69 research outputs found
New ANCs for synthesis obtained using extrapolation method and the -factor for radiative capture
Background: The O reaction, determining the
survival of carbon in red giants, is of interest for nuclear reaction theory
and nuclear astrophysics. Numerous attempts to obtain the astrophysical factor
of the O reaction, both experimental and
theoretical, have been made for almost 50 years. The specifics of the O
nuclear structure is the presence of two subthreshold bound states, (6.92 MeV,
2) and (7.12 MeV, 1), dominating the behavior of the low-energy
-factor. The strength of these subthreshold states is determined by their
asymptotic normalization coefficients (ANCs) which need to be known with high
accuracy. Recently, using the model-independent extrapolation method,
Blokhintsev {\it et al.} [Eur. Phys. J. A {\bf 59}, 162 (2023)] determined the
ANCs for the three subthreshold states in O.
Purpose: In this paper, using these newly determined ANCs, we calculated the
low-energy astrophysical -factors for the O radiative capture.
Method: The -factors are calculated within the framework of the -matrix
method using the AZURE2 code.
Conclusion: Our total -factor includes the resonance and
transitions to the ground state of O interfering with the corresponding
direct captures and cascade radiative captures to the ground state of O
through four subthreshold states: and . Since our
ANCs are higher than those used by deBoer {\it et al.} [Rev. Mod. Phys. {\bf
89}, 035007 (2017)], the present total -factor at the most effective
astrophysical energy of 300 keV is 174 keVb versus 137 keVb of that work.
Accordingly, our calculated reaction rate at low temperatures () is
higher than the one given in the aforesaid paper
Trojan Horse as an indirect technique in nuclear astrophysics. Resonance reactions
The Trojan Horse method is a powerful indirect technique that provides
information to determine astrophysical factors for binary rearrangement
processes at astrophysically relevant energies by measuring
the cross section for the Trojan Horse reaction in
quasi-free kinematics. We present the theory of the Trojan Horse method for
resonant binary subreactions based on the half-off-energy-shell R matrix
approach which takes into account the off-energy-shell effects and initial and
final state interactions.Comment: 6 pages and 1 figur
Bound, virtual and resonance -matrix poles from the Schr\"odinger equation
A general method, which we call the potential -matrix pole method, is
developed for obtaining the -matrix pole parameters for bound, virtual and
resonant states based on numerical solutions of the Schr\"odinger equation.
This method is well-known for bound states. In this work we generalize it for
resonant and virtual states, although the corresponding solutions increase
exponentially when . Concrete calculations are performed for the
ground and the first excited states of , the resonance
states (, ), low-lying states of and
, and the subthreshold resonances in the proton-proton system. We
also demonstrate that in the case the broad resonances their energy and width
can be found from the fitting of the experimental phase shifts using the
analytical expression for the elastic scattering -matrix. We compare the
-matrix pole and the -matrix for broad resonance in
Comment: 14 pages, 5 figures (figures 3 and 4 consist of two figures each) and
4 table
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