International Journal of Modern Physics E

Nuclei in the p- and sd-shell are studied within the Fermionic Molecular Dynamics (FMD) model that uses Gaussian wave packets as single-particle states. Intrinsic many-body basis states are given by Slater determinants which have to be projected on parity, angular momentum and total linear momentum to restore the symmetries of the Hamiltonian. The flexibility of the Gaussian basis allows to economically describe states with shell structures as well as states featuring clustering or halos. The same effective interaction derived from the realistic Argonne V18 interaction in the Unitary Correlation Operator Method (UCOM) framework is used for all nuclei. We discuss the spectrum of ¹²C with a special emphasis on the structure of the first excited 0⁺ state, the famous Hoyle state. In the FMD approach the Hoyle state is found to be dominated by dilute α-cluster configurations. Recent measurements of the charge radii of Neon isotopes show an intriguing behaviour. This can be explained in FMD calculations by a structure change from ¹⁷Ne and ¹⁸Ne which can be essentially considered as an ¹⁵O or ¹⁶O core plus two protons in s² or d² configurations, respectively. For the heavier isotopes we find that the admixture of ³He and ⁴He cluster configurations in the ground states leads to much larger charge radii than obtained in a mean-field calculation.

The binary and ternary nuclear fission are treated within the statistical model. At the scission point we calculate the potentials as functions of the deformations of the fragments in the dinuclear model. The potentials give the mass and charge distributions of the fission fragments. The ternary fission is assumed to occur during the binary fission.

New methods to identify the high- and low-spin highly deformed nuclear states are suggested.

The presence of alpha cluster structures in light nuclei is well established. This paper concentrates on the medium light nuclei between ¹⁶O and ⁴⁴Ti. Especially the nucleus ³²S has been examined in detail and new data is presented. The elastic scattering data of alpha particles on ²⁸Si forming ³²S shows a peculiar disappearance of cross section at 31 MeV excitation energy and above. Also, the energy versus J(J + 1) plot shows at least one clear rotational-like band of alpha cluster states, with the main energy levels split into many narrow and closely lying levels with the same spin.

Furthermore, few experiments have been carried out investigating the alpha cluster structure of non-nα nuclei, especially on the proton rich side of stability. The evidence at hand indicates that adding neutrons retains some alpha cluster structures and in some cases might even enhance them, but adding protons seems to destroy the structures.

A fast rotating ⁴⁸Cr is predicted to be highly prolate and deformed after a Jacobi shape transition and just before fission. In this article, it is proposed that a narrow and high spin ²⁴Mg+²⁴Mg resonance corresponds to the formation of this exotic ⁴⁸Cr. Moreover the ²⁴Mg+²⁴Mg reaction has been studied at the Legnaro Tandem at a CM bombarding energy of 45.7 MeV, where a narrow and high spin resonance has been reported previously. To establish the connection between the resonance and a molecular state of ⁴⁸Cr, the decay of the resonance into the inelastic and fusion-evaporation channels has been investigated. The ON and OFF resonance decay yields have been measured using, for the inelastic channels, the fragment spectrometer PRISMA and the γ array CLARA, and, for the fusion-evaporation channels, the Si array EUCLIDES and the γ array GASP. Strong resonant effects have been observed in the inelastic channels involving the 2⁺ and 4⁺ states of the ²⁴Mg ground state (g.s.) band. Weaker effects are also seen in certain fusion-evaporation channels. Both results will be discussed here.

Molecular model developed for resonances observed in medium light heavy-ion collisions is described briefly. At high spins, a stable di-nuclear configuration is found to be equator-equator touching one. Energy spectrum of the normal modes around the equilibrium is shown. These modes are expected to be the origin of the large number of resonances observed. Theoretical analyses for the angular distributions and angular correlations are given and compared with recent experiment performed in Strasbourg.

Resonances in light heavy ion reactions are a much studied but little understood phenomenon. New measurements are reported of the ¹²C(¹²C,γ)²⁴Mg radiative capture reaction with the aim of performing spectroscopic measurements on the previously identified resonances. The preliminary analysis is outlined relating to the identification of the ²⁴Mg using a triple ion chamber setup.

