Speaker
Prof.
Pierre Capel
(Univ. Bruxelles)
Description
Coulomb breakup has been proposed as an indirect method to deduce the cross section of radiative captures of astrophysical interest [1]. In Coulomb breakup, the projectile dissociates into lighter fragments through its interaction with a heavy (high Z) target. Assuming the dissociation to be due to the sole Coulomb interaction, the reaction can be described as an exchange of virtual photons between the projectile and the target. It can thus be seen as the time-reversed reaction of the radiative capture of the fragments, which should enable us to deduce easily the radiative-capture cross section from breakup measurements [1].
Using accurate reaction models, various studies have shown that higher-order effects and other reaction artefacts play a significant role in Coulomb breakup, which hinder the simple extraction of radiative-capture cross sections from breakup measurements [2,3]. Nevertheless, recent analyses show that accurate calculations of the breakup of 15C on Pb at 70AMeV can be used to deduce the Asymptotic Normalisation Coefficient (ANC) of the 15C bound state from experimental data [4,5]. These analyses suggest that this ANC can then be used to compute a cross section for the 14C(n,g) radiative capture in agreement with direct measurements.
In the present work the influence of the description of the 15C continuum upon breakup calculations is analysed. Interestingly, it is shown to be nearly as significant as that of the ANC. Fortunately, it can be accounted for by fitting the theoretical predictions to the breakup data in the low 14C-n energy range. These results revive the original idea of inferring radiative-capture cross sections from Coulomb breakup measurements.
In addition to its application in nuclear astrophysics, this work also indicates which information of the structure of the projectile actually matters in reaction modelling. This shows how the simple description of nuclei used in accurate reaction codes could be improved from state-of-the-art nuclear-structure models.
[1] G. Baur, C. A. Bertulani, and H. Rebel, Nucl. Phys. A458, 188 (1986).
[2] H. Esbensen, G. F. Bertsch, and K. A. Snover, Phys. Rev. Lett. 94, 042502 (2005).
[3] P. Capel and D. Baye, Phys. Rev. C 71, 044609 (2005).
[4] N. C. Summers and F. M. Nunes, Phys. Rev. C 70, 011602 (2004).
[4] H. Esbensen, Phys. Rev. C 80, 024608 (2009).
Primary author
Prof.
Pierre Capel
(Univ. Bruxelles)
