12 results on '"Peter Sprung"'
Search Results
2. High precision half-life measurement of the extinct radio-lanthanide Dysprosium-154
- Author
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Nadine Mariel Chiera, Rugard Dressler, Peter Sprung, Zeynep Talip, and Dorothea Schumann
- Subjects
Medicine ,Science - Abstract
Abstract Sixty years after the discovery of 154Dy, the half-life of this pure alpha-emitter was re-measured. 154Dy was radiochemically separated from proton-irradiated tantalum samples. Sector field- and multicollector-inductively coupled plasma mass spectrometry were used to determine the amount of 154Dy retrieved. The disintegration rate of the radio-lanthanide was measured by means of α-spectrometry. The half-life value was determined as (1.40 ± 0.08)∙106 y, with an uncertainty reduced by a factor of ~ 10 compared to the currently adopted value of (3.0 ± 1.5)∙106 y. This precise half-life value is useful for the the correct testing and evaluation of p-process nucleosynthetic models using 154Dy as a seed nucleus or as a reaction product, as well as for the safe disposal of irradiated target material from accelerator driven facilities. As a first application of the half-life value determined in this work, the excitation functions for the production of 154Dy in proton-irradiated Ta, Pb, and W targets were re-evaluated, which are now in agreement with theoretical calculations.
- Published
- 2022
- Full Text
- View/download PDF
3. Efficient Production of High Specific Activity Thulium-167 at Paul Scherrer Institute and CERN-MEDICIS
- Author
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Reinhard Heinke, Eric Chevallay, Katerina Chrysalidis, Thomas E. Cocolios, Charlotte Duchemin, Valentin N. Fedosseev, Sophie Hurier, Laura Lambert, Benji Leenders, Bruce A. Marsh, Nicholas P. van der Meulen, Peter Sprung, Thierry Stora, Marianna Tosato, Shane G. Wilkins, Hui Zhang, and Zeynep Talip
- Subjects
medical radionuclides ,thulium-167 ,mass separation ,laser resonance ionization ,MEDICIS ,Auger electrons ,Medicine (General) ,R5-920 - Abstract
Thulium-167 is a promising radionuclide for nuclear medicine applications with potential use for both diagnosis and therapy (“theragnostics”) in disseminated tumor cells and small metastases, due to suitable gamma-line as well as conversion/Auger electron energies. However, adequate delivery methods are yet to be developed and accompanying radiobiological effects to be investigated, demanding the availability of 167Tm in appropriate activities and quality. We report herein on the production of radionuclidically pure 167Tm from proton-irradiated natural erbium oxide targets at a cyclotron and subsequent ion beam mass separation at the CERN-MEDICIS facility, with a particular focus on the process efficiency. Development of the mass separation process with studies on stable 169Tm yielded 65 and 60% for pure and erbium-excess samples. An enhancement factor of thulium ion beam over that of erbium of up to several 104 was shown by utilizing laser resonance ionization and exploiting differences in their vapor pressures. Three 167Tm samples produced at the IP2 irradiation station, receiving 22.8 MeV protons from Injector II at Paul Scherrer Institute (PSI), were mass separated with collected radionuclide efficiencies between 11 and 20%. Ion beam sputtering from the collection foils was identified as a limiting factor. In-situ gamma-measurements showed that up to 45% separation efficiency could be fully collected if these limits are overcome. Comparative analyses show possible neighboring mass suppression factors of more than 1,000, and overall 167Tm/Er purity increase in the same range. Both the actual achieved collection and separation efficiencies present the highest values for the mass separation of external radionuclide sources at MEDICIS to date.