The radiative capture process of the ¹²C+¹²C and ¹²C+¹⁶O reactions has been studied using the very selective 0° Dragon spectrometer at Triumf and its associated BGO γ-array. The experiments have been performed at energies around the Coulomb barrier where resonances in the process have been reported. Our results show previously unobserved γ-decay to doorway states in the ²⁴Mg and ²⁸Si respectively around 10 to 12 MeV. The nature of the states is discussed and two scenarii are proposed.

Charged particle and γ-decays in light α-like nuclei are investigated for ²⁴Mg +¹²C. Various theoretical predictions for the occurence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are presented. The inverse kinematics reaction ²⁴Mg +¹²C is studied at E_lab(²⁴Mg) = 130 MeV. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated γ-decays studied. Coincident events from α-transfer channels were selected by choosing the excitation energy or the entry point via the two-body Q-values. The analysis of the binary reaction channels is presented with a particular emphasis on ²⁰Ne-γ and ¹⁶O-γ coincidences.

The robust (spin and isospin zero) α-particle remains one of the best projectiles to probe the nuclear isoscalar excitations. In the present work, a microscopic folding model analysis of the α+¹²C inelastic scattering to the 2⁺ (4.44 MeV), 0⁺ (7.65 MeV), 3^- (9.64 MeV), 0⁺ (10.3 MeV) and 1^- (10.84 MeV) states in ¹²C has been performed using the 3-α resonating group method wave functions. The isoscalar transition strengths of these states were carefully studied based on the coupled-channel analysis using the microscopic folded form factors. A correlation between the weak binding and/or short lifetime of the excited state and absorption in the exit channel of inelastic scattering has been established.

The α+⁸He low-energy reactions and the exotic structures of ¹²Be are studied using the generalized two-center cluster (α+α+N) model. In the two-neutron transfer reactions, α + ⁸He_g.s. → ⁶He_g.s.+⁶He_g.s., a resonant peak with J^π = 0⁺ appears around E ~ 1.3 MeV above the ⁶He_g.s. + ⁶He_g.s. threshold as the result of the formation of the covalent superdeformation, which has a hybrid structure of covalent and ionic configurations for the valence neutrons. The covalent superdeformation gives rise to an isomeric state with a sharp width of Γ ~ 400 keV.

The structure of the neutron-rich isotope ¹²Be has been studied using different transfer reactions, which populate distinct structures in ¹²Be. This concerns two-neutron and three-neutron stripping reactions and two-proton pick-up reactions at incident energies of 15–20 MeV/u. Band structures of positive and negative parity are discussed.

The cluster structures of the excited states in ¹¹B and ¹³C were discussed by measuring the isoscalar monopole strengths in the inelastic α scattering at E_α = 388 MeV. It was found that the , , and states in ¹³C are candidates for the α cluster states with a 3α + n molecular configuration.

We study the structure of low-lying states of ¹³C with a microscopic cluster model. In addition to the 3α-n model space, the breaking effect of one of the α-clusters due to the spin-orbit interaction is also taken into account. The iso-scalar E0 transition probabilities from the ground 1/2^- state to the excited 1/2^- states have been shown to be large associated with the cluster structure of these states. However the values are small due to the effect of one additional valence neutron compared to the case of the second 0⁺ state in ¹²C.

We propose a new approach of the Brueckner-AMD that makes the antisymmetrized molecular dynamics (AMD) calculations possible with realistic nuclear forces. In this method, we solve the Bethe-Goldstone equation and calculate the G-matrix for every nucleon pair described by wave packets of AMD. In addition, we calculate the G-matrix in the spin and parity projection correctly using the two-body correlation functions derived from the solutions of the Bethe-Goldstone equation. We report the results of applications to light nuclei with the Brueckner-AMD plus the spin and parity projection.

Low density states near the 3α and 4α breakup threshold in ¹²C and ¹⁶O, respectively, are discussed in terms of the α-particle condensation. Calculations are performed in OCM (Orthogonality Condition Model) and THSR (Tohsaki-Horiuchi-Schuck-Röpke) approaches. The state in ¹²C and the state in ¹⁶C are shown to have dilute density structures and give strong enhancement of the occupation of the S-state c.o.m. orbital of the α-particles. The state in ¹⁶C has a large component of configuration, which is another reliable evidence of the state to be of 4α condensate nature. The possibility of the existence of α-particle condensed states in heavier nα nuclei is also discussed.

The experimental evidence for dilute α-particle states in ¹²C and ¹⁶O is discussed. The question of the location of the 2⁺ excitation of the 7.65 MeV ¹²C state remains unresolved. It is proposed that the 17.1 and 17.5 MeV 2⁺ excited states in ¹⁶O may correspond to the excitation of the α-particle 4α gas state.

