38 results on '"Martschini, Martin"'
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2. Collision-induced electron detachment and dissociation of carbon cluster dianions: (C7)2− and (C10)2−
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Martschini, Martin, Gnaser, Hubert, and Golser, Robin
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- 2023
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3. Isobar suppression studies for 99Tc detection using Ion-Laser InterAction Mass Spectrometry (ILIAMS)
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Hain, Karin, Adler, Stephanie, Gülce, Fadime, Martschini, Martin, Pitters, Johanna, and Golser, Robin
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- 2022
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4. Pulsed operation of a SNICS ion source – ionization efficiency and ion current output
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Martschini, Martin, Holzer, Petra, Hrnjic, Esad, Priller, Alfred, Steier, Peter, and Golser, Robin
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- 2022
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5. Highly sensitive 26Al measurements by Ion-Laser-InterAction Mass Spectrometry
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Lachner, Johannes, Martschini, Martin, Kalb, Andreas, Kern, Michael, Marchhart, Oscar, Plasser, Felix, Priller, Alfred, Steier, Peter, Wieser, Alexander, and Golser, Robin
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- 2021
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6. Comparison of methods for the detection of 10Be with AMS and a new approach based on a silicon nitride foil stack
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Steier, Peter, Martschini, Martin, Buchriegler, Josef, Feige, Jenny, Lachner, Johannes, Merchel, Silke, Michlmayr, Leonard, Priller, Alfred, Rugel, Georg, Schmidt, Edith, Wallner, Anton, Wild, Eva Maria, and Golser, Robin
- Published
- 2019
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7. 93Zr developments at the Heavy Ion Accelerator Facility at ANU
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Pavetich, Stefan, Carey, Alexander, Fifield, L.K., Froehlich, Michaela B., Halfon, Shlomi, Kinast, Angelina, Martschini, Martin, Nelson, Dominic, Paul, Michael, Shor, Asher, Sterba, Johannes H., Tessler, Moshe, Tims, Stephen G., Weissman, Leonid, and Wallner, Anton
- Published
- 2019
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8. New and upgraded ionization chambers for AMS at the Australian National University
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Martschini, Martin, Fifield, L. Keith, Froehlich, Michaela B., Leckenby, Guy, Pavetich, Stefan, Tims, Stephen G., Tranter, Ben, and Wallner, Anton
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- 2019
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9. Spontaneous and photo-induced decay processes of WF5− and HfF5− molecular anions in a cryogenic storage ring.
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Gnaser, Hubert, Martschini, Martin, Leimbach, David, Karls, Julia, Hanstorp, Dag, Indrajith, Suvasthika, Ji, Mingchao, Martini, Paul, Simonsson, Ansgar, Zettergren, Henning, Schmidt, Henning T., and Golser, Robin
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ACCELERATOR mass spectrometry , *STORAGE rings , *ANIONS , *THRESHOLD energy , *LASER ranging , *NUCLEOSYNTHESIS - Abstract
Spontaneous and photo-induced decay processes of HfF5− and WF5− molecular anions were investigated in the Double ElectroStatic Ion Ring ExpEriment (DESIREE). The observation of these reactions over long time scales (several tens of ms) was possible due to the cryogenic temperatures (13 K) and the extremely low residual gas pressure (∼10−14 mbar) of DESIREE. For photo-induced reactions, laser wavelengths in the range 240 to 450 nm were employed. Both anion species were found to undergo spontaneous decay via electron detachment or fragmentation. After some ms, radiative cooling processes were observed to lower the probability for further decay through these processes. Photo-induced reactions indicate the existence of an energy threshold for WF5− anions at about 3.5 eV, above which the neutralization yield increases strongly. By contrast, HfF5− ions exhibit essentially no enhanced production of neutrals upon photon interaction, even for the highest photon energy used in this experiment (∼5.2 eV). This suppression will be highly beneficial for the efficient detection, in accelerator mass spectrometry, of the extremely rare isotope 182Hf using the 182HfF5− anion while effectively reducing the interfering stable isobar 182W in the analyte ion 182WF5−. The radionuclide 182Hf is of great relevance in astrophysical environments as it constitutes a potential candidate to study the events of nucleosynthesis that may have taken place in the vicinity of the solar system several million years ago. [ABSTRACT FROM AUTHOR]
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- 2022
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10. Selective laser photodetachment of intense atomic and molecular negative ion beams with the ILIAS RFQ ion beam cooler
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Martschini, Martin, Pitters, Johanna, Moreau, Tobias, Andersson, Pontus, Forstner, Oliver, Hanstorp, Dag, Lachner, Johannes, Liu, Yuan, Priller, Alfred, Steier, Peter, and Golser, Robin
