Search

A Coulomb-excitation experiment to study electromagnetic properties of Ca42 was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in Ca42 were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2 matrix elements coupling six low-lying states in Ca42, including the diagonal E2 matrix elements of 21+ and 22+ states, were determined using the least-squares code gosia. The obtained set of reduced E2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 01,2+ and 21,2+ states, as well as triaxiality for 01,2+ states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in Ca42.

Pre-equilibrium emissions affect the production of excited systems in nuclear reactions, thus modifying their properties which enter as input parameters in the comparison with statistical models. In this contribution, we discuss this subject referring to recent results from experiments performed at Legnaro National Laboratories (Italy) with the GARFIELD apparatus complemented with other detectors. ispartof: Acta Physica Polonica B vol:48 issue:3 pages:635-639 ispartof: location:Zakopane: POLAND status: published

A study of fusion-evaporation and (partly) fusion-fission channels for the $^{88}$Mo compound nucleus, produced at different excitation energies in the reaction $^{48}$Ti + $^{40}$Ca at 300, 450 and 600 MeV beam energies, is presented. Fusion-evaporation and fusion-fission cross sections have been extracted and compared with the existing systematics. Experimental data concerning light charged particles have been compared with the prediction of the statistical model in its implementation in the Gemini++ code, well suited even for high spin systems, in order to tune the main model parameters in a mass region not abundantly covered by exclusive experimental data. Multiplicities for light charged particles emitted in fusion evaporation events are also presented. Some discrepancies with respect to the prediction of the statistical model have been found for forward emitted $\alpha$-particles; they may be due both to pre-equilibrium emission and to reaction channels (such as Deep Inelastic Collisions, QuasiFission/QuasiFusion) different from the compound nucleus formation.

The lineshapes and peak position of Doppler corrected γ -ray spectra from in-beam experiments at relativistic energies are investigated with respect to the intrinsic energy resolution of the employed detectors, the particles’ velocities, and the photons’ emission angle uncertainties at the moment of γ -ray emission. The uncertainties in velocity and photon emission angle are dependent on the lifetime of the excited state. The impact of these two observables on the lineshape and energy resolution are studied for the RISING γ -spectrometer by means of simulations and experimental results from a two-step fragmentation experiment at ≈ 200 MeV / u . Potential use of the distinct lineshape for lifetime determination is demonstrated for measured γ -ray transitions.

The first excited 2+2+ state of 36Ca has been identified by its γ -decay, exploiting the two-step fragmentation technique at the FRS-RISING setup at GSI. This is the heaviest Tz=−2Tz=−2 nucleus in the Segré chart in which a γ-decay of an excited state has been observed. A stable beam of 40Ca at View the MathML source420AMeV impinged on a primary 9Be target. Out of the secondary beam of fragmentation products, 37Ca was separated by the FRS and struck on a second 9Be target at the final focus of the FRS. The energy for the View the MathML source21+ decay of 36Ca was determined to be 3015(16) keV, which is 276 keV lower than in its T=2T=2 mirror 36S. This mirror energy difference (MED) is discussed in the framework of shell model calculations using a 16O core, the sd shell isospin symmetric interaction USD and experimental single-particle energies from 17O and 17F. The results show that the MED within the sd shell provide a sensitive test for the evolution of the N , Z=14,16Z=14,16 subshell gaps towards the driplines. Especially the N , Z=16Z=16 gap is determined by Thomas–Ehrman shift in the A=17A=17, T=1/2T=1/2 isospin doublet, while Coulomb effects are found to have marginal influence. ispartof: Physics Letters B vol:647 issue:4 pages:237-242 status: published

Fil: Rodrigues Ferreira Maltez, Dario Pablo. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Comision Nacional de Energia Atomica. Gerencia del Area de Investigacion y Aplicaciones No Nucleares. Gerencia Fisica (Centro Atomico Constituyentes). Proyecto Tandar; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisica; Argentina

