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The Trojan Horse method (THM) is a well-established experimental technique to measure nuclear reactions of astrophysical interest avoiding the suppression of the Coulomb barrier affecting experimental direct measurements. In this paper it will describe some of the THM studies involving few-body system of interest for both nuclear physics and nuclear astrophysics, such as the sub-Coulomb proton-proton elastic scattering and the deuteron-deuteron fusion at energies of interest for primordial nucleosynthesis. Moreover, the role of the intercluster motion in nuclei used for THM measurement will be highlight for the discussed physics cases.

The low-energy 19 F(p, α ) 16 O reaction has significant implications for nuclear astrophysics. The 19 F(p, α ) 16 O reaction occurs via three channels: (p, α 0 ), (p, α π ), and (p, α γ ). At lower temperatures, below 0.15 GK, the (p, α 0 ) channel is the dominant contributor of the reaction. The 19 F(p, α 0 ) 16 O reaction cross section in the energy range of 400–900 keV was studied in this work. Recent data in the literature reveals a roughly 1.4 increase compared to prior findings reported in the NACRE (Nuclear Astrophysics Compilation of REactions) compilation. Therefore, we present new additional result of the study published in EPJA [ 22 ] employing a silicon strip detector array (LHASA - Large High-resolution Array of Silicon for Astrophysics). The anguar distributions, the reaction cross sections and the astrophysical S-factors of the (p, α 0 ) channel were obtained through this experiment. Our findings resolve the discrepancies that exist between the two previously available data sets in the literature.

A broad range of Nuclear Physics research activities have been carried out at INFN-LNS until the summer 2020, when the accelerators were stopped for the upgrade. The upgrade of LNS is a project mainly funded by a PON-FESR (National Program for Research and Innovation) strategic line for boosting the research infrastructures, having its own goals, time-schedule and deadlines. In addition to such an action promoted by the Italian Ministry of Research, further funds have been made available from INFN budget. The end of the phase supported by the PON for procurement and tenders is currently set for the end of 2023. A series of actions will therefore be implemented to improve scientific opportunities for users. In particular, the focus is on the commissioning of the Tandem and Superconducting Cyclotron with the new set-up, completed by the renewal of the experimental areas and the commissioning of the new fragment separator FRAISE, also financed under the PON. The high-intensity program, including the determination of the nuclear matrix elements (NME) for the double beta decay and the study of EOS for nuclear matter with large neutron content, will be made feasible by these improvements to accelerators, beamlines and detectors. Some highlights of the whole activity as well as of the Applied Physics perspectives and the Astroparticle Physics multi-messenger program, strictly connected to the Nuclear Physics program, are given.

In astrophysics, the abundance of 26Al is essential for understanding nucleosynthesis in the Milky Way and Galactic core-collapse supernovae rates. Detection methods involve γ-ray lines and comparing 26Mg overabundance with the common Mg isotope in meteorites. Therefore, stable isotopes 27Al and 24Mg play a crucial role and the MgAl cycle affecting aluminum and magnesium production has to be carefully studied. Recent surveys reveal complexities in stellar populations whose understanding may also benefit from better constraining the closure of the MgAl cycle. The 27Al(p, α)24Mg fusion reaction, a key 27Al destruction channel, is central to these scenarios. Due to uncertainties, the Trojan Horse Method is applied, allowing high-precision spectroscopy on the compound nucleus 28Si. It reveals crucial fusion cross section information in the astrophysically relevant energy range. The indirect measurement by means of the 2H(27Al,α24Mg)n process made it possible to assess the contribution of the 84.3 keV resonance and to set upper limits on nearby resonances. This study evaluates the THM recommended rate’s impact on intermediate-mass asymptotic giant branch stars, showing a notable increase in surface aluminum abundance at lower masses due to fusion cross section modification, while 24Mg remains largely unaffected.

The 19 F(p, α ) 16 O reaction is of paramount importance for understanding the fluorine abundance in the outer layers of asymptotic giant branch (AGB) stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. Theoretical models overestimate F abundances in AGB stars with respect to the observed values, thus calling for further investigation of the reactions involved in the fluorine nucleosynthesis. In the last years, new direct and indirect measurements improved significantly the knowledge of the 19 F(p, α 0 ) 16 O cross section at deeply sub-Coulomb energies (below 0.8 MeV). Those data are larger by a factor of about 1.4 with respect to the previous data reported in the NACRE compilation in the energy region 0.6–0.8 MeV. In order to solve these discrepancies, here we present a new direct experiment performed using a silicon strip detector array (LHASA – Large High-resolution Array of Silicon for Astrophysics). Our results clearly confirm the trend of the latest experimental data in the energy region of interest, pointing towards a larger S-factor value than the one reported in the NACRE compilation.

