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In this paper, the validity of the shell-evolution picture is investigated on the basis of shell-model calculations for the atomic mass number 25≲A≲55 neutron-rich nuclei. For this purpose, the so-called SDPF-MU interaction is used. Its central, two-body spin–orbit, and tensor forces are taken from a simple Gaussian force, the M3Y (Michigan 3-range Yukawa) interaction, and a π+ρ meson exchange force, respectively. Carrying out almost a complete survey of the predicted effective single-particle energies, it is confirmed here that the present scheme is quite effective for describing shell evolution in exotic nuclei.

One of the most complicated problems of experimental nuclear physics is the synthesis of exotic nuclei near the boundaries of stability. These nuclei, as a rule, are 10 or more neutrons away from stable nuclei, have a short lifetime (less than 1 ms) and low binding energy. All this determines special requirements to the choice of reactions for the synthesis of such nuclei and the method of their transportation and registration. Mainly, for the synthesis of exotic nuclei, reactions of fragmentation of the bombarding heavy ion, direct reactions of the types (p, d) , (d, p) , (d, n) , ( d , 3 He), etc., as well as reactions of fission and deep inelastic transfer are used.

The isobaric-analog resonancesfor nuclei around the neutron shell closures at N = 20, 50, 82 are treated in the fully self-consistent Density Functional plus Continuum Quasiparticle Random Phase Approximation (DF+CQRPA).The aim is to check how the self-consistency is preserved in the calculations for long isotopic chains. The beta-decay half-lives and delayed multi-neutron emission branchingare calculated for the reference Ni isotopic chain. The relative contributions of the GT and first-forbidden transitions are compared with that of the relativistic QRPA and Finite Amplitude Method. The accuracy of the global beta decay calculations performed within FRDM+RPA, DF+CQRPA and RHB+QRPA models are analysed.

Differential cross sections of elastic scattering of 12,14 Be on 12 C and protons are analyzed within the microscopic model of the optical potential (OP). The microscopic OP consists of the double folding real part and the imaginary part which is constructed using the high energy approximation theory. The OP depends on the nuclear density distributions of 12,14 Be and thus, their microscopic models are tested in our study.

11 pags., 16 figs., 3 tabs., DTAS is a segmented total absorption γ-ray spectrometer developed for the DESPEC experiment at FAIR. It is composed of up to eighteen NaI(Tl) crystals. In this work we study the performance of this detector with laboratory sources and also under real experimental conditions. We present a procedure to reconstruct offline the sum of the energy deposited in all the crystals of the spectrometer, which is complicated by the effect of NaI(Tl) light-yield non-proportionality. The use of a system to correct for time variations of the gain in individual detector modules, based on a light pulse generator, is demonstrated. We describe also an event-based method to evaluate the summing-pileup electronic distortion in segmented spectrometers. All of this allows a careful characterization of the detector with Monte Carlo simulations that is needed to calculate the response function for the analysis of total absorption γ-ray spectroscopy data. Special attention was paid to the interaction of neutrons with the spectrometer, since they are a source of contamination in studies of β-delayed neutron emitting nuclei., This work has been supported by the Spanish Ministerio de Economia y Competitividad under grants FPA2011-24553, AIC-A-2011-0696, FPA2014-52823-C2-1-P and the program Severo Ochoa (SEV-2014-0398), by the European Commission under the FP7/EURATOM contract 605203, and by the Spanish Ministerio de Educacion Cultura y Deporte under the FPU12/01527 grant. The work was also supported by the UK Science and Technology Facilities Council (STFC) grant 14 ST/P005314/1. E. Ganioglu was supported by the Istanbul University Scientic Research Project Unit under FYO-2017-24144 project.

We study multi-hadron systems with a single heavy quark (charm or bottom) in the limit of heavy quark mass. The spin degeneracy of the states with quantum numbers $(j+1/2)^{P}$ and $(j-1/2)^{P}$ for $j \neq 0$, known in a normal hadron, can be generalized to multi-hadron systems. The spin degeneracy is the universal phenomena for any multi-hadron systems with a single heavy quark, irrespective of their internal structures, including compact multi-quarks, hadronic molecules and exotic nuclei. We demonstrate the spin degeneracy in the hadronic systems formed by a heavy hadron effective theory; $P^{(\ast)}N$ states with a $P^{(\ast)}=\bar{D}^{(\ast)}$, $B^{(\ast)}$ meson and a nucleon $N$, and a $P^{(\ast)}$ meson in nuclear matter., Comment: 9 pages, 1 figure

We have around ninety chemical elements available in nature, which were produced mainly by nuclear reactions inside stars. The fusion reactions are the main synthesis process which generates the light and intermediate masses elements. The synthesis begins with the hydrogen burning reaching the region of iron mass nuclei. Heavier elements are synthesized by neutron capture processes, forming exotic nuclei with large neutron excess. These systems present characteristics very different from nuclei inside of stable atoms; they only occur in particular astrophysical environments or are produced artificially in special laboratory conditions. This work discusses some properties of the exotic nuclei and how they participate in the synthesis of elements.

