Speaker
Description
The reaction $^7$Li(p,$\gamma$)$^8$Be is part of the pp-chain in the Sun, leading to the formation of $^8$Be. In the present work, the analysis of the experimental astrophysical S factors S$^{exp}$(E) for the nuclear-astrophysical $^7$Li(p,$\gamma$)$^8$Be reaction in the off-resonance energy region measured in [1] are performed within the modified two body potential approach [2], and assuming that, in this energy region ($E\le200$ keV) radiative proton capture by $^7$Li nucleus is direct.
The method involves two additional conditions that verify the peripheral character of the direct radiative capture reaction $^7$Li(p,γ)$^8$Be in the off-resonance energy region: 1) $R(E,b)=const$ for arbitrary variation of the single particle asymptotic normalization coefficient b for each fixed experimental value of the energy $E$; 2) the ratio $C_{p^7Li}^2=S^{exp}(E)⁄R(E,b)$ must not depend neither from $b$ and nor from the energy $E$ for each experimental point of the energy ($E$=98.3, 147.6 and 198.3 keV), where $R(E,b)=S^{(sp)}(E)⁄b^2$ in which $S^{(sp)}(E)$ is a single-particle astrophysical $S$ factor. Fulfillment of the conditions above, it allows to determine “experimental” values of ANCs $C_{p^7Li}^2 [=(C_{p^7Li}^{exp})^2]$ for ground and first excited states of $^8$Be with their uncertainty. The obtained values of ANCs $(C_{p^7Li}^{exp})^2$ can be used in the expression $S(E)=(C_{p^7Li}^{exp})^2 R(E,b)$ for obtaining the extrapolated values of $S(E)$ and its uncertainties within the energy range $E< 98.3$ keV, including $E=0$.
Variation of values of the parameters of the Woods-Saxon potential $r_0$ and $a$ is done in the wide range ($1.1\le r_0 \le 1.4$ fm, $0.59\le a \le 0.72$ fm) and it is shown that the reaction is strongly peripheral. As a result, the new values of ANCs $(C_{p^7Li}^{exp})^2$ with their uncertainties for $^7$Li+p→$^8$Be were obtained. The obtained values of ANCs are used for calculation of the astrophysical S factor of the radiative resonance capture $^7$Li(p,$\gamma$)$^8$Be reaction within the modified R-matrix method [3].
- D. Zahnow, C.Angulo, C.Rolfs, S.Schmidt, and et al., Z. Phys. A 351, 229-236 (1995).
- S.B. Igamov and R.Yarmukhamedov, Nucl. Phys. A 673, 509 (2007).
- K.I. Tursunmakhatov, R.Yarmukhamedov and S.B.Igamov, EPJ Web of Conf. 227, 02016 (2019).
| The speaker is a student or young scientist | No |
|---|---|
| Section | 2. Experimental and theoretical studies of nuclear reactions |