The structure of ¹³C is studied with the semi-microscopic cluster model, 3α+n orthogonality condition model (OCM). The energy spectra of four 1/2^- states and three 1/2⁺ states up to E_x ~ 13 MeV are successfully reproduced, in particular, three monopole transition strengths are in fair agreement with the observed ones. We discuss the cluster states and alpha particle condensation in the 1/2^± states appearing around the ¹²C+n, ⁹Be+α and 3α+n thresholds.

A nucleon is available for examining the property of α-condensate, which consists of composite bosons. Only a microscopic model, which fully takes into account the Pauli principle between all the constituent nucleons, can play its role. We give numerical results by equidistant spectrum model for the system of a neutron and 3α-cluster states. We discuss whether an extra nucleon can exist in the center of α-condensate or not.

We investigate the possible formation of a molecular condensate, which might be, for instance, the analogue of the alpha condensate of nuclear physics, in the context of multicomponent cold atoms fermionic systems. A simple paradigmatic model of N-component fermions with contact interactions loaded into a one-dimensional optical lattice is studied by means of low-energy and numerical approaches. For attractive interaction, a quasi-long-range molecular superfluid phase, formed from bound-states made of N fermions, emerges at low density. We show that trionic and quartetting phases, respectively for N = 3,4, extend in a large domain of the phase diagram and are robust against small symmetry-breaking perturbations.

Study of some properties of the lowest states of ¹²C, including the second 0⁺, 7.65 MeV (Hoyle) state by inelastic scattering of alpha-particles and ³He were carried out. Two independent methods of measuring the radii of the short-lived excited states based on the analysis of diffraction and rainbow patterns of the angular distributions were proposed. Both methods showed that Hoyle state radius is by factor ~ 1.2 – 1.3 larger than that of the ground state. ⁸Be transfer reaction was identified. The probability of L = 0 configuration in Hoyle state occurred to be 3 times larger than in the ground state indicating to the significant presence of condensate configuration in the former one.

An algebraic approach, based on dynamical symmetries, to Bose-Einstein condensates will be illustrated. It allows to write symmetry-dictated exact energy formulas for boson condensates that depend typically on a few quantum numbers. The application to alpha condensation in nuclei will be discussed in detail, showing that symmetry alone is sufficient to predict the energy of N-alpha states in alpha conjugate nuclei. Experiments that might improve the present knowledge will be suggested.

Conditions for a phase change with the formation of an α-particle condensate in excited N=Z nuclei, a dilute Bose-Gas, are discussed for excitation energies around E_Bα = 0, These are second order phase transitions in a mixed gas of Fermions and Bosons. The de-Broglie wavelength of relative motion for α-particles in these states is much larger then the nuclear radii. The experimental observation of the decay of such condensed α-particle states is proposed, with the coherent emission of several correlated α-particles, a decay not described by the Hauser-Feshbach approach for statistical compound nucleus decay. Examples of such observations with the enhanced emission of unbound resonances of ⁸Be and — clusters are discussed. The experiments involved the ISIS-GASP-detection systems at the Laboratorii Nationale di Legnaro.

Following closely BCS theory for pairs, an eventually viable theory for α-particle condensation (quartetting) is sketched. In the final formula the quartet wave function is replaced by a Slater determinant projected on good total momentum. The only variational field is then the single particle 0S wave function. This should reduce the numerical complexity to solve the quartet equations considerably.

Nuclei with N=Z heavier than 100Sn were not identified until now. Meanwhile, they can demonstrate some new unusual features, e.g. the existing of alpha-particle skin, the appearance of a new domain of cluster radioactivity and the most aspiring one, alpha-particle Bose condensate.

Bound state formation is considered in nuclear matter within the frame of many-particle theory. Medium effects such as self-energy and Pauli blocking will modify the single-particle properties as well as the cluster properties. Consequences for the composition, the formation of quantum condensates and the symmetry energy are given.

The simple alpha-cluster model was used for the consideration of the chain states and Bose-Einstein condensation in the light self-conjugated nuclei. Obtained results were compared with predictions of the shell-model for the deformed nuclei, with calculations based on Gross-Pitaevskii equation and with recent experimental results.