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- 2017
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11. Using the nuclear activation AMS method for determining chlorine in solids at ppb-levels and below
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Winkler, Stephan R., Eigl, Rosmarie, Forstner, Oliver, Martschini, Martin, Steier, Peter, Sterba, Johannes H., and Golser, Robin
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- 2015
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12. The ILIAS project for selective isobar suppression by laser photodetachment
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Forstner, Oliver, Andersson, Pontus, Hanstorp, Dag, Lahner, Johannes, Martschini, Martin, Pitters, Johanna, Priller, Alfred, Steier, Peter, and Golser, Robin
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- 2015
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13. Isobar separation of 93Zr and 93Nb at 24 MeV with a new multi-anode ionization chamber
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Martschini, Martin, Buchriegler, Josef, Collon, Philippe, Kutschera, Walter, Lachner, Johannes, Lu, Wenting, Priller, Alfred, Steier, Peter, and Golser, Robin
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- 2015
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14. Developments towards detection of 135Cs at VERA
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Lachner, Johannes, Kasberger, Magdalena, Martschini, Martin, Priller, Alfred, Steier, Peter, and Golser, Robin
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- 2015
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15. The quest for AMS of 182Hf – why poor gas gives pure beams
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Martschini Martin, Lachner Johannes, Merchel Silke, Priller Alfred, Steier Peter, Wallner Anton, Wieser Alexander, and Golser Robin
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Physics ,QC1-999 - Abstract
The long-lived radioisotope 182Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide insight into recent r-process nucleosynthesis in the vicinity of our solar system. Despite substantial efforts, it could not be measured at natural abundances with conventional AMS so far due to strong isobaric interference from stable 182W. Equally important is an increase in ion source efficiency for the anions of interest. The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio-frequency quadrupole (RFQ) ion cooler. The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also facilitate anion separation via chemical reactions with the buffer gas. We present first results with this approach on AMS-detection of 182Hf. With He +O2 mixtures as buffer gas in the RFQ, suppression of 182WF5− vs 180HfF 5− by >105 has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel. The overall Hf-detection efficiency at VERA presently is 1.4% and the W-corrected blank value is 182Hf/180Hf = (3.4 ± 2.1)×10−14. In addition, a survey of different sample materials for highest negative ion yields of HfF 5− with Cs-sputtering has been conducted.
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- 2020
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16. Interlaboratory study of the ion source memory effect in 36Cl accelerator mass spectrometry
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Pavetich, Stefan, Akhmadaliev, Shavkat, Arnold, Maurice, Aumaître, Georges, Bourlès, Didier, Buchriegler, Josef, Golser, Robin, Keddadouche, Karim, Martschini, Martin, Merchel, Silke, Rugel, Georg, and Steier, Peter
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- 2014
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17. AMS of 36Cl with the VERA 3 MV tandem accelerator
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Martschini, Martin, Andersson, Pontus, Forstner, Oliver, Golser, Robin, Hanstorp, Dag, Lindahl, Anton O., Kutschera, Walter, Pavetich, Stefan, Priller, Alfred, Rohlén, Johan, Steier, Peter, Suter, Martin, and Wallner, Anton
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- 2013
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18. Light induced suppression of sulfur in a cesium sputter ion source
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Martschini, Martin, Rohlén, Johan, Andersson, Pontus, Golser, Robin, Hanstorp, Dag, Lindahl, Anton O., Priller, Alfred, Steier, Peter, and Forstner, Oliver
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- 2012
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19. Recent advances in AMS of 36Cl with a 3-MV-tandem
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Martschini, Martin, Forstner, Oliver, Golser, Robin, Kutschera, Walter, Pavetich, Stefan, Priller, Alfred, Steier, Peter, Suter, Martin, and Wallner, Anton
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- 2011
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20. Novel 90Sr analysis of environmental samples by Ion-Laser InterAction Mass Spectrometry.
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Honda, Maki, Martschini, Martin, Marchhart, Oscar, Priller, Alfred, Steier, Peter, Golser, Robin, Sato, Tetsuya K., Kazuaki, Tsukada, and Sakaguch, Aya
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- 2022
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21. 5 YEARS OF ION-LASER INTERACTION MASS SPECTROMETRY—STATUS AND PROSPECTS OF ISOBAR SUPPRESSION IN AMS BY LASERS.