High-energy giant dipole resonance (GDR) γ rays were measured following the decay of the hot, rotating compound nucleus of 88Mo, produced at excitation energies of 124 and 261 MeV. The reaction 48Ti+ 40Ca at 300 and 600 MeV bombarding energies has been used. The data were analyzed using the statistical modelMonte Carlo code GEMINI++. It allowed extracting the giant dipole resonance parameters by fitting the high-energy γ -ray spectra. The extracted GDR widths were compared with the available data at lower excitation energy and with theoretical predictions based on (i) The Lublin-Strasbourg drop macroscopic model, supplemented with thermal shape fluctuations analysis, and (ii) The phonon damping model. The theoretical predictions were convolutedwith the population matrices of evaporated nuclei from the statistical model GEMINI++. Also a comparison with the results of a phenomenological expression based on the existing systematics, mainly for lower temperature data, is presented and discussed. A possible onset of a saturation of the GDR width was observed around T = 3 MeV.

The FRS-RISING set-up at GSI uses secondary radioactive beams at relativistic energies for nuclear structure studies. At GSI the fragmentation or fission of stable primary beams up to 238U provide secondary beams with suffcient intensity to perform γ-ray spectroscopy. The RISING set-up is described and results of the first RISING campaign are presented. New experimental methods at relativistic energies are being investigated. Future experiments focus on state-of-the art nuclear structure physics covering exotic nuclei all over the nuclear chart.

High-spin states of the $^{44}$Sc nucleus, populated in the 68 MeV $^{18}$O + $^{30}$Si reaction, have been studied in a $\gamma-\gamma$-recoil coincidence experiment. The detailed decay pattern, with various paths and cross-transitions, has been extended up to 9.1 MeV. High-quality DCO and polarization information assign spins and parities for the majority of the observed levels. The negative-parity states are discussed and compared with rotational bands in neighbouring $f_{7/2}$-shell nuclei.

Excited states in 110Sn and 111Sn nuclei have been investigated using in-beam γ-ray spectroscopic methods. An 16O beam with an energy of 60-80MeV was used to bombard a 98Mo target. On the basis of the relative excitation functions, γ-ray angular distributions, γ-γ and γ-time distributions, γ-ray multiplicity and total energy data, the level schemes of 110Sn and 111Sn have been studied and extended up to Eexc ∼ 11.5MeV, I = 24ℏ, and Eexc ∼ 11.1MeV and I = (51/2)ℏ, respectively. An extension of the intruder, g.s. and negative-parity bands, as well as 5 new band-like structures are proposed in 110Sn. The nature of newly introduced collective band 8 as well as 10+ states fed in the decay of the collective band is discussed. In the 111Sn nucleus an intruder band based on the 23/2- state has been reinvestigated and the extension of the g.s. band and second negative-parity band is given. Evidence for neutron-core coupling in 111Sn is found. The structure and systematics of excited states in light Sn isotopes is discussed.

Isospin mixing in the hot compound nucleus ${}^{80}$Zr was studied by measuring and comparing the $\ensuremath{\gamma}$-ray emission from the fusion reactions ${}^{40}\text{Ca}+{}^{40}\text{Ca}$ at ${E}_{\text{beam}}=200$ MeV and ${}^{37}\text{Cl}+{}^{44}\text{Ca}$ at ${E}_{\text{beam}}=153$ MeV. The $\ensuremath{\gamma}$ yield associated with the giant dipole resonance is found to be different in the two reactions because, in self-conjugate nuclei, the E1 selection rules forbid the decay between states with isospin $I=0$. The degree of mixing is deduced from statistical-model analysis of the $\ensuremath{\gamma}$-ray spectrum emitted by the compound nucleus ${}^{80}$Zr with the standard parameters deduced from the $\ensuremath{\gamma}$ decay of the nucleus ${}^{81}$Rb. The results are used to deduce the zero-temperature value, which is then compared with the latest predictions. The Coulomb spreading width is found to be independent of temperature.

