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Nuclear deexcitation lines are regularly observed in the $\ensuremath{\gamma}$-ray emission spectra of strong solar flares. The most prominent lines are produced by interactions of protons and $\ensuremath{\alpha}$ particles, accelerated up to hundreds of MeV, with abundant nuclei of the solar atmosphere. Analysis and interpretation of these lines, which carry valuable information on the solar flare properties, need cross-section data for the $\ensuremath{\gamma}$-ray line emission in these interactions for a wide particle energy range. To this purpose, we measured the $\ensuremath{\gamma}$-ray emission in interactions of $\ensuremath{\alpha}$-particle beams of ${E}_{\ensuremath{\alpha}}=50\text{--}90$ MeV with target foils of C, Mg, Si, and Fe at the center for proton therapy of the Helmholtz-Zentrum Berlin. Setups of three high-purity Ge detectors and one $\mathrm{La}{\mathrm{Br}}_{3}$:Ce detector have been employed to detect the $\ensuremath{\gamma}$ rays in two experiment campaigns. Relatively large distances of the detectors from the target and pulsed beams with sub-ns-wide pulses allowed the separation of beam-induced prompt $\ensuremath{\gamma}$-ray emission from the targets from other $\ensuremath{\gamma}$ rays and neutron-induced background. $\ensuremath{\gamma}$-ray production cross sections for about 60 deexcitation lines from excited target nuclei or reaction products have been determined. For the strongest deexcitation lines from the major target isotopes, $^{12}\mathrm{C}$, $^{24}\mathrm{Mg}$, $^{28}\mathrm{Si}$, $^{56}\mathrm{Fe}$, there are now measured cross-section data from reaction threshold to ${E}_{\ensuremath{\alpha}}=90$ MeV that can be directly used for astrophysical applications like solar flares. Comparison of the results with a cross-section compilation for strong $\ensuremath{\gamma}$-ray lines in solar flare emissions and the predictions of the talys nuclear reaction code were done. They underline the importance of cross-section determinations at accelerator laboratories for the establishment of an accurate cross-section data base in a wide projectile energy range.

Background: Neutron-rich nuclei in the $\mathrm{A}\ensuremath{\approx}140--160$ mass region provide valuable information on nuclear structure such as quadrupole- and octupole-shape coexistence and the evolution of the collectivity. These nuclei have also a nuclear engineering interest because they contribute to the total decay heat after a fission burst. The information concerning $^{145}\mathrm{La}$ is very limited.Purpose: The study of low-spin states in $^{145}\mathrm{La}$ will provide a more detailed level scheme and enable the determination of the half-lives of the excited states.Methods: Low-spin excited states in $^{145}\mathrm{La}$ have been investigated from the $^{145}\mathrm{Ba}\phantom{\rule{4pt}{0ex}}{\ensuremath{\beta}}^{\ensuremath{-}}$ decay. The $^{145}\mathrm{Ba}$ nuclei were directly produced by photofission in the ALTO facility or obtained from the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{145}\mathrm{Cs}$ also produced by photofission. Gamma spectroscopy and fast-timing techniques were used.Results: A new level scheme was proposed including 67 excited levels up to about 3 MeV and 164 transitions. Half-lives in the few-nanosecond range were measured for the first excited states. Configurations for levels up to $\ensuremath{\approx}600$ keV were discussed.Conclusions: The available information on the low-spin states of $^{145}\mathrm{La}$ has been modified and considerably extended. The analysis of the properties of the first excited states, such as excitation energies, decay modes, log $\mathit{\text{ft}}$ values, reduced transition probabilities, and Weisskopf hindrance factors, has enabled the identification of the first members of the bands corresponding to the ${g}_{7/2},$ ${d}_{5/2},$ and ${h}_{11/2}$ proton configurations.

International audience; Excited states in the mirror nuclei 31P and 31S were populated in the 1p and 1n exit channels of the reaction 20Ne + 12C, at a beam energy of 33 MeV. The 20Ne beam was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident γ-rays and Doppler-shift attenuation lifetime measurements were performed using the multi-detector array GASP in conjunction with the EUCLIDES charged particle detector. In the observed B(E1) strengths, the isoscalar component, amounting to 24% of the isovector one, provides strong evidence for breaking of the isospin symmetry in the A=31 mass region. Self-consistent beyond mean field calculations using Equation of Motion method based on a chiral potential and including two- and three-body forces reproduce well the experimental B(E1) strengths, reinforcing our conclusion. Coherent mixing from higher-lying states involving the Giant Isovector Monopole Resonance accounts well for the effect observed. The breaking of the isospin symmetry originates from the violation of the charge symmetry of the two- and three-body parts of the potential, only related to the Coulomb interaction.