Exactly solvable models have played an important role in helping to elucidate the physics of strongly correlated systems. Recently, we have extended the Richardson-Gaudin (RG) models of SU(2) like particle pairing to higher rank algebras. In particular, we will discuss here the SO(8) RG model of proton-neutron pairing as a model of strong quartet correlations. The failure of proton-neutron BCS suggests that new approaches have to be developed to account for them.

An approach is proposed to nuclear pairing at finite temperature and angular momentum, which includes the effects of the quasiparticle-number fluctuation and dynamic coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations of pairing gaps, total energies, and heat capacities are carried out within a doubly folded multilevel model as well as several realistic nuclei. The results obtained show that, in the region of moderate and strong couplings, the sharp transition between the superconducting and normal phases is smoothed out, causing a thermal pairing gap, which does not collapse at a critical temperature predicted by the conventional Bardeen-Cooper-Schrieffer's (BCS) theory, but has a tail extended to high temperatures. The theory also predicts the appearance of a thermally assisted pairing in hot rotating nuclei.

General properties of low-energy cross sections and of reaction rates are presented. We describe different models used in nuclear astrophysics: microscopic models, the potential model, and the R-matrix method. Two important reactions, ⁷Be(p,γ)⁸B and ¹²C(α,γ)¹⁶O, are then briefly discussed.

Present status of the ¹²C(α,γ)¹⁶O cross section knowledge at stellar helium-core burning temperature is presented. Its consequences on the reaction rate uncertainties are discussed considering available models to extrapolate experimental results down to stellar helium-core burning temperature. Some experimental perspectives to reach the desired precision at stellar temperatures are described.

The E2 component of the ¹²C(α,γ)¹⁶O cross section is investigated in three ways: by a microscopic cluster model, by R-matrix fits and by a combination of both. The microscopic calculation leads to an estimate of the S-factor at a typical energy of 300 keV of S_E2(300 keV)≈ 50 keV-b for ground-state transitions. Cascade transitions to the and excited states of ¹⁶O are also studied. Then the S-factor is analyzed in the phenomenological R-matrix theory. We show that the background term plays a crucial role, and cannot be determined without ambiguity. Consequently only an upper limit on the extrapolated S-factor can be obtained [S_E2(300 keV)< 190 keV-b]. Finally, we use the microscopic Asymptotic Normalization Constant (ANC) of the level, well known to be a cluster state to constrain the R-matrix analysis. This procedure strongly reduces the uncertainties on the R-matrix fits, and we end up with a recommended value of S_E2(300 keV) = 42 ± 2 keV-b.

The nuclear structure of states in ¹²C have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0⁺ and 2⁺ states in the triple alpha continuum. A series of experiments have been performed using β-decay of ¹²N and ¹²B to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three α-particles directly. Preliminary results from this experiment will be presented.

The computed α particle momentum distributions from the decay of low-lying ¹²C resonances are shown. The wave function of the decaying fragments is computed by means of the complex scaled hyperspherical adiabatic expansion method. The large-distance part of the wave functions is crucial and has to be accurately calculated. We discuss energy distributions, angular distributions and Dalitz plots for the 4⁺, 1⁺ and 4^- states of ¹²C.

The astrophysical S-factor for ¹⁶O+¹⁶O is investigated within the adiabatic molecular picture. It very well explains the available experimental data. The collective radial mass causes a pronounced resonant structure in the S-factor excitation function, providing a motivation for measuring the ¹⁶O+¹⁶O fusion cross section at deep sub-barrier energies

Dynamics of heavy-ion low energy damped collisions is studied within the model based on the Langevin type equations. Shell effects on the multi-dimensional potential energy surface play an important role in these reactions. This leads to several local minima on the fission path of heavy nucleus — so called isomeric states which are nothing else but the two-cluster configurations with magic or semi-magic cores surrounded with a certain number of shared nucleons. In a giant nuclear system (formed, for example, in U + U collision) the three-body clustering configurations may also appear. Enhanced yield of the nuclides far from the projectile and target masses was found in the multi-nucleon transfer reactions due to the shell effects. It suggests that the low-energy damped collisions of transactinide nuclei may be used as an alternative way for the production of surviving superheavy long-living neutron-rich nuclei.

