rejection capability of this γ–ray tracking array will allow to perform γ–ray spectroscopy experiments using fragmentation beams with sources moving at velocities up to β ∼ 0.5 .

High-efficiency arrays for γ spectroscopy, now available in several Laboratories, make possible the measurement of very weak cross-over transitions of high potential interest. A limit to the measurement possibilities comes, however, from the simultaneous detection of two γ-rays of a stop-over cascade (or “sum-up”), which cannot be distinguished from the true detection of the cross-over transition. We propose a new method to measure (and correct for) the sum-up effect, which can be used with symmetric γ detector arrays (like GASP and GAMMASPHERE), and discuss the possible techniques for identifying and estimating quantitatively the contribution of random pile-up, which can be sizeable at high counting rate. These ideas have been experimented at GASP in a dedicated measurement with a radioactive source of 52 Mn . The results of this measurement are presented and discussed. Moreover, as a significant example, the method is applied to deduce the intensity of the E3 cross-over transition from the lowest 3− state of 148 Gd .

DSAM lifetimes have been determined in the middle of 1f7/2 shell for the cross-conjugated nuclei 47 Va nd 49 Cr, populated with the reaction 28 Si on 28 Si at 115 MeV using a Au backed target. B(E2) and B(M1) reduced rates agree very well with large scale shell model predictions. The interplay between spherical and collective structures is discussed.  2001 Elsevier Science B.V. All rights reserved.

A flexible program to calculate the pulse shapes from highly segmented HPGe detectors of various geometrical shapes has been developed. Signals originating from single points of interaction in both the quasi-true-coaxial and the closed-end part of the detector are discussed. In order to present the main features of these signals, we have introduced simplified characteristic curves. These curves are analysed with regard to the application of pulse shape analysis for three-dimensional position determination in detectors for a g-ray tracking array. # 2001 Elsevier Science B.V. All rights reserved.

High-spin states in the neutron-deficient nuclide I-111 have been populated with the fusion reaction Ni-58 + Ni-58 at a beam energy of 210 MeV, in an experiment performed at the Tandem Accelerator of the Laboratori Nazionali di Legnaro. The gamma spectrometer GASP was used in time coincidence with the ISIS Si-ball and the CAMEL recoil mass spectrometer for the positive identification of the nuclide. Gamma transitions and structure details previously attributed to I-111 by Other authors are only partially confirmed. The obtained level scheme includes new rotational bands and a new low lying structure which suggests the presence of octupole correlations at predicted rotational frequency values.

The next generation of 4 pi arrays for high-precision gamma -ray spectroscopy will involve gamma -ray tracking detectors. They consist of high-fold segmented Ge detectors and a front-end electronics, based on new digital signal processing techniques, which allows to extract energy, timing and spatial information for a gamma -ray by pulse shape analysis of the Ge detector signals. Utilizing the information on the positions of the interaction points and the energies released at each point the tracks of the gamma -rays in a Ge shell can be reconstructed in three dimensions.

The isotopes 159–163Dy have been investigated using the incomplete fusion reactions 7Li → 158,160Gd at beam energies of 8 MeV/u. The γ-rays were detected in the GASP spectrometer in coincidence with the fast charged particles detected in the ISIS silicon ball. The level schemes of all five isotopes could be amply extended. The most important result was the observation of both the ground state and Stockholm bands in 162Dy up to high spin covering the band crossing region. The crossing in this nucleus is shifted to a higher frequency in comparison to the lighter Dy isotopes. The interaction strength between the two bands could be determined with high precision and with this result, a full oscillation of the interaction strength from one node to the next within an isotopic chain could be observed for the first time.

The lifetimes of five levels of the two-quasineutron band in 128 Ba populated via the 116 Cd( 16 O ,4 n) reaction were measured for the first time by means of the recoil-distance Doppler-shift method. For the data-analysis, a new version of the differential decay-curve method in singles-like mode was developed which takes into account the velocity distribution of the recoils and the effect of the Doppler-shift attenuation in the stopper. The high values of 〈K 2 〉 and K eff characterising the band are confirmed by the determined B (E2 ,I→I−2 ) and B (M1 ,I→I−1 ) transition strengths. At the same time, the rigid-rotor model is not able to describe the behaviour of the experimental B (E2 ,I→I−1 ) and B (M1 ,I→I−1 ) values. A new theoretical effort seems to be needed for a consistent explanation of the intraband transition strengths within two-quasiparticle bands in γ -soft nuclei.