Gamma-ray production cross section excitation functions have been measured for $30$, $42$, $54$ and $66$ MeV proton beams accelerated onto targets of astrophysical interest, $^{nat}$C, C + O (Mylar), $^{nat}$Mg, $^{nat}$Si and $^{56}$Fe, at the Sector Separated Cyclotron (SSC) of iThemba LABS (near Cape Town, South Africa). The AFRODITE array equipped with 8 Compton suppressed HPGe clover detectors was used to record $\gamma$-ray data. For known, intense $\gamma$-ray lines the previously reported experimental data measured up to $E_{p}\simeq$ $25$ MeV at the Washington and Orsay tandem accelerators were extended to higher proton energies. Our experimental data for the last 3 targets are reported here and discussed with respect to previous data and the Murphy \textit{et al.} compilation [ApJS 183, 142 (2009)], as well as to predictions of the nuclear reaction code TALYS. The overall agreement between theory and experiment obtained in first-approach calculations using default input parameters of TALYS has been appreciably improved by using modified optical model potential (OMP), deformation, and level density parameters. The OMP parameters have been extracted from theoretical fits to available experimental elastic/inelastic nucleon scattering angular distribution data by means of the coupled-channels reaction code OPTMAN. Experimental data for several new $\gamma$-ray lines are also reported and discussed. The astrophysical implications of our results are emphasised.

Inelastic ${}^{6}$Li scattering at 100 MeV/u on ${}^{12}$C and ${}^{93}$Nb have been measured with the high-resolution magnetic spectrometer Grand Raiden. The magnetic-rigidity settings of the spectrometer covered excitation energies from 10 to 40 MeV and scattering angles in the range $0^\circ < \theta_{\text{lab.}}< 2^\circ$. The isoscalar giant monopole resonance was selectively excited in the present data. Measurements free of instrumental background and the very favorable resonance-to-continuum ratio of ${}^{6}$Li scattering allowed for precise determination of the $E0$ strengths in ${}^{12}$C and ${}^{93}$Nb. It was found that the monopole strength in ${}^{12}$C exhausts $52 \pm 3^\text{(stat.)} \pm 8 ^\text{(sys.)}$\% of the energy-weighted sum rule (EWSR), which is considerably higher than results from previous $\alpha$-scattering experiments. The monopole strength in ${}^{93}$Nb exhausts $92 \pm 4^\text{(stat.)} \pm 10 ^\text{(sys.)}$\% of the EWSR, and it is consistent with measurements of nuclei with mass number of $A\approx90$. Such comparison indicates that the isoscalar giant monopole resonance distributions in these nuclei are very similar, and no influence due to nuclear structure was observed.

Background: Shape coexistence in the Z≈82 region has been established in mercury, lead, and polonium isotopes. For even-even mercury isotopes with 100≤N≤106 multiple fingerprints of this phenomenon are observed, which seems to be no longer present for N≥110. According to a number of theoretical calculations, shape coexistence is predicted in the Hg188 isotope. Purpose: The aim of this work was to measure lifetimes of excited states in Hg188 to infer their collective properties, such as the deformation. Extending the investigation to higher-spin states, which are expected to be less affected by band-mixing effects, can provide additional information on the coexisting structures. Methods: The Hg188 nucleus was populated using two different fusion-evaporation reactions with two targets, Gd158 and Gd160, and a beam of S34 provided by the Tandem-ALPI accelerator complex at the Laboratori Nazionali di Legnaro. The channels of interest were selected using the information from the Neutron Wall array, while the γ rays were detected using the GALILEO γ-ray spectrometer. Lifetimes of excited states were determined using the recoil-distance Doppler-shift method, employing the dedicated GALILEO plunger device. Results: Lifetimes of the states up to spin 16ℏ were measured and the corresponding reduced transition probabilities were calculated. Assuming two-band mixing and adopting, as done commonly, the rotational model, the mixing strengths and the deformation parameters of the unperturbed structures were obtained from the experimental results. In order to shed light on the nature of the observed configurations in the Hg188 nucleus, the extracted transition strengths were compared with those resulting from state-of-the-art beyond-mean-field calculations using the symmetry-conserving configuration-mixing approach, limited to axial shapes, and the five-dimensional collective Hamiltonian, including the triaxial degree of freedom. Conclusions: The first lifetime measurement for states with spin ≥6 suggested the presence of an almost spherical structure above the 121+ isomer and allowed elucidating the structure of the intruder band. The comparison of the extracted B(E2) strengths with the two-band mixing model allowed the determination of the ground-state band deformation. Both beyond-mean-field calculations predict coexistence of a weakly deformed band with a strongly prolate-deformed one, characterized by elongation parameters similar to those obtained experimentally, but the calculated relative position of the bands and their mixing strongly differ.

Cross sections for the strongest gamma-ray emission lines produced in alpha-particle reactions with C, Mg, Si, Fe have been measured in the range E_alpha = 50 - 90 MeV at the center for proton therapy at the Helmholtz-Zentrum Berlin. Data for more than 60 different gamma-ray lines were determined, with particular efforts for lines that are in cross section compilations/evaluations with astrophysical purpose, and where data exist at lower projectile energies. The data are compared with predictions of a modern nuclear reaction code and cross-section curves of the latest evaluation for gamma-ray line emission in accelerated-particle interactions in solar flares., Comment: 5 pages, 5 figures, contribution to the XXIII International School on Nuclear Physics, Neutron Physics and Applications, Varna, Bulgaria, September 22-28, 2019

The high-spin states of the neutron-rich Ga81, with three valence protons outside a Ni78 core, were measured. The measurement involved prompt γ-ray spectroscopy of fission fragments isotopically identified using the combination of the variable mode spectrometer (VAMOS++) and the advanced gamma tracking array (AGATA). The new γ-ray transitions, observed in coincidence with Ga81 ions, and the corresponding level scheme do not confirm the high-spin levels reported earlier. The newly observed high-spin states in Ga81 are interpreted using the results of state-of-the-art large-scale shell model (LSSM) calculations. The lower excitation energy levels are understood as resulting from the recoupling of three valence protons to the closed doubly magic core, while the highest excitation energy levels correspond to excitations of the magic N=50 neutron core. These results support the doubly magic character of Ni78 and the persistence of the N=50 shell closure but also highlight the presence of strong proton-neutron correlations associated with the promotion of neutrons across the magic N=50 shell gap, only few nucleons away from Ni78.

