Recent results in nuclear astrophysics at the n_TOF facility at CERN

The neutron time of flight (n_TOF) facility at CERN is a spallation source characterized by a white neutron spectrum. The innovative features of the facility, in the two experimental areas, (20 m and 185 m), allow for an accurate determination of the neutron cross section for radioactive samples or for isotopes with small neutron capture cross section, of interest for Nuclear Astrophysics. The recent results obtained at n_TOF facility are presented

Cross section measurements of 155,157Gd(n, γ) induced by thermal and epithermal neutrons

Neutron capture cross section measurements on 155Gd and 157Gd were performed using the time-of-flight technique at the n_TOF facility at CERN on isotopically enriched samples. The measurements were carried out in the n_TOF experimental area EAR1, at 185 m from the neutron source, with an array of 4 C6D6 liquid scintillation detectors. At a neutron kinetic energy of 0.0253 eV, capture cross sections of 62.2(2.2) and 239.8(8.4) kilobarn have been derived for 155Gd and 157Gd, respectively, with up to 6% deviation relative to values presently reported in nuclear data libraries, but consistent with those values within 1.6 standard deviations. A resonance shape analysis has been performed in the resolved resonance region up to 181 eV and 307 eV, respectively for 155Gd and 157Gd, where on average, resonance parameters have been found in good agreement with evaluations. Above these energies and up to 1 keV, the observed resonance-like structure of the cross section has been analysed and characterised. From a statistical analysis of the observed neutron resonances we deduced: neutron strength function of 2. 01 (28) × 10 - 4 and 2. 17 (41) × 10 - 4; average total radiative width of 106.8(14) meV and 101.1(20) meV and s-wave resonance spacing 1.6(2) eV and 4.8(5) eV for n + 155Gd and n + 157Gd systems, respectively.European Atomic Energy Community (Euratom) 605203Ministerio de Economía y Competitividad FPA2014-52823-C2-1-

Catálogo y distribución geográfica de los Odonatos en la Región de Murcia (SE España).

Se actualiza el catálogo y la distribución del orden Odonata en la Región de Murcia, comparándolo a uno anterior realizado en los años 50 del siglo XX. Los resultados indican que a mitad del siglo pasado se localizaron 40 especies en 17 localidades, mientras que las 2.087 citas recopiladas entre 1991-2017 confirman la presencia de 47 especies en 191 localidades. Se han identificado 11 nuevas especies para la Región de Murcia, que se pueden haber visto favorecidas por la construcción de charcas, embalses y otras infraestructuras para abastecer a las 225.000 ha de regadíos. De ellas, 9 especies se están expandiendo su área de distribución hacia el norte de Europa y/o Asia, efecto que podría estar relacionado con el proceso de cambio climático actual. Por el contrario, en la revisión actual no han sido detectadas 4 especies citadas en el estudio realizado a mediados del siglo XX