Understanding the total width of the $3_{1}^{-}$ state in $\mathrm{^{12}C}$
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| Autores principales: | , , , , , , , , , , , , , , |
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| Formato: | Preprint |
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2023
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| author | Li, K. C. W. Neveling, R. Adsley, P. Fujita, H. Papka, P. Smit, F. D. Brümmer, J. W. Donaldson, L. M. Harakeh, M. N. Kokalova, Tz. Nikolskii, E. Paulsen, W. Pellegri, L. Siem, S. Wiedeking, M. |
| author_facet | Li, K. C. W. Neveling, R. Adsley, P. Fujita, H. Papka, P. Smit, F. D. Brümmer, J. W. Donaldson, L. M. Harakeh, M. N. Kokalova, Tz. Nikolskii, E. Paulsen, W. Pellegri, L. Siem, S. Wiedeking, M. |
| contents | Recent measurements indicate that the previously established upper limit for the $γ$-decay branch of the $3_{1}^{-}$ resonance in $^{12}\textrm{C}$ at $E_{x} = 9.641(5)$ MeV may be incorrect. As a result, the $3_{1}^{-}$ resonance has been suggested as a significant resonance for mediating the triple-$α$ reaction at high temperatures above 2 GK. Accurate estimations of the $3_{1}^{-}$ contribution to the triple-$α$ reaction rate require accurate knowledge of not only the radiative width, but also the total width. In anticipation of future measurements to more accurately determine the $γ$-decay branch of the $3_{1}^{-}$ resonance, the objective of this work is to accurately determine the total width of the $3_{1}^{-}$ resonance. An evaluation was performed on all previous results considered in the current ENSDF average of 46(3) keV for the physical total width (FWHM) of the $3_{1}^{-}$ resonance in $^{12}\textrm{C}$. Significant unaccounted-for uncertainties and a misstated result were discovered in these previous results, leading to an invalid ENSDF average. In this work, the new global \textbf{R}-matrix analysis performed on direct-reaction data yields a formal total width of $Γ(E_{r}) = 46(2)$ keV and an observed total width of $Γ_{\textrm{obs}}(E_{r}) = 38(2)$ keV for the $3_{1}^{-}$ resonance. An observed total width of $Γ_{\textrm{obs}}(E_{r}) = 38(2)$ keV is recommended for the $3_{1}^{-}$ resonance in $\mathrm{^{12}C}$. This observed total width should be employed for future evaluations of the observed total radiative width for the $3_{1}^{-}$ resonance and its contribution to the high-temperature triple-$α$ reaction rate. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2307_07917 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Understanding the total width of the $3_{1}^{-}$ state in $\mathrm{^{12}C}$ Li, K. C. W. Neveling, R. Adsley, P. Fujita, H. Papka, P. Smit, F. D. Brümmer, J. W. Donaldson, L. M. Harakeh, M. N. Kokalova, Tz. Nikolskii, E. Paulsen, W. Pellegri, L. Siem, S. Wiedeking, M. Nuclear Experiment Nuclear Theory Recent measurements indicate that the previously established upper limit for the $γ$-decay branch of the $3_{1}^{-}$ resonance in $^{12}\textrm{C}$ at $E_{x} = 9.641(5)$ MeV may be incorrect. As a result, the $3_{1}^{-}$ resonance has been suggested as a significant resonance for mediating the triple-$α$ reaction at high temperatures above 2 GK. Accurate estimations of the $3_{1}^{-}$ contribution to the triple-$α$ reaction rate require accurate knowledge of not only the radiative width, but also the total width. In anticipation of future measurements to more accurately determine the $γ$-decay branch of the $3_{1}^{-}$ resonance, the objective of this work is to accurately determine the total width of the $3_{1}^{-}$ resonance. An evaluation was performed on all previous results considered in the current ENSDF average of 46(3) keV for the physical total width (FWHM) of the $3_{1}^{-}$ resonance in $^{12}\textrm{C}$. Significant unaccounted-for uncertainties and a misstated result were discovered in these previous results, leading to an invalid ENSDF average. In this work, the new global \textbf{R}-matrix analysis performed on direct-reaction data yields a formal total width of $Γ(E_{r}) = 46(2)$ keV and an observed total width of $Γ_{\textrm{obs}}(E_{r}) = 38(2)$ keV for the $3_{1}^{-}$ resonance. An observed total width of $Γ_{\textrm{obs}}(E_{r}) = 38(2)$ keV is recommended for the $3_{1}^{-}$ resonance in $\mathrm{^{12}C}$. This observed total width should be employed for future evaluations of the observed total radiative width for the $3_{1}^{-}$ resonance and its contribution to the high-temperature triple-$α$ reaction rate. |
| title | Understanding the total width of the $3_{1}^{-}$ state in $\mathrm{^{12}C}$ |
| topic | Nuclear Experiment Nuclear Theory |
| url | https://arxiv.org/abs/2307.07917 |