Light Particle Emission Mechanisms in Heavy-Ion Reactions at 5-20 MeV/u

V.L. Kravchuk^1a, S. Barlini² and O.V. Fotina³ for the NUCL-EX - HECTOR collaboration

¹ INFN Laboratori Nazionali di Legnaro, I-35020 Legnaro (Padova), Italy and Dipartimento di Fisica dell’Università di Bologna, I-40126 Bologna, Italy
² INFN, Sezione di Firenze, I-50125 Firenze, Italy
³ Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119992 Moscow, Russia

^a e-mail: kravchuk@lnl.infn.it

Abstract

Light Charged Particle emission mechanisms were studied for different mass entrance channel nuclear reactions. The 300, 400, 500 MeV ⁶⁴Ni + ⁶⁸Zn and 130, 250 MeV ¹⁶O + ¹¹⁶Sn reactions were measured at the Legnaro National Laboratory using the beams from the TANDEM-ALPI acceleration system. Light Charged Particles were measured in coincidence with Evaporation Residues and their spectra were analyzed using the global moving source fit technique. The characterization of different emission sources (evaporative, pre-equilibrium, break-up) is discussed. The behavior of pre-equilibrium emission as a function of projectile energy, excitation energy and mass-asymmetry in the entrance channel was studied, evaluating the energy, mass and charge lost by the composite systems and using Griffin exciton model for the pre-equilibrium neutron emission. The present results are compared with the systematics of the asymmetric mass entrance channel reactions. The present work shows that also at the onset the pre-equilibrium emission depends not only on the projectile velocity but also on the reaction entrance channel mass-asymmetry. The first attempt of the particle spectra analysis using the Griffin exciton model is demonstrated for the case of proton emission in the 130 MeV ¹⁶O + ¹¹⁶Sn reaction.