- Published
- 2021
- Full Text
- View/download PDF
4. Constraining the process of intracontinental subduction in the Austroalpine Nappes: Implications from petrology and Lu‐Hf geochronology of eclogites
- Author
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Carsten Münker, Marian Janák, Irena Miladinova, Raúl O.C. Fonseca, Thorsten J. Nagel, Peter Sprung, and Nikolaus Froitzheim
- Subjects
Eoalpine (Cretaceous) event ,Lu-Hf geochronology ,Eastern Alps ,Subduction ,high-pressure metamorphism ,Geochemistry and Petrology ,Geochronology ,Geology ,Eclogite ,Petrology ,thermodynamic modelling ,Nappe - Abstract
High- and ultrahigh-pressure rocks occur in the Austroalpine Nappes in a ~400 km long belt from the Texel Complex in the west to the Sieggraben Unit in the east. Garnet growth during pressure increase was dated using Lu-Hf chronometry. The results range between c. 100 and 90 Ma, indicating a short-lived period of subduction. Combined with already published data, our estimates of metamorphic conditions indicate a field gradient with increasing pressure and temperature from the northwest to the southeast, where the rocks experienced ultrahigh-pressure metamorphism. The P-T conditions of the eclogites generally lie on the ‘warm’ side of the global range of subduction-zone metamorphic conditions. The oldest Cretaceous eclogites (c. 100 Ma) are found in the Saualpe-Koralpe area derived from widespread gabbros formed during Permian to Triassic rifting. In the Texel Complex garnets showing two growth phases yielded a Variscan-Eoalpine mixed age indicating re-subduction of Variscan eclogite-bearing continental crust during the Eoalpine orogeny. Jurassic blueschist-facies metamorphism at Meliata in the Western Carpathians and Cretaceous eclogite-facies metamorphism in the Austroalpine are separated by a time gap of c. 50 Ma and therefore do not represent a transition from oceanic to continental subduction but rather separate events. Thus, we propose that subduction initiation was intracontinental at the site of a Permian rift.
- Published
- 2021
5. Correction to: Redox-dependent Ti stable isotope fractionation on the Moon: implications for current lunar magma ocean models
- Author
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Laura Jennifer Anabel Rzehak, Sebastian Kommescher, Liam Hoare, Florian Kurzweil, Peter Sprung, Felipe P. Leitzke, and Raúl O. C. Fonseca
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Geophysics ,Geochemistry and Petrology - Published
- 2022
6. Redox-dependent Ti stable isotope fractionation on the Moon: implications for current lunar magma ocean models
- Author
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Laura J. A. Rzehak, Sebastian Kommescher, Liam Hoare, Florian Kurzweil, Peter Sprung, Felipe P. Leitzke, and Raúl O. C. Fonseca
- Subjects
Geophysics ,Geochemistry and Petrology - Abstract
In terrestrial magmas titanium is predominantly tetravalent (Ti4+), in contrast, lunar magmas are more reduced (IW-1) and hence approximately 10% of their bulk Ti content is trivalent (Ti3+). Changes in oxidation state and coordination number are both important parameters that can serve to drive Ti stable isotope fractionation. As such, mineral–mineral and mineral-melt Ti stable isotope fractionation factors determined for terrestrial samples may not be appropriate for lunar samples that formed under more reducing conditions. To address this issue, several experiments were carried out in gas mixing furnaces over a range offO2(air to IW-1) to determine Ti stable isotope fractionation factors for minerals, such as ilmenite, clinopyroxene and rutile that are highly abundant on the Moon. Results show that the extent of Ti stable isotope fractionation significantly increases with decreasingfO2. For example, the isotopic difference between ilmenite and residual melt (Δ49Tiilmenite-melt) is resolvably lower by ~ 0.44 ‰ from terrestrial-like FMQ-0.5 to lunar-like IW-1 at an intermediate precision of ± 0.003 ‰ (95% c.i. OL–Ti). This confirms that fractionation factors determined for terrestrial conditions are indeed not applicable to lunar settings. Our new fractionation factors for ilmenite, clinopyroxene and silicate melt are mostly consistent with those previously determined by ab initio modelling based on density-functional theory. Using our new experimental data in conjunction with previously published high-precision HFSE data and Ti stable isotope data of lunar basalts, we modelled the solidification of the Lunar Magma Ocean (LMO). The model for LMO solidification included fractionation of Ti stable isotopes not only by Ti-oxides, but also by typical lunar silicate minerals as pyroxene or olivine. The resulting δ49Ti for urKREEP and ilmenite-bearing cumulates are within error of previous estimates, but also indicate that ilmenite-bearing cumulates must have contained around 15% ilmenite.
- Published
- 2022
7. Determination of the half-life of gadolinium-148
- Author
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Nadine M. Chiera, Rugard Dressler, Peter Sprung, Zeynep Talip, and Dorothea Schumann
- Subjects
Radiation - Published
- 2023
8. Redox-dependent Ti stable isotope fractionation on the Moon: implications for current lunar magma ocean models
- Author
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Laura, Rzehak J. A., Sebastian, Kommescher, Liam, Hoare, Florian, Kurzweil, Peter, Sprung, Felipe, Leitzke P., Raul, Fonseca O. C., Laura, Rzehak J. A., Sebastian, Kommescher, Liam, Hoare, Florian, Kurzweil, Peter, Sprung, Felipe, Leitzke P., and Raul, Fonseca O. C.
