Broken seniority symmetry in the semimagic proton mid-shell nucleus ⁹⁵Rh

Lifetime measurements of low-lying excited states in the semimagic ( N = 50 ) nucleus 95Rh have been performed by means of the fast-timing technique. The experiment was carried out using γ -ray detector arrays consisting of LaBr3(Ce) scintillators and germanium detectors integrated into the DESPEC experimental setup commissioned for the Facility for Antiproton and Ion Research (FAIR) Phase-0, Darmstadt, Germany. The excited states in 95Rh were populated primarily via the β decays of 95Pd nuclei, produced in the projectile fragmentation of a 850 MeV/nucleon 124Xe beam impinging on a 4 g / cm2 9Be target. The deduced electromagnetic E2 transition strengths for the γ -ray cascade within the multiplet structure depopulating from the isomeric Iπ = 21 / 2+ state are found to exhibit strong deviations from predictions of standard shell model calculations which feature approximately conserved seniority symmetry. In particular, the observation of a strongly suppressed E2 strength for the 13 / 2+ → 9 / 2+ ground state transition cannot be explained by calculations employing standard interactions. This remarkable result may require revision of the nucleon-nucleon interactions employed in state-of-the-art theoretical model calculations, and might also point to the need for including three-body forces in the Hamiltonian

Biodiversity-friendly designs for gravel pit lakes along the Drina River floodplain (the Middle Danube Basin, Serbia)

Massive gravel excavation is one of the most destructive forces affecting riverine habitats in Europe. However, gravel pit lakes are also recognized as valuable wildlife refuge areas. Different hydromorphological characteristics of gravel pits may influence aquatic biota differently. Optimal selection of gravel excavation procedures may create favorable conditions for ecosystem diversity. The aim of this study was to correlate hydromorphological variables against macrophyte composition and metrics in gravel pit lakes along the lower course of the Drina River. Field research was carried out at 18 gravel pit lakes (60 survey sectors) and four fluvial lakes (13 survey sectors), during the summer months of 2015, 2016 and 2018. The role of hydromorphological variables in structuring macrophyte assemblages was tested using the partial Canonical Correspondence Analysis, while the Generalized Linear Model was performed to test the ability of selected hydromorphological attributes to predict macrophyte quantitative metrics. The results demonstrated high habitat quality and conservation value of the gravel pit lakes compared to natural sites. Hydromorphological predictors for different macrophyte assemblages were defined. General recommendation is that two pit types should be excavated within a single extraction field, with the minimal impact to the riparian and shore zones. The first type should be located up to 100 m from river main channel, having area < 1000 m2 and a relative depth ratio > 5%. The second type should be optimally located 300 m form river main channel, with maximum depth of 3–4 m, surface area of 10,000–20,000 m2, and a relative depth ratio < 5%