few body reactions investigated with the trojan horse method

The Trojan Horse Method is an indirect method to measure reaction cross sections at energies of interest for nuclear astrophysics, exploiting the nuclei clustering properties. Here it is presented with its general features and detailed for the case of the ^22H(d,p)^33H and ^22H(d,n)^33He measurements, where interesting results for astrophysics and energy fusion power plants have been obtained

Application of the THM to the investigation of reactions induced by unstable nuclei: the

The Trojan Horse Method is applied to the investigation of the 18F(p,α)15O reaction, by extracting the quasi free contribution to the 2H(18F,α15O)n process. For the first time the method is applied to a reaction of astrophysical importance involving a radioactive nucleus. After investigating the reaction mechanism populating the a + 15O + n exit channel, we could extract the 18F(p,α)15O cross section and calculate the astrophysical factor over the 0 – 1 MeV energy interval. The possibility of exploring the cross section with no need of extrapolation allowed us to to point out the possible occurrence of a 7/2+ state at 126 keV, which would strongly influence the trend of the astrophysical factor at the energies of astrophysical interest. However, the low energy resolution prevents us to draw definite conclusions. Possible astrophysical consequences are also discussed, motivating further work on this reaction

Application of the THM to the investigation of reactions induced by unstable nuclei: the 18F(p,α)15O case

The Trojan Horse Method is applied to the investigation of the 18F(p,α)15O reaction, by extracting the quasi free contribution to the 2H(18F,α15O)n process. For the first time the method is applied to a reaction of astrophysical importance involving a radioactive nucleus. After investigating the reaction mechanism populating the a + 15O + n exit channel, we could extract the 18F(p,α)15O cross section and calculate the astrophysical factor over the 0 – 1 MeV energy interval. The possibility of exploring the cross section with no need of extrapolation allowed us to to point out the possible occurrence of a 7/2+ state at 126 keV, which would strongly influence the trend of the astrophysical factor at the energies of astrophysical interest. However, the low energy resolution prevents us to draw definite conclusions. Possible astrophysical consequences are also discussed, motivating further work on this reaction

Resonant reactions of astrophysical interest studied by means of the Trojan Horse Method. Two case studies

Resonant reactions in astrophysics play and important role as un- expected resonances may enhance the astrophysical factor with respect to the direct reaction contribution, altering the predicted nucleosynthesis scenarios by changing, for instance, the expected nucleosynthesis path. They also are of great interest in nuclear structure studies, since the determination of energies, spin-parities and partial widths sheds light on the occurrence of cluster structures, for instance. However, nuclear reactions in most astrophysical environments usually take place at energies below about 1 MeV, leading to an exponential de- crease of the cross sections due to the effect of the penetration of the Coulomb barrier. Also, at energies so low to be comparable with those associated to elec- tronic degrees of freedom, the effect of atomic and/or molecular clouds cannot be neglected, resulting in a shielding of nuclear charges and in an enhancement of the cross sections with respect to the case of bare nuclei (the so called elec- tron screening effect). Owing to vanishingly small cross sections and ambigui- ties in the extrapolation due to the electron screening, supplying accurate cross sections for astrophysical modeling is extremely challenging. Indirect methods have been introduced to explore the energy range of astrophysical interest with no need of extrapolation, even guided by theoretical arguments. In particular, the Trojan Horse Method makes use of quasi-free reactions with three particles in the exit channel, a+A ^ c + C + s, to deduce the cross section of the reaction of astrophysical interest, a + x ^ c + C, under the hypothesis that A shows a strong x + s cluster structure. Even if measurements are carried out above astro- physical energies to be free from Coulomb suppression and electron screening, the range of astrophysical interest can be covered thanks to the x - s intercluster motion and binding energy. In these proceedings we will show the application of the THM, in the case of resonant reactions, using the generalised R-matrix approach introduced by A.M. Mukhamedzhanov. We will discuss the possibil- ity to extract resonance parameters from the Trojan Horse data and perform a full spectroscopic study of low-energy and even sub-threshold resonances. In particular, we will focus on the 19F(p, a)16O and the 13C(a, n)16O reactions, of particular importance in the case of asymptotic giant branch stars and in the synthesis of heavy elements by means of the s-process

Resonant reactions of astrophysical interest studied by means of the Trojan Horse Method. Two case studies

Resonant reactions in astrophysics play and important role as un- expected resonances may enhance the astrophysical factor with respect to the direct reaction contribution, altering the predicted nucleosynthesis scenarios by changing, for instance, the expected nucleosynthesis path. They also are of great interest in nuclear structure studies, since the determination of energies, spin-parities and partial widths sheds light on the occurrence of cluster structures, for instance. However, nuclear reactions in most astrophysical environments usually take place at energies below about 1 MeV, leading to an exponential de- crease of the cross sections due to the effect of the penetration of the Coulomb barrier. Also, at energies so low to be comparable with those associated to elec- tronic degrees of freedom, the effect of atomic and/or molecular clouds cannot be neglected, resulting in a shielding of nuclear charges and in an enhancement of the cross sections with respect to the case of bare nuclei (the so called elec- tron screening effect). Owing to vanishingly small cross sections and ambigui- ties in the extrapolation due to the electron screening, supplying accurate cross sections for astrophysical modeling is extremely challenging. Indirect methods have been introduced to explore the energy range of astrophysical interest with no need of extrapolation, even guided by theoretical arguments. In particular, the Trojan Horse Method makes use of quasi-free reactions with three particles in the exit channel, a+A ^ c + C + s, to deduce the cross section of the reaction of astrophysical interest, a + x ^ c + C, under the hypothesis that A shows a strong x + s cluster structure. Even if measurements are carried out above astro- physical energies to be free from Coulomb suppression and electron screening, the range of astrophysical interest can be covered thanks to the x - s intercluster motion and binding energy. In these proceedings we will show the application of the THM, in the case of resonant reactions, using the generalised R-matrix approach introduced by A.M. Mukhamedzhanov. We will discuss the possibil- ity to extract resonance parameters from the Trojan Horse data and perform a full spectroscopic study of low-energy and even sub-threshold resonances. In particular, we will focus on the 19F(p, a)16O and the 13C(a, n)16O reactions, of particular importance in the case of asymptotic giant branch stars and in the synthesis of heavy elements by means of the s-process