Marco Mazzocco

Proton-induced reactions on F 19 can lead to different branches of the CNO cycles, possibly resulting in the synthesis of heavier nuclei. For instance, CNO breakout is considered to be a viable path to the production of calcium in the most metal-poor stars. Present-day observational studies indicate that F 19 is mostly produced in the asymptotic giant branch phase of low- and intermediate-mass stars, and its synthesis and surface abundance are strictly intertwined with the production of heavy elements through slow neutron captures (s-process). Therefore, F 19 can act as a probe of nucleosynthesis scenarios and stars inner structure. In recent years, new experimental data on F 19 destruction reactions have been published, highlighting the occurrence of several resonances at astrophysical energies close to the proton threshold. While direct measurements relied on extrapolation from higher energies, indirect measurements made it possible to cover the astrophysical energies. In this work we will focus on the threshold region, which has been studied by means of the Trojan Horse method (THM) in the framework of the modified R -matrix approach. Thanks to this novel measurement, we could derive the asymptotic normalization coefficient (ANC) of the − 448 keV subthreshold resonance and the strength of the 11 keV one, which turned out to be significantly lower than previously extrapolated. To evaluate the astrophysical impact, we calculated the astrophysical reaction rates using a modern Monte Carlo approach, constraining them with the ANC and threshold resonance strengths measured via the THM.

The K -isomeric states in the heaviest nuclei are among the interesting topics in superheavy-element research. In the present work, we report on the discovery of µ s isomers in Sg 258 , 259 , 260 which deexcite with half-lives of 120 − 55 + 578 µ s , 85 ± 6 µ s , and 8 . 5 − 1.8 + 3.1 µ s , respectively, and are attributed to high- K states formed in multiquasiparticle couplings. In Sg 261 , activity with 12 . 6 − 1.6 + 2.2 µ s half-life was observed and it is suggested to originate from decays of a high- K multiquasiparticle and/or single-particle isomeric states.

Fluorine abundance in stars is a sensitive indicator of the physical conditions and processes occurring within their interiors. Recent extrapolated results on the ^{19}F(p,αγ)^{16}O fluorine destruction cross section suggested an increase of the astrophysical factor by several orders of magnitude at astrophysical energies, with profound implications for our understanding of stellar evolution and nucleosynthesis. We have indirectly measured the ^{19}F(p,αγ)^{16}O cross section using the Trojan horse method, fully covering astrophysical energies with no need of extrapolations. The strength of the 11 keV resonance was extracted and a significant reduction of the reaction rate was determined, compared to previous studies. The analysis of the astrophysical impact suggests that our measurement challenges existing predictions about fluorine and heavier elements' abundances, reigniting unresolved questions in the field.

The MAGNEX large acceptance magnetic spectrometer is installed at the Laboratori Nazionali del Sud of the Istituto Nazionale di Fisica Nucleare (INFN-LNS) in Catania. In the past, MAGNEX experimental campaigns were performed using ion beams up to 10¹⁰ pps provided by the Superconducting Cyclotron (SC) accelerator. Nevertheless, in the context of the NUMEN (Nuclear Matrix Elements for Neutrinoless double beta decay) project, which aims to get accurate values of the tiny Double Charge Exchange (DCE) cross-sections for a large number of nuclei of interest for the neutrinoless double beta decay (0νββ), the SC is being fully refurbished featuring ion beams with energies from 15 up to 70 MeV/u and intensities up to 10¹³ pps. The high rate of incident particles demands a complete upgrade of the MAGNEX detectors, which will consist of a new Particle Identification (PID) system and a new gas tracker detector along with a γ-calorimeter. The PID system is equipped with a large number (720) of Silicon Carbide-Cesium Iodide (Tallium doped) telescopes. A prototype of the PID wall has been built and studied thanks to an experimental test with an ¹⁸O beam at 275 MeV incident energy performed at INFN-Laboratori Nazionali di Legnaro, Italy. In this manuscript, the design of the new PID system, the in-beam test experimental set-up, and the prototype's performances are presented.