The decay of the neutron unbound ground state of 18 B was studied for the first time through a single-proton knockout reaction from a 62 MeV/u 19 C beam. The decay energy spectrum was reconstructed from coincidence measurements between the emitted neutron and the 17 B fragment using the MoNA/Sweeper setup. An s -wave line shape was used to describe the experimental spectrum resulting in an upper limit for the scattering length of − 50 fm which corresponds to a decay energy s -wave decay of 18 B provides an experimental verification that the ground state of 19 C includes a large s -wave component. The presence of this s -wave component shows that s – d mixing is still present in 18 B and that the s 1 / 2 orbital has not moved significantly below the d 5 / 2 orbital.

International audience; The coupling of very efficient gamma-ray arrays with large acceptance (or highly selective) spectrometers in the context of radioactive beams has pushed away the limits and opened up new possibilities in nuclear physics studies. At GANIL the EXOGAM array (a large efficiency gamma-ray array) has been coupled to VAMOS (a large acceptance spectrometer) and to SPEG (a highly selective spectrometer) to study many different aspects of nuclear structure and reactions covering the whole nuclear chart: indeed, this combination has been used to study neutron rich nuclei toward 54Ca, neutron deficient Sn isotopes around A=103, heavy elements around Md and No, reaction mechanism using the borromean light He isotopes, the nuclear structure in the island of inversion around 32Mg, and many other examples in various domain and energy regime. This is also the case for the very efficient large BaF2 array “Château de crystal” which is frequently coupled to SPEG to study nuclear structure far from stability. In this talk, the various possibilities offered at GANIL with such a coupling will be given. In the future, AGATA will be installed at GANIL to exploit the beams produced by the SPIRAL2 facility. The scientific objectives motivating this installation will be discussed. Again, it is anticipated that this new generation array will be coupled to spectrometers to better exploit the future beams

At the FRS Ion Catcher at GSI, relativistic exotic ions produced by projectile fragmentation/fission are range-focused, slowed down and thermalised in a gas-filled stopping cell, extracted and made available to high-precision experiments with ions almost at rest. It is a prototype for a gas cell system at the Low-Energy Branch of the Super-FRS at FAIR. In an online experiment, the FRS Ion Catcher was commissioned successfully with relativistic nickel fragments. The overall efficiency of the system was measured as (1.8 ± 0.3)% and can be divided into a stopping efficiency of (5.0 ± 1.1)% and an extraction and transport efficiency of (35.8 ± 9.4)%. The overall efficiency is hence limited mostly by the stopping efficiency, which could be increased in the future by operating at higher gas cell pressures. From extraction time measurements of polyatomic ions formed in the gas cell extraction times of atomic ions of 20–50 ms can be derived. The potential of the system was illustrated by the half-life measurement of 54Co with a short half-life of 193 ms only. ispartof: Nuclear Instruments & Methods in Physics Research B vol:266 issue:19 pages:4493-4497 ispartof: location:FRANCE, Deauville status: published

The main purpose of the present manuscript is to review the structural evolution along the isotonic and isotopic chains around the "traditional" magic numbers 8; 20; 28; 50; 82 and 126. The exotic regions of the chart of nuclides have been explored during the three last decades. Then the postulate of permanent magic numbers was de nitely abandoned and the reason for these structural mutations has been in turn searched for. General trends in the evolution of shell closures are discussed using complementary experimental information, such as the binding energies of the orbits bounding the shell gaps, the trends of the rst collective states of the even-even semi-magic nuclei, and the behavior of certain single-nucleon states. Each section is devoted to a particular magic number. It describes the underlying physics of the shell evolution which is not yet fully understood and indicates future experimental and theoretical challenges. The nuclear mean eld embodies various facets of the Nucleon- Nucleon interaction, among which the spin-orbit and tensor terms play decisive roles in the shell evolutions. The present review intends to provide experimental constraints to be used for the re nement of theoretical models aiming at a good description of the existing atomic nuclei and at more accurate predictions of hitherto unreachable systems., to be published in Prog. Part. Nucl. Phys

