Search results for "thorium"

Conjunctive use of spectral gamma-ray logs and clay mineralogy in defining late Jurassic-early Cretaceous palaeoclimate change (Dorset, U.K.).

2006

Abstract Detrital clay mineralogy is controlled by weathered source rock, climate, transport and deposition that in turn influence the spectral gamma-ray (SGR) response of resultant sediments. Whilst a palaeoclimate signal in clay mineralogy has been established in some ancient successions, the SGR response remains contentious, largely because the data sets have yet to be collected at the same or appropriate vertical scales to allow comparison. In addition, the influence of organic matter on SGR is not always considered. Here, we present clay mineralogical, total organic carbon (TOC) and SGR analyses from the late Jurassic and early Cretaceous of the Wessex Basin, a period of previously doc…

A radiometric and petrographic approach to risk assessment at Alte Madonie Mounts region (Sicily, Italy)

2013

The main goal of this work was to assess the radiological hazard at Alte Madonie Mounts region (north-central Sicily, Italy) in response to rumours of an increase in the incidence of cancer in this area. A correlation between the natural radionuclide contents and the petrographic features of the soil and rock samples was also evaluated. A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in 'Marinelli' beakers for 20 d prior to measurement to ensure that a radioactive equilibrium between (226)Ra and (214)Bi had been reached. A gamma-ray spectrometer was used to quantify the radioactivity concentrations. To determine (238)U and (232)Th activities, the…

Resonance ionization spectroscopy of thorium isotopestowards a laser spectroscopic identification of the low-lying 7.6 eV isomer of 229Th

2011

International audience; In-source resonance ionization spectroscopy was used to identify an efficient and selective three step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in preparation of laser spectroscopic investigations for an identification of the low-lying 229 m Th isomer predicted at 7.6 ± 0.5 eV above the nuclear ground state. Using a sample of 232 Th, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing states were identified. Level energies were determined with an accuracy of 0.06 cm −1 for inte…

Gas cell studies of thorium using filament dispensers at IGISOL

2020

Abstract Filament-based dispensers of thorium have been investigated at the IGISOL facility, Jyvaskyla, for potential use as a thorium ion source for future collinear laser spectroscopy experiments. Several different filaments were manufactured in the Institute of Atomic and Subatomic Physics of TU Wien, with 232Th and 229Th prepared on tantalum substrates either by drying thorium nitrate solution or via molecular plating, while adding a layer of zirconium for oxide reduction. The filaments were characterized in a helium-filled gas cell by performing selective and efficient in-gas-cell resonance laser ionization and by analyzing the resulting ion beams by mass spectrometry. Additionally, th…

Separation of plutonium and neptunium species by capillary electrophoresis-inductively coupled plasma-mass spectrometry and application to natural gr…

2003

Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different a…

Isomeric Yield Ratios of 134I and 136I and Independent Fractional Yields of some Halogen Isotopes in the Fission of 232Th with Reactor Neutrons

1990

(Supplement Table S2) Results of 230Th/U-dating

2016

We compared the suitability of two skeletal materials of the Atlantic brain coral Diploria strigosa for 230Th/U-dating: the commonly used bulk material comprising all skeletal elements and the denser theca wall material. Eight fossil corals of presumably Last Interglacial age from Bonaire, southern Caribbean Sea, were investigated, and several sub-samples were dated from each coral. For four corals, both the ages and the activity ratios of the bulk material and theca wall agree within uncertainty. Three corals show significantly older ages for their bulk material than for their theca wall material as well as substantially elevated 232Th content and (230Th/238U) ratios. The bulk material sam…

Geo-neutrino results with Borexino

2015

International audience; Borexino is a liquid scintillator detector primary designed to observe solar neutrinos. Due to its low background level as well as its position in a nuclear free country, Italy, Borexino is also sensitive to geo-neutrinos. Borexino is leading this interdisciplinary field of neutrino geoscience by studying electron antineutrinos which are emitted from the decay of radioactive isotopes present in the crust and the mantle of the Earth. With 2056 days of data taken between December 2007 and March 2015, Borexino observed 77 antineutrino candidates. If we assume a chondritic Th/U mass ratio of 3.9, the number of geo-neutrino events is found to be 23.7(+6.5) (-5.7)(stat) (+…

Synthesis and Structure of ThTe2I2

2001

Narrow rim CMPO/adamantylcalix[4]arenes for the extraction of lanthanides and actinides

2011

Abstract Six p-(1-adamantyl)calix[4]arenes 7, 8 with four differently attached diphenyl-carbamoylmethylphosphine oxide (CMPO) functions at the narrow rim were synthesized. This series was extended by adamantylcalix[4]arenes with two CMPO and two ester, acid or (diethylphosphono)acetylamino groups. Structures of new compounds were proved by NMR, mass-spectrometry and a single-crystal X-ray analysis for the intermediate di-phthalimide 103. The extraction studies towards selected lanthanides and thorium showed that the ligands 7 surpassed the corresponding p-H, p-tert-butyl and p-tert-octyl analogues 3–5 in lanthanide extraction while thorium was extracted with the same or lesser extent. For t…