The success encountered in the systematic studies of the electric and magnetic strength functions for almost all even-even nuclei proves the quality of our HFB+QRPA calculations which use the Gogny interaction within the whole nuclear chart. In this paper, we study the dipole electromagnetic strength distribution in 158-166Dy. The scalar or the vector nature, in the isospin as well as in the spin space, is analysed according to transition density for some of the M1 excitations in 162Dy., SCOPUS: ar.j, info:eu-repo/semantics/published

International audience; The TETRA long neutron counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of β-decay properties of short-lived neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of β-delayed one-neutron emission probabilities (P1n). It requires the use of a well-known β-neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P1n and T1/2 of 96,97Rb nuclei using TETRA . The results obtained are in a good agreement with the values available in the literature. This proves that the developed techniques can be applied to unknown P1n and T1/2 of neutron-rich species.

Excited states in mirror nuclei 31S and 31P were populated in the 1n and 1p exit channels, respectively, of the reaction 20Ne + 12C. The beam of 20Ne, with an energy of 33 MeV, was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident pairs and Doppler-shift attenuation lifetime measurements in 31S and 31P were performed using the multidetector array GASP in conjunction with the EUCLIDES charged particle detector. A comparison of the determined B(E1) strengths of the analog mirror 7/2- → 5/2+ transitions indicates the presence of a violation of isospin symmetry.

The structure of low-lying excited states in $^{251}\mathrm{Fm}$, populated by the $\ensuremath{\alpha}$ decay of $^{255}\mathrm{No}$, has been investigated by means of combined $\ensuremath{\gamma}$ and internal conversion electron spectroscopy. The values for the internal conversion coefficients for the $1/{2}^{+}\ensuremath{\rightarrow}5/{2}^{+}$ and $5/{2}^{+}\ensuremath{\rightarrow}9/{2}^{\ensuremath{-}}$ transitions have been measured. The determined $M2/E3$ mixing ratio and lifetime for the $5/{2}^{+}$ decay to the ground state allowed to determine the corresponding reduced transitions strengths of $B(E3)=18(6)$ W.u. and $B(M2)=3.0(6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ W.u. These results, as well as the results of previous studies in $N=151$ isotopes, are compared to theoretical calculations beyond the mean-field approach, including the first QRPA calculations using the Gogny D1M parametrization for such heavy odd-$N$ nuclei. The comparison points to the importance of accounting for the octupole vibrations for a proper understanding of the low-lying nuclear structure of some of the heaviest elements.

The structure of the S33 nucleus was investigated in the Mg24(N14,αp) fusion-evaporation reaction using a 40-MeV N14 beam. The level scheme was extended up to an excitation energy of 11.7 MeV and spin 19/2+. Lifetimes of the intermediate- and high-spin states have been investigated by the Doppler shift attenuation method. Data were compared with different shell-model calculations where effective interactions involving two main shells, the sd and the fp, are used.

Prompt γ-ray spectroscopy of the neutron-rich $^{96}$Kr, produced in transfer- and fusion-induced fission reactions, has been performed using the combination of the Advanced Gamma Tracking Array and the VAMOS++ spectrometer. A second excited state, assigned to $J^π$ = $4^+$, is observed for the first time, and a previously reported level energy of the first 2+ excited state is confirmed. The measured energy ratio R4/2 = E($4^+$)/E($2^+$) = 2.12(1) indicates that this nucleus does not show a well-developed collectivity contrary to that seen in heavier N = 60 isotones. This new measurement highlights an abrupt transition of the degree of collectivity as a function of the proton number at Z = 36, of similar amplitude to that observed at N = 60 at higher Z values. A possible reason for this abrupt transition could be related to the insufficient proton excitations in the g9/2, d5/2, and s1/2 orbitals to generate strong quadrupole correlations or to the coexistence of competing different shapes. An unexpected continuous decrease of R4/2 as a function of the neutron number up to N = 60 is also evidenced. This measurement establishes the Kr isotopic chain as the low-Z boundary of the island of deformation for N = 60 isotones. A comparison with available theoretical predictions using different beyond mean-field approaches shows that these models fail to reproduce the abrupt transitions at N = 60 and Z = 36.