We propose to use antiprotons to investigate the sizes of stable and neutron-rich exotic nuclei by measurements of the $\pbar A$ absorption cross section along isotopic chains in inverse kinematics. The expected effects are studied theoretically in a microscopic model. The $\pbar U$ optical potentials are obtained by folding free space $\pbar N$ scattering amplitudes with HFB ground state densities and solving the scattering equations by direct integration. The mass dependence of absorption cross sections is found to follow closely the nuclear root-mean-square radii. The total absorption cross section is shown to be a superposition of cross sections describing partial absorption on neutrons and protons, respectively. Thus measuring the differential cross sections for absorption on neutrons and protons will give information on their respective distributions. In neutron-rich nuclei the outer neutron layer shields the absorption on the protons giving access to investigations of antiproton-neutron interactions in matter., Comment: 8 pages, 4 figures

V. Guadilla et al. ; 4 págs.; 4 figs.; 1 tab., The new Decay Total Absorption Spectrometer (DTAS) has been commissioned with low energy radioactive beams at the upgraded IGISOL IV facility. The DTAS is a segmented detector composed of up to 18 NaI(Tl) crystals and it will be a key instrument in the DESPEC experiment at FAIR. In this document we report on the experimental setup and the first measurements performed with DTAS at IGISOL. The detector was characterized by means of MC simulations, and this allowed us to calculate the response function of the spectrometer and analyse the first cases of interest. 2015 Elsevier B.V. All rights reserved., This work has been supported by the Spanish Ministerio de Economía y Competitividad – Spain under the FPA2011-24553, the AIC-A-2011-0696, the FPA2014-52823-C2-1-P and the SEV-2014-0398 Grants, by the European Commission – Belgium under the FP7/EURATOM contract 605203, and by the Spanish Ministerio de Educación – Spain under the FPU program.

The half-lives of isomeric states of fully ionized 144Tb, 149Dy and 151Er have been measured. These nuclides were produced via fragmentation of about 900 MeV/u 209Bi projectiles, separated in flight with the fragment separator (FRS) and stored in the cooler ring (ESR). The decay times of the cooled fragments have been measured with time-resolved Schottky spectrometry. We observed for the first time drastic increases of the half-lives of bare isomers by factors of up to 30 compared to their neutral counterparts. This is due to the exclusion of the strong internal conversion and electron-capture channels in the radioactive decay of these bare nuclei. The experimental results are in good agreement with theoretical calculations.

The ground state nucleon (neutron and proton) distributions for A=20 isobars (Z=6–12) are investigated. For this purpose, the relativistic mean field equations are solved in the coordinate space and also by using the conventional basis expansion method. The pairing is treated in the simple constant gap approximation and also self consistently through the Bogoliubov transformation employing the realistic Gogny D1S interaction as well as the zero range density dependent effective interaction. The comparative study of the results thus obtained indicates the level and the extent of differences in the physical observables like binding energies, sizes, densities, etc. of these nuclei, arising due to the use of these different variants of solving the RMF/RHB equations. Though the results are qualitatively similar, the deviations do appear at a finer level, especially for large Tz (20 O and 20 N ). The calculations also reveal mirror symmetry about Tz=0 for all physical observables, which is in accordance with the experiment. The calculated nucleon densities are compared with those obtained by using a semi-phenomenological model that incorporates correctly the asymptotic behavior. The reaction cross-sections with these A=20 isobars as projectiles incident on a 12 C target at 950 A MeV incident energy, calculated within the Glauber model using the RMF/RHB and model densities agree well with the experiment.

Coulomb breakup of unstable neutron-rich carbon isotopes 15,17 C has been studied at energies around ∼500–600 MeV/nucleon. Non-resonant low-lying dipole strength is observed in these isotopes which can be explained by a direct breakup mechanism. In addition to the decay neutron from excited projectile, γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence, giving access to quantitative spectroscopic information. The spectroscopic factor deduced for a valence neutron occupying the s1/2 level in the 15C ground state is consistent with that obtained earlier from (d,p) transfer reactions. The analysis for Coulomb breakup of 17C shows that most of the cross section yields the 16C core in excited states. The predominant ground-state configuration of 17C is found to be 16 C (2 + )⊗ν s,d .