The shape transition in the neutron-rich Os isotopes is studied by investigating the neutron-rich 196Os nucleus through in-beam γ-ray spectroscopy using a two-proton transfer reaction from a 198Pt target to a 82Se beam. The beam-like recoils were detected and identified with the large-acceptance magnetic spectrometer PRISMA, and the coincident γ rays were measured with the advanced gamma tracking array (AGATA) demonstrator. The de-excitation of the low-lying levels of the yrast-band of 196Os were identified for the first time. The results are compared with state-of-the-art beyond-mean-field calculations, performed for the even-even 188-198Os isotopes. The new results suggest a smooth transition in the Os isotopes from a more axial rotational behavior towards predominately vibrational nuclei through triaxial configurations. An almost perfect γ-unstable/triaxial rotor yrast band is predicted for 196Os which is in agreement with the experimentally measured excited states

High-spin states in 45Sc, 45Ti and 43Ca were studied by means of multiple γ- and γ-recoil-coincidences with the use of the GASP array and the Recoil Mass Spectrometer. The nuclei were populated in the 60 MeV 18O +30Si reaction. For the DSAM lifetime measurement the 35Cl +12C reversed kinematics reaction was used. In the article, a complete description of the experimental techniques used in course of the performed experiments is presented. The level schemes and the detailed information on the observed state properties, including B(M1) and B(E2) transition rates are inserted as well as their shell model interpretation.

We investigated the response of a 3″ × 3″ (7.62 cm × 7.62 cm) LaBr 3 :Ce detector to monochromatic protons within an energy range of 70–230 MeV. The experiment was performed at the new cyclotron at the Cyclotron Centre Bronowice (CCB) of the Henryk Niewodniczanski Institute of Nuclear Physics, Krakow, Poland. Protons with energies between 70 and 185 MeV were stopped inside the crystal. Three different values of PMT high voltage were used, in each case, the energy resolution, the quenching factor with respect to the gamma rays were measured. In addition, the anode pulses were acquired for both gamma rays (from a CmC source) and protons and the comparison between them will be shown.

High-spin states of the 42Ca nucleus, populated in the 68 MeV 18O + 30Si reaction, have been studied in a γ-γ-recoil coincidence experiment. The level scheme of 42Ca has been extended up to 13.7 MeV. An elaborate decay pattern with various paths, together with high-quality DCO and polarization information assigns spins and parities for almost all observed levels. The sequence of non-yrast positive-parity states is discussed and compared with highly deformed bands in 36Ar and 40Ca.

This work was supported by the Italian Istituto Nazionale di Fisica Nucleare and partially by the Spanish MICINN (AIC10-D-000568 bilateral action and FPA2008-06419) and Generalitat Valenciana (Grant PROMETEO/2010/101). The work has also been partially supported by the Polish Ministry of Science and Higher Education (Grant No. N N202 309135)

Lifetimes of high-spin states in 69As have been measured using Doppler shift attenuation technique with the GASP and RFD setup. The determined transition probabilities indicate large deformation associated with some rotational bands in this nucleus.