Relatively neutron-rich thorium isotopes lie at the heart of a nuclear region of nuclei exhibiting octupole correlation effects. The detailed level structure of Th223 has been investigated in measurements of γ radiation following the fusion-evaporation channel of the Pb208(O18,3n)Th223 reaction at 85 MeV beam energy. The level structure has been extended up to spin 49/2, and 33 new γ rays have been added using triple-γ coincidence data. The spins and parities of the newly observed states have been confirmed by angular distribution ratios. In addition to the two known yrast bands based on a K=5/2 configuration, a non-yrast band has been established up to spin 35/2. We interpret this new structure as based on the same configuration as the yrast band in Th221 having dominant K=1/2 contribution. At the highest spin a backbending occurs around a rotational frequency of ℏω=0.23 MeV, very close to the one predicted in Th222, where a sharp transition to a reflection-symmetric shape is expected.

High-spin states in $^{139}\mathrm{Ce}$ have been populated using the $^{130}\mathrm{Te}(^{14}\mathrm{C},5n)$ reaction. The level scheme has been extended to higher spins, including a new band of dipole transitions. The parity of several states has been changed from negative to positive, mainly based on the comparison with the level structure of the core nucleus $^{140}\mathrm{Ce}$ and the results of a realistic shell-model calculation. The dipole band is interpreted as a magnetic rotation band with $\ensuremath{\pi}{h}_{11/2}^{2}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}^{\ensuremath{-}1}$ configuration built on small deformation axial shape with $({\ensuremath{\varepsilon}}_{2}=0.12,\ensuremath{\gamma}={0}^{\ensuremath{\circ}})$.

International audience; The N=52 Ga83 β decay was studied at ALTO. The radioactive 83 Ga beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of γ -ray emission following β decay. While β -delayed neutron emission has been measured to be 56–85% of the decay path, in this experiment an unexpected high-energy 5–9 MeV γ -ray yield of 16(4)% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow–Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the β -decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei.

Dipole excitations of nuclei are crucial since they play an important role in nuclear reaction modeling in connection with the photoabsorption and the radiative capture processes. We present here results for the gamma-ray strength function obtained in large-scale axially-symmetric deformed quasiparticle (qp) random phase approximations approach using the finite-range Gogny force, with a particular emphasis on the E1 mode. The convergence with respect to the number of harmonic oscillator shells adopted and the cut-off introduced in the 2-quasiparticle excitation energy space is analyzed. The microscopic nature of our self-consistent Hartree-Fock-Bogoliubov plus QRPA (HFB+QRPA) calculation has unfortunately to be broken, some phenomenological corrections being needed to take into account effects beyond the standard 2-qp QRPA excitations and the coupling between the single-particle and low-lying collective phonon degrees of freedom. The corresponding phenomenological parameters are adjusted on experimental photoabsorption data. In such a procedure, a rather satisfactory description of experimental data is obtained. To study the sensitivity of these phenomenological corrections on the extrapolation, both at low energies and towards exotic neutron-rich nuclei, three different prescriptions are considered. They are shown to lead to rather similar predictions of the E1 strength at low energies as well as for exotic neutron-rich nuclei. The Gogny-HFB+QRPA strength is finally applied to the calculation of radiative neutron capture cross sections and the predictions compared with those obtained with more traditional Lorentzian-type approaches., SCOPUS: cp.p, info:eu-repo/semantics/published

International audience; In this paper we present theoretical results on the dipole response in the proton spin-saturated$^{90-94}$Zr isotopes. The electric and magnetic dipole excitations are obtained in Hartree-Fock-Bogolyubov plus Quasi-particle Random Phase Approximation (QRPA) calculations performed with the D1M Gogny force. A pnQRPA charge exchange code is used to study the Gamow-Teller response. The results on the pygmy, the giant dipole resonances as well as those on the magnetic nuclear spin-flip excitation and the Gamow-Teller transitions are compared with available experimental or theoretical information. In our approach, the proton pairing plays a role in the phonon excitations, in particular in the M1 nuclear spin-flip resonance.

Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1 \ensuremath{\gamma}$-ray strength function, obtained in the framework of the axially- symmetric-deformed quasiparticle random phase approximation (QRPA) based on the finite-range D1M Gogny force, to the calculation of the $M1$ strength function. We compare our QRPA prediction of the $M1$ strength with available experimental data and show that a relatively good agreement is obtained provided the strength is shifted globally by about 2 MeV and increased by an empirical factor of 2. Predictions of the $M1$ strength function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed. Its impact on the radiative neutron capture cross section is also analyzed.

International audience; The lifetimes of eight lower spin levels of the yrast band in 168Yb, populated via the 154Sm(18O,4n) and 124Sn(48Ca,4n) reactions, were measured, six of them for the first time, by means of the recoil-distance Doppler-shift method. Two versions of the differential decay-curve method have been applied for the data analysis resulting in a very good agreement. The reduced transition probabilities indicate some reduction of the collectivity for states just above the View the MathML source61+ level, i.e. well below the band-crossing. The reasons of this effect are discussed in terms of an interaction between the ground-state band and yet unknown part of the two-quasiparticle (ν13/2ν13/2) spin-aligned S-band by invoking the shell-structure or alternatively/additionally, as changes in the internal structure/shape induced by the rotation.

