We discuss how the new measurement of the 12C + 12C fusion cross section carried out with the Trojan Horse Method affects the compactness of a star, i.e., basically the binding energy of the inner ...mantle, at the onset of the core collapse. In particular, we find that this new cross section significantly changes the dependence of the compactness on the initial mass with respect to previous findings obtained in Chieffi & Limongi by adopting the classical cross section provided by Caughlan & Fowler. A non-monotonic but well-defined behavior is also confirmed in this case and no scatter of the compactness around the main trend is found. Such an occurrence could impact the possible explodability of the stars.
The Trojan Horse Method (THM) represents an indirect path to determine the bare nucleus astrophysical
S
-factor for reactions among charged particles at astrophysical energies. This is achieved by ...measuring the quasi-free cross section of a suitable three-body process. The method is also suited to study neutron-induced reactions, especially in the case of radioactive ion beams. A comprehensive review of the theoretical as well as experimental features behind the THM is presented here. An overview is given of some recent applications to demonstrate the method's practical use for reactions that have a great impact on selected astrophysical scenarios.
Neutron induced reactions on stable and unstable nuclei play a significant role in the nucleosynthesis of the elements in the cosmos. In the last years, several efforts have been made to investigate ...the possibility of applying the Trojan Horse Method (THM) to neutron induced reactions mostly by using deuteron as “TH-nucleus”. Here, the main advantages of using THM will be given together with a more focused discussion on the recent
7
Be(n,
α
)
4
He and the
14
N(n,p)
14
C reactions.
For nucleosynthesis calculations, precise reaction rates should be known at energies within the Gamow window. At these energies, electron screening cannot be neglected. Despite the significance of ...the effect, a huge disagreement between experimental data and theoretical predictions is still not understood. In order to address to this problem, we investigated the dependence of the electron screening potential on the target host lattice structure by measuring the rate of the
2
H(
19
F,p)
20
F reaction in zirconium, titanium and palladium targets containing deuterium.
In the last decades, many indirect methods have been developed to measure the cross section of nuclear reactions at the low energies interesting in many astrophysical scenarios. The Trojan Horse ...Method uses a three body reaction, involving by a strong clusterized nucleus, to infer information about a two body reaction of interest, selecting the events that proceed through the quasi-free reaction mechanism. To reconstruct the reaction kinematic and to identify the useful reaction mechanism, the energy and angle of at least two of the three outgoing particles must be carefully measured. Moreover, enough statistics is required, as the quasi-free events usually represent just a small fraction of the acquired statistic. These requirements hardly match with the typical characteristics of radioactive ion beams: low intensity, large divergence and possible presence of contaminants. For this reason, only recently the Trojan Horse Method has been applied to study reactions induced by radioactive beams. This application gives also the opportunity to measure cross section of neutron induced reactions on radioactive isotopes, even if they have a short lifetime. In the following some results obtained in the study of the reactions 18F(p,α)15O and 18F(n,α)15N will be presented.
The Trojan Horse Method in Nuclear Astrophysics Tumino, Aurora; Spitaleri, Claudio; Cherubini, Silvio ...
EPJ Web of Conferences,
01/2018, Letnik:
184
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Trojan Horse Method (THM) represents the indirect way to measure reactions between charged particles at astrophysical energies. This is done by measuring the quasi free cross section of a ...suitable three body process. The basic features of the THM will be presented together with some applications to demonstrate its practical use.
The Trojan Horse Method is an indirect technique to measure nuclear reactions of astrophysical relevance at the energies of interest, free of Coulomb suppression and electron screening effects. Its ...basic features in the framework of the theory of direct reactions will be discussed and the physics case of the 12
C
+12
C
fusion will be addressed.
Some observed abundances in globular clusters have suggested the existence of multiple generations of stars within the clusters as the observations require temperature ranges higher than current ...stars. The 30Si(p,γ)31P reaction plays a key role in the synthesis of the observed abundances. The study of the 30Si(3He,d)31P transfer reaction is a tool for constraining the strengths of low-lying resonances, and the proton partial widths are the main ingredients for calculating those strengths. We present the method used for estimating the proton partial widths and their associated uncertainties.
The Big Bang Nucleosynthesis (BBN) model is a great success of nuclear astrophysics due to the outstanding agreement between observational and predicted light elements abundances. One exception, ...however, is the so-called “lithium problem.” In this context, experimental efforts to measure the relevant reactions have been brought to an increased level of accuracy in measuring primordial abundances, and the introduction of indirect methods has allowed researchers to overcome the natural limitations of direct measurements in the energy range of interest for BBN. Here we review the results obtained from the application of the Trojan Horse Method to some of the most influential reactions of the standard network, such as 2H(d,p)3H, 2H(d,n)3He, 3He(d,p)4He, 7Li(p,α) 4He, and 7Be(n,α) 4He. The relevant cross sections have been then used as new inputs to a classical BBN code, resulting in important constraints that make suggestions for a possible solution for the lithium problem outside of nuclear physics.
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