The 6Li + d reaction was studied in order to investigate the quasi-free 6Li(n, α)3H reaction, off the proton in 2H. A kinematically complete experiment was performed at a beam energy of 14 MeV. ...Coincidence spectra show the contribution of the quasi-free n+6Li reaction in the relative energy range from 1.5 MeV down to zero. The extracted 6Li(n, α)3H quasi-free cross-section was compared with the behavior of direct data throughout the investigated energy range. No penetrability corrections were introduced on the quasi-free data, being the 6Li(n, α)3H direct reaction free of Coulomb suppression.
The Trojan Horse Method (THM) was applied to the 3He+7Li interaction in order to investigate the quasi-free 7Li(p, α)4He reaction. The three-body experiment was performed at 33 MeV corresponding to a ...7Li-p relative energy ranging from 50 keV to 7 MeV. The extracted 7Li(p, α)4He quasi-free cross-section was compared with the behavior of direct data, as well as with the result of a previous THM investigation on the 7Li(p, α)4He reaction off the neutron in 2H. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM.
Owing to the presence of the Coulomb barrier at astrophysically relevant kinetic energies it is very difficult, or sometimes impossible, to measure astrophysical reaction rates in the laboratory. ...That is why different indirect techniques are being used along with direct measurements. Here we address two important indirect techniques, the asymptotic normalization coefficient (ANC) and the Trojan Horse (TH) methods. We discuss the application of the ANC technique for calculation of the astrophysical processes in the presence of subthreshold bound states, in particular, two different mechanisms are discussed: direct capture to the subthreshold state and capture to the low-lying bound states through the subthreshold state, which plays the role of the subthreshold resonance. The ANC technique can also be used to determine the interference sign of the resonant and nonresonant (direct) terms of the reaction amplitude. The TH method is unique indirect technique allowing one to measure astrophysical rearrangement reactions down to astrophysically relevant energies. We explain why there is no Coulomb barrier in the sub-process amplitudes extracted from the TH reaction. The expressions for the TH amplitude for direct and resonant cases are presented.
Indirect techniques in nuclear astrophysics Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Brown, B. A. ...
The 2nd International Conference on Nuclear Physics in Astrophysics
Book Chapter
Owing to the presence of the Coulomb barrier at astrophysically relevant kinetic energies it is very difficult, or sometimes impossible, to measure astrophysical reaction rates in the laboratory. ...That is why different indirect techniques are being used along with direct measurements. Here we address two important indirect techniques, the asymptotic normalization coefficient (ANC) and the Trojan Horse (TH) methods. We discuss the application of the ANC technique for calculation of the astrophysical processes in the presence of subthreshold bound states, in particular, two different mechanisms are discussed: direct capture to the subthreshold state and capture to the low-lying bound states through the subthreshold state, which plays the role of the subthreshold resonance. The ANC technique can also be used to determine the interference sign of the resonant and nonresonant (direct) terms of the reaction amplitude. The TH method is unique indirect technique allowing one to measure astrophysical rearrangement reactions down to astrophysically relevant energies.We explain why there is no Coulomb barrier in the sub-process amplitudes extracted from the TH reaction. The expressions for the TH amplitude for direct and resonant cases are presented.