The N = 48 Ge-80 nucleus is studied by means of beta-delayed electron-conversion spectroscopy at ALTO. The radioactive Ga-80 beam is produced through the isotope separation on line photofission technique and collected on a movable tape for the measurement of gamma and e(-) emission following beta decay. An electric monopole E0 transition, which points to a 639(1) keV intruder 0(2)(+) state, is observed for the first time. This new state is lower than the 2(1)(+) level in Ge-80, and provides evidence of shape coexistence close to one of the most neutron-rich doubly magic nuclei discovered so far, Ni-78. This result is compared with theoretical estimates, helping to explain the role of monopole and quadrupole forces in the weakening of the N = 50 gap at Z = 32. The evolution of intruder 0(2)(+) states towards Ni-78 is discussed.

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

26Al was the first cosmic radioactivity ever detected in the galaxy as well as one of the first extinct radioactivity observed in refractory phases of meteorites. Its nucleosynthesis in massive stars is still uncertain mainly due to the lack of nuclear information concerning the 26Al(n,p)26Mg and 26Al(n,α)23Na reactions. We report on a single and coincidence measurement of the 27Al(p,p’)27Al(p)26Mg and 27Al(p,p’)27Al(α)23Na reactions performed at the Orsay TANDEM facility aiming at the spectroscopy study of 27Al above the neutron threshold. Fourteen states are observed for the first time within 350 keV above the 26Al+n threshold.

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

International audience; The vibrational mass parameters entering the quadrupolar 5DCH Hamiltonian are commonly obtained neglecting beyond mean-field correlations and the dynamical mean-field rearrangement. The Quasiparticle Random Phase Approximation (QRPA) framework would allow to avoid these disadvantages [1], if the computation time, when using density dependent force, was not prohibitive. Here, a significant time reduction is obtained by applying valence space (VS) techniques (energy cut-off and inert core) in QRPA calculations. The VS techniques allow to probe the physical content of the mass parameter. The QRPA mass parameter exhibit robustness toward VS limitations contrarily to the intrinsic QRPA outputs, that show deceptive appearance when an inert core is used. Excited states energy, and associated transition probabilities, should not be considered for optimizing the valence space limits.

Systematic off-line fluorination studies on all the stable lanthanide isotopes have been performed. The results are presented as a function of various parameters such as the target temperature, the type of ion source used (hot plasma or surface ionization) and the quantity of CF4 introduced. The first on-line measurements allowed us to determine the optimal experimental conditions for producing radioactive lanthanide isotopes. Fil: Roussière, B.. Université Paris Sud; Francia Fil: Deloncle, I.. Université Paris Sud; Francia Fil: Barrè Boscher, N.. Université Paris Sud; Francia Fil: Cardona, Maria Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentina Fil: Mhamed, M. Cheikh. Université Paris Sud; Francia Fil: Corbin, T.. Université Paris Sud; Francia Fil: Cottereau, E.. Université Paris Sud; Francia Fil: Croizet, H.. Université Paris Sud; Francia Fil: Dimitrov, B.. Institute For Nuclear Research And Nuclear Energy Bulgarian Academy Of Sciences; Bulgaria Fil: Essabaa, S.. Université Paris Sud; Francia Fil: Gavrilov, G.. Institute For Nuclear Research And Nuclear Energy Bulgarian Academy Of Sciences; Bulgaria Fil: Gottardo, A.. Université Paris Sud; Francia Fil: Goutev, N.. Institute For Nuclear Research And Nuclear Energy Bulgarian Academy Of Sciences; Bulgaria Fil: Guillot, J.. Université Paris Sud; Francia Fil: Hojman, Daniel Leonardo. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lau, C.. Université Paris Sud; Francia Fil: Roccia, S.. Université Paris Sud; Francia. Centre de Sciences Nucleaires Et de Sciences de la Matiere; Francia Fil: Tusseau-Nenez, S.. Université Paris Sud; Francia Fil: Verney, D.. Université Paris Sud; Francia Fil: Yavahchova, M.. Institute For Nuclear Research And Nuclear Energy Bulgarian Academy Of Sciences; Bulgaria

International audience; For the first time, using a unique finite range interaction (D1M Gogny force), a fully coherent and time-feasible calculation of the Bohr Hamiltonian vibrational mass is envisioned in a Hartree-Fock-Bogoliubov + Quasiparticle Random Phase Approximation (QRPA) framework. In order to reach handable computation time, we evaluate the feasibility of this method by considering the insertion of a valence space for QRPA. We validate our approach in the even-even tin isotopes comparing the convergence scheme of the mass parameter with those of built-in QRPA outputs: excited state energy and reduced transition probability. The seeming convergence of these intrinsic quantities is shown to be misleading and the difference with the theoretical expected value is quantified. This work is a primary step towards the systematic calculation of mass parameters.

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

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

Matière Nucléaire; The $^{84}$Se nucleus has been produced as fission fragment in the fusion reaction $^{18O} + ^{208}$Pb at 85MeV bombarding energy and studied with the Euroball IV array. Medium-spin states of this neutron-rich isotope have been identified for the first time. Its level scheme has been obtained up to 4.9MeV excitation energy and spin I sim 7plankv. Its structure is interpreted by analogy with those of the stable heavier isotones. The evolution of the energy of the N = 50 neutron-core excitation is discussed as a function of the proton number.

