9Be Nuclei Research Articles

Study of resonances produced in Heavy Ion Collisions

At Laboratori Nazionali del Sud of Catania an experiment has been carried out in order to investigate the correlations between particles produced in 12C+24Mg reaction at 35 AMeV incident energy. Two α correlation has been explored because provide information about temperature of 8Be nuclei produced in the reaction, while three α correaltion has been studied in order to evaluate the competition between sequential and direct decay mode of resonances produced in 12C quasi-projectiles.

8He Spectroscopy in Stopped Pion Absorption By 9Be

Level structure of 8He has been studied in the reaction of stopped pion absorption by 9Be nuclei. The missing mass spectrum in the range 0 MeV ≤ MM ≤ 10 MeV has been described by the superposition of phase-space distributions and the three states of 8He. Parameters of these states have been compared with data of other experimental and theoretical works.

Nuclear Track Emulsion in Search for the Hoyle’s State in Dissociation of Relativistic 12C Nuclei

Study of production of ensembles of alpha-particle triples associated with the Hoyle state (the second excited state 0+ 2 of the 12 C nucleus) in peripheral dissociation of relativistic 12C nuclei is started. Stacks of pellicles of nuclear track emulsion exposed to 12C of energy from hundreds MeV to few GeV per nucleon serve as the material of the study. The Hoyle state decays are reconstructed via measurements of emission angles of α-particles with accuracy that allows one to identify the unstable 8Be nucleus. A role in the Hoyle state of alpha-particle bonds corresponding to 8Be is determined.

Energy spectra of vibron and cluster models in molecular and nuclear systems

The relation of the algebraic cluster model, i.e., of the vibron model and its extension, to the collective structure, is discussed. In the first section of the paper, we study the energy spectra of vibron model, for diatomic molecule then we derive the rotation-vibration spectrum of \( 2\alpha\), \( 3\alpha\) and \(4\alpha\) configuration in the low-lying spectrum of 8Be, 12C and 16O nuclei. All vibrational and rotational states with ground and excited A, E and F states appear to have been observed, moreover the transitional descriptions of the vibron model and \( \alpha\)-cluster model were considered by using an infinite-dimensional algebraic method based on the affine \(\widehat{SU(1,1)}\) Lie algebra. The calculated energy spectra are compared with experimental data. Applications to the rotation-vibration spectrum for the diatomic molecule and many-body nuclear clusters indicate that there are solvable models and they can be approximated very well using the transitional theory.

Ab initio calculation of one-nucleon halo states

We develop an approach to microscopic and ab initio description of clustered systems, states with halo nucleon and one-nucleon resonances. For these purposes a basis combining ordinary shell-model components and cluster-channel terms is built up. The transformation of clustered wave functions to the uniform Slater-determinant type is performed using the concept of cluster coefficients. The resulting basis of orthonormalized wave functions is used for calculating the eigenvalues and the eigenvectors of Hamiltonians built in the framework of ab initio approaches. Calculations of resonance and halo states of 5He, 9Be and 9B nuclei demonstrate that the approach is workable and labor-saving.

Relativistic effects in the study of weakly bound $${}^{17}$$17F and $${}^{11}$$11Be nuclei

Relativistic effects are employed to describe the weakly bound nuclei of $${}^{17}$$ F and $${}^{11}$$ Be. In order to calculate the energy levels of the ground state and the excited states of these nuclei, we solved the Dirac equation with pseudospin symmetry in the shell model by using the basic concept of supersymmetric shape invariance method. The results obtained from this approach are compared with a non-relativistic approach and experiment. It was then seen that the relativistic approach matches more with the experimental results.

MANIFESTATION OF NUCLEAR CLUSTERIZATION IN COULOMB SUMS

The new experimental Coulomb sums values of 6Li and 7Li nuclei have been obtained at momentum transfers range q = 0.750¸ 1.000 fm-1 and q = 0.750¸ 1.125 fm-1, respectively, extending significantly the earlier reported momentum transfers range of Coulomb sums for these nuclei. The dependence of the 6Li and 7Li Coulomb sums on the momentum transferred is shown to differ substantially from same dependences for all the other investigated nuclei. It is suggested that the observed feature of the 6Li and 7Li Coulomb sums is related to a strong clusterization of these nuclei. The parameter qp corresponding to the value of the momentum transferred, at which the Coulomb sum ceases to grow and remains constant for larger momentum transfers, is introduced. The values of the parameter qp for the lithium isotopes nuclei were obtained (qp(7Li) = 1.20 ± 0.10fm-1 and qp(7Li) = 1.35 ± 0.10 fm-1), which are much lower than qp of 4He, 12C, 40Ca, 48Ca and 56Fe nuclei (qp » 2 fm-1). The graph represented the qp values of the nuclei as a function of the isolation parameter x, which characterizing the degree of nuclear clusterization, is constructed. The obtained graph shows the explicit proportionality of the qp dependence from the parameter x and predicts the qp value for the Coulomb sum of the 9Be nucleus not yet measured.

