Structure of 23Al from one-proton breakup reaction and astrophysical implications

Abstract

The ground state of the proton-rich nucleus 23Al has been studied by one-proton removal on a carbon target at about 50 MeV/nucleon using the EXOGAM + SPEG experimental setup at GANIL. Longitudinal momentum distributions of the 22Mg breakup fragments, inclusive and in coincidence with gamma rays de-exciting the residues, were measured. The ground-state structure of 23Al is found to be a configuration mixing of a d-orbital valence proton coupled to four core states - 0${}_{gs}^{+}$, 2${}_1^{+}$, 4${}_1^{+}$, 4${}_2^{+}$. We confirm the ground state spin and parity of 23Al as $J^{\pi }=5/2^{+}$. The measured exclusive momentum distributions are compared with extended Glauber model calculations to extract spectroscopic factors and asymptotic normalization coefficients (ANCs). The spectroscopic factors are presented in comparison with those obtained from large-scale shell model calculations. We determined the asymptotic normalization coefficient of the nuclear system ${}^{23}$Al${}_{gs}$ $\to$ ${}^{22}$Mg(0${}^{+}$) + p to be $C_{d_{5/2}}^2$(${}^{23}A{l}_{gs}$) = (3.90 $\pm$ 0.44) $\times$ 10${}^3$ fm${}^{-1}$, and used it to infer the stellar reaction rate of the direct radiative proton capture ${}^{22}$Mg(p,$\gamma$)${}^{23}$Al. Astrophysical implications related to ${}^{22}$Na nucleosynthesis in ONe novae and the use of one-nucleon breakup at intermediate energies as an indirect method in nuclear astrophysics are discussed.

8 pages, 4 figures submitted to PRC, March 2 2011

References in corpus (7)

• Survey of excited state neutron spectroscopic factors for Z=8-28 nuclei
• Direct measurements of 22Na(p,g)23Mg resonances and consequences for 22Na production in classical novae
• Examining exotic structure of proton-rich nucleus ${}^{23}$Al
• Neutron spectroscopic factors of Ni isotopes from transfer reactions
• Absolute Determination of the 22Na(p,g) Reaction Rate in Novae
• Astrophysical S factor for the radiative capture 12N(p,gamma)13O determined from the 14N(12N,13O)13C proton transfer reaction
• In-beam gamma-ray spectroscopy at the proton dripline: 23Al

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• Coupling to two target-state bands in the study of the n+22Ne system at low energy
• Coulomb distortion and medium corrections in nucleon-removal reactions
• The 2025 Evaluation of Experimental Thermonuclear Reaction Rates (ETR25)