A superdeformed band has been discovered in 143Gd consisting of 15 transitions. It does not show the band crossing observed in the neighbouring heavier Gd isotopes and it is degenerate with the superdeformed band in 143Eu. In contrast to other degenerate bands at superdeformed shape, the configurations of the bands are quite different here. They result from the exchange of a ν64 with a π[404]9/2 configuration. In addition, a collective band has been observed which adopts a well-deformed triaxial shape at high spins according to calculations. The transition from highly to superdeformed shapes proceeds via triaxial shapes.

High-spin states in 180Os have been populated by means of the 150Nd(36S,6n) reaction at 177 MeV and studied with the γ-spectrometers OSIRIS and GASP. Eight known bands have been extended to higher spins and a new strongly coupled band has been discovered. Configuration assignments of the bands have been carried out in the framework of the tilted-axis cranking model utilizing experimental ratios of reduced transition probabilities B( M1 ) B( E2 ) . The investigation of the alignment behaviour of the bands revealed that besides the well-known first band crossing caused by the alignment of an i 13 2 quasineutron pair, a second band crossing occurs in four of the bands. The crossing frequency is ⩾ 0.38 MeV and the alignment gain is fairly small, ranging between 2 and ⩾4 ℏ;. The crossing can consistently be explained as a two-quasineutron (ν 7 2 − [514]) 2 alignment. This crossing has been observed for the first time.

Subpicosecond mean lifetimes of eight excited states in 128Ba populated via the 96Zr(36S,4n) reaction were measured by the Doppler-shift attenuation (DSA) technique using a line-shape analysis. The differential decay-curve method (DDCM) was applied for the lifetime determination. The B(E2) values in the yrast band indicate that the first band-crossing is with a proton S-band. The configuration πh 11 2 d 5 2 of the negative-parity semi-decoupled bands is confirmed by the measured B(E2, I → I − 2) and B(M1, I → I − 1) transition strengths. The higher-lying “dipole” band in 128Ba can be described as a high-K four-quasiparticle band built on the prolate configuration (πh 11 2 d 5 2 ) ⊗ (νh 11 2 g 7 2 ) .

High-spin rotational structures in the odd-odd nuclei 130,132Pr have been studied via the 104 Pd + 32 S reaction at 160 MeV. Several states below the previously reported negative- and positive-parity states have been established through the observation of low-energy transitions, leading to new spin assignments for all observed levels. The bands based on the πh 11 2 ⊗ vg 7 2 and πh 11 2 ⊗ vh 11 2 configurations have been extended at much higher spins. Detailed interacting boson-fermion-fermion model calculations have been performed for the two nuclei, which reveal the complex structure of the new observed low-lying states. The change from inverted to normal signature at high spin and the staggering pattern of all observed bands are well reproduced, being explained by the interplay between a new term introduced in the boson quadrupole operator and the residual quadrupole-quadrupole interaction.

Thick target γγ coincidence measurements for the system 130 Te + 275 MeV 64 Ni have been performed using the GASP Ge detector array at Legnaro. For the isotopic assignments of previously unknown γ-ray cascades, prompt γγ coincidences observed between Te and Ni partner products were of vital importance. The results yield much new information about excited states of moderate spins in A = 126–131 tellurium nuclei, especially about yrast excitations of the little studied odd- A isotopes 127 Te, 129 Te, and 131 Te. Level systematics of tellurium nuclei are presented, and both single-particle and collective aspects of the level spectra are discussed.

The structure of Kr-72 has been investigated at GASP through the Ca-40(Ca-40,2 alpha) reaction at a beam energy of 160 MeV using the 4 pi ISIS Si-ball for reaction channel selection. The level scheme has been extended up to an excitation energy of approximate to 8.5 MeV. The spins and parities of the observed levels are assigned tentatively. The observed band shows the predicted change from oblate to prolate shape. The four quasi-particle g(9/2) alignment is found to be significantly delayed in rotational frequency with respect to the heavier Kr isotopes. Such a delay contradicts the predictions of standard mean-field calculations and may reflect either additional correlations in the T = 0 pairing channel or coupling to vibrational degrees of freedom or both. (C) 1997 Elsevier Science B.V. (Less)

A 4π Si-ball detector system has been constructed as a trigger device for the γ-ray spectrometer GASP. The construction and operation of the detector is reported, together with a brief description of the electronics and of the data acquisition system used. Results are presented for the 32S + 40Ca reaction at 140 MeV of32S beam energy.

