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  • 1. Abbuehl, Luca M.
    et al.
    Norton, Kevin P.
    Schlunegger, Fritz
    Kracht, Oliver
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    El Niño forcing on 10Be-based surface denudation rates in the northwestern Peruvian Andes?2010In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 123, no 3-4, p. 257-268Article in journal (Refereed)
    Abstract [en]

    High magnitude precipitation events provide large contributions to landscape formation and surface denudation in arid environments. Here, we quantify the precipitation-dependent geomorphic processes within the Rio Piura drainage basin located on the Western Escarpment of the northern Peruvian Andes at 5 degrees S latitude. In this region, monsoonal easterly winds bring precipitation to the >3000 m asl high headwaters, from where the annual amount of precipitation decreases downstream toward the Pacific coast. Denudation rates are highest in the knickzones near the headwaters, similar to 200-300 mm ky(-1), and sediment discharge is limited by the transport capacity of the channel network. Every few years, this situation is perturbed by westerly, wind-driven heavy precipitation during El Nino events and results in supply-limited sediment discharge as indicated by bedrock channels. The detailed analysis of the stream-long profiles of two river basins within the Rio Piura catchment reveals a distinct knickzone in the transition zone between the easterly and westerly climatic influences, suggesting an En Nino forcing on the longitudinal channel profiles over at least Holocene timescales. Measured trunk stream catchment-wide denudation rates are up to ca. 300 mm ky(-1) and decrease successively downstream along the river profiles. Denudation rates of tributary rivers are ca. 200 mm ky(-1) near the plateau and show a stronger downstream decreasing trend than trunk stream rates. This suggests that the landscape is in a transient stage of local relief growth, which is driven by fluvial incision. This corroborates the results of paleoclimate studies that point towards higher El Nino frequencies during the past ca. 3000 years, leading to higher runoff and more erosion in the trunk channel compared to the hillslopes and thus growth of local relief. Downstream increases in channel gradient spatially coincide with the reaches of highest precipitation rates during El Nino events, we therefore interpret that Holocene landscape evolution has largely been controlled by climate. The ky-timescale of the Be-10 data together with the transience of the landscape implies that El Nino events in northwestern Peru have occurred since at least the Holocene, and that adjustment to channel incision is still taking place.

  • 2. Abbühl, Luca M.
    et al.
    Norton, Kevin P.
    Jansen, John D.
    Schlunegger, Fritz
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Erosion rates and mechanisms of knickzone retreat inferred from (10)Be measured across strong climate gradients on the northern and central Andes Western Escarpment2011In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 36, no 11, p. 1464-1473Article in journal (Refereed)
    Abstract [en]

    A steep escarpment edge, deep gorges and distinct knickzones in river profiles characterize the landscape on the Western Escarpment of the Andes between similar to 5 degrees S and similar to 18 degrees S (northern Peru to northern Chile). Strong north-south and east-west precipitation gradients are exploited in order to determine how climate affects denudation rates in three river basins spanning an otherwise relatively uniform geologic and geomorphologic setting. Late Miocene tectonics uplifted the Meseta/Altiplano plateau (similar to 3000 m a.s.l.), which is underlain by a series of Tertiary volcanic-volcanoclastic rocks. Streams on this plateau remain graded to the Late Miocene base level. Below the rim of the Meseta, streams have responded to this ramp uplift by incising deeply into fractured Mesozoic rocks via a series of steep, headward retreating knickzones that grade to the present-day base level defined by the Pacific Ocean. It is found that the Tertiary units on the plateau function as cap-rocks, which aid in the parallel retreat of the sharp escarpment edge and upper knickzone tips. (10)Be-derived catchment denudation rates of the Rio Piura (5 degrees S), Rio Pisco (13 degrees S) and Rio Lluta (18 degrees S) average similar to 10 mm ky(-1) on the Meseta/Altiplano, irrespective of precipitation rates; whereas, downstream of the escarpment edge, denudation rates range from 10 mm ky(-1) to 250 mm ky(-1) and correlate positively with precipitation rates, but show no strong correlation with hillslope angles or channel steepness. These relationships are explained by the presence of a cap-rock and climate-driven fluvial incision that steepens hillslopes to near-threshold conditions. Since escarpment retreat and the precipitation pattern were established at least in the Miocene, it is speculated that the present-day distribution of morphology and denudation rates has probably remained largely unchanged during the past several millions of years as the knickzones have propagated headward into the plateau.