High-spin states from the three-quasiparticle (3qp) configuration $\pi$ g $_{9/2}\nu$ h11/2 2 in the neutron-rich 49In isotopes have been studied in the framework of shell model calculation. The two-body residual interactions needed for such calculations have been extracted from the level schemes of neighbouring nuclei. In particular, the evolution of the proton-neutron $\pi g_{9/2}\nu h_{11/2}$ interaction has been analyzed as a function of the neutron number. When the gradual filling of the $\nu h_{11/2}$ sub-shell is taken into account, the results of the 3qp configuration calculations are found to be very close to the experimental positive-parity yrast states located above 2 MeV excitation energy in $^{113\mbox{--}121}$ In. Moreover, several long-lived isomeric states with positive parity are predicted in 123,125,127In.

High-spin states in 108,110Pd isotopes are studied by $\gamma$ -ray spectroscopy of heavy-ion-induced fission. The Pd isotopes are produced in the fission channel of the 31P + 176Yb reaction at beam energy 152 MeV. The prompt $\gamma$ -rays are detected with the EUROBALL4 multidetector array. The yrast states of 108,110Pd have been observed above the region of the first backbend. The level scheme of 108Pd was extended with a new negative-parity band. The yrast sequence in 110Pd is observed up to spin I = 14 + and negative-parity bands have also been identified. The backbending in these even-mass Pd isotopes is associated with the alignment of the neutron (h 11/2)2 pair. The negative-parity states arise from two neutron configurations $\nu h_{11/2} \otimes \nu g_{7/2}$ and $\nu h_{11/2} \otimes \nu d_{5/2}$ and they are interpreted in the frame of two-quasiparticle + rotor model as semidecoupled bands. The observed experimental staggering in the $\gamma$ -bands of 108,110Pd supports the theoretical predictions for $\gamma$ -instability of their shapes.

The response of a scintillation detector with a cylindrical 1.5-inch LaBr3:Ce crystal to incident neutrons has been measured in the energy range En = 2-12 MeV. Neutrons were produced by proton irradiation of a Li target at Ep = 5-14.6 MeV with pulsed proton beams. Using the time-of-flight information between target and detector, energy spectra of the LaBr3:Ce detector resulting from fast neutron interactions have been obtained at 4 different neutron energies. Neutron-induced gamma rays emitted by the LaBr3:Ce crystal were also measured in a nearby Ge detector at the lowest proton beam energy. In addition, we obtained data for neutron irradiation of a large-volume high-purity Ge detector and of a NE-213 liquid scintillator detector, both serving as monitor detectors in the experiment. Monte-Carlo type simulations for neutron interactions in the liquid scintillator, the Ge and LaBr3:Ce crystals have been performed and compared with measured data. Good agreement being obtained with the data, we present the results of simulations to predict the response of LaBr3:Ce detectors for a range of crystal sizes to neutron irradiation in the energy range En = 0.5-10 MeV, Comment: 28 pages, 10 figures, 4 Tables

International audience; One of the first fusion–evaporation experiments using radioactive ion beams was performed at GANIL in order to study proton-rich nuclei of the light rare-earth region. The low production cross-section of the exotic species of interest, in combination with the low intensity of the beam and its induced background, demanded the use of a highly efficient experimental setup. This consisted of the EXOGAM γ-ray spectrometer coupled for the first time with both the DIAMANT charged-particle array and the VAMOS recoil spectrometer. In this report the experimental challenges of such studies will be discussed and the experimental achievements of the in-beam spectroscopy of proton drip-line nuclei using EXOGAM will be presented.

The ${}^{26}\mathrm{Al}$ radioisotope is of great importance for understanding the chemical and dynamical evolution of our galaxy. Among the possible stellar sources, massive stars are believed to be the main producer of this radioisotope. Understanding ${}^{26}\mathrm{Al}$ nucleosynthesis in massive stars requires estimates of the thermonuclear reaction rates of the $^{26}\mathrm{Al}$${(n,p)}^{26}$Mg, $^{26}\mathrm{Al}$${(n,\ensuremath{\alpha})}^{23}$Na, and $^{23}\mathrm{Na}$${(\ensuremath{\alpha},p)}^{26}$Mg reactions. These reaction rates depend on the spectroscopic properties of ${}^{27}\mathrm{Al}$ states above the neutron and alpha thresholds. In this context, the $^{27}\mathrm{Al}$${(p,{p}^{\ensuremath{'}})}^{27}$Al* reaction was studied at 18 MeV using a high-resolution Enge Split-Pole spectrometer. States from the ground state up to excitation energies of $\ensuremath{\approx}$14 MeV were populated. While up to the ${}^{23}\mathrm{Na}$ + $\ensuremath{\alpha}$ threshold no additional states are observed, we report for the first time 30 new levels above the ${}^{23}\mathrm{Na}$ + $\ensuremath{\alpha}$ threshold and more than 30 new states above the ${}^{26}\mathrm{Al}$ + n threshold for which excitation energies are determined with an uncertainty of 4--5 keV.

Expérience GANIL; International audience; A fusion-evaporation experiment has been performed with a SPIRAL 76Kr radioactive beam in order to study the deformation of rare-earth nuclei near the proton drip-line. The experimental setup consisted in the EXOGAM gamma-array, coupled to the light-charged particles (LCP) DIAMANT detector and to the VAMOS heavy-ion spectrometer. The difficulties inherent to such measurements are enlightened. The coupling between EXOGAM and DIAMANT has been used to decrease the huge background caused by the radioactivity of the beam. It further permits assigning new gamma-ray transitions to specific residual nuclei. A gamma-ray belonging to the 130Pm level scheme has thus been observed for the first time.