7Be and 8B reaction dynamics at Coulomb barrier energies

We investigated the reaction dynamics induced by the 7Be,8B+208Pb collisions at energies around the Coulomb barrier. Charged particles originated by both the col- lisions were detected by means of 6 ΔE-Eres telescopes of a newly developed detector array. Experimental data were analysed within the framework of the Optical Model and the total reaction cross-sections were compared together and with the 6,7Li+208Pb colli-sion data. According to the preliminary results, 7Be nucleus reactivity is rather similar to the 7Li one whereas the 8B+208Pb total reaction cross section appears to be much larger than those measured for reactions induced by the other weakly-bound projectiles on the same target.

Total reaction cross sections and neutron-removal cross sections of neutron-rich light nuclei measured by the COMBAS fragment-separator

Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one –neutron removal cross sections 8Li and 9Be were measured.

Study of the Involvement of 8Be and 9B Nuclei in the Dissociation of Relativistic 10C, 10B, and 12C Nuclei

The results obtained by estimating the contribution of 8Be and 9B nuclei to the coherent dissociation of 10C, 10B, and 12C relativistic nuclei in nuclear track emulsions (“white” stars) are presented. The selection of white stars accompanied by 9B leads to a distinct peak appearing in the distribution of the excitation energy of 2α2p ensembles and having a maximum at 4.1 ± 0.3 MeV. A 8Be nucleus manifests itself in the coherent-dissociation reaction 10B → 2He + H with a probability of (25 ± 5)%, (14 ± 3)% of it being due to 9B decays. The ratio of the branching fractions of the 9B + n and 9Be + p mirror channels is estimated at 6 ± 1. An analysis of the relativistic dissociation of 12C nuclei in a nuclear track emulsion revealed nine 3α events corresponding to the Hoyle state.

A comprehensive analysis of elastic scattering of 14N projectile on 7Li, 9Be, 11B, 12C, 16O, 26Mg, 28Si, 40Ca, 56Fe, 59Co, 60,62Ni, 70,74Ge, 90Zr, 112Cd, 118Sn, 159Tb and 197Au at various incident energies

Elastic scattering data of 14N projectile on 7Li, 9Be, 11B, 12C, 16O, 26Mg, 28Si, 40Ca, 56Fe, 59Co, 60,62Ni, 70,74Ge, 90Zr, 112Cd, 118Sn, 159Tb and 197Au target nuclei are investigated at various incident energies. To obtain nuclear potential, two different approaches are applied. In first approach, the imaginary potential is assumed as the Woods-Saxon potential while the real potential is determined using the double folding model. In a second approach, both real and imaginary potentials are evaluated within the double folding model. The real and imaginary volume integrals and cross-sections of the systems investigated under different approaches are provided. Then, new equations which give the imaginary potential are obtained from the elastic scattering results. Finally, the effect of 10B + α and 13C + p cluster cases of 14N nucleus on the elastic scattering analysis is investigated by a simple approach.

Реакція 7Li(15N,14C)8Be та взаємодія ядер 13,14C + 8Be

Реакція 7Li(15N,14C)8Be та взаємодія ядер 13,14C + 8Be

Analysis of 11Be + p elastic scattering using a BHF approach

The elastic scattering of the halo nucleus 11Be on the proton at various incident energies has been analysed using the microscopic optical potential (OP) calculated within the first order non-relativistic Brueckner–Hartree–Fock (BHF) approach. Argonne v-18 inter-nucleon potential is employed to calculate the microscopic OP. The nuclear density distribution has been obtained using a semi-phenomenological model. The density used shows extended neutron distribution indicating a possible halo structure. We have also compared our results with an empirical analysis using CH89 global OP. The analysis reveals that the BHF approach provides good agreement with the experimental data for all incident energies considered in this paper.

Study of ground states of 3H, 3,4,6He, 6Li, and 9Be nuclei by Feynman’s continual integrals method

The ground-state energies and the squared moduli of the ground-state wave functions are calculated for the 3H, 3,4,6He, 6Li, and 9Be nuclei by Feynman’s continual (path) integrals method. The results are in satisfactory agreement with experimental data.