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Martschini, Martin, Lachner, Johannes, Hain, Karin, Kern, Michael, Marchhart, Oscar, Pitters, Johanna, Priller, Alfred, Steier, Peter, Wiederin, Andreas, Wieser, Alexander, and Golser, Robin
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MASS spectrometry ,ACCELERATOR mass spectrometry ,ION energy ,MOLECULAR gas lasers ,ION beams - Abstract
A setup for ion-laser interaction was coupled to the state-of-the-art AMS facility VERA five years ago and its potential and applicability as a new means of isobar suppression in accelerator mass spectrometry (AMS) has since been explored. Laser photodetachment and molecular dissociation processes of anions provide unprecedented isobar suppression factors of >10
10 for several established AMS isotopes like36 Cl or26 Al and give access to new AMS isotopes like90 Sr,135 Cs or182 Hf at a 3-MV-tandem facility. Furthermore, Ion-Laser InterAction Mass Spectrometry has been proven to meet AMS requirements regarding reliability and robustness with a typical reproducibility of results of 3%. The benefits of the technique are in principle available to any AMS machine, irrespective of attainable ion beam energy. Since isobar suppression via this technique is so efficient, there often is no need for any additional element separation in the detection setup and selected nuclides may even become accessible without accelerator at all. [ABSTRACT FROM AUTHOR]- Published
- 2022
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22. Accelerator mass spectrometry measurement of the reaction 35Cl(n,γ)36Cl at keV energies
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Pavetich, Stefan, Wallner, Anton, Martschini, Martin, Akhmadaliev, Shavkat, Dillmann, Iris, Fifield, L. Keith, Halfon, Shlomi, Heftrich, Tanja, Käppeler, Franz, Lederer, Claudia, Merchel, Silke, Paul, Michael, Reifarth, Rene, Rugel, Georg, Steier, Peter, Tessler, Moshe, Tims, Stephen, Weigand, Mario, and Weissman, Leo
- Abstract
The nuclide 35Cl can act as a minor “neutron poison” in the stellar slow neutron capture process. Neutron activation combined with accelerator mass spectrometry (AMS) was applied to measure the (n,γ) cross section of 35Cl for neutron spectra simulating Maxwell-Boltzmann distributions of kT,∼,30,keV and 40,keV, respectively. The neutron activations were performed at the Karlsruhe Van de Graaff accelerator and at the superconducting linear accelerator of the Soreq Applied Research Accelerator Facility utilizing the 7Li(p,n)7Be reaction. AMS measurements of the irradiated samples were performed at the 3,MV Vienna Environmental Research Accelerator, the 6,MV tandem accelerator at the Dresden AMS facility, and the 14,UD tandem accelerator of the Australian National University in Canberra. Our method is independent of previous measurements. For an energy of kT,=,30,keV, we report a Maxwellian averaged cross sections of 8.33(32),mb. Using this new value in stellar isotopic abundance calculations, minor changes for the abundances of 35Cl, 36Cl and 36S are derived.
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- 2019
23. The quest for AMS of 182Hf – why poor gas gives pure beams.
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Mitchell, A.J., Pavetich, S., Koll, D., Martschini, Martin, Lachner, Johannes, Merchel, Silke, Priller, Alfred, Steier, Peter, Wallner, Anton, Wieser, Alexander, and Golser, Robin
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RADIOISOTOPES ,ASTROPHYSICAL radiation ,ATOMIC beams ,NUCLEOSYNTHESIS ,ATMOSPHERIC pressure ,SPUTTERING (Physics) - Abstract
The long-lived radioisotope
182 Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide insight into recent r-process nucleosynthesis in the vicinity of our solar system. Despite substantial efforts, it could not be measured at natural abundances with conventional AMS so far due to strong isobaric interference from stable 182W. Equally important is an increase in ion source efficiency for the anions of interest. The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio-frequency quadrupole (RFQ) ion cooler. The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also facilitate anion separation via chemical reactions with the buffer gas. We present first results with this approach on AMS-detection of182 Hf. With He +O2 mixtures as buffer gas in the RFQ, suppression of182 WF5 vs− 180 HfF5 by >10− 5 has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel. The overall Hf-detection efficiency at VERA presently is 1.4% and the W-corrected blank value is182 Hf/180 Hf = (3.4 ± 2.1)×10−14 . In addition, a survey of different sample materials for highest negative ion yields of HfF5 with Cs-sputtering has been conducted. [ABSTRACT FROM AUTHOR]− - Published
- 2020
- Full Text
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24. The ILIAMS project – An RFQ ion beam cooler for selective laser photodetachment at VERA.
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Martschini, Martin, Hanstorp, Dag, Lachner, Johannes, Marek, Christoph, Priller, Alfred, Steier, Peter, Wasserburger, Paul, and Golser, Robin
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ION bombardment , *ACCELERATOR mass spectrometry , *PHOTODETACHMENT , *CHEMICAL reactions , *LASERS , *RADIO frequency - Abstract