R. Lica et al. -- 14 pags., 7 figs., tab. -- Open Access funded by Creative Commons Atribution Licence 3.0, Neutron-rich Ba isotopes are expected to exhibit octupolar correlations, reaching their maximum in isotopes around mass A = 146. The odd-A neutron-rich members of this isotopic chain show typical patterns related to non-axially symmetric shapes, which are however less marked compared to even-A ones, pointing to a major contribution from vibrations. In the present paper we present results from a recent study focused on Cs β-decay performed at the ISOLDE Decay Station equipped with fast-timing detectors. A detailed analysis of the measured decay half-lives and decay scheme of Ba is presented, giving a first insight in the structure of this neutron-rich nucleus., The IDS collaboration acknowledges financial support from: Istituto Nazionale di Fisica Nucleare, the Italian ‘Programmi di Ricerca Scientifica di Rilevante Interesse Nazionale (PRIN)’ contract number 2001024324 01302, the European Union’s seventh framework through ENSAR, contract no. 262010, the European Unions Horizon 2020 Framework research and innovation programme under grant agreement no. 654002 (ENSAR2), the FATIMA-NuPNET network via the PRI-PIMNUP-2011-1338 project, the Spanish MINECO projects reference numbers FPA2013-41467-P and FPA2015-646969-P, the German BMBF under contract 05P15PKCIA and ‘Verbundprojekt 05P2015’, the FWO-Vlaanderen (Belgium) and the IAP Belgian Science Policy (BriX network P7/12). VCh and ZP acknowledge support by the polish grant of Narodowe Centrum Nauki nr 2015/18/M/ST2/00523.

13 pags, 5 figures.-- PACS nrs.: 24.60.−t; 25.70.Ef; 27.20.+n., Momentum distributions and invariant mass spectra from the breakup of He-6 ions with an energy of 240 MeV/u interacting with a carbon target have been studied. The data were used to extract information about the reaction mechanism which is influenced by the structure of He-6. It is found that the dominant reaction mechanism is a two-step process: knock out of one neutron followed by the decay of the He-5 resonance. The shape of the (α+n) two-body invariant mass spectrum is interpreted as mainly reflecting the 5He ground state which is a J(π) = 3/2(-) resonance. However, no evidence for correlations between cu particles and neutrons is observed in the momentum widths of the distributions. It is demonstrated that a combined analysis of the two-body invariant mass spectrum and an appropriate correlation function may be used to determine the properties of the intermediate resonance., This work was supported by the German Federal Minister for Education and Research (BMBF) under Contracts 06 DA 820, 06 OF 474 and 06 MZ 476 and by GSI via Hochschulzusammenarbeitsvereinbarungen under Contracts DARIK, OF ELK, MZ KRK and partly supported by the Polish Committee of Scientific Research under Contract PB2/P03B/113/09, EC under Contract ERBCHGE-CT92-0003 and CICYT under Contract AEN92-0788-C02-02 (MJGB) and by Deutsche Forschungsgemeinschaft (DFG) under Contract 436 RUS 130/127/1. One of us (B.J.)acknowledges the support through an Alexander von Humboldt Research Award.

The structure of exotic nuclei is one of the main interests in current nuclear physics. Exotic nuclei present unusual properties, such as a low breakup energy, a short lifetime and/or a halo structure. Because of their short lifetimes, they can not be studied by usual spectroscopic techniques. Indeed, targets of such nuclei are impossible to build. But since the availability of radioactive beams, nuclear reactions have provided possibilities of exploring nuclei far from stability.The investigation of exotic nuclei has been recently reactivated by the development of intense radioactive nuclear beams. As firstly observed for the deuteron, and then for other exotic projectiles such as $^6$He and $^{11}$Be, the internal structures of the interacting nuclei can have a significant effect on the elastic cross sections. Due to their low binding energy, the projectile dissociation process, leaving the target in its ground state, highly affects elastic cross sections but also other measurements such as transfer and fusion reactions. Accurate reaction theories are therefore needed. The coupled discretized-continuum channel (CDCC) method is one of those theories and assumes a projectile made of N clusters (usually N=2 or 3) impinging on a target which is structureless. The N+1-body Schrödinger equation is approximately solved by expanding the total wave function over the bound and continuum states of the projectile. These latter take into account the dissociation events and are approximately described by a truncated set of square-integrable wave functions. There are two available methods for discretizing the continuum, the pseudostate method where the projectile Hamiltonian is diagonalized within a finite basis of square-integrable functions, or the bin method where exact scattering wave functions of the projectile are averaged over bins in a finite region of space. In both cases, the N+1-body Schrödinger equation is replaced by a set of coupled-channel differential equations, which provides the physical quantities such as the collision matrix. In principle, the CDCC method can be very close to the exact N+1-body wave function and is adapted to low as well as to high energy reactions. However, its main interest consists in the low-energy domain.In the present work, we propose a new approach to solve the CDCC equations. This method is based on the R-matrix theory associated with a Lagrange mesh basis. We will show that the combination of both approaches provides a fast and accurate technique to solve the CDCC equations, even for large systems, where traditional methods meet convergence problems. Before investigating collisions with exotic projectiles, we restrict ourselves to the simplest nucleus, the deuteron. Then we make a step towards a more complicated system, the $^6$Li which is a well known stable nucleus. We apply the CDCC method to the d + $^{58}$Ni and $^6$Li + $^{40}$Ca elastic scattering and breakup. These systems are considered in the literature as test cases. They have been investigated by several authors who showed the importance of the breakup channels in the elastic cross sections.After having validated the present version of the CDCC method, we focus on $^{11}$Be, a typical example of a halo nucleus, with low binding energy and large quadrupole moment. Elastic, inelastic and breakup cross sections are computed in the CDCC formalism, at energies near the Coulomb barrier, where continuum effects in the scattering of exotic nuclei, and more specifically on the $^{11}$Be + $^{64}$Zn scattering, are observed. We show that converged cross sections need high angular momenta as well as large excitation energies in the wave functions of the projectile.A Borromean nucleus is made of three constituents which are weakly linked together, but where each pair of those three constituents does not form a bound system. The name "Borromean" comes from the Borromean rings where, if any one of three rings is removed, the remaining two become unbound. Collisions with $^6$He and $^9$Be Borromean projectiles are studied in the present work. Again we compare our method with the $^6$He + $^{208}$Pb and $^6$He + $^{12}$C benchmark calculations. Afterwards, the convergence against the parameters of the description of the $^9$Be projectile is tested for the elastic cross section. The sensitivity to the technique employed to remove the forbidden states and also the sensitivity to the collision energy are investigated., Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