Five superdeformed (SD) bands have been identified in 144Gd with the GASP array using the reaction 100 Mo + 48 Ti . The J(2) moments of inertia of the four excited SD bands are flat as a function of rotational frequency, indicating the blocking of the N = 6 proton crossing observed in the yrast SD band. According to cranked shell model calculations, the excited bands have two-quasiproton configurations with one proton in the N = 6 orbital and the other in each signature partner of the [404]9 2 + or [411]3 2 + orbitals, lying above the Z = 64 gap. The interpretation of the excited SD bands in terms of proton excitations points to the high stability of the N = 80 shell closure at SD shapes. The population of the yrast SD band as a function of the beam energy has been also investigated. Our data shows that the intensity of the yrast SD band is not configuration dependent, being comparable to that of yrast SD bands in the neighboring nuclei. By comparing experimental and theoretical alignments, spins and configurations are assigned to all observed SD bands in the A = 140–150 region.

Using the (18O,5n) 163Er reaction a multitude of rotational bands have been established with firm spin and parity assignments in 163Er. In 17 out of 24 band crossings E2 cross-band transitions have been observed. The interaction strength varies between ∼ 1 and ∼ 50 keV with many of the values in the range 10–15 keV. These interactions sample a variety of the lowest (multi) -quasiparticle configurations. For some bands, in particular those with high K-values, the configurations can be established rather well. Quite complicated changes in the wavefunctions must occur at these crossings, and to explain the observed interaction strengths coupling to various vibrational degrees of freedom, in addition to possible residual neutron-proton interactions, may be needed.

Three bands consisting of dipole M1 and quadrupole E2 crossover transitions have been identified in 134 Nd using the GASP array and the 110 Pd( 28 Si, 4n) reaction at 130 MeV. Calculations with the projected shell model are used to assign configurations to the different bands and to infer their K -composition. The properties of the band built on the I π = 8 − isomer confirm the previously assigned two-quasineutron [404] 7 2 + ⊗ [514] 9 2 − configuration of the isomeric state. The other two bands are interpreted as coexisting prolate and oblate four-quasiparticle configurations.

A high precision RDDS lifetime experiment on 126Ba is presented. Evidences for a dynamic shape change in this nucleus are given. Experimental results on the magnetic dipole band in 128Ba are shown and compared with earlier TAC calculations. The results of low spin experiments for 134Ce and 126Xe are shown and discussed in the framework of the IBM. Relative B(E2) strengths are compared to IBM and triaxial RVM calculations. The Q phonon scheme for the IBM is discussed. Experimental data on low lying negative parity states in 125Xe is shown and compared to IBFM-2 calculations.

The study of superdeformation in nuclei around the nucleus 144Gd, which can be considered as doubly-closed at superdeformed shape, provided detailed knowledge about the structure of superdeformed bands in this region. The chain of Gd isotopes showing superdeformation could be extended to 143Gd. Since highly-deformed bands are known in 139,141Gd, it appears that the transition between the regions of superdeformed nuclei with A ≈ 150 and of highly-deformed nuclei with A ≈ 130 is rather sharp and takes place around N = 78 as theoretically predicted. In 144Gd four excited superdeformed bands have been found in addition to the yrast superdeformed band. They form two pairs of signature partner bands of π6 1 π[404]9 2ν7 0 and π6 1 π[411]3 2ν7 0 configurations. In 145Gd for the first time two crossings have been observed in a superdeformed band, which are assigned to the alignment of an i 13 2 proton pair and a subsequent crossing of the i 13 2 [642]5 2 and i 11 2 [651]1 2 neutron orbitals, respectively.

Alpha particle spectra in coincidence both with normal deformed (ND) and superdeformed (SD) bands of 150 Tb have been measured using the reaction 120 Sn( 37 Cl,α3n) at 187 MeV bombarding energy. A clear difference is observed between the two spectra, that in coincidence with the SD states being shifted to lower energies. This effect is understood in terms of different angular momentum regions from which the ND and SD states orginate. The standard statistical model fails to describe the angular momentum dependence of the alpha particle energies.