International audience; An experiment has been performed using a SPIRAL $^{76}$Kr radioactive beam at GANIL to investigate rare-earth nuclei near the proton drip-line. The EXOGAM gamma array was coupled with the DIAMANT light charged-particle detector and the VAMOS spectrometer. We report here on the powerful of this setup to extract fusion-evaporation $\gamma$-rays from a large beam contamination.

The nucleus 35S has been studied by in-beam ?-ray spectroscopy using the 24Mg(14N,3p) fusion-evaporation reaction at Elab=40 MeV. A level scheme extended up to J?=17/2+ at 8023 keV and J?=13/2- at 6352 keV has been established. Lifetimes of six excited states have been determined by applying the Doppler shift attenuation method. The experimental data have been compared with the results of large-scale shell model calculations performed using different effective interactions and model spaces allowing particle-hole excitations across the N=Z=20 shell gap. © 2014 American Physical Society.

The high-spin states of the two neutron-rich nuclei ${}^{88}$Kr${}_{52}$ and ${}^{89}$Rb${}_{52}$ have been studied from the ${}^{18}$O+${}^{208}$Pb fusion-fission reaction. Their level schemes were built from triple $\ensuremath{\gamma}$-ray coincidence data, and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ angular correlations were analyzed in order to assign spin and parity values to most of the observed states. The two level schemes evolve from collective structures to single-particle excitations as a function of the excitation energy. Comparison with results of shell-model calculations gives the specific proton and neutron configurations which are involved to generate the angular momentum along the yrast lines.

Odd-odd ${}^{136}$Cs nuclei have been produced in the ${}^{18}\mathrm{O}+{}^{208}$Pb and ${}^{12}\mathrm{C}+{}^{238}$U fusion-fission reactions and their $\ensuremath{\gamma}$ rays studied with the Euroball array. The high-spin level scheme was built up to $\ensuremath{\sim}$4.7 MeV excitation energy and spin $I\ensuremath{\sim}16\ensuremath{\hbar}$ from the triple $\ensuremath{\gamma}$-ray coincidence data. The configurations of the three structures observed above $\ensuremath{\sim}$2 MeV excitation energy are first discussed by analogy with the proton excitations identified in the semimagic ${}^{137}$Cs${}_{82}$ nucleus, which involve the three high-$j$ orbits lying above the $Z=50$ gap, $\ensuremath{\pi}{g}_{7/2}$, $\ensuremath{\pi}{d}_{5/2}$, and $\ensuremath{\pi}{h}_{11/2}$. This is confirmed by the results of shell-model calculations performed in this work.

Excited states in the doubly-odd{sup 184}Au nucleus have been studied by in-beam {gamma}-ray spectroscopy. This nucleus was produced through the fusion-evaporation reactions {sup 165}Ho({sup 24}Mg, 5{ital n}), {sup 170}Yb({sup 19}F, 5{ital n}), and {sup 161}Dy({sup 27}Al, 4{ital n}). Different rotational band structures have been observed and interpreted as specific couplings of proton and neutron single-particle excitations present in neighboring odd Au and Pt nuclei. {copyright} {ital 1996 The American Physical Society.}

Nine lifetimes have been determined for the first time in the 5 / 2 − [ 523 ] and 5 / 2 + [ 642 ] bands of 167Yb by means of Recoil distance Doppler-shift measurements carried out at the Cologne FN tandem. For the data analysis, a dedicated version of the Differential decay curve method was used. The newly deduced transition strengths and the level scheme are reasonably described by the Particle plus triaxial rotor model (PTRM) calculations except for the behavior of the quadrupole collectivity in the two signatures of the 5 / 2 + [ 642 ] band. The stretched B(E2)ʼs in the favored signature are appreciably larger than those in the unfavored signature. The effect increases with spin. In the PTRM calculations, the wave functions of the favored signature levels contain larger contribution of low-Ω orbitals from ν i 13 / 2 parentage than those of the unfavored levels. This could selectively increase the deformation of the favored signature band members. If so, rotation and Coriolis interaction would give rise to a dynamic shape coexistence taking place between the two signatures.

The data obtained with the new generation of Ge multidetectors, like EUROGAM, can be considered as multidimensional, or high fold, objects. New codes have been written for the handling of these data which remains very delicate. For example the data sort procedure can affect the relative intensities of γ -rays belonging to rare and long cascade of transitions, as a superdeformed band. A new code, FANTASTIC, devoted to the treatment of high-fold data, offers the possibility to perform such sensitive analyses as, for instance, the study of relative intensities or angular distributions of γ -transitions.

Five $N=82$ isotones have been produced in two fusion-fission reactions and their $\ensuremath{\gamma}$ rays studied with the Euroball array. The high-spin states of ${}^{139}$La have been identified, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis, spin values have been assigned to some states of ${}^{136}$Xe and ${}^{137}$Cs. Several cascades involving $\ensuremath{\gamma}$ rays of ${}^{139}$La have been found to be delayed; they deexcite an isomeric state with ${T}_{1/2}=315(35)$ ns located at 1800 keV excitation energy. The excited states of these five $N=82$ isotones are expected to be due to various proton excitations involving the three high-$j$ subshells located above the $Z=50$ shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in ${}^{136}$Xe, ${}^{137}$Cs, and ${}^{138}$Ba.

The ${}^{119--126}$Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: ${}^{12}\text{C}+{}^{238}\text{U}$ at a bombarding energy of 90 MeV and ${}^{18}\text{O}+{}^{208}\text{Pb}$ at 85 MeV. Their level schemes have been built from $\ensuremath{\gamma}$ rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the even- and odd-$A$ ${}^{120--126}$Sn nuclei have been identified. Moreover, isomeric states lying around 4.5 MeV have been established in ${}^{120,122,124,126}$Sn from the delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. The states located above 3 MeV excitation energy are ascribed to several broken pairs of neutrons occupying the $\ensuremath{\nu}{h}_{11/2}$ orbit. The maximum value of angular momentum available in such a high-$j$ shell, i.e., for midoccupation and the breaking of the three neutron pairs, has been identified. This process is observed for the first time in spherical nuclei.

WOS: 000308129400006, Excited states up to J(pi) = 11(-) at 10 296 keV and J(pi) = 10(+) at 10 707 keV have been populated in the odd-odd Cl-36 nucleus using the Mg-24(N-14,2p) fusion-evaporation reaction at E-lab = 31 MeV. Twenty new states and 62 new gamma transitions have been identified by employing gamma-gamma and gamma-gamma-gamma coincidences. Lifetimes have been investigated by the Doppler shift attenuation method. The experimental data have been compared with the results of large-scale shell-model calculations performed using different effective interactions and model spaces allowing particle-hole excitations across the N = Z = 20 shell gap., MICINN, Spain; INFN, Italy [ACI2009-1070]; Spanish MINECO [AIC-D-2011-0746, AIC10-D-000568, FPA2011-29854]; Generalitat Valenciana [PROMETEO/2010/101], This work was carried out at the INFN Laboratori Nazionali di Legnaro (LNL), Italy. Authors are thankful to the XTU Tandem staff of LNL for delivering good-quality beam. S. Aydin thanks Sudeb Bhattacharya for very useful discussions during the preparation of the manuscript. A. Gadea and E. Farnea acknowledge the support of MICINN, Spain, and INFN, Italy, through the ACI2009-1070 bilateral action. A. Gadea activity has been partially supported by the Spanish MINECO under Grants No. AIC-D-2011-0746, No. AIC10-D-000568, and No. FPA2011-29854 and the Generalitat Valenciana under Grant No. PROMETEO/2010/101.

The192Hg nucleus was populated in the160Gd(36S, 4n) reaction at a beam energy of E=159 MeV. Emittedγ-rays were detected with the EUROGAM array comprising 43 Compton-suppressed large volume Ge detectors. The level scheme of192Hg has been extended up to an excitation energy of E=10.4 MeV and spin I=34 ħ. Two new structures, made of competing ΔI=1 and ΔI=2 transitions have been observed and their connexions with the low-lying levels established. Their lowest levels are located at 6.304 MeV and 6.879 MeV excitation energy. The experimental results are compared with mean-field HF+BCS calculations. It is proposed that the new structures originate from deformation-aligned quasi-proton excitations π(i13/2 * h9/2)K=11 andπ (h9/2) K=8 2 , coupled to rotation-aligned quasi-neutron ν(i13/2)n and quasi-proton π(h11/2)2 excitations.

Two regular dipole gamma -ray cascades have been observed in 194Pb. A comprehensive level scheme related to these structures has been built and first members of rotational bands built on K=8 and K=11 two-proton oblate states have been identified. From the excitation energies, spin values, behaviours of the moments of inertia and alignments, and from the comparison with the isotone 192Hg, multiparticle configurations can be attributed to three high-spin structures of 194Pb built respectively on the 4966 keV, 4334 keV and 6198 keV levels: ( pi 9/2(505) pi 13/2(606))(vi13/2)2, ( pi 9/2(505) pi 13/2(606))(vf5/2vi13/2), ( pi 9/2(505) pi 13/2(606)) (vf5/2(vi13/2)3). Within this interpretation, the regular dipole bands correspond to the presence of two or three i13/2 decoupled neutrons.

The ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}$As nuclei have been produced as fission fragments in the fusion reaction ${}^{18}$O + ${}^{208}$Pb at 85 MeV bombarding energy and studied with the Euroball array. Medium-spin states of ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}$As have been established up to $\ensuremath{\sim}3.5$ MeV excitation energy. From angular correlation analysis, spin values have been assigned to most of the ${}^{81}\phantom{\rule{-0.16em}{0ex}}$As excited states. The behaviors of the yrast structures identified in this work are discussed in comparison with the general features known in the mass region. Then they are compared to the results of two theoretical approaches: the ``rotor + quasiparticle'' for ${}^{81}\phantom{\rule{-0.16em}{0ex}}$As and the shell model using the effective interactions JUN45 for ${}^{83,81}\phantom{\rule{-0.16em}{0ex}}\phantom{\rule{-0.16em}{0ex}}$As.