Abstract
Big Bang Nucleosynthesis (BBN) requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of is given, being these ones among the ...most uncertain bare-nucleus cross sections. A particular attention is devoted to recently indirectly measured cross-section which give important hints for the nuclear astrophysics community.
In reality, a significant experimental effort has been made over the past 10 years to explore reactions important to the BBN and determine their astrophysical S(E)-factor using the Trojan Horse Method (THM). Then, numerical calculations are made in the relevant temperature ranges for BBN (0.01<T
9
<10) to determine the reaction rates and the relative error for the four reactions of interest. The effects of these values on the calculated primordial abundances and isotopical composition for H, He, and Li were then assessed by using them as input physics for computations of primordial nucleosynthesis. Additionally, recent findings regarding the 7Be(n,
alpha
)4He reaction rate were taken into consideration. These were put up against estimates of primordial abundance derived from observation at various astrophysical places. Additionally, perspectives on reactions will be examined.
Astrophysics studies with the Trojan Horse Method Spitaleri, C.; La Cognata, M.; Lamia, L. ...
The European physical journal. A, Hadrons and nuclei,
09/2019, Letnik:
55, Številka:
9
Journal Article
Recenzirano
.
The Trojan Horse Method represents an indirect approach to investigate reactions of astrophysical relevance at the energies of interest, free of Coulomb suppression and electron screening effects. ...In this review, we will examine how the Trojan Horse Method has evolved from the study of the quasi-free reaction mechanism. We will first present the basic features of the quasi-free reaction mechanism in the framework of the theory of direct reactions, from quasi-free scattering to quasi-free reactions processes, and its evolution towards the Trojan Horse Method with its modern theory. We will review the validity tests to assess the technique, the procedure to analyze the data and to extract the astrophysical factor. Finally, we will discuss some of the most important experimental results recently published related to nuclear astrophysics and applications.
Crucial information on nova nucleosynthesis can be potentially inferred from γ-ray signals powered by 18F decay. Therefore, the reaction network producing and destroying this radioactive isotope has ...been extensively studied in the last years. Among those reactions, the 18F(p, )15O cross-section has been measured by means of several dedicated experiments, both using direct and indirect methods. The presence of interfering resonances in the energy region of astrophysical interest has been reported by many authors including the recent applications of the Trojan Horse Method. In this work, we evaluate what changes are introduced by the Trojan Horse data in the 18F(p, )15O astrophysical factor recommended in a recent R-matrix analysis, accounting for existing direct and indirect measurements. Then the updated reaction rate is calculated and parameterized and implications of the new results on nova nucleosynthesis are thoroughly discussed.
The bare nucleus S(E) factors for the H2(d,p)H3 and H2(d,n)He3 reactions have been measured for the first time via the Trojan Horse Method off the proton in 3He from 1.5 MeV down to 2 keV. This range ...overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4±1.8 MeVb for H3+p and 60.1±1.9 MeVb for He3+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.
Nuclear astrophysics and the Trojan Horse Method Spitaleri, C.; La Cognata, M.; Lamia, L. ...
The European physical journal. A, Hadrons and nuclei,
04/2016, Letnik:
52, Številka:
4
Journal Article
Recenzirano
.
In this review, we discuss the new recent results of the Trojan Horse Method that is used to determine reaction rates for nuclear processes in several astrophysical scenarios. The theory behind ...this technique is shortly presented. This is followed by an overview of some new experiments that have been carried out using this indirect approach.
In the last 15 years the FRIBs@LNS facility has successfully produced Radioactive Ion Beams using the In-Flight technique. We report on the current status and future perspectives opened by FRAISE, a ...new fragment separator that will be build in connection with the upgrade of Superconducting Cyclotron of the INFN-LNS laboratories.
Nuclear reaction rates are among the most important input for understanding primordial nucleosynthesis and, therefore, for a quantitative description of the early universe. An up-to-date compilation ...of direct cross-sections of super(2)H(d, p) super(3)H, super(2)H(d, n) super(3)He, super(7)Li(p, alpha ) super(4)He, and super(3)He(d, p) super(4)He reactions is given. These are among the most uncertain cross-sections used and input for big bang nucleosynthesis calculations. Their measurements through the Trojan Horse method are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the 2H, super(3,4)He, and super(7)Li primordial abundances, which are then compared with observations.
The abundance of 26Al carries a special role in astrophysics, since it probes active nucleosynthesis in the Milky Way and constrains the Galactic core-collapse supernovae rate. It is estimated ...through the detection of the 1809 keV γ-line and from the superabundance of 26Mg in comparison with the most abundant Mg isotope (A = 24) in meteorites. For this reason, high precision is necessary also in the investigation of the stable 27Al and 24Mg isotopes. Moreover, these nuclei enter the so-called MgAl cycle, playing an important role in the production of Al and Mg. Recently, high-resolution stellar surveys have shown that the Mg–Al anticorrelation in red-giant stars in globular clusters may hide the existence of multiple stellar populations, and that the relative abundances of Mg isotopes may not be correlated with Al. The common thread running through these astrophysical scenarios is the 27Al(p,α)24Mg reaction, which is the main 27Al destruction channel and directly correlates its abundance with the 24Mg one. Since available reaction rates show large uncertainties owing to the vanishingly small cross section at astrophysical energies, we have applied the Trojan Horse Method to deduce the reaction rate with no need of extrapolation. The indirect measurement made it possible to assess the contribution of the 84 keV resonance and to lower upper limits on the strength of nearby resonances. In intermediate-mass AGB stars experiencing hot bottom burning, a sizeable increase in surface aluminum abundance is observed at the lowest masses, while 24Mg is essentially unaffected by the change in the reaction rate.
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