High-spin states of 40K have been populated in the fusion-evaporation reaction 12C(30Si,np)40K and studied by means of γ-ray spectroscopy techniques using one triple-cluster detector of the Advanced Gamma Tracking Array at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. Several states with excitation energy up to 8 MeV and spin up to 10 have been discovered. These states are discussed in terms of J=3 and T=0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum, This work was financed by EURONS AGATA (Contract No. 506065-R113), the Swedish Research Council under Contracts No. 621-2008- 4163, No. 621-2011-4522, No. 822-2005-3332, and No. 821- 2010-6024, the Japan Society for the Promotion of Science (JSPS) Kakenhi Grant No. 23·01752, Ankara University (BAP Project No. 05B4240002), the Polish Ministry of Science and Higher Education under Grants No. DPN/N190/AGATA/2009 and No. N N202 073935, the German BMBF under Grants No. 06K-167, No. 06KY205I, and No. 06KY9136I, the Knut and Alice Wallenberg Foundation Contract No. 2005.0184, and STFC (UK). A. Gadea and E. Farnea acknowledge the support of MICINN, Spain, and INFN, Italy, through the AIC-D-2011-0746 bilateral action. A. Gadea’s activity has been partially supported by the Generalitat Valenciana, Spain, under Grant PROMETEO/2010/101. A. Gadea, A. Jungclaus, A. Poves, and B. Quintana acknowledge support from the MICINN, Spain, under Grant FPA2011-29854. A. Poves is partially supported by the Comunidad de Madrid (Spain) (HEPHACOS S2009-ESP-1473). G. Jaworski acknowledges the support of the Center for Advanced Studies of Warsaw University of Technology. B. Cederwall acknowledges the support of the Goran Gustafsson Foundation.

This work was supported by the Italian Istituto Nazionale di Fisica Nucleare and partially by the Spanish MICINN (ACI2009-1070 bilateral action) and Generalitat Valenciana (Grant Nos. BEST/2009/073 and PROMETEO/2010/101). The work has also been partially supported by the Polish Ministry of Science and Higher Education (Grant No. N N202 309135).

The population and gamma decay of neutron rich nuclei around 48Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions (DIC) on 64Ni, at an energy approximately twice the Coulomb barrier. The reaction properties of the main products are investigated, focusing on total cross sections and angular distributions both integrated in energy and associated to the population of specific excited states. Gamma spectroscopy studies are also performed, giving evidence, for the first time in transfer reactions with heavy ions, of a large spin alignment (~70%), perpendicular to the reaction plane. This makes possible the use of angular distributions and polarization measurements to firmly establish the spin and parity of excited states populated in nucleon transfer channels, as in the case of 49Ca, where candidates for particle-core coupling are investigated. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for a detailed investigation of moderately neutron rich systems.

The deep inelastic reaction (DIC) 48Ca+64Ni, at an energy approximately 2.5 times above the Coulomb barrier, was studied using the CLARA‐PRISMA setup at the Laboratori Nazionali di Legnaro. Total cross sections and angular distributions, both energy integrated and associated to the population of selected excited states, are measured for the most intense reaction channels. The γ‐decay of the most intense reaction products is also studied. The use of angular distributions and polarization measurements of γ transitions allows to firmly establish spin and parity of excited states. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for the investigation of moderately neutron rich systems.

Isospin mixing induced by Coulomb interaction has been measured in the compound nucleus Z = N = 40 80Zr at T∼2 MeV produced in a fusion‐evaporation reaction. The observable sensitive to the isospin purity of the compound nucleus is the Giant Dipole Resonance γ decay. The degree of mixing of the compound nucleus has been obtained via Statistical Model analysis of the measured γ spectrum.

WOS: 000290082600015, The interaction position resolution of the segmented HPGe detectors of an AGATA triple cluster detector has been studied through Monte Carlo simulations and in an in-beam experiment. A new method based on measuring the energy resolution of Doppler-corrected gamma-ray spectra at two different target to detector distances is described. This gives the two-dimensional position resolution in the plane perpendicular to the direction of the emitted gamma-ray. The gamma-ray tracking was used to determine the full energy of the gamma-rays and the first interaction point, which is needed for the Doppler correction. Five different heavy-ion induced fusion-evaporation reactions and a reference reaction were selected for the simulations. The results of the simulations show that the method works very well and gives a systematic deviation of, EURONS AGATA [506065-R113]; Swedish Research Council; Ankara University [0584240002]; Polish Ministry of Science and Higher Education [DPN/N190/AGATA/2009]; MICINN, Spain; INFN, Italy [FPA2008-03774-E/INFN]; MICINN; Generalitat Valenciana, Spain [FPA2008-06419, PROMETEO/2010/101]; Science and Technology Facilities Council [ST/J000108/1, ST/F004052/1], We would like to thank the Swedish National Infrastructure for Computing (SNIC) and the Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX) for the computer resources used in parts of the analysis. This work was financed by EURONS AGATA (Contract no. 506065-R113), the Swedish Research Council, Ankara University (BAP Project number 0584240002) and the Polish Ministry of Science and Higher Education under grant number DPN/N190/AGATA/2009. A. Gadea and E. Farnea acknowledge the support of MICINN, Spain, and INFN, Italy through the FPA2008-03774-E/INFN bilateral action. A. Gadeas activity has been partially supported by the MICINN and Generalitat Valenciana, Spain, under grants FPA2008-06419 and PROMETEO/2010/101.

