Measurement of the 20 and 90 keV resonances in the 18O(p,α)15{}^{18}{\rm O}(p,\alpha){}^{15}N reaction via THM

The $^{18}{\rm O}(p,\alpha)^{15}{\rm N}$ reaction is of primary importance in several astrophysical scenarios, including fluorine nucleosynthesis inside AGB stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus the indirect measurement of the low energy region of the $^{18}{\rm O}(p,\alpha)^{15}{\rm N}$ reaction has been performed to reduce the nuclear uncertainty on theoretical predictions. In particular the strength of the 20 and 90 keV resonances have been deduced and the change in the reaction rate evaluated.Comment: 4 pages, 4 figures, submitted to PR

Measurement of the 10 keV resonance in the 10^{10}B(p,α0p, \alpha_0)7^7Be reaction via the Trojan Horse Method

The $^{10}$B(p,$\alpha_0$)$^7$Be bare nucleus astrophysical S(E)-factor has been measured for the first time at energies from about 100 keV down to about 5 keV by means of the Trojan Horse Method (THM). In this energy region, the S(E)-factor is strongly dominated by the 8.699 MeV $^{11}$C level (J$^{\pi}$=$\frac{5}{2}$$^+$), producing an s-wave resonance centered at about 10 keV in the entrance channel. Up to now, only the high energy tail of this resonant has been measured, while the low-energy trend is extrapolated from the available direct data. The THM has been applied to the quasi-free $^2$H($^{10}$B,$\alpha_0$$^7$Be)n reaction induced at a boron-beam energy of 24.5 MeV. An accurate analysis brings to the determination of the $^{10}$B(p,$\alpha_0$)$^7$Be S(E)-factor and of the corresponding electron screening potential $U_e$, thus giving for the first time an independent evaluation of it.Comment: Authors thank the (anonymous) referee for detailed comments and suggestions. The paper is already submitted to Physical Review

On the magnitude of the 8Li + 4He → 11B + n reaction cross section at the Big-Bang temperature

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New High-Precision Measurement of the Reaction Rate of the 18O(p,alpha)15N Reaction via THM

The 18O(p,alpha)15N reaction rate has been extracted by means of the Trojan-Horse method. For the first time the contribution of the 20-keV peak has been directly evaluated, giving a value about 35% larger than previously estimated. The present approach has allowed to improve the accuracy of a factor 8.5, as it is based on the measured strength instead of educated guesses or spectroscopic measurements. The contribution of the 90-keV resonance has been determined as well, which turned out to be of negligible importance to astrophysics.Comment: 6 pages, 4 figures, 1 table. Torino workshop 200

A NOVEL APPROACH TO MEASURE THE CROSS SECTION OF THE 18O(p, α)15N RESONANT REACTION IN THE 0-200 keV ENERGY RANGE

The 18O(p, α)15N reaction is of primary importance to pin down the uncertainties, due to nuclear physics input, affecting present-day models of asymptotic giant branch stars. Its reaction rate can modify both fluorine nucleosynthesis inside such stars and oxygen and nitrogen isotopic ratios, which allow one to constrain the proposed astrophysical scenarios. Thus, an indirect measurement of the low-energy region of the 18O(p, α)15N reaction has been performed to access, for the first time, the range of relevance for astrophysical application. In particular, a full, high-accuracy spectroscopic study of the 20 and 90 keV resonances has been performed and the strengths deduced to evaluate the reaction rate and the consequences for astrophysics

A fast and complete GEANT4 and ROOT Object-Oriented Toolkit: GROOT

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

Study of the 6Li(n,)3H reaction via the 2H quasi-free break-up

International audienceThe quasi-free break-up of deuteron was used to study the neutron induced 6 Li + n reaction via the 2 H(6 Li, α 3 H)p. The aim of the experiment was to check whether the deuteron can be considered as a source of virtual neutrons. This was done by studying the excitation function of the 6 Li(n, α) 3 H two body reaction at low energy where the resonance corresponding to the excited level at 7.454 MeV of 7 Li is present. Two experimental runs were performed at the Laboratori Nazionali del Sud (LNS) in Catania, Italy. In both experiments, the energy and the position of the outgoing α and 3 H particles were measured and the kinematics were reconstructed assuming a proton as third particle. The quasi-free events were selected in order to reconstruct the 6 Li(n, α) 3 H cross section in the center of mass energy by using the Plane Wave Impulse Approximation approach. The obtained cross section is in very good agreement with the directly measured one

A fast and complete GEANT4 and ROOT Object-Oriented Toolkit: GROOT

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

A Geant4-based Monte Carlo Tool for Nuclear Astrophysics

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, whose data mostly come from theoretical calculations. We developed a Monte Carlo (MC) software that makes use of the validatedtracking Geant4 libraries and the n-body event generator of ROOT libraries in order to provide a fast, realiable and complete MC tool to be used for nuclear physics experiments, with a particular focus on photo-nuclear processes. We discuss the results of the MC simulations performed in order to evaluate the effects of the electromagnetic background, the straggling of the emitted particles due to the target thickness and the resolution of the silicon detectors. Finally we present the preliminary results on some nuclear reactions involved in the p-process, which will be studied with ELISSA and the GBS at ELI-NP

A Geant4-based Monte Carlo Tool for Nuclear Astrophysics

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, whose data mostly come from theoretical calculations. We developed a Monte Carlo (MC) software that makes use of the validatedtracking Geant4 libraries and the n-body event generator of ROOT libraries in order to provide a fast, realiable and complete MC tool to be used for nuclear physics experiments, with a particular focus on photo-nuclear processes. We discuss the results of the MC simulations performed in order to evaluate the effects of the electromagnetic background, the straggling of the emitted particles due to the target thickness and the resolution of the silicon detectors. Finally we present the preliminary results on some nuclear reactions involved in the p-process, which will be studied with ELISSA and the GBS at ELI-NP