The MAGNEX spectrometer: Results and perspectives

Abstract

This article discusses the main achievements and future perspectives of the MAGNEX spectrometer at the INFN-LNS laboratory in Catania (Italy). MAGNEX is a large acceptance magnetic spectrometer for the detection of the ions emitted in nuclear collisions below Fermi energy. In the first part of the paper an overview of the MAGNEX features is presented. The successful application to the precise reconstruction of the momentum vector, to the identification of the ion masses and to the determination of the transport efficiency is demonstrated by in-beam tests. In the second part, an overview of the most relevant scientific achievements is given. Results from nuclear elastic and inelastic scattering as well as from transfer and charge exchange reactions in a wide range of masses of the colliding systems and incident energies are shown. The role of MAGNEX in solving old and new puzzles in nuclear structure and direct reaction mechanisms is emphasized. One example is the recently observed signature of the long searched Giant Pairing Vibration. Finally, the new challenging opportunities to use MAGNEX for future experiments are briefly reported. In particular, the use of double charge exchange reactions toward the determination of the nuclear matrix elements entering in the expression of the half-life of neutrinoless double beta decay is discussed. The new NUMEN project of INFN, aiming at these investigations, is introduced. The challenges connected to the major technical upgrade required by the project in order to investigate rare processes under high fluxes of detected heavy ions are outlined. Magnetic spectrometers in Nuclear Reaction studies .

Exclusive breakup of Li7 incident on a proton target at 5.44A MeV

“…Specifically, in Ref. [5] the authors investigated * Corresponding author: apakou@cc.uoi.gr breakup coupling effects on near barrier 6 Li, 7 Be, and 8 B + 58 Ni elastic scattering in the CDCC approach. They observed the following paradox: 6 Li, with a relatively small breakup cross section, exhibits an important breakup coupling effect on the elastic scattering, whereas 8 B, with a large breakup cross section, shows a very modest coupling effect.…”

“…Motivated by the above aspects, we present exclusive breakup measurements for 7 Li incident on a proton target which, together with the chosen energy, should ensure that the breakup cross section is dominated by direct (i.e. nonresonant) decay to the continuum.…”

“…nonresonant) decay to the continuum. The 7 Li nucleus has a well established α + t cluster structure with a relatively large separation energy of 2.47 MeV in comparison with the α + 3 He separation energy of 1.59 MeV of its radioactive mirror nucleus 7 Be. The breakup fragments, α and t, may originate either from sequential and/or direct processes.…”

“…The breakup fragments, α and t, may originate either from sequential and/or direct processes. By sequential breakup we mean excitation of a relatively long-lived resonant state in the 7 Li continuum which subsequently decays into an α particle and a triton, as opposed to direct breakup which omits the intermediate step of the excitation of the resonant state. 7 Li + p at 38.1 MeV.…”

“…The solid black curve (labeled "CDCC") denotes the full calculation, including couplings to the α + t continuum. The dotted red curve (labeled "1 -channel") denotes the result of a calculation including ground state reorientation of 7 Li only. The dot-dashed blue curve (labeled "2 -channel") denotes the result of a calculation including ground state reorientation and excitation of the 0.478 MeV 1/2 − bound first excited state of 7 Li.…”