We report on a quantitative study of the evolution of the nuclear shell structure, in particular, effective single-particle energies (ESPEs), based on the spin-tensor decomposition of an effective two-body shell-model interaction. While the global trend of the ESPEs is mainly due to the central term of the effective interaction, variations of shell gaps invoke various components of the in-medium NN force. From a detailed analysis of a well-fitted realistic interaction in the sdpf shell-model space, two most important contributions for the evolution of the N = 20 and N = 28 shell gaps are confirmed to be the central term and the tensor term. The role of the latter is dominant to explain the energy shift of spin-orbit partners. Spin-tensor analysis of microscopic effective interactions in sd, pf, and gds shell-model spaces, contrasted with that of the phenomenologically adjusted ones, shows no evidence of amplification of the tensor component contribution; however, it points toward the neglect of three-body forces in the present microscopic interactions.

The validity of the stabilization method in core+valence systems including the possibility of exciting the core is studied. A pseudostate method, based on the transformed harmonic oscillator basis, is extended to include the core degrees of freedom. The method is applied to the case of 11Be structure considering the 0+ ground state and the 2+ first excited state of the 10Be core. The stabilization method is defined in terms of one parameter that can be chosen either discrete or continuous. In the application to 11Be, both cases are analyzed. Ministerio de Ciencia e Innovación FIS2011-28738-c02-01, FPA2009-07653, FPA2009-08848, CSD2007-00042 Junta de Andalucía FQM160, P07-FQM-02894

The nature of the low-lying dipole states in neutron-rich nuclei, often associated to the Pygmy Dipole Resonance, has been investigated. This has been done by describing them within the Hartree-Fock plus RPA formalism. The analysis shows that they are not of collective nature although many particle-hole configurations participate to their formation. Taking advantage of their strong isospin mixing one can envisage combined reaction processes involving the Coulomb and different mixtures of isoscalar and isovector nuclear interactions in order to provide more hints to unveil the characteristic features of these states.

International audience; Studies of -delayed emission of protons for 43Cr and 51Ni were performed with a Time Projection Chamber. This detection setup allows to reconstruct in the three-dimensional space the tracks of the protons emitted. For the first time, -delayed emission of two protons is directly observed for 43Cr and 51Ni. The question about correlations between protons can be accessed. Finally, we show that 43Cr can emit up to three delayed protons.

The electronion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. © 2011 Elsevier B.V. All rights reserved., The authors acknowledge financial support from the EC via the INTAS pro- gramme, grants No. 03-54-6545 and 05-1000008-8272. This work was partially supported by the Hessian LOEWE initiative Helmholtz International Center for FAIR

The nuclear electric quadrupole moment (Q moment) of the neutron-rich nucleus 33Al (I = 5/2 , T 1/2 = 41 ms) has been measured by the $ \beta$ -ray detected nuclear quadrupole resonance ( $ \beta$ -NQR) method for the first time. The 33Al nucleus is considered to be on the border of the island of inversion within which a significant intrusion of the pf orbits occurs across the N = 20 shell gap and the intrusion causes an anomalous enhancement of the Q moment. Polarized 33Al nuclei were produced from 36S (77.5MeV/u beams through the fragmentation process and separated by LISE fragment separator at GANIL. The 33Al nuclei were implanted into a Al2O3 single-crystal plate and the $ \beta$ -NQR spectrum was successfully obtained.

