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Level lifetimes for the candidate chiral doublet bands of $^{80}$Br were extracted by means of the Doppler-shift attenuation method. The absolute transition probabilities derived from the lifetimes agree well with the M1 and E2 chiral electromagnetic selection rules, and are well reproduced by the triaxial particle rotor model calculations. Such good agreements among the experimental data, selection rules of chiral doublet bands and theoretical calculations are rare and outstanding in researches of nuclear chirality. Besides odd-odd Cs isotopes, odd-odd Br isotopes in the A≈ 80 mass region represent another territory that exhibits the ideal selection rules expected for chiral doublet bands.

Lithium and its isotopes can provide information on continental silicate weathering, which is the primary natural drawdown process of atmospheric CO2 and a major control on climate. Lithium isotopes themselves can help our understanding of weathering, via globally important processes such as clay formation and cation retention. Both these processes occur as part of weathering in modern surface environments, such as rivers, soil pore waters, and groundwaters, but Li isotopes can also be used to track weathering changes across major climate-change events. Lithium isotope evidence from several past climatic warming and cooling episodes shows that weathering processes respond rapidly to changes in temperature, meaning that weathering is capable of bringing climate back under control within a few tens of thousands of years.

International audience; The cycling of Li at the Earth's surface results in marked isotopic fractionations (~40) that lead to the subduction of isotopically heavy Li. This scenario suggests that Li isotope ratios should provide a distinctive tracer of subducted components in oceanic basalts. Such promise is based on the tacit assumption of equilibrium, in which only low temperature processes can significantly fractionate stable isotopes. However, several recent experimental and observational studies have highlighted that Li isotopes are readily fractionated in magmatic processes by diffusion. In order to use Li isotopes as a tracer of recycled material it is thus critical to understand the role of diffusion on Li isotopes at different length scales. We have examined Li isotopic profiles in phenocrysts of lava flows. Except in glassy samples, we commonly find zoned crystals. Such isotopic zoning appears to be the natural consequence of cooling, during which the partition coefficient of Li in phenocrysts increases. We have reproduced the forms of isotopic profiles in a self-consistent model driven only by cooling. Deriving absolute cooling rates depends on several paramaters which are currently poorly constrained (e.g. the diffusivity of Li in olivine), but the data plausibly imply temperature drops of a few hundred degrees in hours. The influence of diffusion on the Li isotopic composition of a whole lava flow, rather than its redistribution during final cooling, is more difficult to determine. The general over-lap of (unzoned) olivines from peridotitic xenoliths with many mantle derived melts suggest that whole rock compositions are not ubiquitously fractionated by diffusion. As an empirical assessment of possible diffusively driven differences in bulk Li isotopic compositions, we have analysed a suite of samples from the East Pacific Rise (9-10°N). These samples show near homogeneity in long-lived radiogenic isotope tracers but contrasting U-series disequilibria, suggesting their derivation from different depths of the melting regime. This should give rise to differential chemical gradients between the melts and mantle through which they finally ascend, potentially driving different diffusional loss of Li. Although the sample suite shows a significant range in ..7Li related to disequilibrium, its magnitude is small (0.7), suggesting that the role of diffusion in influencing these lava compositions is minor.

Excited states of the nucleus 79Br were investigated via the reaction 76Ge(7Li,4n) at 35 MeV. Coincidence data of emitted gamma rays were measured with an arrangement of six EUROBALL CLUSTER detectors. The E2 bands built on the 9/2+ and 3/2- states were extended up to J = 37/2 at E \approx 8.8 MeV. The M1 band starting with a 15/2- state at 2.6 MeV was extended to J = (29/2) at E = 6.4 MeV. Cross-over E2 transitions within this band were observed for the first time. Mean lifetimes of 17 levels were deduced using the Doppler-shift-attenuation method. The M1 band can be described within theTilted-Axis-Cranking model on the basis of the tilted three-quasiparticle configuration pi(g9/2) nu (g9/2) nu (fp) which has a triaxial shape. This band appears as a mixed case including contributions of both, magnetic and collective rotation.

High-spin states of the nucleus $^{88}$Sr have been studied via the reaction $^{80}$Se($^{11}$B,$p$2$n$) at a beam energy of 45 MeV. Gamma-rays were detected with the six-detector array OSIRIS CUBE. The level scheme of $^{88}$Sr has been extended up to $E \approx$ 11 MeV and $J = 17$. Mean lifetimes of three levels have been determined using the Doppler-shift-attenuation method. The level structures in $^{88}$Sr have been interpreted in terms of the shell model. The calculations were performed in the configuration space $(0f_{5/2}, 1p_{3/2}, 1p_{1/2}, 0g_{9/2})$ for the protons and $(1p_{1/2}, 0g_{9/2}, 1d_{5/2})$ for the neutrons. These calculations describe the high-spin level sequences linked by $M1$ transitions with strengths of $B(M1) \leq 1.4$ W.u. as multiplets of seniority $\upsilon$ = 4 and 6 states including proton configurations and neutron-core excitations.

Más del 95% de los afloramientos del basamento metamórfico del Paleozoico inferior en el Noroeste de A rgentina y Norte de Chile están compuestos por rocas félsicas. Los contenidos de elementos mayores, trazas y las composiciones isotópicas de Pb, Rb-Sr y Sm-Nd son típicos de las rocas que conforman la corteza superior. Las edades modelos Sm-Nd de las rocas estudiadas son de ca 1.8 Ga. Estas rocas han sido afectadas por un evento principal de metamorfismo del Paleozoico temprano (ca. 500 Ma). Se considera que el reciclado de la corteza, con un importante evento de metamorfismo durante el Paleozoico temprano, es el proceso dominante en la generación de muchos de los magmas con composiciones graníticas originados desde el Paleozoico temprano hasta el Reciente. Las espesas secuencias sedimentarias ordovícicas son derivadas también de esa misma corteza en común. Los xenolitos félsicos de la corteza inferior extraídos por el magmatismo perteneciente al sistema del Rift Salta, son muy similares composicionalmente al basamento del Paleozoico inferior. Se estima que la composición de la corteza desde la parte superior hasta la inferior sería principalmente félsica. Las rocas máficas tienen muy poco volumen y forman principalmente diques. Sus edades modelos Sm-Nd revelan dos grupos, uno con edades de ca 1.8 Ga y otro con edades de ca £ 1.0 Ga No ha sido posible realizar una interpretación ajustada del ambiente geodinámico en donde se ha desarrollado este magmatismo básico., Felsic rocks comprise more than 95% of the outcropping Early Paleozoic metamorphic basement. Their major and trace element contents and Pb, Rb-Sr and Sm-Nd isotope compositions are typical for upper crustal rocks. Sm-Nd model ages are ca 1.8 Ga. The principal ages of high-grade metamorphism is Early Paleozoic (ca 500 Ma). Recycling of this crust is the dominating process in the formation of granitoid magmatic rocks from Early Paleozoic to Recent. Ordovician sediments are also derivates of this crust. Felsic lower crustal xenoliths from the Salta Rift system are compositionally very similar compared to the early Paleozoic basement. The crustal composition from top to the bottom seems mainly felsic. Early Paleozoic mafic rocks are of minor volume and form mainly dikes. Their Sm-Nd model ages reveal two groups; one with ages of ca 1.8 Ga another with ages of £ 1.0 Ga. A meaningful interpretation of their geodynamic setting is not possible.