Yrast states of the nuclei 188Pb and 186Pb located in the middle of the 82 < N < 126 shell have been studied for the first time in the reactions 156,154Gd (36Ar, 4n ) at 175 MeV. Gamma rays following the heavy-ion fusion-evaporation reactions were detected in coincidence with evaporation residues. Both nuclei exhibit a structure very different from the heavier even-even lead isotopes and show low-lying, probably prolate rotational bands.

The {gamma} decay associated with the warm rotation of the superdeformed nuclei {sup 151}Tb and {sup 196}Pb has been measured with the Euroball IV array. Several experimental quantities are presented, putting strong constraints on the decay dynamics in the superdeformed well. The data are successfully reproduced using a Monte Carlo simulation of the {gamma} decay based on microscopically calculated energy levels, E2 decay probabilities, collective mass parameters, and potential energy barriers between the wells associated with normal and super deformation. This allows one to test the basic ingredients of the physical process, such as the strength of the two-body residual interaction and the potential barriers as a function of spin and excitation energy. We also show that the data probe the E1 strength function, indicating an enhancement around 1-2 MeV {gamma} rays, which might be related to octupole vibrations.

The $\ensuremath{\gamma}$ decay from Coulomb excitation of $^{68}\mathrm{Ni}$ at $600\text{ }\text{ }\mathrm{MeV}/\mathrm{\text{nucleon}}$ on a Au target was measured using the RISING setup at the fragment separator of GSI. The $^{68}\mathrm{Ni}$ beam was produced by a fragmentation reaction of $^{86}\mathrm{Kr}$ at $900\text{ }\text{ }\mathrm{MeV}/\mathrm{\text{nucleon}}$ on a $^{9}\mathrm{Be}$ target and selected by the fragment separator. The $\ensuremath{\gamma}$ rays produced at the Au target were measured with HPGe detectors at forward angles and with ${\mathrm{BaF}}_{2}$ scintillators at backward angles. The measured spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in terms of an enhanced strength of the dipole response function (pygmy resonance). Such pygmy structure has been predicted in this unstable neutron-rich nucleus by theory.

The reaction 48Ca+64Ni has been studied in the deep inelastic regime at approximately 6 MeV/A, by the CLARA‐PRISMA setup. Angular distributions of the reaction cross sections have been obtained for the most intense reaction products, taking into account the response function of the magnetic spectrometer. The response of PRISMA has been calculated making use of a MonteCarlo simulation of the transport of the ions in the spectrometer, starting from known events distributions. For the one‐nucleon transfer channels, the experimental data are in good agreement with predictions from a semiclassical multi‐nucleon transfer model.

The γ decay associated with the warm rotation of the superdeformed nuclei 151 Tb and 196 Pb has been measured with the EUROBALL IV array. Several independent quantities provide a stringent test of the population and decay dynamics in the superdeformed well. A Monte Carlo simulation of the y decay based on microscopic calculations gives remarkable agreement with the data only assuming a large enhancement of the B(El) strength for 1-2 MeV y rays, which may be related to the evidence for octupole vibrations in both mass regions.

