Speaker
Description
The Carbon-11 nucleus plays an important role in first start nucleosynthesis patterns [1] as a composite of the reaction $^{10}\mathrm{B}(p,\alpha)^{7}\mathrm{Be}$, which act in the hot pp-chains [2] by back processing material branching across the mass $A = 5$ and $A = 8$ mass gap towards $^{10}\mathrm{B}$. The $^{11}\mathrm{C}$ resonances $J^\pi = 5/2^+_2$ and $J^\pi = 7/2^+_1$, 10 keV above and 40 keV below the proton-threshold [3,4], respectively, may impact on the $^{10}\mathrm{B}(p,\alpha)^{7}\mathrm{Be}$ reaction. A shell-model embed in the continuum analysis [5] found that the strong coupling to the one-proton channel $\left[^{10}\mathrm{B}(3^+)\otimes p(lj)\right]^{J^+}$ changes their structure significantly.
To deepen the theoretical analysis, we propose the Gamow shell model (GSM) [6,7] approach. GSM offers a unifying framework with the open quantum system formulation thanks to couplings between discrete and scattering states, as it makes use of the Berggren ensemble [8] of single-particle states. In order describe the scattering properties and reactions, we formulate the GSM in the couple-channel representation (GSM-CC) [9]. Then, the Hamiltonian matrix becomes complex symmetric since the resonances are calculated using the Berggren basis.
Using different mass partitions in the coupled-channel representation, we applied the GSM-CC to reproduce the energies and widths of the $^{11}\mathrm{C}$ excited states above the alpha-threshold. We were able to identify how the excited channel of $\left[^{10}\mathrm{B}\otimes p\right]^{J^+}$ and the presence of the alpha-channels affects the near threshold resonances. Furthermore, we applied the GSM-CC to describe the cross-sections of different types of elastic ($^{10}\mathrm{B}(p,p)^{10}\mathrm{B}$, $^{11}\mathrm{C}(\alpha,\alpha)^{11}\mathrm{C}$), radiative capture ($^{10}\mathrm{B}(p,\gamma)^{11}\mathrm{C}$, $^{7}\mathrm{Be}(\alpha,\gamma)^{11}\mathrm{C}$) and transfer ($^{10}\mathrm{B}(p,\alpha)^{7}\mathrm{Be}$) reactions.
References:
[1] M. Wiescher, O. Clarkson, R. J. deBoer, and P. Denisenkov, The European Physical Journal A 57, 24 (2021).
[2] M. Wiescher, J. Gorres, S. Graff, L. Buchmann, and F. K. Thielemann, The Astrophysical Journal 343, 352 (1989).
[3] M. Wiescher, R. J. deBoer, J. Görres, and R. E. Azuma, Physical Review C 95, 044617 (2017).
[4] C. Angulo, W. H. Schulte, D. Zahnow, G. Raimann, and C. Rolfs, Zeitschrift für Physik A Atoms and Nuclei 345, 333 (1993).
[5] J. Okolowicz, M. Ploszajczak, and W. Nazarewicz, Physical Review C 107, L021305 (2023).
[6] N. Michel, W. Nazarewicz, M. Ploszajczak, and T. Vertse, Journal of Physics G: Nuclear and Particle Physics 36 (2009).
[7] N. Michel and M. Ploszajczak, Gamow Shell Model: The Unified Theory of Nuclear Structure and Reactions, Lecture Notes in Physics, Vol. 983 (Springer International Publishing, Cham, 2021).
[8] T. Berggren, Nuclear Physics A 109, 265 (1968).
[9] Y. Jaganathen, N. Michel, and M. Ploszajczak, Physical Review C 89, 034624 (2014).