  • 3. Adolphi, Florian
    et al.
    Muscheler, Raimund
    Svensson, Anders
    Aldahan, Ala
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Beer, Jurg
    Sjolte, Jesper
    Bjorck, Svante
    Matthes, Katja
    Thieblemont, Remi
    Persistent link between solar activity and Greenland climate during the Last Glacial Maximum2014In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 7, no 9, p. 662-666Article in journal (Refereed)
    Abstract [en]

    Changes in solar activity have previously been proposed to cause decadal- to millennial-scale fluctuations in both the modern and Holocene climates(1). Direct observational records of solar activity, such as sunspot numbers, exist for only the past few hundred years, so solar variability for earlier periods is typically reconstructed from measurements of cosmogenic radionuclides such as Be-10 and C-14 from ice cores and tree rings(2,3). Here we present a high-resolution Be-10 record from the ice core collected from central Greenland by the Greenland Ice Core Project (GRIP). The record spans from 22,500 to 10,000 years ago, and is based on new and compiled data(4-6). Using C-14 records(7,8) to control for climate-related influences on Be-10 deposition, we reconstruct centennial changes in solar activity. We find that during the Last Glacial Maximum, solar minima correlate with more negative delta O-18 values of ice and are accompanied by increased snow accumulation and sea-salt input over central Greenland. We suggest that solar minima could have induced changes in the stratosphere that favour the development of high-pressure blocking systems located to the south of Greenland, as has been found in observations and model simulations for recent climate(9,10). We conclude that the mechanism behind solar forcing of regional climate change may have been similar under both modern and Last Glacial Maximum climate conditions.

  • 4.
    Aldahan, Ala Adin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Morad, Sadoon
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Sturesson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    ElSaiy, A.
    10Be in rhodochrosite nodules from Neogene sediments along the Galapagos Ridge, equatorial Pacific2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 7-8, p. 1253-1256Article in journal (Refereed)
    Abstract [en]

    Microcrystalline, calcian rhodochrosite occurs as nodules around burrows in late Neogene pelagic sediments from the Galapagos Ridge in the Guatemala Basin, eastern equatorial Pacific (DSDP Leg 68; Site 503). Be-10 isotope revealed that the rhodochrosite nodules have formed under growth conditions much faster than those reported for Fe-Mn nodules. The overall REE patterns of the nodules and host pelagic sediments indicate element derivation mainly from marine pore water. However, variations in the shale normalised Eu values suggest influx of hydrothermal fluids into mounds area at Galapagos, which is also evidenced by the similar minor and major element contents in the nodules and host sediments.

  • 5.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hedfors, Jim
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Kulan, Abdulhadi
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Berggren, Ann-Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Söderström, C.
    FOI, Swedish Defence Research Agency, Stockholm, Sweden.
    Atmospheric impact on beryllium isotopes as solar activity proxy2008In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, no L21812Article in journal (Refereed)
    Abstract [en]

    Reconstructing solar activity variability beyond the time scale of actual measurements provides invaluable data for modeling of past and future climate change. The 10 Be isotope has been a primary proxy archive of past solar activity and cosmic ray intensity, particularly for the last millennium. There is, however, a lack of direct high-resolution atmospheric time series on 10 Be that enable estimating atmospheric modulation on the production signal. Here we report quasi-weekly data on 10 Be and 7 Be isotopes covering the periods 1983-2000 and 1975-2006 respectively, that show, for the first time, coherent variations reflecting both atmospheric and production effects. Our data indicate intrusion of stratosphere/upper troposphere air masses that can modulate the isotopes production signal, and may induce relative peaks in the natural 10 Be archives (i.e., ice and sediment). The atmospheric impact on the Be-isotopes can disturb the production signals and consequently the estimate of past solar activity magnitude. Citation: Aldahan, A., J. Hedfors, G. Possnert, A. Kulan, A.-M. Berggren, and C. Soderstrom (2008), Atmospheric impact on beryllium isotopes as solar activity proxy, Geophys. Res. Lett., 35, L21812, doi: 10.1029/2008GL035189.

