IRIS: The ISAC charged particle reaction spectroscopy facility for reaccelerated high-energy ISOL beams
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IRIS: The ISAC charged particle reaction spectroscopy facility for reaccelerated high-energy ISOL beams R. Kanungo
Published online: 23 October 2013 © Springer Science+Business Media Dordrecht 2013
Abstract The development of a new charged particle reaction spectroscopy station, IRIS, at ISAC II TRIUMF is described. The facility will be used for studying transfer reactions and inelastic scattering of rare isotopes in inverse kinematics. Keywords Transfer reactions · Inelastic scattering · Solid hydrogen target · Silicon detector · Ionization chamber · Inorganic scintillator 1 Introduction The charged particle spectroscopy in direct reactions of rare isotopes is one of the most effective ways to unveil new features in the proton- and neutron-rich nuclei. The fast rare isotope beams from in-flight production allowed the discovery of exotic structures like the neutron halo [1] and skin through direct reactions. The low-energy reaccelerated beams from the ISOL production technique on the other hand allow complementary precision studies on the nature of the halo and structure of exotic nuclei. These exotic forms of rare isotopes exhibit unusual ordering of nuclear orbitals in regions far away from the line of stability. The arrangement deviates largely from the scheme predicted by the conventional nuclear shell model formulated by Mayer [2] and Haxel et al. [3]. It is found that the higher lying orbitals move lower down in energy intruding into the preceeding shell gap. Thus, the nucleon magic numbers that form the fundamental basis of the nuclear shell structure are modified [4–6]. In order to identify and understand this change in nuclear shell structure it is necessary to know which orbitals the valence nucleons occupy and with what occupation probability.
ISAC and ARIEL: The TRIUMF Radioactive Beam Facilities and the Scientific Program. R. Kanungo (B) Astronomy and Physics Department, Saint Mary’s University, 923 Robie Street, Halifax, NS B3H 3C3, Canada e-mail: [email protected]
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R. Kanungo
One-nucleon transfer reactions provide angular momentum selectivity to decisively determine the unknown spin of energy levels in the exotic nuclei [7]. The orbital occupied by the valence nucleons is reflected in the shape of the angular distribution. Reactions of interest in the IRIS facility are those using hydrogen isotopes as target, such as, ( p, d), (d, p), (d,3 He). Contrary to reactions using stable isotopes, due to the short lifetime of the unstable nuclei, the targets in these reactions are the light hydrogen isotopes and the projectile is the heavy unstable isotope. This laboratory condition of reversed roles of projectile and target in relation to conventional reactions is termed as inverse kinematics. The ( p, d) and (d,3 He) reactions, where respectively one neutron and one proton from the unstable projectile nucleus, A, is transferred to the target, provide information on the configuration mixing in the ground state of the unstable nucleus of interest with mass number A. They also serve as the tool to determi
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