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SUMMARY:Theoretical analysis of astrophysical S-factors of nuclear reactio
 ns 7Be(n\,α)4He and 7Be(n\,p)7Li
DTSTART;VALUE=DATE-TIME:20260922T133000Z
DTEND;VALUE=DATE-TIME:20260922T133500Z
DTSTAMP;VALUE=DATE-TIME:20260914T043927Z
UID:indico-contribution-545@indico.bitp.kiev.ua
DESCRIPTION:Speakers: Victor Zhaba (Інститут теоретично
 ї фізики ім. М.М. Боголюбова НАН України)\n
 Theoretical analysis of astrophysical S-factors of nuclear reactions\n$^{7
 }$Be(n\,$\\alpha )^{4}$He and $^{7}$Be(n\,p)$^{7}$Li\n\nV.I. Zhaba\, V.S. 
 Vasilevsky\, Yu.A. Lashko\n\nBogolyubov Institute for Theoretical Physics\
 , National Academy of Sciences\nof Ukraine\n\nIn this report\, we study a 
 range of reactions induced by the interactions $^{7}$Li+p\, $^{7}$Be+n and
  $^{6}$Li+d. Special attention is paid to the low-energy region in the inp
 ut channels of reactions that take into account the dynamics of synthesis 
 and decay of $^{6}$Li\, $^{7}$Li and $^{7}$Be nuclei. This study is perfor
 med within a microscopic three-cluster model\, which allows us to involve 
 all binary channels of the $^{8}$Be decay. Besides\, this model takes into
  account polarizability of interacting nuclei (clusters) [1\, 2]. In Ref. 
 [3]\, this model was successfully applied to study the structure of the $^
 {8}$Be nucleus and the nature of high-energy resonance states of $^{8}$Be.
 \nWithin the framework of our model\, the astrophysical S-factors of the r
 eactions $^{7}$Be(n\,$\\alpha )^{4}$He\, $^{7}$Be(n\,p$_{0})^{7}$Li and $^
 {7}$Be(n\,p$_{1})^{7}$Li in the energy range E$_{cm}$=0-2 MeV were calcula
 ted. The dependence of the astrophysical S-factors on the form and intensi
 ty of the nucleon-nucleon interaction was investigated in detail. For the 
 astrophysical S-factor of $^{7}$Be(n\,$\\alpha)^{4}$He reaction\, the part
 ial 2$^{+}$ wave dominates over the entire energy range\, and is then enha
 nced by the 0$^{+}$ wave. The calculated S-factors for $^{7}$Be(n\,$\\alph
 a )^{4}$He reaction are further decomposed into contributions from reactio
 ns with $^{7}$Be in its ground and first excited states. For $^{7}$Be(3/2$
 ^{-}$)(n\,$\\alpha)^{4}$He reaction\, the 2$^{+}$ wave has a maximum that 
 is due to resonance. In our microscopic model\, this 2$^{+}$ resonance sta
 te appears at energy E$\\approx $1.27 MeV above $^{7}$Be+n decay threshold
 \, which is in good agreement with the experimental data obtained in [4].\
 nFor $^{7}$Be(n\,p$_{0})^{7}$Li reaction\, the 3$^{+}$ partial wave domina
 tes in the region of the maximum at Ecm=0.5 MeV\, while the 2$^{-}$ partia
 l wave determines the behavior at low and high energies. For $^{7}$Be(n\,p
 $_{1})^{7}$Li reaction\, the 1$^{-}$ partial wave dominates in the entire 
 energy range and together with the  $^{+}$\, 2$^{-}$\, 2$^{+}$ states prov
 ide the main contribution to the astrophysical S-factor. It was demonstrat
 ed that the cluster polarization has a large impact on value and energy de
 pendence of the S-factor for the $^{7}$Be(n\,p)$^{7}$Li reaction.\nThe cal
 culated astrophysical S-factors for the reactions $^{7}$Be(n\,$\\alpha)^{4
 }$He and $^{7}$Be(n\,p)$^{7}$Li are in good agreement with experimental da
 ta from leading laboratories. Our partial astrophysical S-factors for the 
 $^{7}$Be+n reactions are compared with calculations in the R-matrix theory
  and with data in the ENDF database.\n\n[1] Y.A. Lashko\, G.F. Filippov\, 
 V.S. Vasilevsky. Nucl. Phys. A 958\, 78 (2017).\n[2] V.S. Vasilevsky\, F. 
 Arickx\, J. Broeckhove\, T.P. Kovalenko. Nucl. Phys. A\n824\, 37 (2009).\n
 [3] V.I. Zhaba\, Yu.A. Lashko\, V.S. Vasilevsky. Phys. Rev. C 112 014328 (
 2025).\n[4] D.R. Tilley\, J.H. Kelley\, J.L. Godwin et al. Nucl. Phys. A 7
 45 155 (2004).\n\nhttps://indico.bitp.kiev.ua/event/18/contributions/545/
LOCATION:Bogolyubov Institute for Theoretical Physics Conference Hall
URL:https://indico.bitp.kiev.ua/event/18/contributions/545/
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