- Abstract
In terrestrial magmas titanium is predominantly tetravalent (Ti4+), in contrast, lunar magmas are more reduced (IW-1) and hence approximately 10% of their bulk Ti content is trivalent (Ti3+). Changes in oxidation state and coordination number are both important parameters that can serve to drive Ti stable isotope fractionation. As such, mineral-mineral and mineral-melt Ti stable isotope fractionation factors determined for terrestrial samples may not be appropriate for lunar samples that formed under more reducing conditions. To address this issue, several experiments were carried out in gas mixing furnaces over a range of fO(2) (air to IW-1) to determine Ti stable isotope fractionation factors for minerals, such as ilmenite, clinopyroxene and rutile that are highly abundant on the Moon. Results show that the extent of Ti stable isotope fractionation significantly increases with decreasing fO(2). For example, the isotopic difference between ilmenite and residual melt (Delta Ti-49(ilmenite-melt)) is resolvably lower by similar to 0.44 parts per thousand from terrestrial-like FMQ-0.5 to lunar-like IW-1 at an intermediate precision of +/- 0.003 parts per thousand (95% c.i. OL-Ti). This confirms that fractionation factors determined for terrestrial conditions are indeed not applicable to lunar settings. Our new fractionation factors for ilmenite, clinopyroxene and silicate melt are mostly consistent with those previously determined by ab initio modelling based on density-functional theory. Using our new experimental data in conjunction with previously published high-precision HFSE data and Ti stable isotope data of lunar basalts, we modelled the solidification of the Lunar Magma Ocean (LMO). The model for LMO solidification included fractionation of Ti stable isotopes not only by Ti-oxides, but also by typical lunar silicate minerals as pyroxene or olivine. The resulting delta Ti-49 for urKREEP and ilmenite-bearing cumulates are within error of previous estimates, but a
- Published
- 2022
9. High Precision Half‑Life Measurement of the Extinct Radio‑Lanthanide Dysprosium-154
- Author
-
Nadine Mariel Chiera, Rugard Dressler, Peter Sprung, Zeynep Talip, and Dorothea Schumann
- Abstract
Sixty years after the discovery of 154Dy, the half-life of this pure alpha-emitter was re-measured. 154Dy was radiochemically separated from proton-irradiated tantalum samples. Sector field- and multicollector-inductively coupled plasma mass spectrometry were used to determine the amount of 154Dy retrieved. The disintegration rate of the radio-lanthanide was measured by means of α-spectrometry. The half-life value was determined as (1.33 ± 0.07)∙106 y, with an uncertainty reduced by a factor of ~10 compared to the currently adopted value of (3.0 ± 1.5)∙106 y. This precise half-life value is crucial for the correct estimation of p-process nucleosynthetic reactions in the lanthanide region, as well as for the safe disposal of irradiated target material from spallation facilities. As a first application of the half-life value found in this work, the excitation functions for the production of 154Dy in proton-irradiated Ta, Pb, and W targets were re-evaluated, which found to be in agreement with theoretical calculations.
