Estruturas Nucleares e Reações

N. Deshmukh and J. Lubian.

Eur. Phys. J. A (2018) 54: 101. Published online: 21 June 2018

ABSTRACT

The investigation is made to extract the total reaction cross section from a previous work where the elastic scattering of the tightly bound 11B on the 58Ni target was measured, at energies close to the Coulomb barrier. Total reaction cross sections were extracted from the elastic scattering analysis using the Optical Model with double-folding type potentials. We have also taken the total reaction cross section of the systems with almost the same mass range targets and different projectiles from the literature and tried to compare with our system by reducing the cross sections, for the elimination of trivial effects due to different sizes and different Coulomb barriers. In addition to that, for all the systems considered, one-channel calculations that account only for fusion have been performed to study the quantitative effect of the direct reaction channels on the total reaction cross section.

DOI: 10.1140/epja/i2018-12538-x

E. N. Cardozo, J. Lubian, R. Linares, F. Cappuzzello, D. Carbone, M. Cavallaro, J. L. Ferreira, A. Gargano, B. Paes, and G. Santagati

Phys. Rev. C 97, 064611 – Published 20 June 2018

Abstract

In this work we study the simultaneous and sequential two-neutron transfer mechanisms to the 28Sinucleus induced by (t,p) and (18O,16O) reactions. New experimental cross sections for the 28Si(18O,16O)30Si reaction at 84 MeV are also presented. Direct reaction calculations are carried out within the exact finite range coupled reaction channel, for the simultaneous transfer of the two-neutron cluster, and the second-order distorted wave Born approximation, for the sequential transfer. Two different models are considered to describe the two-neutron cluster. The spectroscopic information was obtained from a shell-model calculation with a psdmod interaction for the target overlaps where the 1p3/2, 1p1/2, 1d3/2, 1d5/2, and 2s1/2 orbitals are included as valence subspace. We show that simultaneous and sequential two-neutron transfers are competing mechanisms for the population of the ground state in 30Si. A systematic analysis of the two-neutron transfer induced by the (18O,16O)reaction indicates that the static deformation of target nuclei impacts the two-neutron transfer mechanism.

DOI:10.1103/PhysRevC.97.064611

R. Higa, G. Rupak, A. Vaghani

The European Physical Journal A 54, 89 (2018)

Abstract

In this work we study the radiative capture of 3He on 4He within the halo effective field theory
(EFT) framework. At leading order the capture amplitude comprises the initial state s-wave strong and
Coulomb interactions summed to all orders. At the same order in the expansion, leading two-body currents
contribute as well. We find delicate cancelations between the various contributions, and the two-body
current contributions can be replaced by appropriately enhancing the asymptotic normalizations of the
7Be ground and first excited state wave functions. The next-to-leading order corrections come from the
s-wave shape parameter and the pure Coulomb d-wave initial state interactions. We fit the EFT parameters
to available scattering data and most recent capture data. Our zero-energy astrophysical S-factor estimate,
S34 ∼ 0.55 keV b, is consistent within error bars with the average in the literature.

10.1140/epja/i2018-12486-5

S. R. Souza and R. Donangelo

Phys. Rev. C 97, 054619

ABSTRACT

The internal temperatures of fragments produced by an excited nuclear source are investigated by using the microcanonical version of the statistical multifragmentation model, with discrete energy. We focus on the fragments’ properties at the breakup stage, before they have time to deexcite by particle emission. Since the adopted model provides the excitation energy distribution of these primordial fragments, it allows one to calculate the temperatures of different isotope families and to make inferences about the sensitivity to their isospin composition. It is found that, due to the functional form of the nuclear density of states and the excitation energy distribution of the fragments, proton-rich isotopes are hotter than neutron-rich isotopes. This property has been taken to be an indication of earlier emission of the former from a source that cools down as it expands and emits fragments. Although this scenario is incompatible with the prompt breakup of a thermally equilibrated source, our results reveal that the latter framework also provides the same qualitative features just mentioned. Therefore they suggest that this property cannot be taken as evidence for nonequilibrium emission. We also found that this sensitivity to the isotopic composition of the fragments depends on the isospin composition of the source, and that it is weakened as the excitation energy of the source increases.

