Study of elastic scattering and breakup cross section of 9Be to 9Be+12C reaction at energies near the Coulomb barrier

Author(s)

Renato Aparecido Negrão de Oliveira

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2009-09-22

Examining board members

Alexandre Alarcon do Passo Suaide; Dirceu Pereira; Hugo Reuters Schelin

• Advisor: Alexandre Alarcon do Passo Suaide

Abstract

In this work we performed particle coincidence measurements for the 9Be+12C nuclear reaction at ELab=21MeV in order to obtain information about the breakup of 9Be 8Be+n + +n. We observe evidences of nuclear breakup by reconstructing 8Be ground state particles. From the systematics analysis of the 8Be energy spectrum we observe two different situations: i) at high energies there are evidences which support that the main reaction mechanism is nucleon transfer, and ii) at low energies, a continuum region maybe related to the 9Be breakup process. Further studies are necessary to confirm those hypotheses. In order to check breakup threshold anomalies into the optical potential, we also measured elastic angular distributions at energies around the Coulomb barrier (ELab=13, 14.5, 17.32, 19 e 21MeV). The data were analyzed in the framework of the São Paulo potential, where the normalization of the real and imaginary potential was adjusted to obtain a good description of data at forward angles. At 17.32, 19 and 21MeV, the elastic cross section shows an enhancement at intermediate and backward angles. This can be explained by the elastic transfer mechanisms. (AU)