Present and future gamma-beam facilities represent a great opportunity to validate and evaluate the cross-sections of many photonuclear reactions at near-threshold energies. Monte Carlo (MC) simulations are very important to evaluate the reaction rates and to maximize the detection efficiency but, unfortunately, they can be very cputime-consuming and in some cases very hard to reproduce, especially when exploring near-threshold cross-section. We developed a software that makes use of the validated tracking GEANT4 libraries and the n-body event generator of ROOT in order to provide a fast, realiable and complete MC tool to be used for nuclear physics experiments. This tool is indeed intended to be used for photonuclear reactions at γ-beam facilities with ELISSA (ELI Silicon Strip Array), a new detector array under development at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP). We discuss the results of MC simulations performed to evaluate the effects of the electromagnetic induced background, of the straggling due to the target thickness and of the resolution of the silicon detectors.

In equation (1) of this Letter, the closing bracket was missing; in Extended Data Fig. 1 and the accompanying legend, '[PHI](p.sub.d)' should have been '[PHI].sup.2(p.sub.d)', and in the Methods the text \"Odd J assignments are uncertain by [plus or minus]1.\" has been added. These errors have all been corrected online.

In equation (1) of this Letter, the closing bracket was missing; in Extended Data Fig. 1 and the accompanying legend, ‘ Φ ( p d )’ should have been ‘ Φ 2 ( p d )’, and in the Methods the text “Odd J assignments are uncertain by ±1.” has been added. These errors have all been corrected online.

Carbon burning powers scenarios that influence the fate of stars, such as the late evolutionary stages of massive stars 1 (exceeding eight solar masses) and superbursts from accreting neutron stars 2 , 3 . It proceeds through the 12 C +  12 C fusion reactions that produce an alpha particle and neon-20 or a proton and sodium-23—that is, 12 C( 12 C, α) 20 Ne and 12 C( 12 C, p ) 23 Na—at temperatures greater than 0.4 × 10 9 kelvin, corresponding to astrophysical energies exceeding a megaelectronvolt, at which such nuclear reactions are more likely to occur in stars. The cross-sections 4 for those carbon fusion reactions (probabilities that are required to calculate the rate of the reactions) have hitherto not been measured at the Gamow peaks 4 below 2 megaelectronvolts because of exponential suppression arising from the Coulomb barrier. The reference rate 5 at temperatures below 1.2 × 10 9 kelvin relies on extrapolations that ignore the effects of possible low-lying resonances. Here we report the measurement of the 12 C( 12 C, α 0,1 ) 20 Ne and 12 C( 12 C, p 0,1 ) 23 Na reaction rates (where the subscripts 0 and 1 stand for the ground and first excited states of 20 Ne and 23 Na, respectively) at centre-of-mass energies from 2.7 to 0.8 megaelectronvolts using the Trojan Horse method 6 , 7 and the deuteron in 14 N. The cross-sections deduced exhibit several resonances that are responsible for very large increases of the reaction rate at relevant temperatures. In particular, around 5 × 10 8 kelvin, the reaction rate is boosted to more than 25 times larger than the reference value 5 . This finding may have implications such as lowering the temperatures and densities 8 required for the ignition of carbon burning in massive stars and decreasing the superburst ignition depth in accreting neutron stars to reconcile observations with theoretical models 3 . The rate of carbon burning— 12 C +  12 C fusion—in stars is boosted by resonant behaviour at astrophysical energies.

Carbon burning powers scenarios that influence the fate of stars, such as the late evolutionary stages of massive stars.sup.1 (exceeding eight solar masses) and superbursts from accreting neutron stars.sup.2,3. It proceeds through the .sup.12C + .sup.12C fusion reactions that produce an alpha particle and neon-20 or a proton and sodium-23--that is, .sup.12C(.sup.12C, [alpha]).sup.20Ne and .sup.12C(.sup.12C, p).sup.23Na--at temperatures greater than 0.4 × 10.sup.9 kelvin, corresponding to astrophysical energies exceeding a megaelectronvolt, at which such nuclear reactions are more likely to occur in stars. The cross-sections.sup.4 for those carbon fusion reactions (probabilities that are required to calculate the rate of the reactions) have hitherto not been measured at the Gamow peaks.sup.4 below 2 megaelectronvolts because of exponential suppression arising from the Coulomb barrier. The reference rate.sup.5 at temperatures below 1.2 × 10.sup.9 kelvin relies on extrapolations that ignore the effects of possible low-lying resonances. Here we report the measurement of the .sup.12C(.sup.12C, [alpha].sub.0,1).sup.20Ne and .sup.12C(.sup.12C, p.sub.0,1).sup.23Na reaction rates (where the subscripts 0 and 1 stand for the ground and first excited states of .sup.20Ne and .sup.23Na, respectively) at centre-of-mass energies from 2.7 to 0.8 megaelectronvolts using the Trojan Horse method.sup.6,7 and the deuteron in .sup.14N. The cross-sections deduced exhibit several resonances that are responsible for very large increases of the reaction rate at relevant temperatures. In particular, around 5 × 10.sup.8 kelvin, the reaction rate is boosted to more than 25 times larger than the reference value.sup.5. This finding may have implications such as lowering the temperatures and densities.sup.8 required for the ignition of carbon burning in massive stars and decreasing the superburst ignition depth in accreting neutron stars to reconcile observations with theoretical models.sup.3.