The electric dipole response of 140Ce is investigated using the fully consistent relativistic quasiparticle random phase approximation. By analyzing the isospin structure of the E1 response, it is shown that the low-energy (pygmy) strength separates into two segments with different isospin character. The more pronounced pygmy structure at lower energy is composed of predominantly isoscalar states with surface-peaked transition densities. At somewhat higher energy the calculated E1 strength is primarily of isovector character, as expected for the low-energy tail of the giant dipole resonance. The results are in qualitative agreement with those obtained in recent (gamma, gamma') and (alpha, alpha'gamma) experiments, and provide a simple explanation for the splitting of low-energy E1 strength into two groups of states with different isospin structure and radial dependence of the corresponding transition densities.

The concept of isochronous mass spectrometry (IMS) applying two time-of-flight (TOF) detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor $\gamma$-value far away from the transition point $\gamma _t$ of the storage ring CSRe., Comment: published in Chinese Physics C Vol. 39, No. 10 (2015) 106201

Recent data on inclusive and exclusive breakup and on fusion at Coulomb barrier energies are presented and comparatively discussed for the systems 6Li,17F+208Pb. Both projectiles are very loosely bound and moreover 17F is an unstable beam. The breakup strength in 6Li, bound by 1.47 MeV, is one order of magnitude larger than in 17F, bound by 0.60 MeV; this is at contrary to simple expectations and suggests that other effects, maybe connected to the specific structure of the nuclei (e.g. 6Li cluster structure ?), in addition to the binding energies, influence the breakup process.

In the even-even nuclei around A=100 a transition from spherical to deformed shapes occurs from N=58 to N=60. The isotones with N=59 are of special interest, because they are just at the border between the two regions. Very recently, we have studied odd-neutrons and odd-odd nuclei with N=59, by means of prompt $\gamma$-ray spectroscopy of the spontaneous fission of $^{247}$Cm, using the EUROGAM 2 multi-detector, and by measurements of $\mu$s isomers produced by fission of $^{239,241}$Pu with thermal neutrons at ILL (Grenoble). In the latter case, the detection is based on time correlation measurements between fission fragments detected by the LOHENGRIN mass spectrometer and $\gamma$-rays or conversion electrons from the isomer decay. It was found that three shapes coexist in the odd $^{97}$Sr and $^{99}$Zr and two shapes coexist in the odd-odd $^{96}$Rb. A simple explanation of the shape-coexistence mechanism is proposed. It is based upon the Nilsson diagram and stresses the fundamental importance of the unique parity states.

The collective excitation phenomena in atomic nuclei are studied in two different formulations of the Random Phase Approximation (RPA): (i) RPA based on correlated realistic nucleon-nucleon interactions constructed within the Unitary Correlation Operator Method (UCOM), and (ii) relativistic RPA (RRPA) derived from effective Lagrangians with density-dependent meson-exchange interactions. The former includes the dominant interaction-induced short-range central and tensor correlations by means of an unitary transformation. It is shown that UCOM-RPA correlations induced by collective nuclear vibrations recover a part of the residual long-range correlations that are not explicitly included in the UCOM Hartree-Fock ground state. Both RPA models are employed in studies of the isoscalar monopole resonance (ISGMR) in closed-shell nuclei across the nuclide chart, with an emphasis on the sensitivity of its properties on the constraints for the range of the UCOM correlation functions. Within the Relativistic Quasiparticle RPA (RQRPA) based on Relativistic Hartree-Bogoliubov model, the occurrence of pronounced low-lying dipole excitations is predicted in nuclei towards the proton drip-line. From the analysis of the transition densities and the structure of the RQRPA amplitudes, it is shown that these states correspond to the proton pygmy dipole resonance., Comment: 15 pages, 4 figures, submitted to Physics of Atomic Nuclei, conference proceedings, "Frontiers in the Physics of Nucleus", St. Petersburg, 28. June-1. July, 2005

The optical model, and its applications to elastic, inelastic and transfer reactions is reviewed. The applicability of the optical model to the collisions of exotic nuclei is discussed. The sensitivity of recent experimental data of elastic scattering of 6He on 208Pb to the characteristics of the optical potential is investigated. Comisión Interministerial de Ciencia y Tecnología (CICYT). España FPA2002-04181-C04-02, FPA2002-04181-C04-04, FPA2003-05958