- Published
- 2021
10. High precision half-life measurement of the extinct radio-lanthanide Dysprosium-154
- Author
-
Nadine Mariel, Chiera, Rugard, Dressler, Peter, Sprung, Zeynep, Talip, and Dorothea, Schumann
- Subjects
Dysprosium ,Proton Therapy ,Protons ,Lanthanoid Series Elements ,Half-Life - Abstract
Sixty years after the discovery of
- Published
- 2021
11. Reply to: No 182W evidence for early Moon formation
- Author
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Vinciane Debaille, Felipe Padilha Leitzke, Jonas Tusch, Peter Sprung, Carsten Münker, Raúl O.C. Fonseca, Mario Fischer-Gödde, Maxwell Thiemens, Analytical, Environmental & Geo-Chemistry, and Chemistry
- Subjects
Archean ,late veneer ,tungsten ,General Earth and Planetary Sciences ,Earth and Planetary Sciences(all) ,planetary formation ,isotope ,Moon ,Geology ,Astrobiology - Published
- 2021
12. Carbonates at the supergiant Olypmic Dam Cu-U-Au-Ag deposit, South Australia part 2: Sm-Nd, Lu-Hf and Sr-Pb isotope constraints on the chronology of carbonate deposition
- Author
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Peter Sprung, Olga B. Apukhtina, Vadim S. Kamenetsky, Kathy Ehrig, Roland Maas, and Carsten Münker
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Mineralization (geology) ,020209 energy ,Geochemistry ,Geology ,02 engineering and technology ,010502 geochemistry & geophysics ,Iron oxide copper gold ore deposits ,01 natural sciences ,chemistry.chemical_compound ,Uraninite ,chemistry ,Geochemistry and Petrology ,Breccia ,0202 electrical engineering, electronic engineering, information engineering ,Carbonate ,Economic Geology ,Radiometric dating ,Sedimentary rock ,Mafic ,0105 earth and related environmental sciences - Abstract
Mineralization at the supergiant Cu-U-Au-Ag Olympic Dam deposit (South Australia), the ‘uranium endmember’ of the iron-oxide copper–gold (IOCG) spectrum of ore deposits, is hosted in a breccia complex developed entirely within granite of the 1.59 Ga Hiltaba Suite (Gawler Craton). Earlier studies suggested brecciation and mineralization occurred within a magmatically-driven hydrothermal system at 1.59 Ga, with a critical role for mafic–ultramafic intrusions. In contrast, recent radiometric dating of the breccia complex indicates a prolonged, multi-stage history of brecciation and mineralization from 1.59 to 0.5–0.4 Ga. Ca-Fe-Mg-Mn-carbonate gangue minerals are associated with ore minerals at virtually every stage of mineralization. In a companion study (Apukhtina et al., 2020), this mineralogically, texturally and compositionally diverse carbonate mineral suite was assigned to seven associations defined on the basis of host lithology and texture. Here we report Sm-Nd, Pb-Pb and Lu-Hf isotope ages for these carbonates, which are used to examine the chronology of carbonate deposition. Initial Sr-Nd isotopic compositions are used to place constraints on fluid sources. Sm-Nd and Pb-Pb isotope systematics of calcite veins in ~1.59 Ga IOCG ore indicate 1.59–1.55 Ga deposition ages. Likewise, locally abundant laminated siderites have Sm-Nd ages in this age interval. A world-first attempt to apply Lu-Hf dating to carbonate gangue in an ore deposit yields ages that are 70–100 Ma younger than corresponding Sm-Nd ages, presumably reflecting isotopic exchange of carbonate Lu-Hf isotope systems with host rocks. Sm-Nd ages for carbonates assigned to other carbonate associations (hosted in highly altered inferred 1.59 Ga basalt and picrite; diverse settings within granite-dominated breccia; locally abundant megaclasts of green and red bedded sandstone/mudstone sequences; ~0.82 Ga doleritic dykes) are more diverse and range from ~1.59 to 0.5 Ga. The structurally youngest carbonates (unbrecciated fluorite-barite veins; carbonate matrix in polymict conglomerate above the breccia complex) yield ~0.50 Ga Sm-Nd ages. Inferred carbonate ages are broadly consistent with radiometric dates for other hydrothermal minerals (e.g., hematite, uraninite, apatite, fluorite). They suggest that mineralization initiated at 1.59 Ga was reworked and possibly increased in size in response to large-scale tectonic, magmatic, sedimentary and hydrothermal events. Initial 87Sr/86Sr in the carbonates is higher and more variable (0.710–0.752, average ~0.721) than could be explained by ore and gangue mineral formation from magmatic-hydrothermal fluids during a single event at 1.59 Ga, a model favored in several earlier studies. By contrast, carbonate formation over a long period, as inferred from the Sm-Nd chronology presented here, would allow ingrowth of 87Sr in the granitic host rocks to develop the heterogeneous initial 87Sr/86Sr recorded in the carbonates. Carbonate-bearing fluids appear to have sourced Nd (and most likely also Sr) locally, within the host granite and breccia, with contributions from mafic rocks. The emerging evidence for protracted, multi-stage mineralization implies that single-stage models for Olympic Dam need to be revisited and that all studies of sulfide and gangue minerals in this deposit require careful radiometric dating. We speculate that the polymetallic nature and unusually large metal reserves of the Olympic Dam mineralization are related to its multi-stage formation history.
- Published
- 2022
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