Selective laser photodetachment of anions is a novel technique for isobar suppression in Accelerator Mass Spectrometry (AMS). Ion-laser interaction times on the order of ms required for near-complete isobar suppression are achieved by retarding the ions in a gas-filled radio frequency quadrupole cooler. Inside this RFQ, the cooled anion beam is overlapped collinearly with an intense cw-laser beam. Within the Ion Laser InterAction Mass Spectrometry (ILIAMS) project at the University of Vienna, a dedicated injector beamline has been coupled to the VERA-AMS facility to explore and develop this method. In this work, experimental investigations on ion beam transmission, stability and elemental selectivity of the new setup are presented. A 532 nm laser at 10 W transmitted power provides suppression factors larger than ten orders of magnitude for S− and MgO− under AMS conditions with simultaneous beam transmission for the ions of interest of up to 80%. The excellent ion identification capabilities of the subsequent AMS system also facilitate the study of destruction and formation of molecular anions inside the ion cooler. These kinetic and chemical reactions with the buffer gas provide additional elemental selectivity in certain cases, whereas others constitute a source of background. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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25. Development of methods for isobar suppression in AMS and measurements of 36Cl with the VERA 3-MV-tandem accelerator
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Martschini, Martin
- Abstract
Der Nachweis von 36Cl in natürlichen Häufigkeiten mittels Beschleunigermassenspektrometrie (AMS) erfordert hohe Teilchenenergien für die Unterdrückung des stabilen Isobars 36S und konnte bisher nur an Beschleunigeranlagen mit mindestens 5MV Terminalspannung durchgeführt werden. Im Rahmen dieser Arbeit konnten wir zeigen, dass 36Cl und 36S bereits bei Energien von 24MeV, welche auch an mittelgroßen Beschleunigern mit 3MV Terminalspannung wie VERA (Vienna Environmental Research Accelerator) zur Verfügung stehen, getrennt werden können. Diese Entwicklung wurde erst durch technische Fortschritte bei Ionisationskammern und einem genauen Verständnis der relevanten Ionen-Atom-Stoßprozesse möglich. Der Vergleich experimenteller Daten über den Energieverlust in Ionisationskammern mit Simulation und publizierten Werten lieferte wichtige Erkenntnisse über die Physik der Isobarentrennung, insbesondere bei Energien unterhalb des Bragg-Maximums. Der Effekt der Energiefokussierung bei großen Energieverlusten führt zu einer starken Abnahme der Energie-Unschärfe und somit zu einem Anstieg der Isobarentrennung bis zu beinahe vollem Energieverlust. Die experimentelle Bestimmung der relevanten Eigenschaften von mehreren Detektorgasen brachte eine deutliche Verbesserung des Trennvermögens. Mit C4H10+Ar als Zählgas und einem optimierten Detektoraufbau bestehend aus einer Ionisationskammer mit geteilter Anode und einem Silizium-Streifendetektor wurden schließlich 36S Unterdrückungsfaktoren >2×10E4 gemessen. Detaillierte Untersuchungen des Einflusses von Probengröße, Kathoden-Design, Träger-Material sowie der Ionenquellen-Betriebsparameter führten zu einer signifikanten Reduktion des Schwefelanteils im Ionenstrahl. Aufgrund zahlreicher Verbesserungen im Messablauf und der folgenden Datenauswertung ist die Reproduzierbarkeit für Proben mit einem 36Cl/Cl Verhältnis >10E−12 besser als 2 %. Die Injektor-Detektor Effizienz ist mit 8% ebenfalls konkurrenzfähig zu größeren Anlagen. Dank einer systematischen Bestimmung des zeitlichen Übersprechens der Ionenquelle und der Cross-Kontamination ist der Messuntergrund 36Cl/Cl, Accelerator mass spectrometry (AMS) of 36Cl (t1/2 = 0.30Ma) at natural isotopic concentrations requires high particle energies for the separation from the stable isobar 36S and up to now was considered the exclusive domain of tandem-accelerators with at least 5MV terminal voltage. With this work we demonstrated that the separation of 36Cl and 36S is feasible at particle energies of 24MeV, which are also accessible for medium-sized facilities with 3MV terminal voltage like VERA (Vienna Environmental Research Accelerator). Progress in the technology of ionization chambers and detailed understanding of the relevant ion-atom collision processes made this achievement possible. Within the framework of this thesis, the limitations of isobar suppression in an ionization chamber were closely studied. Comparison of experimental energy loss data with simulations and published data revealed how physics favors isobar separation even at energies below the maximum of the Bragg curve. The strong energy focusing effect at high energy losses significantly reduces energy straggling, hence isobar separation steadily increases up to almost full energy loss. To further optimize the 36S suppression, energy loss, energy straggling and angular scattering in various counter gases were investigated theoretically and experimentally. With C4H10+Ar in an optimized detection setup consisting of a split-anode ionization chamber and a silicon strip detector, 36S suppression factors >2×10E4 have been achieved. The sulfur content of the ion beam was significantly reduced by assessing the influence of sample size, cathode design, backing material and ion source operating conditions. Due to advances in measurement procedure and data evaluation, the reproducibility for high ratio samples (36Cl/Cl >10E−12) is better than 2 %. The injector to detector efficiency of 8% for 36Cl also compares favorable to other facilities. Following an in-depth investigation of the cross contamination and the memory effect of our ion source, the blank value is 36Cl/Cl
- Published
- 2012
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26. Tectonic implications of fluvial incision and pediment deformation at the northern margin of the Central Anatolian Plateau based on multiple cosmogenic nuclides.
- Author
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Yildirim, Cengiz, Schildgen, Taylor F., Echtler, Helmut, Melnick, Daniel, Bookhagen, Bodo, Çiner, Attila, Niedermann, Samuel, Merchel, Silke, Martschini, Martin, Steier, Peter, and Strecker, Manfred R.
