A solid thick tritiated W sample was produced in order to probe the efficiency of detecting tritium via 3He ion beam using nuclear reactions analysis (NRA). Extensive literature search showed that ...there were only a few measurements done more than sixty years ago using the reaction with 3He. Their aim was mainly to measure the absolute cross section of the reaction. In order to use this reaction as an analysing tool for low level radioactive waste we need the differential cross section at certain angles. Using a thick tritiated W sample we measured the NRA signal in the 3He energy range from 0.7 MeV to 5.1 MeV and we have detected reaction products with energies between 6.5 MeV and 9.75 MeV that were not present on a deuterated W sample prepared in the same manner. This NRA signal proved to be due to deuterium and protons coming from the nuclear reaction between tritium and 3He. The detection signal increased with 3He energy up to 3.4 MeV and decreased with energy at the highest beam energies. At higher energies particles from W and target impurities start to disturb the measurement. Their origin might be due to other nuclear reactions, for example between 3He and W or 3He with 13C or 14N.
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.
Abstract
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
3
He(
α,γ
)
7
Be 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
7
Be and
8
B 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
3
He(
α,γ
)
7
Be 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
6
Li(
3
He,
d
)
7
Be
α
-transfer reaction were detected with high precision at E
3
He
=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
3
He(
α,γ
)
7
Be reaction was calculated to equal 0.534 ± 0.025 keVb. Both our experimental and theoretical approaches were tested through the analysis of the
6
Li(p,
γ
)
7
Be astrophysical factor, with further interesting astrophysical implications.
The
p
-
p
-chain reaction
3
He(
α
,
γ
)
7
Be can sensitively influence the prediction of the
7
Be and
8
B neutrino fluxes. Despite its importance, the knowledge of its reaction cross section at ...energies of the core of the Sun (15 keV 30 keV) is limited and the accuracy far from the desired 3% level. In the present paper the indirect measurement of the external capture contribution using the asymptotic normalization coefficient (ANC) technique is reported. The angular distributions of deuterons emitted in the
6
Li(
3
He,
d
)
7
Be
α
-transfer reactions were measured and the ANCs extracted from the scaling of distorted-wave Born approximation (DWBA) and coupled-channel (CC) calculations. Then, the astrophysical S-factor for the
3
He(
α
,
γ
)
7
Be reaction was calculated assuming
E
1 direct capture and the zero energy value turned out to be 0.534 0.025 keVb. Both our experimental and theoretical approaches were benchmarked through the analysis of the
6
Li(p,
γ
)
7
Be astrophysical factor, with interesting astrophysical applications to the understanding of the primordial lithium problem. In particular, the present work disfavors the occurrence of a claimed 200 keV resonance in the astrophysical factor.
The p - p-chain reaction 3He(α, γ)7Be can sensitively influence the prediction of the 7Be and 8B neutrino fluxes. Despite its importance, the knowledge of its reaction cross section at energies of ...the core of the Sun (15 keV 30 keV) is limited and the accuracy far from the desired 3% level. In the present paper the indirect measurement of the external capture contribution using the asymptotic normalization coefficient (ANC) technique is reported. The angular distributions of deuterons emitted in the 6Li(3He,d)7Be α-transfer reactions were measured and the ANCs extracted from the scaling of distorted-wave Born approximation (DWBA) and coupled-channel (CC) calculations. Then, the astrophysical S-factor for the 3He(α, γ)7Be reaction was calculated assuming E1 direct capture and the zero energy value turned out to be 0.534 0.025 keVb. Both our experimental and theoretical approaches were benchmarked through the analysis of the 6Li(p,γ)7Be astrophysical factor, with interesting astrophysical applications to the understanding of the primordial lithium problem. In particular, the present work disfavors the occurrence of a claimed 200 keV resonance in the astrophysical factor.
The
10
B
(p,α0)
7
Be reaction has been studied by applying the Trojan Horse method to the 2H(
10
B,α0
7
Be)
n
reaction. The bare-nucleus astrophysical
S(E)
-factor in absolute units was extracted in ...a wide energy range, from 2.2 MeV to 3 keV and normalized to the direct experimental data, thus allowing determination of the electron screening potential for which a value of
U
e
=391±74 eV was obtained.
Neutron induced reactions are fundamental for the nucleosynthesis of elements in the universe. Indeed, to correctly study the reactions involved in the well-known s-process in stars, which produce ...about half of the elements beyond the iron peak, it is mandatory to know the neutron abundance available in those stars. The 17O(n, a)14C reaction is one of the so-called “neutron poisons” for the pro- cess and it could play an important role in the balance of the neutron abundance. The reaction is therefore investigated in the energy range of astrophysical inter- est between 0 and 350 keV in the center of mass by applying the Trojan Horse Method to the three body reaction 2H(17O, a14C)H.
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