Coulomb dissociation is an especially simple and important reaction mechanism. Since the perturbation due to the electric field of the (target) nucleus is exactly known, firm conclusions can be drawn from such measurements. Electromagnetic matrixelements and astrophysical S-factors for radiative capture processes can be extracted from experiments. We describe the basic elements of the theory of nonrelativistic and relativistic electromagnetic excitation with heavy ions. This is contrasted to electromagnetic excitation with leptons (electrons), with their small electric charge and the absence of strong interactions. We discuss various approaches to the study of higher order electromagnetic effects and how these effects depend on the basic parameters of the experiment. The dissociation of neutron halo nuclei is studied in a zero range model using analytical methods. We also review ways how to treat nuclear interactions, show their characteristics and how to avoid them (as far as possible). We review the experimental results from a theoretical point of view. Of special interest for nuclear structure physics is the appearence of low lying electric dipole strength in neutron rich nuclei. Applications of Coulomb dissociation to some selected radiative capture reactions relevant for nuclear astrophysics are discussed. The Coulomb dissociation of 8B is relevant for the solar neutrino problem. The potential of the method especially for future investigations of (medium) heavy exotic nuclei for nuclear structure and astrophysics is explored. We conclude that the Coulomb dissociation mechanism is theoretically well understood, the potential difficulties are identified and can be taken care of. Many interesting experiments have been done in this field and many more are expected in the future., Comment: review article accepted for publication in "Prog. in Part. and Nucl. Physics", 75 pages, 31 figures

A Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the relativistic framework is presented. In this relativistic mean field (RMF) approach a set of coupled differential equations namely the Dirac equation with potential terms for the nucleons and the Glein-Gordon type equations with sources for the meson and the electromagnetic fields are to be solved self-consistently. The well tested basis expansion method is used for this purpose. Accordingly a set of harmonic oscillator basis generated by an axially deformed potential are used in the expansion. The solution gives the nucleon spinors, the fields and level occupancies, which are used in the calculation of the ground state properties., Comment: 18 pages, LaTex, 6 p.s figures, To appear in Comput. Phys. Commun

This article provides an insight into several open problems in the quest for novel modes of excitation in nuclei with isospin asymmetry, deformation and finite temperature characteristic in stellar environment. Major unsolved problems include the nature of pygmy dipole resonances, the quest for various multipole and spin-isospin excitations both in neutron-rich and proton drip-line nuclei mainly driven by loosely bound nucleons, excitations in unstable deformed nuclei and evolution of their properties with the shape phase transition. Exotic modes of excitation in nuclei at finite temperatures characteristic for supernova evolution present open problems with possible impact in modeling astrophysically relevant weak interaction rates. All these issues challenge self-consistent many body theory frameworks at the frontiers of on-going research, including nuclear energy density functionals, both phenomenological and constrained by the strong interaction physics of QCD, models based on low-momentum two-nucleon interaction V_{low-k} and correlated realistic nucleon-nucleon interaction V_{UCOM}, supplemented by three-body force, as well as two-nucleon and three-nucleon interactions derived from the chiral effective field theory. Joined theoretical and experimental efforts, including research with radioactive isotope beams, are needed to provide insight into dynamical properties of nuclei away from the valley of stability, involving the interplay of isospin asymmetry, deformation and finite temperature., 14 pages, submitted to the Journal of Physics G special issue on Open Problems in Nuclear Structure (OPeNST)

Nuclear spherical shell structure evolves towards more and more exotic regions of the nuclear chart. Therefore, conventional magic numbers (2, 8, 20, 28, 50, 82, 126) can disappear while new ones appear. The evolution of gaps between single-particle states far from stability has essentially two origins : monopole drift and the collectivity enhancement. The monopole drifts are mostly coming from neutron-proton interaction (spin-isospin term of the nuclear interaction). In this thesis, we focused on the study of N=51 isotones and in particular 83Ge, the closest to 79Ni that can be studied nowadays by detailled γ-spectroscopy. For this purpose, two complementary experiments were performed. A first experiment, at GANIL with AGATA, VAMOS and the OUPS plunger device allowed us to measure lifetime of Yrast excited states in the 238U(9Be,f) reaction products. A second experiment for the study of β-delayed γ-spectroscopy of 83Ge was performed in order to populate non-Yrast states so that has an overview of the spectroscopy of 83Ge.The complementarity of these two experiments allowed highlighting for the first time an intruder state above the N=50 gap in 83Ge and thus, it adds information about the evolution of the νg9/2νd5/2 gap corresponding to the N=50 shell closure.A detailed analysis of both experiments is presented in this manuscript. In addition, a comparison to a semi-microscopic core-particle model is performed., La structure nucléaire en couches sphériques évolue en allant vers des régions de plus en plus exotiques de la carte des noyaux. Par conséquent, les nombres magiques conventionnels (2, 8, 20, 28, 50, 82, 126) peuvent disparaître loin de la stabilité, tandis que de nouveaux apparaissent.L’évolution des gaps entre états de particule individuelle loin de la stabilité a essentiellement deux origines : les dérives monopolaires et l’augmentation de la collectivité. Les dérives monopolaires sont essentiellement dues à l’interaction proton-neutron (composante spin-isospin de l’interaction nucléaire). On se concentre dans cette thèse sur les isotopes impairs N=51 et en particulier sur 83Ge, le plus proche de 79Ni que l’on peut étudier actuellement par spectroscopie γ de précision. Pour cela, deux expériences complémentaires ont été réalisées. Une première expérience, au GANIL avec AGATA, VAMOS et le plunger OUPS a permis de mesurer les durées de vie des états excités Yrast des produits de la réaction 238U(9Be,f). Une seconde expérience pour l’étude par spectroscopie γ β-retardée de 83Ge afin de peupler les états non-Yrast a été réalisée afin d’avoir une vue d’ensemble de la spectroscopie de 83Ge.La complémentarité de ces deux expériences a permis de mettre en évidence un état intru pour la première fois au delà du gap N=50 dans 83Ge et ainsi avoir plus d’information sur l’évolution du gap νg9/2νd5/2 associé au nombre magique de spin-orbite N=50. Une analyse détaillée de ses deux expériences est présentée dans ce manuscript. De plus, une comparaison avec un modèle semi-microscopique coeur-particule est aussi réalisée.