The level scheme of the doubly odd 136Pr nucleus has been investigated via the 136Ce(p,n), 122Sn(19F,5n) and 110Pd(30Si,p3n) reactions at beam energies of 14, 84 and 125 MeV, respectively. A complex decay scheme has been established for the 90 ns isomeric level with Ex = 594.7 keV and Jπ = 6+. The two previously reported bands, one based on the πh 11 2 ⊗ νh 11 2 configuration and one with suggested negative parity consisting of only dipole transitions, have been extended at higher spins and connected firmly to the 6+ isomer. Six new bands have been also identified: two consist of strong dipole and crossover quadrupole transitions, whereas the other four, very weakly populated, consist of only quadrupole transitions. The observed level structures are compared to theoretical calculations performed within the interacting boson model for odd-odd nuclei (IBFFM) and the cranked shell model. The experimental B (M1) B (E2) ratios of the yrast band are well reproduced by the IBFFM calculations, while those of the other semi-decoupled structures are in good agreement with the values obtained from the semiclassical model of Donau.

The g -factors of the ground state band members up to the 10 + level and of the 2 + state in the γ-vibrational band have been measured in 164,166,168 Er using the Coulomb excitation transient field technique. In the g-band the g -factor values were found to be nearly constant as a function of spin. For the 2 + states of the γ-band, values about 20% larger than those in the g-band have been determined. This latter fact is consistent with the known decay properties of the γ-band.

A project has been realized to link the CAMEL recoil mass spectrometer to the GASP γ-spectrometer in order to perform high resolution and efficiency γ-recoil coincidence measurements. To preserve high flexibility and autonomy in the operation of the two complex apparatus a rough factor two of reduction in the overall heavy ion transmission was accepted in designing the optics of the particle transport from the GASP center to the CAMEL focal plane. The coupled configuration has been tested with the fusion reaction 58 Ni (E = 212 MeV ) + 64 Ni , obtaining a mass resolution of 1 300 and efficiency between ∼ 11% and ∼ 15% for different evaporation products.

Unfavored components of doubly decoupled bands are reported for the first time. They can be interpreted as having the pseudo-spin flipped relative to the orientation in the favored components, i.e. antialigned with respect to the rotation axis. In addition, the differences in consecutive transition energies along the favored and unfavored sequences are strikingly similar among them up to Iπ = 15+and 14+ respectively. This feature arises from a cancellation of differences in alignments and moments of inertia.

The high-spin states in 45 Sc were studied with the GASP multidetector array. The nuclei were excited by the 30 Si( 18 O,p2n) 45 Sc reaction at E LAB =60 MeV and separated with the Recoil Mass Spectrometer. Several new high-spin levels extending the known single-particle and collective structures were observed. Energies of the negative-parity states agree with the shell model predictions whereas the positive-parity-intruder rotational band extends up to very high rotational frequencies and continues beyond the maximum angular momentum available from the single-particle f 7 2 configuration.

Very proton rich nuclei in the A≈100 region have been investigated using the GASP array coupled with the Recoil Mass Spectrometer (RMS) and the GASP Si-ball. High-spin states of 105Sn and 103In nuclei formed with the reaction 58 Ni + 50 Cr at 210 MeV have been investigated up to ≈ 10 and 7 MeV of excitation energy respectively. We have confirmed the known excited states for both nuclei and extended to higher spin the level scheme. The experimental level schemes are compared with shell model calculations.

The hyperdeformed ridge structure recently observed in the reaction of 187 MeV 37 Cl on 120 Sn has been confirmed in a new proton-γ coincidence experiment at the GASP spectrometer and assigned to the nucleus 152 Dy. Proton spectra have been measured in coincidence with γ-rays belongings to the different structures in 152 Dy (oblate, prolate, super- and hyper-deformed). The deformation of the final evaporation residue affects only weakly the proton evaporation from the compound nucleus. Evidence has been found that the energy of the protons in coincidence with the hyperdeformed structure is larger than expected. This effect is discussed in the framework of the fission-evaporation competition.