Mass and energy distributions of binary fragments are discussed for a wide range of nuclei with Z = 82–122 produced in reactions induced by ¹²C, ¹⁶O, ²⁶Mg, ⁴⁸Ca, ⁵⁰Ti, ⁵⁸Fe, ⁶⁴Ni and ⁸⁶Kr ions at energies close and below the Coulomb barrier. It is found that clustering phenomena have a great influence on the formation of the reaction products for fusion-fission and quasifission processes.

The Two-Step Model for fusion of massive systems is briefly recapitulated, which clarifies the mechanism of so-called fusion hindrance. Since the neck changes the potential landscape, especially the height of the conditional saddle point, time evolution of the neck degree of freedom plays a crucial role in fusion. We analytically solve time-evolution of nuclear shape of the composite system from di-nucleus to mono-nucleus. The time-dependent distribution function of the neck is obtained, which elucidates dynamics of fusion processes in general, and thus, is useful for theoretical predictions on synthesis of the superheavy elements with various combinations of incident heavy ions.

The two center shell model is used to calculate the level scheme transition from the superheavy parent nucleus to the emitted cluster plus the daughter nucleus. The three center shell model is also employed to compute the transition toward eventual three equal fragment partition from the superheavy nuclei. The levels are used to compute the shell corrections within the Strutinsky method. The liquid drop part is calculated using the Yukawa-plus-exponential model. The total deformation energy is then minimized over a multidimensional space of deformation. Dynamics is completed with the Werner-Wheeler tensor calculation, and cluster emission paths for binary and ternary splitting is obtained for Z = 120 isotopes.

Two different modes of the multibody collinear decay from the reaction ²³⁸U+⁴He (40MeV) are discussed. Basing on the masses of three detected fragments one can come to conclusion that the decaying system in each mode looks like a chain consisting of two or three magic clusters respectively. Some of the clusters involved undergo "second" clusterisation in the scission point leading to formation of dinuclear molecules. These latter can disintegrate via inelastic scattering on the materials on the flight path.

Nuclear reaction studies at beam energies of 5.9 and 8.7 × A MeV have been performed with the collision system ²⁵Mg +²⁰⁶Pb at the velocity filter SHIP of GSI Darmstadt. The velocity filter offers the possibility to detect the reaction products under zero degree with respect to the beam direction. This allows, together with the measurement of the product velocities, for an identification of the underlying reaction mechanism. Besides fusion-evaporation reactions we found strong signatures for rotation and quasi-fission of nuclear molecules formed after the capture stage in the entrance channel.

We searched for a long-living component in the collision of ²³⁸U+²³⁸U between 6.09 A and 7.35 A MeV. The experiment was performed at GANIL using the spectrometer VAMOS, tuned for observing reactions with kinematics similar to quasi-fission events. Theoretical calculations indicate that reactions with strong energy dissipation and a large number of transferred nucleons are correlated to a time delay in the decay of the giant system. We detected events of such type in the focal plane of VAMOS. These events present an excitation function increasing with bombarding energy.

A new description of the fission process is presented, based on the tendency of nuclear matter to clusterize.

Clustering phenomenon in nuclei is studied within the relativistic as well as non-relativistic mean field approaches, and also as a collective clusterization process in the decaying hot compound nucleus.

Results of the experiments aimed at revealing of manifestations of collinear cluster tri-partition (CCT) of the ²⁵²Cf and ²³⁶U* nuclei are reported. Presumably, the ternary decay of nuclear molecules based on heavy magic clusters such as isotopes of Ni, Ge, Sn, Te gives rise to the effect observed. Experimental conditions allow one to distinguish two CCT partners flying almost in the same direction, while analysis of their charges ensures the discrimination of the background due to scattering. A total yield of the CCT originated events found at the order of 10^-3 per binary fission.

The half-lives of cluster emitters predicted by the analytical superasymmetric fission model have been experimentally confirmed. Potential energy surfaces of cluster emitters are showing deep valleys due to the strong shell effect of the doubly magic daughter ²⁰⁸Pb. Cluster radioactivities allow us to study transitions from a deformed parent nucleus, with a complex structure resulted from mixing of several single-particle states, to a spherical daughter possessing a pure well known state. Recently, preliminary data concerning the ¹⁴C radioactivity of ²²³Ac were reported. The following modes have been experimentally confirmed: ¹⁴C, ²⁰O, ^24,25Ne, ^28,30Mg, and ^32,34Si; lower limits for ¹⁸O, ²³F and ²⁶Ne are available. We give a list of some other experiments which have a good chance to be performed in the future. Applications for true ternary fission, 2α-accompanied fission, and atomic clusters are outlined.