- Abstract
We document Quaternary fluvial incision driven by fault-controlled surface deformation in the inverted intermontane Gök𝚤rmak Basin in the Central Pontide mountains along the northern margin of the Central Anatolian Plateau. In-situ-produced
10 Be,21 Ne, and36 Cl concentrations from gravel-covered fluvial terraces and pediment surfaces along the trunk stream of the basin (the Gök𝚤rmak River) yield model exposure ages ranging from 7 ± 1 ka to 346 ± 45 ka and average fluvial incision rates over the past ~350 ka of 0.28 ± 0.01 mm a-1 . Similarities between river incision rates and coastal uplift rates at the Black Sea coast suggest that regional uplift is responsible for the river incision. Model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 60 ± 5 ka to 110 ± 10 ka, demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region. Together, our data demonstrate cumulative incision that is linked to active internal shortening and uplift of ~0.3 mm a-1 in the Central Pontide orogenic wedge, which may ultimately contribute to the lateral growth of the northern Anatolian Plateau. [ABSTRACT FROM AUTHOR]- Published
- 2013
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27. AMS of 36Cl with the VERA 3MV tandem accelerator
- Author
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Martschini, Martin, Andersson, Pontus, Forstner, Oliver, Golser, Robin, Hanstorp, Dag, Lindahl, Anton O., Kutschera, Walter, Pavetich, Stefan, Priller, Alfred, Rohlén, Johan, Steier, Peter, Suter, Martin, and Wallner, Anton
- Subjects
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CHLORINE isotopes , *ACCELERATOR mass spectrometry , *IONIZATION chambers , *NUCLEAR isobars , *SEPARATION (Technology) , *ENERGY dissipation - Abstract
Abstract: Recent progress with compact ionization chambers has opened new possibilities for isobar suppression in accelerator mass spectrometry (AMS). Separation of 36Cl (t 1/2 =0.30Ma) at natural isotopic levels from its stable isobar 36S became feasible at particle energies of 24MeV, which are also accessible for medium-sized tandem accelerators with 3MV terminal voltage like VERA (Vienna Environmental Research Accelerator). Investigations with an ionization chamber revealed how physics favors isobar separation even at energies below the maximum of the Bragg curve. The strong energy focusing effect at high energy losses reduces energy straggling significantly and isobar separation steadily increases up to almost full energy loss. With an optimized detection setup, sulfur suppression factors of 2×104 have been achieved. Refraining from the additional use of degrader foils has the benefit of high transmission to the detector (∼16%), but requires a low sulfur output from the ion source. Therefore several backing materials have been screened for sulfur content. The dependence of the sulfur output on the AgCl sample size has been investigated as well. Precision and accuracy have been thoroughly assessed over the last two years. Since drifts in the spectra are efficiently corrected by monitoring the position of the 36S peak, the reproducibility for high ratio samples (36Cl/Cl>10−12) is better than 2%. Our blank value of 36Cl/Cl≈(5±5)×10−16 is competitive to other labs. 36Cl has become a routine AMS-isotope at VERA. Recently we also explored novel techniques for additional sulfur suppression already in the ion source. While results with a small gas reaction cell in front of the sputter target were discouraging, a decrease in the sulfur/chlorine ratio by one order of magnitude was achieved by directing 300mW continuous wave laser beam at 445nm towards the cathode in the ion source. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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28. Recent advances in AMS of 36Cl with a 3-MV-tandem
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Martschini, Martin, Forstner, Oliver, Golser, Robin, Kutschera, Walter, Pavetich, Stefan, Priller, Alfred, Steier, Peter, Suter, Martin, and Wallner, Anton
- Subjects
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ACCELERATOR mass spectrometry , *ATMOSPHERIC pressure , *IONIZATION (Atomic physics) , *ELECTRIC potential , *ISOTOPES , *ENERGY dissipation , *CATHODES - Abstract
Abstract: Accelerator mass spectrometry (AMS) of 36Cl (t 1/2 =0.30Ma) at natural isotopic concentrations requires high particle energies for the separation from the stable isobar 36S and was so far the exclusive domain of tandem accelerators with at least 5MV terminal voltage. Using terminal foil stripping and a detection setup consisting of a split-anode ionization chamber and an additional energy signal from a silicon strip detector, a 36S suppression of >104 at 3MV terminal voltage was achieved. To further increase the 36S suppression energy loss straggling in various counter gases (C4H10, Ar–CH4 and C4H10–Ar) and the effect of “energy focusing” below the maximum of the Bragg curve was investigated. The comparison of experimental data with simulations and published data yielded interesting insights into the physics underlying the detectors. Energy loss, energy straggling and angular scattering determine the 36S suppression. In addition, we improved ion source conditions, target backing materials and the cathode design with respect to sulfur output and cross contamination. These changes allow higher currents during measurement (35Cl− current≈5μA) and also increased the reproducibility. An injector to detector efficiency for 36Cl ions of 8% (16% stripping yield for the 7+ charge state in the accelerator, 50% 36Cl detection efficiency) was achieved, which can favorably be compared to other facilities. The memory effect in our ion source was also thoroughly investigated. Currently our measured blank value is 36Cl/Cl≈3×10−15 when samples with a ratio of 10−11 are used in the same sample wheel and 36Cl/Cl≈5×10−16 if measured together with samples with a ratio of 10−12 or below. This is in good agreement with the lowest so far published isotope ratios around 5×10−16 and demonstrates that 3MV tandems can achieve the same sensitivity for 36Cl as larger machines. [Copyright &y& Elsevier]
- Published
- 2011
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29. Cosmic pears from the Havelland (Germany): Ribbeck, the twelfth recorded aubrite fall in history.