Heavy-ion fusion at energies below the Coulomb barrier, as evidenced by recent experiments (1,2,3), is a process by far more likely than how models based on one-dimensional barrier penetration (4) predict, also when considering empirical barrier heights and positions (5). This paper is a short and preliminary report on experiments in progress at the XTU Tandem accelerator facility of Legnaro, aiming at a detailed understanding of the mechanism leading to fusion in medium-light systems. The systems investigated so far are 28-3°Si (beams) on 58-62-64Ni (targets) at energies ranging from 0.9 to 1.2 times the Coulomb barrier. The Nickel targets were rolled, self-supporting foils (250 ~g/cm -2) enriched to 99.8, 97.8, 96.5% in mass 58, 62 and 64 respectively. The reaction 28Si+SSNi was also reversed (58Ni beam), to have a check of the absolute cross-section scale. Differential cross-sections at 0 ° were measured using an electrostatic deflector to separate the transmitted beam from the evaporation residues (ER),and a time-of-flight energy telescope (6) with micro-chan nel-plates and a solid state detector was placed after the deflector. The beam rejection factor was typically 108 and the ER's were

A detector has been designed and built to assist in-beam γ-ray spectroscopy with fusion–evaporation reactions. It measures with high efficiency the evaporation residues that recoil out of a thin target into the angular interval from 1.8° to 9.0° at an adjustable distance of 1000–1350 mm from a target, in coincidence with \gamma-rays detected in a Ge-detector array. This permits filtering of such \gamma-rays out of a much stronger background of other reaction products and scattered beam. Evaporation residues are identified by their time-of-flight and the pulse height using a pulsed beam. The velocity vector of the \gamma-emitting recoil is also measured in the event-by-event mode, facilitating to correct the registered \gamma-ray energy for the Doppler shift, with the resulting significant improvement of the energy resolution. The heavy-ion detection scheme uses emission of secondary electrons caused by the recoiling ions when hitting a thin foil. These electrons are then electrostatically accelerated and focused onto a small scintillator that measures the summed electron energy, which is proportional to the number of electrons. The detector is able to operate at high frequency of the order of 1 MHz and detect very heavy nuclei with as low kinetic energy as 5 MeV. The paper describes the properties of the detector and gives examples of measurements with the OSIRIS, GAREL+ and EUROBALL IV \gamma-ray spectrometers. The usefulness of the technique for spectroscopic investigations of nuclei with a continuous beam is also discussed.

We report on a set of in-beam studies of excited states in $^{250}\mathrm{Fm}$. We detected prompt \ensuremath{\gamma} rays by using the JUROSPHERE IV array and conversion electrons by using the SACRED spectrometer. Both devices were used in conjunction with the RITU gas-filled recoil separator located at the University of Jyv\"askyl\"a. $^{250}\mathrm{Fm}$ nuclei were produced through the $^{204}\mathrm{Hg}$($^{48}\mathrm{Ca}$,$2n)$$^{250}\mathrm{Fm}$ fusion-evaporation reaction. An experimental excitation function gave a maximum reaction cross section of (980 \ifmmode\pm\else\textpm\fi{} 160) nb at an energy of 209 MeV in the center of the target. Tagging techniques were employed, and a number of E2 transitions were observed that connected the ground-state band levels from spin ${4}^{+}$ up to ${18}^{+}$. The highly converted ${4}^{+}\ensuremath{\rightarrow}{2}^{+}$ transition is observed only by use of conversion electron spectroscopy. The observed ground-state band transitions indicate a rotational structure. We deduce a quadrupole deformation parameter of ${\ensuremath{\beta}}_{2}=0.28$ \ifmmode\pm\else\textpm\fi{} 0.02. A low-energy background of apparent nuclear origin is observed in conversion electrons and postulated to arise from the decay of high-K bands. The half-life of $^{250}\mathrm{Fm}$ is measured to be 30.4 \ifmmode\pm\else\textpm\fi{} 1.5 min.