DOI: 10.1103/PhysRevC.97.054619

D. Carbone, F. Cappuzzello, C. Agodi , M. Cavallaro , L. Acosta , D. Bonanno , D. Bongiovanni , T. Borello , I. Boztosun, S. Calabrese, D. Calvo, E.R. Chávez Lomelí, N. Deshmukh, P.N. de Faria, P. Finocchiaro, M. Fisichella, A. Foti, G. Gallo, A. Hacisalihoglu, F. Iazzi, R. Introzzi, G. Lanzalone, R. Linares, F. Longhitano, D. Lo Presti, N. Medina, A. Muoio, J.R.B. Oliveira, A. Pakou, L. Pandola, F. Pinna, S. Reito, G. Russo, G. Santagati, O. Sgouros, S.O. Solakcı, V. Soukeras, G. Souliotis, A. Spatafora, D. Torresi, S. Tudisco, A. Yildirim, V.A.B. Zagatto

JOURNAL OF PHYSICS. CONFERENCE SERIES (PRINT), v. 1023, p. 012006-5, 2018.

Abstract

The knowledge of the nuclear matrix elements (NME) entering in the expression of the half-life of the neutrinoless double beta decay is fundamental for neutrino physics. Information on the nuclear matrix elements can be obtained by measuring the absolute cross section of double charge exchange nuclear reactions. The two processes present some similarities, the initial and final-state wave functions are the same and the transition operators are similar. The experimental measurements of double charge exchange reactions induced by heavy ions present a number of challenging aspects, since such reactions are characterized by very low cross sections. Such difficulties are discussed for the measurement of the 116Cd(20Ne,20O)116Sn reaction at 15 AMeV.

DOI:10.1088/1742-6596/1023/1/012006

F. Cappuzzello, C. Agodi, M. Cavallaro, D. Carbone, S. Tudisco, D. Lo Presti, J. R. B. Oliveira, P. Finocchiaro, M. Colonna, D. Rifuggiato, L. Calabretta, D. Calvo, L. Pandola, L. Acosta, N. Auerbach, J. Bellone, R. Bijker, D. Bonanno, D. Bongiovanni, T. Borello-Lewin, I. Boztosun, O. Brunasso, S. Burrello, S. Calabrese, A. Calanna, E. R. Chávez Lomelí, G. D’Agostino, P. N. De Faria, G. De Geronimo, F. Delaunay, N. Deshmukh, J. L. Ferreira, M. Fisichella, A. Foti, G. Gallo, H. Garcia-Tecocoatzi, V. Greco, A. Hacisalihoglu, F. Iazzi, R. Introzzi, G. Lanzalone, J. A. Lay, F. La Via, H. Lenske, R. Linares, G. Litrico, F. Longhitano, J. Lubian, N. H. Medina, D. R. Mendes, M. Moralles, A. Muoio, A. Pakou, H. Petrascu, F. Pinna, S. Reito, A. D. Russo, G. Russo, G. Santagati, E. Santopinto, R. B. B. Santos, O. Sgouros, M. A. G. da Silveira, S. O. Solakci, G. Souliotis, V. Soukeras, A. Spatafora, D. Torresi, R. Magana Vsevolodovna, A. Yildirim, V. A. B. Zagatto

EUROPEAN PHYSICAL JOURNAL A, v. 54, p. 1-76, 2018

Abstract

The article describes the main achievements of the NUMEN project together with an updated and detailed overview of the related R&D activities and theoretical developments. NUMEN proposes an innovative technique to access the nuclear matrix elements entering the expression of the lifetime of the double beta decay by cross section measurements of heavy-ion induced Double Charge Exchange (DCE) reactions. Despite the fact that the two processes, namely neutrinoless double beta decay and DCE reactions, are triggered by the weak and strong interaction respectively, important analogies are suggested. The basic point is the coincidence of the initial and final state many-body wave functions in the two types of processes and the formal similarity of the transition operators. First experimental results obtained at the INFN-LNS laboratory for the 40Ca(18O,18Ne)40Ar reaction at 270MeV give an encouraging indication on the capability of the proposed technique to access relevant quantitative information. The main experimental tools for this project are the K800 Superconducting Cyclotron and MAGNEX spectrometer. The former is used for the acceleration of the required high resolution and low emittance heavy-ion beams and the latter is the large acceptance magnetic spectrometer for the detection of the ejectiles. The use of the high-order trajectory reconstruction technique, implemented in MAGNEX, allows to reach the experimental resolution and sensitivity required for the accurate measurement of the DCE cross sections at forward angles. However, the tiny values of such cross sections and the resolution requirements demand beam intensities much larger than those manageable with the present facility. The on-going upgrade of the INFN-LNS facilities in this perspective is part of the NUMEN project and will be discussed in the article.

10.1140/epja/i2018-12509-3