Advancing the theory of low-energy nuclear reactions populating bound states and resonances and application for nuclear astrophysics

by Prof. Akram Mukhamedzhanov (Cyclotron Institute, Texas A&M University)

Wednesday 8 May 2013, 14:30 → 15:30 Europe/Zurich

26-1-022 (CERN)

The talk is devoted to recent advances in low-energy nuclear reaction theory, a subject that has been mostly neglected for many years, but with the development of new radioactive beam facilities, it became the forefront of contemporary nuclear physics. The overarching objective of the work is to advances the theory of deuteron stripping reactions leading to bound states and resonances, utilizing the state-of-the-art theoretical and computational technology. The results of this research will be made available to experimental groups worldwide in form of new codes for analysis of reactions induced by the radioactive isotopes on deuterium targets. A reliable connection between direct and resonance astrophysical (n,gamma) processes and (d,p) reactions, which are unique tool to investigate neutron captures, will be provided. I will talk about four recent advances [1-4] in low-energy nuclear reaction theory. 1. Separation of nuclear reactions and spectroscopic factors [1]. This work identifies what model-independent spectroscopic information can be extracted from analysis of transfer nuclear reactions. 2. New theory of deuteron stripping based on the surface integral formalism, generalized R-matrix and CDCC was formulated in [2]. It allows us to parameterize deuteron stripping amplitudes in terms of the same observables as in the conventional R matrix. In particular, for stripping to resonance states partial resonance widths can be extracted from the deuteron stripping in the same way as in the traditional R-matrix method for resonance scattering. 3. The developed new theory provides a new tool in using deuteron stripping reactions as indirect methods in nuclear astrophysics: ANC and Trojan Horse methods [3]. I will speak about recent work on determination of the astrophysical factor for the neutron generator 13C(alpha,n)16O using the combination of the Trojan Horse and ANC methods. I will speal also about the application of the Trojan Horse method to analyze the astrophysical reaction 19F(p,n)16O [4] These indirect methods use the developed the developed deuteron stripping theory. The work was supported by the US Department of Energy under Grants No. DE-FG02-93ER40773, No. DE-FG52- 09NA29467, and No. DE-SC0004958 (topical collaboration TORUS) and NSF under Grant No. PHY-0852653. [1]A. M. Mukhamedzhanov and A. S. Kadyrov, Phys. Rev. C 82, 051601(R) (2010). [2] A. M. Mukhamedzhanov, Phys. Rev. C 84, 044616 (2011). [3] M. La Cognata et. al, Phys. Rev. Lett. 109, 232701 (2012). [4] M. La Cognata, A. M. Mukhamedzhanov et. al, Astrophys. J. Lett. 739, L54 (2011).