A new asymptotic theory is proposed for the peripheral transfer A(x,
y)B
reaction at low energies within the three-body (A,
a
and y) model by com bining the dispersion theory and DWBA, where x= y +
...a, B= A + a,
and
a
is a transferred particle. The results of the analysis of the differential cross sections of the proton transfer
9
Be(
1
°B,
9
Be)
1
°B reaction at the
1
°B projectile energy of 100 MeV populating the ground and excited states of the residual nucleus are presented. New estimates and their uncertainties are obtained for values of the asymptotic normalization coefficients for
9
Be +
p ^
1
°B and for the astrophys- ical S factors at stellar energy of the radiative capture
9
Be(ρ, γ)
1
°B reaction.
On the basis of the distorted-wave method, experimental data on the triple-differential cross section for the Coulomb breakup reaction
208
Pb(
6
Li,
αd
)
208
Pb are analyzed by employing a correct ...expression for the final-state
208
Pb–α–
d
three-particle Coulomb wave function. It is shown that the effect of final-state three-particle Coulomb dynamics can be used to assess the kinematical condition of clean Coulomb breakup processes. New values of the astrophysical
S
factor for the direct-radiative-capture reaction
d
(α, γ)
6
Li at ultralow energies in the range of 70 ≤
E
dα
≤ 600 keV were extracted from experimental data. The value of
S
(0) = 1.60 ± 0.17 MeV nb was obtained.
This work is aimed at clarifying the contribution of the proton direct radiative capture to the
12
C
(
p
,
γ
)
13
N
reaction by specifying the value of the asymptotic normalization coefficient (ANC) ...for
12
C
+
p
→
13
N
g
.
s
.
. In order to do this, the differential cross section of the proton transfer in the
12
C
(
10
B
,
9
Be
)
13
N
reaction at an energy of 41.3 MeV has been measured and analyzed through the modified distorted wave Born approximation (MDWBA) method taking into account the reaction channel coupling and
3
He
cluster transfer contributions. The value of the ANC was derived to be 1.63±0.13 fm
-
1
/
2
, which was used in estimating the astrophysical
S
(
E
) factor and the reaction rate of the proton radiative capture by the
12
C
nucleus at energies of astrophysical relevance.
The detection of the neutrinos produced in the p−p chain and in the CNO cycle can be used to test the Standard Solar Model. The 3He(α,γ)7Be reaction is the first reaction of the 2nd and 3rd branch of ...the p−p chain, therefore, the uncertainty of its cross section sensitively influences the prediction of the 7Be and 8B neutrino fluxes. Despite its importance and the large number of experimental and theoretical works devoted to this reaction, the knowledge on the reaction cross section at energies characterizing the core of the Sun (15 keV - 30 keV) is limited and further experimental efforts are needed to reach the desired (≈ 3%) accuracy. The precise knowledge on the external capture contribution to the 3He(α,γ)7Be reaction cross section is crucial for the theoretical description of the reaction mechanism. In the present work the indirect measurement of this external capture contribution using the Asymptotic Normalization Coefficient (ANC) technique is reported. To extract the ANC, the angular distributions of deuterons emitted in the 6Li(3He,d)7Be α-transfer reaction were measured with high precision at EH3e = 3.0 MeV and EH3e = 5.0 MeV. The ANCs were then extracted from comparison of DWBA calculations to the measured data and the zero energy astrophysical S-factor for 3He(α,γ)7Be reaction was found to be 0.534 ± 0.025 keVb.
The observation of neutrinos emitted in the p − p chain and in the CNO cycle can be employed to test the Standard Solar Model. The 3He(α,γ)7Be reaction is the first reaction of the 2nd and 3rd branch ...of the p − p chain, so the indetermination of its cross section significantly affects the predicted 7Be and 8B neutrino fluxes. Notwithstanding its relevance and the great deal of experimental and theoretical papers, information of the reaction cross section at energies of the core of the Sun (15 keV - 30 keV) is sparse and additional experimental work is necessary to attain the target (~ 3%) accuracy. The precise understanding of the external capture component to the 3He(α,γ)7Be reaction cross section is pivotal for the theoretical assessment of the reaction mechanism. In this work, the indirect measurement of this external capture component using the Asymptotic Normalization Coefficient (ANC) technique is discussed. To extract the ANC, the angular distributions of deuterons yielded in the 6Li(3He,d)7Be α-transfer reaction were detected with high precision at E3He=3.0 MeV and 5.0 MeV. The ANCs were then deduced from the juxtaposition of DWBA and CC calculations with the experimental angular distributions and the zero energy astrophysical S-factor for 3He(α,γ)7Be reaction was calculated to equal 0.534 ± 0.025 keVb. Both our experimental and theoretical approaches were tested through the analysis of the 6Li(p,γ)7Be astrophysical factor, with further interesting astrophysical implications.