Nuclear spherical shell structure evolves towards more and more exotic regions of the nuclear chart. Therefore, conventional magic numbers (2, 8, 20, 28, 50, 82, 126) can disappear while new ones appear. The evolution of gaps between single-particle states far from stability has essentially two origins : monopole drift and the collectivity enhancement. The monopole drifts are mostly coming from neutron-proton interaction (spin-isospin term of the nuclear interaction). In this thesis, we focused on the study of N=51 isotones and in particular 83Ge, the closest to 79Ni that can be studied nowadays by detailled γ-spectroscopy. For this purpose, two complementary experiments were performed. A first experiment, at GANIL with AGATA, VAMOS and the OUPS plunger device allowed us to measure lifetime of Yrast excited states in the 238U(9Be,f) reaction products. A second experiment for the study of β-delayed γ-spectroscopy of 83Ge was performed in order to populate non-Yrast states so that has an overview of the spectroscopy of 83Ge.The complementarity of these two experiments allowed highlighting for the first time an intruder state above the N=50 gap in 83Ge and thus, it adds information about the evolution of the νg9/2νd5/2 gap corresponding to the N=50 shell closure.A detailed analysis of both experiments is presented in this manuscript. In addition, a comparison to a semi-microscopic core-particle model is performed.; La structure nucléaire en couches sphériques évolue en allant vers des régions de plus en plus exotiques de la carte des noyaux. Par conséquent, les nombres magiques conventionnels (2, 8, 20, 28, 50, 82, 126) peuvent disparaître loin de la stabilité, tandis que de nouveaux apparaissent.L’évolution des gaps entre états de particule individuelle loin de la stabilité a essentiellement deux origines : les dérives monopolaires et l’augmentation de la collectivité. Les dérives monopolaires sont essentiellement dues à l’interaction proton-neutron (composante spin-isospin de l’interaction nucléaire). On se concentre dans cette thèse sur les isotopes impairs N=51 et en particulier sur 83Ge, le plus proche de 79Ni que l’on peut étudier actuellement par spectroscopie γ de précision. Pour cela, deux expériences complémentaires ont été réalisées. Une première expérience, au GANIL avec AGATA, VAMOS et le plunger OUPS a permis de mesurer les durées de vie des états excités Yrast des produits de la réaction 238U(9Be,f). Une seconde expérience pour l’étude par spectroscopie γ β-retardée de 83Ge afin de peupler les états non-Yrast a été réalisée afin d’avoir une vue d’ensemble de la spectroscopie de 83Ge.La complémentarité de ces deux expériences a permis de mettre en évidence un état intru pour la première fois au delà du gap N=50 dans 83Ge et ainsi avoir plus d’information sur l’évolution du gap νg9/2νd5/2 associé au nombre magique de spin-orbite N=50. Une analyse détaillée de ses deux expériences est présentée dans ce manuscript. De plus, une comparaison avec un modèle semi-microscopique coeur-particule est aussi réalisée.

The framework of relativistic energy density functionals has been applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of -stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure have been investigated with the relativistic quasiparticle random-phase approximation. We present results for the evolution of low-lying dipole (pygmy) strength in neutron-rich nuclei, and charged-current neutrino- nucleus cross sections.