Search results for "nuclide"

Mobility or migration: a case study from the Neolithic settlement of Nieder-Mörlen (Hessen, Germany)

2009

A combination of stable carbon and nitrogen isotope analysis of collagen and radiogenic strontium isotope analysis of tooth enamel was used to investigate diet and mobility at the early Neolithic settlement of Nieder-Morlen in Germany. The carbon and nitrogen ratios suggest a mixed terrestrial based diet that is consistent with data previously published for early Neolithic sites in Europe. The strontium isotope data indicate a high degree of human mobility with only one individual having an isotope ratio consistent with locally derived strontium. Unusually, a group of non-local juveniles with isotope ratios typical of upland regions is also present at the settlement but there are no adult b…

Comparison of gamma-ray coincidence and low-background gamma-ray singles spectrometry

2011

Aerosol samples have been studied under different background conditions using gamma-ray coincidence and low-background gamma-ray singles spectrometric techniques with High-Purity Germanium detectors. Conventional low-background gamma-ray singles counting is a competitive technique when compared to the gamma-gamma coincidence approach in elevated background conditions. However, measurement of gamma-gamma coincidences can clearly make the identification of different nuclides more reliable and efficient than using singles spectrometry alone. The optimum solution would be a low-background counting station capable of both singles and gamma-gamma coincidence spectrometry.

2016

Abstract. Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their av…

RADIONUCLIDE CONCENTRATIONS IN AIR PARTICULATE AT PALERMO (ITALY) FOLLOWING FUKUSHIMA ACCIDENT

2012

Following the Fukushima accident, a series of samplings were carried out with a daily frequency to detect the arrival of radioactive contamination in air at Palermo (Italy) and to follow its evolution during the time. Air particulate collection was performed by suction of atmospheric air through cellulose filter paper by means of a high-volume air sampler (∼15 000 m(3) d(-1)). Spectrometric analysis of the filters highlights the presence of (131)I, (134)Cs, (137)Cs and, only for a few samples, traces of (132)Te-(132)I and (136)Cs. Maximum airborne concentrations were 883 μBq m(-3) for (131)I (only particulate), 81 μBq m(-3) for (137)Cs and 70 μBq m(-3) for (134)Cs. From a dose to population…

The radiogenic isotope composition of the high-latitude North Atlantic mantle

1997

New Sr, Nd, and Pb isotope data on North Atlantic high-latitude (about 69°30'N to 76°30'N) intraplate and ridge volcanic rocks, together with published data, are used to evaluate the mantle sources contributing to Iceland and the surrounding ridges. Considerable overlap between Icelandic lavas and depth-filtered North Atlantic mid-oceanic-ridge basalts (MORBs) in all isotope plots confirm that a MORB asthenosphere-plume mixing model can explain the ranges of isotope compositions found on Iceland. Regional isotope patterns north of lat 53°N show two distinct mantle domains. Lavas forming a low-radiogenic-Pb, high-radiogenic-Sr array occur north of central Iceland, whereas volcanic rocks form…

Geochemical heterogeneities in magma beneath Mount Etna recorded by 2001-2006 melt inclusions

2015

We present a geochemical study on olivine and clinopyroxene-hosted melt inclusions (MIs) from 2001 to 2006 Etna basaltic lavas and pyroclastites. Three MI suites are distinguished on the basis of trace element fingerprinting. Type-1 MIs (from 2001 Upper South and 2002 Northeast vents) share their trace element signature with low-K lavas erupted before 1971. Critical trace element ratios (e.g., K/La, Ba/Nb), along with Pb isotope data of Type-1 MIs provide evidence for a heterogeneous mantle source resulting from mixing of three end-members with geochemical and isotopic characteristics of EM2, DMM, and HIMU components. Type-1 MIs composition does not support involvement of subduction-related…

MORB-type neon in an enriched mantle beneath Etna, Sicily

1997

Abstract Noble gas elemental and isotopic compositions were determined for five CO 2 –CH 4 samples collected around Etna, Sicily, to investigate the geochemical features of the mantle beneath the volcano. The samples contain mantle-derived noble gases. The measured helium isotopic ratios ( 3 He/ 4 He) vary between 5.9 and 6.4 times atmospheric ratio ( R a =1.4×10 −6 ), which are comparable to the ratios of olivines (6.1–8.2 R a ) in the lavas of the same volcano [1]. Neon in the samples is enriched in both 20 Ne and 21 Ne ( 20 Ne/ 22 Ne 9.95–10.7, 21 Ne/ 22 Ne 0.030–0.037), indicating derivation from the mantle. The δ ( 20 Ne/ 22 Ne)/ δ ( 21 Ne/ 22 Ne) values are identical with that of mid-…

Petrology and geochemistry of submarine volcanism in the Sicily Channel Rift

2006

Submarine magmatism in the Sicily Channel Rift began in the early Pliocene and lasted until almost 200 yr ago. We present here petrological and geochemical data on volcanic rocks dredged from Graham and Nameless banks and Pantelleria seamounts in the Pelagian sector of the Sicily Channel Rift. Petrological evidence suggests that the ascent of magmas to the surface was relatively rapid, probably through channels superimposed over the major tectonic discontinuities of the Rift. Major and trace element data indicate an ocean island basalt affinity for Graham and Nameless bank alkaline lavas and a depleted tholeiitic signature for one Pantelleria seamount, which had a shallower mantle source. S…

Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes

2015

Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po196,198,200,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po200,202, the transitional and diagonal matrix elements of the 2+1 state are determined. In Po196,198 multistep Coulomb excitation is observed, populating the 4+1,0+2, and 2+2 states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po196 onwards. Three model descriptions are used to compare to the data. Calculati…

Perspectives for CNO neutrino detection in Borexino

2018

International audience; Borexino measured with unprecedented accuracy the fluxes of solar neutrinos emitted at all the steps of the pp fusion chain. Still missing is the measurement of the flux of neutrinos produced in the CNO cycle. A positive measurement of the CNO neutrino flux is of fundamental importance for understanding the evolution of stars and addressing the unresolved controversy on the solar abundances. The measurement of the CNO neutrino flux in Borexino is challenging because of the low intensity of this component (CNO cycle accounts for about 1% of the energy emitted by Sun), the lack of prominent spectral features and the presence of background sources. The main background c…