A high statistics experiment has been performed at the GASP detector array employing the 110 Pd + 28 Si reaction at 130 MeV to populate 134 Nd. Our findings do not confirm earlier data on the highly-deformed band of this nucleus. On the other hand, two new rotational sequences have been identified which show the characteristics of the intruder bands in the A = 130 mass region. This is one of the first results indicating the presence of excited highly-deformed bands in nuclei of this region. The behaviour of the dynamical moment of inertia of one of the bands is quite different from that of the highly-deformed bands previously known.

The decay properties and the magnetic moment of the 548 keV isomeric state in 136Pr populated in the 122Sn (19F, 5n) reaction were investigated by pulsed beam γ-ray spectroscopy and TDPAD measurements using as host metallic Pt at room temperature. The determined characteristics of the isomeric state, T12 = 90(2) ns, Jπ = 4+ and g = + 0.570(19), are explained by assigning to it a dominant configuration π(1h112)⊗ν(1h112) and an extremely small contribution of configurations involving proton and neutron positive-parity orbits. Firm spin assignment for the upper energy collective structures can be deduced.

Gyromagnetic ratios of the 2 1 + and 4 1 + states in 192,194,196 Pt and of the 2 2 + states in 192,194 Pt were simultaneously measured by the transient-field perturbed angular correlation method in Coulomb excitation using a multi-isotopic Pt target and thin polarized Fe and Gd foils as ferromagnetic hosts. The experimental g -factors were found identical within errors. These and previous existing data indicate the independence of the low-lying state g -factors in even stable Pt nuclei with respect to the spin and neutron number.

The g -factor of the first 2 + states in three stable N =82 nuclei, 140 Ce, 142 Nd and 144 Sm, have been measured using the transient magnetic field technique. The levels under study were Coulomb excited with 110–116 MeV 32 S beams and spin precession after passing a thin polarized iron foil was measured. The field strength has been checked using the first 2 + state in 148 Sm as internal calibration. The obtained values were 0.97 (9), 0.84 (7), 0.76 (11) for 140 Ce, 142 Nd and 144 Sm, respectively. These remarkably lower values with respect to shell-model predictions in a proton subspace are explained in terms of neutron core excitation by quasiparticle random-phase-approximation calculations.

New results on the high spin structure of the N=Z nuclei 48Cr and 52Fe are presented. Experiments were performed using the GASP array in coincidence with the 4π charged particle detector ISIS which allows a better selection of the reaction channel by γ-γ-particles and γ-γ-γ-particles coincidences.

Excited states of 130Ba have been studied by means of in-beam γ-ray spectroscopy and electron-spectroscopy via the reaction 120Sn(13C, 3n). Spin and parity assignments have been made for 28 new levels. A comparison with a cranking-model calculation shows that the negative-parity band based on the 5− state is a two-quasiproton band.

In a high resolution (p,p′) experiment at E=25.5MeV, the complete particle-core coupled multiplet (3 − · f 7 2 ) J in the N=83 143Nd nucleus has been identified and the spins of its members assigned. The experimental results are discussed in connection with the observed large energy splitting of about 650 keV. The comparison with the corresponding multiplet observed in 146Gd is a new strong indication for the shell closure at Z=64.

The nuclei 142 Nd and 142 Nd have been studied by means of high-resolution inelastic proton scattering at E p = 25 MeV. Angular distributions have been measured from θ lab = 20° to 50°. Transitions to 24 levels in 142 Nd and 39 levels in 143 Nd up to an excitation energy of 3.8 MeV were observed. Multipolarities L and transition strengths G L were determined using distorted-wave Born approximation analysis. Particle-core coupled configurations were identified in 143 Nd. In particular, the identification of all members of the octupole multiplet ( 3 − · νf 7 2 ) provides insights on the particle-vibration coupling in this region of nuclei. Coupling to other excitation modes is discussed, and comparison with unified model calculations is made.

The g -factors of the two 10 + states in 140 Sm at 3172 and 3210 keV have been measured by means of the TDPAD method. The obtained values are g = −0.176(20) and g = 1.27(9), respectively. The reaction 116 Cd ( 28 Si, 4n) 140 Sm, at incident beam energy of 125 MeV, has been used. The measured values clearly show that these states can be described as rather pure (νh 11/2 ) −2 and (πh 11/2 ) 2 configurations.