Use of Radioactive Beams of 7Be Nuclei to Study the Wear Resistance of Materials

This work is devoted to the use of beams of radioactive nuclei for applied purposes – to study the wearresistance of materials used in different industries. The crux of the method is that the radioactive nuclei obtained in the nuclear reactions 1H(7Li, 7Be) and 1H(10B, 7Be) are implanted in the experimental sample. After implantation of the nuclei, the sample undergoes wear tests. The γ-radiation of the implanted nuclei is high-energy; the spectrum is comparatively simple and does not produce appreciable radiation damage in the test samples. The method has been successfully tested in determining the wear-resistance of machine parts and mechanisms.

Structure and Reactions of ^{11}Be: Many-Body Basis for Single-Neutron Halo.

The exotic nucleus ^{11}Be has been extensively studied and much experimental information is available on the structure of this system. We treat, within the framework of renormalized nuclear field theory in both configuration and 3D space, the mixing of bound and continuum single-particle states through the coupling to collective vibrations of the ^{10}Be core. We also take care of the Pauli principle acting not only between the single valence particle explicitly considered and those participating in the collective states, but also between fermions involved in two-phonon virtual states dressing the single-particle motion. In this way, it is possible to simultaneously and quantitatively account for the energies of the 1/2^{+}, 1/2^{-} low-lying states, the centroid and line shape of the 5/2^{+} resonance and the one-nucleon stripping and pickup absolute differential cross sections involving ^{11}Be as either target or residual nucleus. Also for the dipole transition connecting the 1/2^{+} and 1/2^{-} parity inverted levels as well as the isotopic shift of the charge radius. Theory provides a unified and exhaustive nuclear structure and reaction characterization of the many-body effects which are at the basis of this paradigmatic one-neutron halo system.

Can nuclear physics explain the anomaly observed in the internal pair production in the Beryllium-8 nucleus?

Recently the experimentalists in Krasznahorkay (2016) [1] announced observing an unexpected enhancement of the e+–e− pair production signal in one of the 8Be nuclear transitions. The subsequent studies have been focused on possible explanations based on introducing new types of particle. In this work, we improve the nuclear physics modeling of the reaction by studying the pair emission anisotropy and the interferences between different multipoles in an effective field theory inspired framework, and examine their possible relevance to the anomaly. The connection between the previously measured on-shell photon production and the pair production in the same nuclear transitions is established. These improvements, absent in the original experimental analysis, should be included in extracting new particle's properties from the experiment of this type. However, the improvements can not explain the anomaly. We then explore the nuclear transition form factor as a possible origin of the anomaly, and find the required form factor to be unrealistic for the 8Be nucleus. The reduction of the anomaly's significance by simply rescaling our predicted event count is also investigated.

Four-body continuum effects in 11Be + d scattering

We present a new reaction model, which permits the description of reactions where both colliding nuclei present a low threshold to breakup. The method corresponds to a four-body extension of the Continuum Discretized Coupled Channel (CDCC) model. We first discuss the theoretical formalism, and then apply the method to 11Be + d scattering at Ec.m.=45.5 MeV. The 11Be nucleus and the deuteron are described by 10Be + n and p+n structures, respectively. The model involves very large bases, but we show that an accurate description of elastic-scattering data may be achieved only when continuum states of 11Be and of the deuteron are introduced simultaneously. We also discuss breakup calculations, and show that the cross section is larger for 11Be than for the deuteron. The present theory provides reliable wave functions that may be used in the analysis of (d,p) or (d,n) experiments involving radioactive beams.

Investigation of the Nuclear Structure for Some p-Shell Nuclei by Harmonic Oscillator and Woods-Saxon Potentials

The single particle radial wave functions of harmonic oscillator potential and Woods-Saxon potential have been used to calculate the charge density distributions, charge form factor and the matter and charge root mean square (rms) radii for some odd-A 1p shell nuclei, namely 9Be, 11B, 13C and 15N nuclei. The calculated results are compared with the measured data. Calculations show that both the Wood-Saxson (WS) and harmonic oscillator (HO) potentials are capable of providing theoretical predictions on the structure of p-shell nuclei and be in a satisfactory description with those of experimental data. The quadrupole form factors contribution for 9Be and 11B nuclei are carried out using undeformed p-shell model and give a well accordance with the measured results.

Studying the reactions of deuteron interaction with 9Be nuclei at low energies

Data on elastic and inelastic scattering, and the reactions of few-nucleon transfers in the interaction between the nuclei of deuteron and 9Be at energies of around 10 MeV/nucleon, are analyzed. A theoretical analysis is performed using the double-folding potential model with the wave function of the ground state of the 9Be nucleus, constructed in the three-cluster α + α + n-approximation. Calculations of the cross section of elastic scattering for the reaction d + 9Be using the calculated folding potential are preformed using the optical model. The resulting optical potential is used to analyze cross sections of transfer reactions and inelastic scattering in the context of the distorted waves method. A comparative analysis of the experimental data and theoretical calculations is performed.