Two proton radioactivity has been observed experimentally in the decay of ⁴⁵Fe and ⁵⁴Zn, and possibly of ⁴⁸Ni. These first experiments only allowed for a limited comparison with theory: T_1/2 and Q_2P values. Experimental efforts have been achieved to measure dynamical observables in order to perform a more detailed study of the decay mechanism. Time projection chambers have been developped by groups of Bordeaux and Warsaw, and were successfully used at GANIL and MSU: those devices allowed for a first direct observation of the individual protons in the 2-proton radioactivity of ⁴⁵Fe, and a first estimate of correlations of these protons.

The α decay potential barriers are determined in the cluster-like shape path within a generalized liquid drop model including the proximity effects between the α particle and the daughter nucleus and adjusted to reproduce the experimental Q_α. The α emission half-lives are determined within the WKB penetration probability. Calculations using previously proposed formulae depending only on the mass and charge of the alpha emitter and Q_α are also compared with new experimental alpha-decay half-lives. The agreement allows to provide predictions for the α decay half-lives of other still unknown superheavy nuclei using the Q_α determined from the 2003 atomic mass evaluation of Audi, Wapstra and Thibault.

The emission of a nucleus of ³⁴Si by the parent is a process in the diffuse borderline between cluster emission and standard mass asymmetric fission. In this paper we analyze in a microscopic framework such process using the standard mean field techniques used to describe cluster emission. They include Hartree-Fock-Bogoliubov constrained calculations with the Gogny D1S interaction and the octupole moment operator as the collective coordinate to describe the process. Collective masses and all kind of zero point energy corrections are considered which allows for a parameter free estimation of the process' half-life. The agreement with experiment is quite satisfactory.

The strength and shape of α-clusters in medium and heavy nuclei are analyzed by using α-decay experimental data. It turns out that the emitters above magic nuclei contain an important α-cluster component, not described within the standard mean field plus pairing approach.

We discuss the U(4|12) supersymmetry scheme that allows the unified treatment of core+α-type configurations of six neighbouring A = 20, 19, and 18 nuclei. The bosons are dipole and monopole excitations of the relative motion, while the fermions are holes on the p-shell core. The validity of the supersymmetry scheme is tested by analyzing correlations in the E2 transitions of the six nuclei and six one-nucleon transfer reactions between them. Further possible cluster supersymmetry schemes are also outlined.

After reviewing some basic features of the temperature-governed phase-transitions in macroscopic systems and in atomic nuclei we consider non-thermal phase-transitions of nuclear structure in the example of cluster states. Phenomenological and semimicroscopical algebraic cluster models with identical interactions are applied to binary cluster systems of closed and non-closed shell clusters. Phase-transitions are observed in each case between the rotational (rigid molecule-like) and vibrational (shell-like) cluster states. The phase of this finite quantum system shows a quasi-dynamical symmetry.

Breakup reactions provide spectroscopic information on exotic nuclei. Coulomb breakup indirectly measures the astrophysical S factor for radiative-capture reactions. The validity of first-order perturbation theory is limited for extended systems such as halo nuclei. More elaborate reaction models are necessary: semi-classical time-dependent Schrödinger equation, eikonal and dynamical eikonal approximations, continuum-discretized coupled-channel method. Breakup experiments do not provide much information on the structure of a two-cluster halo nucleus but accurate exclusive experiments should be more interesting for three-cluster nuclei.

We apply here the dicluster model to the evaluation of static properties of ⁷Li and ⁷Be (e.g.magnetic dipole moment) as well as electromagnetic response to the continuum (in particular E1, E2 and M1). We use Energy Weighted Molecular Sum Rules (EWMSR) to check our calculations and we derive a new expression for the M1 EWMSR. The response functions are then used to evaluate the S-factor for reactions of astrophysical importance, achieving a good agreement.

The Dynamical Eikonal Approximation (DEA) is briefly presented. Resuts obtained within this model for the breakup of ¹¹Be on both light and heavy targets are shown and compared to experiment. The Coulomb Corrected Eikonal (CCE) model is detailed and analysed through comparison with the DEA.

It is shown how many-body correlations involving the symmetry potential naturally arise in the molecular dynamics CoMD-II model. The effect of these correlations on the collision dynamics at the Fermi energies is briefly discussed. The comparison with predictions based on the density functional as obtained through EOS static calculations is also discussed.