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Bischoff, Addi, Patzek, Markus, Barrat, Jean‐Alix, Berndt, Jasper, Busemann, Henner, Degering, Detlev, Di Rocco, Tommaso, Ek, Mattias, Harries, Dennis, Godinho, Jose R. A., Heinlein, Dieter, Kriele, Armin, Krietsch, Daniela, Maden, Colin, Marchhart, Oscar, Marshal, Rachael M., Martschini, Martin, Merchel, Silke, Möller, Andreas, and Pack, Andreas
- Subjects
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SMALL solar system bodies , *PEARS , *METAL sulfides , *ATMOSPHERE , *COSMIC rays , *ASTEROIDS - Abstract
In 1889 the German poet and novelist Theodor Fontane wrote the popular literary ballad “Herr von Ribbeck auf Ribbeck im Havelland.” The Squire von Ribbeck is described as a gentle and generous person, who often gives away pears from his pear trees to children passing by and continued donating pears after his death. Now, 135 years later the rock called Ribbeck is giving us insight into processes that happened 4.5 billion years ago. The meteorite Ribbeck (official find location: 52°37′15″N, 12°45′40″E) fell January 21, 2024, and has been classified as a brecciated aubrite. This meteoroid actually entered the Earth's atmosphere at 00:32:38 UTC over Brandenburg, west of Berlin, and the corresponding fireball was recorded by professional all sky and video cameras. More than 200 pieces (two proved by radionuclide analysis to belong to this fresh fall) were recovered totaling about 1.8 kg. Long‐lived radionuclide and noble gas data are consistent with long cosmic ray exposure (55–62 Ma) and a preatmospheric radius of Ribbeck between 20 and 30 cm. The heavily brecciated aubrite consists of major (76 ± 3 vol%) coarse‐grained FeO‐free enstatite (En99.1Fs<0.04Wo0.9), with a significant abundance (15.0 ± 2.5 vol%) of albitic plagioclase (Ab95.3 An2.0Or2.7), minor forsterite (5.5 ± 1.5 vol%; Fo99.9) and 3.5 ± 1.0 vol% of opaque phases (mainly sulfides and metals) with traces of nearly FeO‐free diopside (En53.2Wo46.8) and K‐feldspar (Ab4.6Or95.4). The rock has a shock degree of S3 (U‐S3), and terrestrial weathering has affected metals and sulfides, resulting in the brownish appearance of rock pieces and the partial destruction of certain sulfides already within days after the fall. The bulk chemical data confirm the feldspar‐bearing aubritic composition. Ribbeck is closely related to the aubrite Bishopville. Ribbeck does not contain solar wind implanted gases and is a fragmental breccia. Concerning the Ti‐ and O‐isotope compositions, the data are similar to those of other aubrites. They are also similar to E chondrites and fall close to the data point for the bulk silicate Earth (BSE). Before the Ribbeck meteoroid entered Earth's atmosphere, it was observed in space as asteroid 2024 BX1. The aphelion distance of 2024 BX1's orbit lies in the innermost region of the asteroid belt, which is populated by the Hungaria family of minor planets characterized by their E/X‐type taxonomy and considered as the likely source of aubrites. The spectral comparison of an average large‐scale emission spectrum of Mercury converted into reflectance and of the Ribbeck meteorite spectrum does not show any meaningful similarities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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30. The anomalous polymict ordinary chondrite breccia of Elmshorn (H3‐6)—Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago.
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Bischoff, Addi, Patzek, Markus, Alosius, Romain M. L., Barrat, Jean‐Alix, Berndt, Jasper, Busemann, Henner, Degering, Detlev, Di Rocco, Tommaso, Ek, Mattias, Gattacceca, Jérôme, Godinho, Jose R. A., Heinlein, Dieter, Krietsch, Daniela, Maden, Colin, Marchhart, Oscar, Martschini, Martin, Merchel, Silke, Pack, Andreas, Peters, Stefan, and Rüfenacht, Miriam
- Abstract
Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3‐6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa21–22). The physical properties like density (3.34 g cm−3) and magnetic susceptibility (logχ <5.0, with χ in 10−9 m3 kg−1) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near‐surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock‐darkened fragments, and (e) clasts of various types of impact melts but no solar wind‐implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25–40 cm, is ~17–20 Myr. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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31. Accelerator mass spectrometry measurement of the reaction Cl 35 ( n , γ ) Cl 36 at keV energies
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Pavetich, Stefan, Wallner, Anton, Martschini, Martin, Akhmadaliev, Shavkat, Dillmann, Iris, Fifield, Keith, Halfon, Shlomi, Heftrich, Tanja, Käppeler, Franz, Lederer-Woods, Claudia, Merchel, Silke, Paul, Michael, Reifarth, René, Rugel, Georg, Steier, Peter, Tessler, Moshe, Tims, Stephen, Weigand, Mario, and Weissman, Leo
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32. 36Cl in a new light: AMS measurements assisted by ion-laser interaction.
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Lachner, Johannes, Marek, Christoph, Martschini, Martin, Priller, Alfred, Steier, Peter, and Golser, Robin
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- *
PHOTOMETRY , *ACCELERATOR mass spectrometry , *ION beams , *ANIONS , *ATMOSPHERIC pressure , *INTERFERENCE suppression - Abstract
The experimental setup at the Vienna Environmental Research Accelerator (VERA) was extended with an ion beam cooler and a 18 W laser to perform Ion-Laser InterAction Mass Spectrometry (ILIAMS). Gas collisions of the decelerated negative ion beam with He buffer gas inside a radio-frequency quadrupole slow down the ions, which facilitates element selective photodetachment to remove isobaric interferences. Here we present the first successful implementation of a suppression of the isobar of 36Cl via laser-photodetachment into an AMS measurement. Whereas conventional AMS measurements require separation of the isobar 36S at high beam energy, ILIAMS takes advantage of the higher electron affinities of Cl− (3.6 eV) compared to S− (2.1 eV). Using 532 nm photons (E ph = 2.3 eV) the isobar 36S is suppressed by 10 orders of magnitude. A high transmission of the Cl− beam through the ion cooler (up to 80%) and a quantitative suppression of the isobaric interference allows for competitive measurements at low accelerator voltages and with lower charge states. This results in high yields for 36Cl transport to the detector. The ILIAMS system is stable over several days of beamtime and blank levels below 36Cl/Cl = 10−15 are reached. The accomplishment of a 36Cl AMS measurement at a final beam energy as low as 5.4 MeV with full separation of isobars and m/q interferences shows the potential of the new isobar suppression method to widen the capabilities of smaller and middle-sized AMS facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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33. Accelerator mass spectrometry measurement of the reaction 35Cl(n,γ)36Cl at keV energies.
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Pavetich, Stefan, Wallner, Anton, Martschini, Martin, Akhmadaliev, Shavkat, Dillmann, Iris, Fifield, Keith, Halfon, Shlomi, Heftrich, Tanja, Käppeler, Franz, Lederer-Woods, Claudia, Merchel, Silke, Paul, Michael, Reifarth, René, Rugel, Georg, Steier, Peter, Tessler, Moshe, Tims, Stephen, Weigand, Mario, and Weissman, Leo
- Subjects
- *
ACCELERATOR mass spectrometry , *NEUTRON absorbers , *NEUTRON capture - Abstract
The nuclide 35Cl can act as a minor "neutron poison" in the stellar slow neutron capture process. Neutron activation combined with accelerator mass spectrometry (AMS) was applied to measure the (n,γ) cross section of 35Cl for neutron spectra simulating Maxwell-Boltzmann distributions of kT≈30 and 40 keV. The neutron activations were performed at the Karlsruhe Van de Graaff accelerator and at the superconducting linear accelerator of the Soreq Applied Research Accelerator Facility utilizing the 7Li(p,n)7Be reaction. AMS measurements of the irradiated samples were performed at the 3 MV Vienna Environmental Research Accelerator, the 6 MV tandem accelerator at the Dresden AMS facility, and the 14 UD tandem accelerator of the Australian National University in Canberra. Our method is independent of previous measurements. For an energy of kT=30keV, we report a Maxwellian averaged cross section of 8.33(32) mb. Using this new value in stellar isotopic abundance calculations, minor changes for the abundances of 35Cl, 36Cl, and 36S are derived. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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34. Interlaboratory study of the ion source memory effect in 36Cl accelerator mass spectrometry.
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Pavetich, Stefan, Akhmadaliev, Shavkat, Arnold, Maurice, Aumaître, Georges, Bourlès, Didier, Buchriegler, Josef, Golser, Robin, Keddadouche, Karim, Martschini, Martin, Merchel, Silke, Rugel, Georg, and Steier, Peter
- Subjects
- *
ION sources , *CHLORINE isotopes , *ACCELERATOR mass spectrometry , *ANIONS , *MATHEMATICAL variables , *DATA analysis - Abstract
Highlights: [•] Long-term memory effect in negative ion sources investigated for chlorine isotopes. [•] Interlaboratory comparison of four up-to date negative ion sources. [•] Ion source improvement at DREAMS for minimization of long-term memory effect. [•] Long-term memory effect is the limitation for precise AMS data of volatile elements. [•] Findings to be considered for samples with highly variable ratios of 36Cl/Cl &129I/I. [Copyright &y& Elsevier]
- Published
- 2014
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35. Comparison of detector systems for the separation of 36Cl and 36S with a 3-MV tandem
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Orlowski, Tobias, Forstner, Oliver, Golser, Robin, Kutschera, Walter, Merchel, Silke, Martschini, Martin, Priller, Alfred, Steier, Peter, Vockenhuber, Christof, and Wallner, Anton
- Subjects
- *
COMPARATIVE studies , *NUCLEAR counters , *ISOTOPE separation , *PARTICLE accelerators , *RADIOACTIVE dating , *IONIZATION chambers , *TIME-of-flight mass spectrometry , *SCATTERING (Physics) - Abstract
Abstract: The possibility of detecting 36Cl for geological exposure dating has been explored for several years at VERA (the Vienna Environmental Research Accelerator). First results on real samples were obtained with an ionization chamber (developed at the ETH/PSI, Zürich, Switzerland) with two anodes. To improve the suppression of 36S, we equipped the ionization chamber with an exit window and added a Time-of-Flight (TOF) system with a double-sided silicon strip detector (50×50mm2) as stop detector. We optimized the TOF setup by using silicon nitride foils to reduce scattering tails in the energy spectra. At 3MV terminal voltage, corresponding to a particle energy of 24MeV of 36Cl7+, we achieved a 36S7+-suppression of 21,500 (50% 36Cl-detector-efficiency). [Copyright &y& Elsevier]
- Published
- 2010
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36. 36Cl exposure dating with a 3-MV tandem
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Steier, Peter, Forstner, Oliver, Golser, Robin, Kutschera, Walter, Martschini, Martin, Merchel, Silke, Orlowski, Tobias, Priller, Alfred, Vockenhuber, Christof, and Wallner, Anton
- Subjects
- *
ACCELERATOR mass spectrometry , *RADIOISOTOPES , *RADIOACTIVE dating , *PARTICLE accelerators , *ISOTOPE separation , *IONIZATION chambers , *ION sources - Abstract
Abstract: 36Cl AMS measurements at natural isotopic concentrations have yet been performed only at tandem accelerators with 5MV terminal voltage or beyond. We have developed a method to detect 36Cl at natural terrestrial isotopic concentrations with a 3-MV system, operated above specifications at 3.5MV. An effective separation was obtained with an optimized split-anode ionization chamber design (adopted from the ETH/PSI Zurich AMS group), providing a suppression factor of up to 30,000 for the interfering isobar 36S. Despite the good separation, a relatively high sulfur output from the ion source (36S−/35Cl− ≈4×10−10 for samples prepared from chemically pure reagents), and a possibly cross contamination resulted in a background corresponding to 36Cl/Cl≈3×10−14. The method was applied to samples containing between 105 and 106 atoms 36Cl/g rock from sites in Italy and Iran, which were already investigated by other laboratories for surface exposure dating. The 36Cl/Cl ratios in the range from 2×10−13 to 5×10−12 show a generally good agreement with the previous results. These first measurements demonstrate that also 3-MV tandems, constituting the majority of dedicated AMS facilities, are capable of 36Cl exposure dating, which is presently the domain of larger facilities. [Copyright &y& Elsevier]
- Published
- 2010
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37. Correction: Novel 90 Sr analysis of environmental samples by Ion-Laser InterAction Mass Spectrometry.
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Honda M, Martschini M, Marchhart O, Priller A, Steier P, Golser R, Sato TK, Kazuaki T, and Sakaguchi A
- Abstract
Correction for 'Novel
90 Sr analysis of environmental samples by Ion-Laser InterAction Mass Spectrometry' by Maki Honda et al. , Anal. Methods , 2022, 14 , 2732-2738, https://doi.org/10.1039/D2AY00604A.- Published
- 2022
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38. Novel 90 Sr analysis of environmental samples by Ion-Laser InterAction Mass Spectrometry.
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Honda M, Martschini M, Marchhart O, Priller A, Steier P, Golser R, Sato TK, Kazuaki T, and Sakaguch A
- Subjects
- Animals, Lasers, Mass Spectrometry methods, Soil, Strontium Radioisotopes analysis
- Abstract
The sensitive analysis of
90 Sr with accelerator mass spectrometry (AMS) was developed to advance environmental radiology. One advantage of AMS is the ability to analyze environmental samples with90 Sr/88 Sr atomic ratios of 10-14 in following a simple chemical separation. Three different IAEA samples with known90 Sr concentrations (moss-soil, animal bone, Syrian soil: 1 g each) were analyzed to assess the validity of the chemical separation and the AMS measurement. The90 Sr measurements were conducted on the AMS system VERA combined with the Ion Laser InterAction Mass Spectrometry (ILIAMS) setup at the University of Vienna, which has excellent isobaric separation performance. The isobaric interference of90 Zr in the90 Sr AMS was first largely removed by chemical separation. The separation factor of Zr in two-step column chromatography with Sr resin and anion exchange resin was 106 . The90 Zr remaining in the sample was effectively suppressed by ILIAMS. This procedure achieved a limit of detection <0.1 mBq in the90 Sr AMS, which is lower than typical β-ray detection. The agreement between AMS measurements and nominal values for the90 Sr concentrations of IAEA samples indicated that the new highly-sensitive90 Sr analysis in the environmental samples with AMS is reliable.- Published
- 2022
- Full Text
- View/download PDF
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