High spin studies of A ≈ 60 nuclei have been carried out with EUROBALL. The nuclei of interest were populated in the fusion‐evaporation reaction with a 125 MeV 16O beam bombarding a thin 56Fe target. The use of the Recoil Filter Detector and the charged particle detector EUCLIDES resulted in a significant reduction of γ‐line widths and facilitated a reaction channel selection. In this article, several new linking transitions of the previously known terminating band in 64Zn are reported. Such bands are also observed in 61Cu and 63Cu. New SD bands identified in 61,63Cu are discussed.

High-voltage diodes with active areas between 1 cm/sup 2/ and 32 cm/sup 2/ were irradiated either with carbon ions having energies between 17 MeV and 252 MeV or /spl alpha/-particles of 98 MeV or neutrons with energies up to 800 MeV. As the voltage across the devices was raised all of them failed eventually, even if there was a 1 MOhm resistor in series. With the high-energy carbon ions it could be shown that the failure can be triggered at locations that are hundreds of microns away from the pn-junction. The neutron experiment indicates that there may be a steep fall-off in failure rate at the lowest voltages.

In heavy ion reactions, in the case of N/Z asymmetry between projectile and target, the process leading to complete fusion is expected to produce pre-equilibrium dipole γ -ray emission. It is generated during the charge equilibration process and it is known as Dynamical Dipole. A new measurement of the dynamical dipole emission was performed by studying 16 O + 116 Sn at 12 MeV/u. These data, together with those measured at 8.1 MeV/u and 15.6 MeV/u for the same reaction, provide the dependence on the Dynamical Dipole total emission yield with beam energy and they can be compared with theoretical expectations. The experimental results show a weak increase of the Dynamical Dipole total yield with beam energies and are in agreement with the prediction of a theoretical model based on the Boltzmann–Nordheim–Vlasov (BNV) approach. The measured trend with beam energy does not confirm the rise and fall behavior previously reported for the same fused compound but with a much higher dipole moment.

The 48Ti on 40Ca reactions have been studied at 300 and 600 MeV focusing on the fusion-evaporation (FE) and fusion-fission (FF) exit channels. Energy spectra and multiplicities of the emitted light charged particles have been compared to Monte Carlo simulations based on the statistical model. Indeed, in this mass region (A about 100) models predict that shape transitions can occur at high spin values and relatively scarce data exist in the literature about coincidence measurements between evaporation residues and light charged particles. Signals of shape transitions can be found in the variations of the lineshape of high energy gamma rays emitted from the de-excitation of GDR states gated on different region of angular momenta. For this purpose it is important to keep under control the FE and FF processes, to regulate the statistical model parameters and to control the onset of possible preequilibrium emissions from 300 to 600 MeV bombarding energy., Comment: 4 pages, 3 figures, Contribution to conference proceedings of the 25th International Nuclear Physics Conference (INPC 2013) Journal-ref: 25th International Nuclear Physics Conference (INPC 2013), Firenze : Italy (2013)

High-spin states of the 44Ca nucleus populated in the 68 MeV 18O + 30Si reaction have been studied in a γ-γ-recoil coincidence experiment. The level scheme of 44Ca has been extended up to 12.2 MeV. In particular, the negative-parity band has been identified with the highest I = 13- level at 10.6 MeV. This state is interpreted as the band-terminating state for the ( d 3/2 -1 f 7/2 5) configuration.

High-spin states in 43Ca, 45Sc, and 45Ti were studied with the GASP multidetector array coupled with the Recoil Mass Spectrometer. The nuclei were excited in the 60 MeV 18O +30Si reaction. Lifetimes were extracted from the analysis of the Doppler-shift attenuation of γ-rays observed in the reversed 35Cl+12C reaction. The lifetimes, B(M1) and B(E2) values for 45Sc are presented. The measurements suggest significant deformation of the positive-parity intruder band in this nucleus. The band is predicted by the mean-field calculations to be the cross-shell particle-hole excitation associated with a strong quadrupole core-polarization. Spherical shell-model calculations reproduce observed excitation energies and transition rates in both spherical and deformed structures.