A generalized optical potential for elastic scattering induced by light weakly bound nuclei is calculated within the Feshbach projection operator method. The model explicitly takes into account the contribution of the projectile break-up continuum treated within a microscopic cluster model. The model is tested on deuteron and ⁶Lielastic scattering by different targets at intermediate energies. The optical potentials are then calculated for the ⁶He(230 MeV)+¹²Creaction treating the projectile nuclei within two (α + ²n) and three (α + n + n) cluster models. The differences are analyzed.

To investigate the structure of two-neutron halo we propose an experimental method of studying neutron-neutron correlations by measuring reactions induced by halo projectile in nuclear photoemulsions. The obtained preliminary data on interaction of halo nucleus ⁶He with hydrogen are compared with results of simple kinematical calculations for the reaction of quasi-free scattering of proton by the clusters existing in halo nucleus ⁶He.

We report three-center cluster structures in the excited states of ¹¹B(¹¹C), ⁸He and ¹⁴C based on theoretical calculations with the antisymmetrized molecular dynamics (AMD). In particular we discuss the cluster gas-like states 2α + t(2α+³He) in ¹¹B(¹¹C) and α + 2n + 2n in ⁸He. In ¹⁴C, the 3α linear-chain structure is discussed.

Isobaric analogues of three states in ¹⁰Be forming a rotational band with high moment of inertia are expected in ¹⁰B and ¹⁰C. This article reports a measurement of excitation spectrum in ¹⁰B obtained through ¹¹B(³He,α)¹⁰B reaction. A T = 1 state is found on 11.3 MeV excitation energy. It is a possible candidate for the 4⁺ state of the analogue rotation band.

Excitation functions for evaporation residues in the reactions ^206,208Pb(^6,4He,2n²¹⁰Po, as well as for the transfer reactions in the interaction of ⁶He and ⁶Li projectiles with Au and Pt were measured at the energies near the Coulomb barrier. Studied reactions were characterized by an increase in the cross-section compared to statistical model calculations.

Breakup couplings are known to have important effects on the near-barrier elastic scattering of ⁶He. However, the (⁶He,⁵He) single neutron stripping has also been found to have a significant coupling effect, although in calculations that did not include breakup. We firstly present calculations for the ⁶He + ²⁰⁸Pb system that include both breakup and single neutron stripping at 22 and 27 MeV to confirm that the significant stripping coupling effect persists in the presence of breakup couplings. We then compare separate calculations including transfer couplings only with recent elastic scattering data at incident ⁶He energies of 14, 16, 18, 22 and 27 MeV. We also include in an approximate way the two-neutron stripping reaction in an attempt to gain some qualitative insight into the possible coupling effects of this other important near-barrier reaction channel.

Cross sections, kinetic energy and angular distributions of fragments with charge 6 ≤ Z ≤ 28 emitted in ^78,82Kr+⁴⁰C at 5.5 MeV/A reactions were measured at the GANIL facility using the INDRA apparatus. This experiment aims to investigate the influence of the neutron enrichment on the decay mechanism of excited nuclei. Data are discussed in comparison with predictions of transition state and Hauser-Feshbach models.

Within the dinuclear system model we analyse the production of yet unknown superheavy nuclei with Z > 118 and neutron-deficient isotopes of Pu in various complete fusion reactions. The yields of superheavies with Z > 118 are sensitive to the location of the next proton shell closure. The emission of neutron from the dinuclear systems is discussed.

A new method to describe the three-body decaying states is developed. In this method, the Lippmann–Schwinger equation is combined with the complex scaling method to take the correct boundary condition into account. For the application, the E1 transition strength of ⁶He is investigated. The energy and Dalitz distributions of the E1 transition are calculated, and the internal correlation of ⁶He is discussed. As results, it is found that the ⁶He → ⁵He(3/2^-)+n → ⁴He+n+n sequential decay process is dominant in the E1 transition reaction of ⁶He.

We have developed a microscopic cluster model for two-neutron halo nuclei with special attention paid to long distance correlations between the core and the valence neutrons. The emphasis put on a good treatment of the asymptotic region is necessary for nuclear reaction calculations involving these nuclei. In this contribution, we present the first results of our model applied to the ground state of ⁶He bound by an effective central Minnesota N-N interaction, and compare with experiment and other theoretical models.