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Remote sensing observations point out that snow grain size in Antarctica follows a clear seasonal evolution, a summer increase and a winter decrease, which is conditioned by atmospheric processes, namely temperature, wind, snowfall, and by mechanisms acting inside the snowpack leading to water vapour transport causing the coarsening of the grains. This study focuses on the evolution of the grain size in the interior part of East Antarctica, where dry metamorphism occurs. For this, we use AMSU-B passive microwave radiometer observations collected from 2020 to 2022. The highest ridges in East Antarctica are the regions where the grain size increases the most in the summer, mainly because the wind speed is low. Moreover, some extreme weather events in this regions, where the grain size increased to large values with respect to the averages (over +3 sigma), were identified. In these cases, the ERA5 reanalysis revealed an atmospheric blocking/ridge situation around the onsets of the summer growing of the grain size, conveying the relatively warm and moist air coming from the mid latitudes, often associated with atmospheric rivers. If the following weeks feature weak wind, low temperature and low snowfall conditions, snow dry metamorphism is facilitated, leading to grain growth, and determining anomalous high value of the snow grain size at the end of the summer season. These grain size changes impact the albedo and have consequence on the energy budget of the surface., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

States in the astrophysically important Ne-19 nucleus have been populated directly using the O-15(alpha, alpha) O-15 reaction with a radioactive O-15 beam. Due to the challenges involved, this represents the first such O-15 measurement with high resolution and the first dedicated to exploring the cluster structure. This measurement comprises three experiments: the first to develop the O-15 radioactive beam, the second the resonant scattering study, and the third to measure the precise energy loss of O ions in He-4 to reduce systematic uncertainties. The results show evidence for O-15 + alpha cluster structure which could explain earlier results pointing to the increased alpha branching ratio in the astrophysical reaction rate for high-spin near-threshold resonances. Absolute differential cross sections have been measured. Additionally, spins, parities, and partial decay widths, essential for nuclear reaction-rate calculations, have been extracted using an R-matrix analysis.

The elastic scattering excitation function for O-15 on He-4 was measured - for the first time - by using the Inverse Kinematic Thick Target scattering method. The obtained spectrum was analysed in an R-matrix framework providing spectroscopic information for several states in the excitation energy of the nucleus Ne-19 from 4.8 to 9 MeV. Eight of them are newly observed states. The set-up and the experimental technique will be described in detail and the results will be shown and discussed.

We investigated the reaction dynamics induced by the Be-7, B-8+Pb-208 collisions at energies around the Coulomb barrier. Charged particles originated by both the collisions were detected by means of 6 Delta E-E-res telescopes of a newly developed detector array. Experimental data were analysed within the framework of the Optical Model and the total reaction cross-sections were compared together and with the Li-6,Li-7+Pb-208 collision data. According to the preliminary results, Be-7 nucleus reactivity is rather similar to the Li-7 one whereas the B-8+Pb-208 total reaction cross section appears to be much larger than those measured for reactions induced by the other weakly-bound projectiles on the same target.

The elastic scattering of the radioactive nucleus Be7 from a Si28 target was studied at four near-barrier energies: 13.2, 17.2, 19.8, and 22.0 MeV (E/VC=1.14, 1.48, 1.71, and 1.90). Angular distribution measurements were performed at each energy with the multidetector array EXPADES in conjunction with two Parallel-Plate Avalanche Counters (PPAC) to enable beam ray reconstruction of the events. The data are analyzed in a double-folding framework and the energy evolution of the optical potential as well as the total reaction cross sections are deduced and discussed. © 2017 American Physical Society.

States in the astrophysically important 19Ne nucleus have been populated directly using the 15O(α, α)15O reaction with a radioactive 15O beam. Due to the challenges involved, this represents the first such 15O measurement with high resolution and the first dedicated to exploring the cluster structure. This measurement comprises three experiments: the first to develop the 15O radioactive beam, the second the resonant scattering study, and the third to measure the precise energy loss of O ions in 4He to reduce systematic uncertainties. The results show evidence for 15O+α cluster structure which could explain earlier results pointing to the increased α branching ratio in the astrophysical reaction rate for high-spin near-threshold resonances. Absolute differential cross sections have been measured. Additionally, spins, parities, and partial decay widths, essential for nuclear reaction-rate calculations, have been extracted using an R-matrix analysis.

We investigated the reaction dynamics induced by the Radioactive Ion Beams Be-7 and B-8 on a Pb-208 target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being Be-7 (S-alpha = 1.586 MeV) the loosely bound core of the even more exotic B-8 (S-p = 0.1375 MeV) nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.

The production of α and He3 particles, the cluster constituents of Be7, in the Be7+Si28 reaction was studied at three near-barrier energies, namely 13, 20, and 22 MeV. Angular distribution measurements were performed at each energy, and the data were analyzed in both statistical model and Distorted-Wave Born Approximation (DWBA) frameworks in order to disentangle the degree of competition between direct and compound channels. The energy evolution of the ratio of direct to total reaction cross section was mapped in comparison with similar data for Li6 and Li7 projectiles on a Si28 target. The results indicate larger transfer contributions for collisions involving the mirror nuclei Be7 and Li7 than in the Li6 case. Fusion cross sections were deduced, taking into account the α-particle cross sections due to compound-nucleus formation and particle multiplicities deduced from our statistical model framework. It was found that fusion is compatible with systematics and single-barrier penetration cross sections to within an uncertainty band of 10% to 20%. Indications of fusion hindrance for Li7 and Be7 compared to Li6, starting from the barrier and below it, are given. This hindrance is attributed to the existence of large transfer channels. Furthermore, the experimental results, analyzed in the DWBA framework, suggest He3 and He4 transfer as the dominant direct reaction mechanism. © 2016 American Physical Society.

We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam Be-7 (S-alpha = 1.586 MeV) on medium-mass (Ni-58) and heavy (Pb-208) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3x10(5) pps Be-7 secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.