The Coulomb excitation experiment to study electromagnetic structure of low-lying states in Ca-42 with a focus on a possible superdeformation in this nucleus was performed at the Laboratori Naziona ...

Sr isotopes. The coexistence of the prolateandoblateshapesisatypicalphenomenoninthenucleiwithmassAˇ70.Here, the number of active nucleons is large enough to create a coherentmotion but, on the other hand, this collectivity can still be tracked to thesingleparticledegreesoffreedom. Excitedstateslifetimemeasurementspro-videinformationonthenucleardeformationandthepropertiesofcollectivestructures,varietyofwhichoccursinthisregionofthenuclearchart. Themeasurements,however,arequitedifficulttoperformandrelevantdataonelectromagneticpropertiesofsuchbandsathighspinarestillunavailable.2. Experimental setupIn the present experiment

Intruder rotational bands in 45 Sc and 45 Ti have been investigated up to the maximum aligned angular momentum by means of EUROBALL IV and the Recoil Filter Detector (RFD). The use of the RFD allowed for a reduction of the $\gamma$ -line Doppler broadening and, moreover, for a determination of very short level lifetimes. In the studied nuclei, the estimated deformation shows a gradual disappearance of the collectivity at the highest available spins.

The Coulomb excitation experiment to study electromagnetic properties of low-lying states in 42Ca with a focus on a presumably superdeformed band was performed at the Laboratori Nazionali di Legnaro in Italy using the \gamma -ray spectrometer AGATA Demonstrator coupled to the DANTE charged particle detector array. First results are presented, including the refinement of the 42Ca level scheme.

The 13/2+ isomeric state in the 199At nucleus has been identified at an excitation energy of 573 keV and its half-life measured to be 580(130) ns using the recoil-decay tagging technique.

Through (α, 4n) and (τ, 3n) reactions the high-spin states in the two-neutron nucleus148Gd were populated up toI π=21− at 7.2 MeV, including numerous states above the yrast line. The148Gd energy spectrum is interpreted in terms of the spherical shell model. Identification of the (νf 7/2 i 1 3/2)10− state gives the νi 13/2 single particle energy free of octupole admixtures as 2.1(1) MeV. Eight high-spin states between 1.2 and 3.7 MeV were identified as the couplings of the two valence-particles to the146Gd octupole phonon, and three above-lying levels are assigned as double-octupole excitations including a 12+ state which decays by anE3-E3 stretched cascade. All these octupole levels can be quantitatively predicted from the one-particle x phonon spectrum of147Gd. The high-spin states above 3 MeV are four-quasiparticle excitations ofπ +1 π −1 ν 2 andπ 2 ν 2 type and their energies are in good accord with shell model estimates.

The deep-inelastic reaction induced by 143 MeV32S on58Ni have been studied detecting projectile-like fragments (PLF) in coincidence withγ-rays in NaI(TI) scintillators. γ-ray multiplicity and anisotropy have been derived for Zplf=14, 15 as a function of energy loss and/or γ-energy. The information obtained are compared with a discrete γ-line study of the same reaction. The effect of the exit channel selection (ejectileZ, energy loss,E γ) on the γ-observables is discussed in connection with the evidence of a strong PLF γ-emission.

The N = 78 isotones 140Sm and 142Gd have been studied with α-particle- and HI-induced reactions. In both nuclei two close-lying 10+ isomers at ∼ 3.2 MeV have been established, and from the feeding E2 cascades they are characterized as the prolate ν h 11 2 −2 and the oblate π h 11 2 2 excitations. A third E2 cascade feeding into the 142Gd 8+ state is interpreted as the continuation of the collective ground state sequence that might assume the properties of a perfect deformed rotor for spins above 10.