Determining the 13C(α, n)16O absolute cross section through the concurrent application of ANC and THM and astrophysical consequences for the s-process in AGB-LMSs.

The 13 C( α , n) 16 O reaction is considered to be the most important neutron source for the s -process main component in low-mass asymptotic giant branch stars. No direct experimental data exist at very low energies and measurements performed through direct techniques show inconsistent results, mostly in their absolute values. In this context, we reversed the usual normalization procedure combining two indirect approaches, the asymptotic normalization coefficient and the Trojan Horse Method, to unambiguously determine the absolute value of the 13 C( α , n) 16 O astrophysical S ( E )-factor in the most relevant energy-region for astrophysics. Adopting the new reaction rate for the n-source in the NEWTON s -process nucleosynthesis code, astrophysical calculations show only limited variations, less than 1%, for those nuclei whose production is considered to be totally due to slow neutron captures

THE 8 Li(α, n) 11 B REACTION RATE AT ASTROPHYSICAL TEMPERATURES

At temperatures (0.5-1.2) × 109 K, the 8Li + 4He → 11B+n reaction can allow for 12C and heavier element production in the framework of the inhomogeneous big bang nucleosynthesis. At temperatures (2.5-5) × 109 K, it can influence the production of seed nuclei, later burnt to heavier elements by means of rapid neutron capture reactions, during Type II supernova explosions. Previous determinations of the reaction rate show an untenable disagreement. In this work, a new reaction rate calculation is proposed for the intervals of astrophysical interest. This new recommendation turns out to be up to a factor of five larger than the most recent rate in the literature, thus enforcing the role of 8Li + 4He → 11B+n as a candidate for key astrophysical reactions. The analytical expression of the recommended reaction rate is given

Determination of alpha spectroscopic factors for unbound 17O states

It has been recently suggested that hydrogen ingestion into the helium shell of massive stars could lead to high 13C and 15N excesses when the blast of a core collapse supernova (ccSN) passes through its helium shell. This prediction questions the origin of extremely high 13C and 15N abundances observed in rare presolar SiC grains which is usually attributed to classical novae. In this context the 13N(α,p)16O reaction plays an important role since it is in competition with 13N β+-decay to 13C. As a first step to the determination of the 13N(α,p)16O reaction rate, we present a study aiming at the determination of alpha spectroscopic factors of 17O states which are the analog ones to those in 17F, the compound nucleus of the 13N(α,p)16O reaction

Nanostructured surfaces for nuclear astrophysics studies in laser-plasmas

The future availability of high-intensity laser facilities capable of delivering tens of petawatts of power (e.g. ELI-NP) into small volumes of matter at high repetition rates will give the unique opportunity to investigate nuclear reactions and fundamental interactions process under extreme plasma conditions [1]. In this context, use of targets with nanostructured surfaces is giving promising indications to reproduce plasma conditions suitable for measurements of thermonuclear reactions rates, in the domain of nanosecond laser pulses

Advanced age, time to treatment and long-term mortality: single centre data from the FAST-STEMI network

Background. Optimization of the techniques and larger accessibility to mechanical reperfusion have significantly improved the outcomes of patients with ST-segment elevation myocardial infarction (STEMI). However, suboptimal results have been observed in certain higher-risk subsets of patients, as in advanced age, where the benefits of primary PCI are more debated. We evaluated the impact of systematic primary percutaneous coronary intervention (PCI) and an optimized STEMI network on the long-term prognosis from a single centre experience.Methods. We included STEMI patients included in the FAST-STEMI network between 2016 and 2019. Ischemia duration was defined as the time from symptoms onset to coronary reopening (pain-to-balloon, PTB). The primary study endpoint (PE) was a composite of mortality and recurrent MI at long-term follow-up. Indywidual outcome endpoints were also assessed.Results. We included 253 patients undergoing primary PCI and discharged alive. Mean age was 67.2 ± 12.5 years, 75.1% males and 19.8% diabetics. At a median follow-up of 581 [307–922] days, the primary endpoint occurred in 24 patients (7.9%), of whom 5.5% died. The occurrence of a cardiovascular event was significantly associated with advanced age (p < 0.001), renal failure (p = 0.03), lower ejection fraction at discharge (p = 0.04) and longer in-hospital stay (p = 0.01). The median PTB was 198 minutes [IQR: 125–340 min], that was significantly longer among patients experiencing the PE (p = 0.01). A linear relationship was observed between age and PTB (r = 0.13, p = 0.009). However, both age ≥ 75 years and PTB above the median emerged as independent predictors of the primary endpoint (age: HR [95%CI] = 5.56 [2.26–13.7], p < 0.001, PTB: HR [95%CI] = 3.59 [1.39–9.3], p = 0.01). Similar results were observed for overall mortality.Conclusion. The present study shows that among STEMI patients undergoing primary PCI in a single centre, the duration of ischemia and advance age are independently associated to long-term mortality and recurrent myocardial infarction. However, longer time to reperfusion was observed among elderly patients

New direct measurement of the 10 B(p,α) 7 Be reaction with the activation technique

Boron plays an important role in astrophysics and, together with lithium and beryllium, is a probe of stellar structure during the pre-main sequence and main-sequence phases. In this context, the 10 B(p, α ) 7 Be reaction is of particular interest.The literature data show discrepancies in the energy range between 100 keV and 2 MeV. This also poses a normalization problem for indirect data obtained with the Trojan Horse Method.A new measurement of the 10 B(p, α ) 7 Be reaction cross section was performed at Legnaro National Laboratories (LNL). At LNL, the cross section was determined with the activation technique by measuring the activated samples at a low-background counting facility. The analysis of that experiment is now complete and the results are here presented

The Nuclear Astrophysics program at n-TOF (CERN)

An important experimental program on Nuclear Astrophysics is being carried out at the n-TOF since several years, in order to address the still open issues in stellar and primordial nucleosynthesis. Several neutron capture reactions relevant to s-process nucleosynthesis have been measured so far, some of which on important branching point radioisotopes. Furthermore, the construction of a second experimental area has recently opened the way to challenging measurements of (n, charged particle) reactions on isotopes of short half-life. The Nuclear Astrophysics program of the n-TOF Collaboration is here described, with emphasis on recent results relevant for stellar nucleosynthesis, stellar neutron sources and primordial nucleosynthesis