On the basis of the distorted-wave method, experimental data on the triple-differential cross section for the Coulomb breakup reaction {sup 208}Pb({sup 6}Li, αd){sup 208}Pb are analyzed by employing ...a correct expression for the final-state {sup 208}Pb–α–d three-particle Coulomb wave function. It is shown that the effect of final-state three-particle Coulomb dynamics can be used to assess the kinematical condition of clean Coulomb breakup processes. New values of the astrophysical S factor for the direct-radiative-capture reaction d(α, γ){sup 6}Li at ultralow energies in the range of 70 ≤ E{sub dα} ≤ 600 keV were extracted from experimental data. The value of S(0) = 1.60 ± 0.17 MeV nb was obtained.
Angular distributions of differential cross sections have been measured for elastic, inelastic scattering and the (He3,d) reaction on 6Li nuclei at the Elab(He3)=34 MeV energy. The new and early ...obtained elastic scattering data at 34, 50, 60 and 72 MeV have been analyzed with Coupled Reaction Channels Method (CRC) taking into account triton transfer mechanism. The spectroscopic factors for t+He3 configuration of 6Li were extracted. Parameters for real part of potential have been also calculated microscopically with double folding model. The differential cross sections for proton stripping to the 7Be ground and first excited states have been analyzed by modified DWBA and CRC methods at 34 MeV. The effect of triton and α exchange on proton transfer reaction Li6(He3,d)Be7 for both ground and excited state is discussed. Spectroscopic factors and asymptotical normalization coefficients for p+Li6 configuration of 7Be have been obtained from the experimental data.
A modified two-body potential approach is proposed for determination of both the asymptotic normalization coefficient (ANC) (or the respective nuclear vertex constant (NVC)) for the
A
+
a
→
B
(for ...the virtual decay
B
→
A
+
a
) from an analysis of the experimental S-factor for the peripheral direct capture
a
+
A
→
B
+
γ
reaction and the astrophysical S-factor,
S
(
E
)
, at low experimentally inaccessible energy regions. The approach proposed involves two additional conditions which verify the peripheral character of the considered reaction and expresses
S
(
E
)
in terms of the ANC. The connection between NVC (ANC) and the effective range parameters for
Aa-scattering is derived. To test this approach we reanalyse the precise experimental astrophysical S-factors for
t
+
α
→
Li
7
+
γ
reaction at energies
E
⩽
1200
keV
C.R. Brune et al., Phys. Rev. C 50 (1994) 2205. The same Wood–Saxon potential form both for the bound (
t
+
α
)-state wave function and for the
αt-scattering wave function is used to guarantee selfconsistency. New estimates have been obtained for the values of the ANC's (the NVC's) for the
α
+
t
→
Li
7
(g.s.),
α
+
t
→
Li
7
(0.478 MeV) and of
S
(
E
)
at
E
⩽
50
keV
. These ANC values have been used for getting information about the “indirect” measured values of the effective range parameters and the
p-wave phase shift for
αt-scattering in the energy range of
100
≲
E
≲
180
keV
.
The 6Li(p,γ) 7Be cross section influences a variety of astrophysical scenarios, including big-bang and stellar nucleosynthesis. In recent years, conflicting results of direct measurements have been ...published, reporting contradictory low-energy trends. To shed light on the contradiction between the existing data sets, the reaction was studied using the asymptotic normalization coefficient (ANC) technique which was up-to-now never used for this reaction. To derive the ANC, the 6Li(3He,d) 7Be transfer reaction, studied at the Department of Physics and Astronomy of the University of Catania and at the John. D. Fox Superconducting Accelerator Laboratory at Florida State University, was re-analyzed, focusing on the proton transfer mechanism the α transfer process is discussed by Kiss et al. Phys. Lett. B 807, 135606 (2020). Here, the energy of the 3He beam impinging on a 6Li target was Elab = 3 MeV and Elab = 5 MeV. The yield of the emitted deuterons was measured with high precision by using silicon ΔE – E telescopes.
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