Interplay of the elastic and inelastic channels in the 16O+27Al scattering at Elab = 280 MeV

Recent data indicated a nuclear rainbow-like pattern in the elastic scattering of 16O + 27Al at Elab = 100 MeV that arises from couplings of the ground to the low-lying states of the 27Al nucleus. Similar effect was identified in the elastic angular distribution of 16O + 12C at Elab = 281 and 330 MeV. These experiments show a crucial role of microscopic details of nuclear structure in the elastic scattering of heavy ions at energies well above the Coulomb barrier. In this work we investigate the 16O + 27Al system at Elab = 280 MeV for which a coupled channel calculation predicts a pronounced nuclear rainbow-like structure. Obtained experimental data show evidences of an important coupling of the elastic channel to the inelastic. Coupled channel calculations reproduce the experimental angular distributions when a re-normalization factor on the real part of the optical potential is introduced. A proper theoretical approach still requires a high degree of accuracy for the nuclear structure models and new tools to deal with collective excitations

The MAGNEX spectrometer: results and perspectives

This article discusses the main achievements and future perspectives of theMAGNEX spectrometer at the INFN-LNS laboratory in Catania (Italy). MAGNEX is alarge acceptance magnetic spectrometer for the detection of the ions emitted innuclear collisions below Fermi energy. In the first part of the paper anoverview of the MAGNEX features is presented. The successful application to theprecise reconstruction of the momentum vector, to the identification of the ionmasses and to the determination of the transport efficiency is demonstrated byin-beam tests. In the second part, an overview of the most relevant scientificachievements is given. Results from nuclear elastic and inelastic scattering aswell as from transfer and charge exchange reactions in a wide range of massesof the colliding systems and incident energies are shown. The role of MAGNEX insolving old and new puzzles in nuclear structure and direct reaction mechanismsis emphasized. One example is the recently observed signature of the longsearched Giant Pairing Vibration. Finally, the new challenging opportunities touse MAGNEX for future experiments are briefly reported. In particular, the useof double charge exchange reactions toward the determination of the nuclearmatrix elements entering in the expression of the half-life of neutrinolessdouble beta decay is discussed. The new NUMEN project of INFN, aiming at theseinvestigations, is introduced. The challenges connected to the major technicalupgrade required by the project in order to investigate rare processes underhigh fluxes of detected heavy ions are outlined

A view of recent results and perspectives on nuclear structure with MAGNEX at the INFN-LNS laboratory

An intense activity in the field of experimental, as well as theoretical, nuclear structure is ongoing at the INFN-LNS laboratory in Catania. A short overview of the main recent results is reported

A mini-phoswich scintillator as a possible stop detector for the NUMEN project

AbstractIn the framework of the NUMEN project, aimed at the investigation of the nuclear matrix elements connected to the neutrinoless double beta decay by means of the Double Charge Exchange nuclear reactions (Cappuzzello et al., 2015), a high granularity stop detector for heavy ions is needed. It has to allow the identification of ions up to Z≈10 while maintaining a total energy resolution around 2%. As the use of silicon detectors is not possible, due to their poor radiation hardness, scintillators are being investigated as possible candidates. In this paper we show a promising result obtained using a plastic+inorganic phoswich scintillator readout by means of a Silicon Photo Multiplier

Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy

The C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions

Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions

Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections