Talk-delayed blog post emission

My apologies to Valdir Guimaraes for this late post, but I was busy selfishly tending to my own interests. Valdir told us about Light Radioactive Nuclei Capture Reactions By Phenomenological Potential models. The point of this talk was to demonstrate the importance of knowing capture cross-sections on light nuclei and show us how he can use a potential model based indirect data as well as direct data on neighbouring nuclei to make predictions for these cross-sections.

The light nuclei Valdir is referring to give us insight on light halo nuclei (e.g. 11Li and 11Be) as well as the A=8 gap present in cosmic abundances (e.g. 8Li 8B). Capture cross sections on light nuclei can effect early r-process nucleosynthesis, the pp-chain in the sun, as well as yields for big bang nucleosynthesis. Unfortunately I have to disagree with a point made by Valdir on the motivation for BBN. He said that observed abundances of 4He, 3He, 2H, and 7Li disagree with experimental capture cross sections, but this is actually only true for 7Li. Initially it was thought that all disagreed, but more careful approaches to observation have proved only 7Li disagrees with current nuclear knowledge (see R. Cyburt's lecture on BBN at http://www.nscl.msu.edu/~cyburt).

Ingredients in Valdir's potential model are the spectroscopic factor, the bound state potential, and the scattering potential. Each of these pieces of information are extracted from various pieces of experimental data, e.g. the spectroscopic factor can be obtained from data on transfer reactions. Valdir showed us a few examples of how his potential model accurately reproduced known capture cross-section data and it seems his model does quite a good job. However, maybe I missed them but I didn't see any predictions for less well known cross sections or the impact of these predictions. Without any interesting predictions, the potential model certainly loses the sexy-factor that comes with predictive power.