  • 6.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Persson, S
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Hou, Xiaolin
    Distribution of I-127 and I-129 in preciptitation at high European latitudes2009In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, p. L11805-Article in journal (Refereed)
    Abstract [en]

     We here present the most extensive data set on the distribution of   I-127 and I-129 in precipitation (rain and snow) covering the period   2000-2006 and European latitudes 55 degrees N-68 degrees N. Our results   indicate a wide variation in the concentrations and fluxes of the two   isotopes associated with generally higher values at near coastal sites   compared to the inland ones. Total wet-related annual deposition of   I-127 and I-129 on Sweden and Denmark is estimated at about 1.2 x 10(9)   g and 60 g respectively. The average annual I-129 wet deposition   accounts for <1% and <0.05% of the total annual gaseous and liquid,   respectively, discharges from the Sellafiled and La Hague Facilities.   The I-127 annual wet deposition represents < 1% of the estimated global   oceanic iodine flux. Air mass trajectories suggest that events of   enhanced I-129 in precipitation are closely related to southwesterly weather fronts from regions of elevated concentrations.

  • 7.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Alfimov, V.
    Cato, I.
    Sveriges geologiska undersökning.
    Kekli, Aziz
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Anthropogenic I-129 in the Baltic Sea2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 259, no 1, p. 491-495Article in journal (Refereed)
    Abstract [en]

    We report here data on the distribution of I-129 in water of the Baltic Sea and Skagerrak-Kattegat basins obtained through sampling campaigns during the years 2000 and 2001. I-129 in the water of the Skagerrak-Kattegat shows persistently high concentrations in both the surface and deep parts. A decreasing trend in surface water I-129 concentration is observed away from the Kattegat basin and into the Baltic Sea. Inventory calculations indicate that at least 95%of the isotope supply to the Baltic Sea is from the North Sea marine water via Skagerrak-Kattegat and only minor part is from riverine inflow and the Chernobyl accident. As the discharges from the nuclear reprocessing facilities were not decreased during the last decade, it is expected that more I-129 will accumulate in the Baltic Sea and related basins in the future. Consequently, systematic sampling is needed to reevaluate the concentration levels not only in the water, but also in the sediments and biota of the region.

  • 8.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    El Saiy, A.
    Abdelghany, O.
    Particle-bound Be-10 from a low latitude arid region2014In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 299, no 3, p. 1709-1713Article in journal (Refereed)
    Abstract [en]

    The Be-10 isotope is widely used in geochronology, climate and environmental analyses and astrophysics where atmospheric deposition model estimate plays a vital role for the initial concentration. Data from arid regions have not been well constrained because of sparse measurement and here we present Be-10 concentration in samples of dust, soil, marine sediments and paleosol collected from an arid to semi-arid low latitude region. These results indicate concentrations that are about a factor of three lower than values expected from latitude zonal models, but are comparable with global atmospheric depositional model. The agreement and discrepancy between model and measured data are rather vital for establishing accurate initial Be-10 in the Earth's surface environment for reconstruction of paleoclimatic variability (precipitation rates and temperature).

  • 9.
    Aldahan, Ala
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Scherer, Reed
    Sjunneskog, C
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Berggren, A-M
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Cosmogenic 10Be as an environmental tracer in subglacial Antarctic Lake2006In: SALE advanced Science and Technology Workshop, 24-26 April, Grenoble, France,, 2006, p. 2-3Conference paper (Refereed)
  • 10. Alfimov, Vasily
    et al.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Water masses and I-129 distribution in the Nordic Seas2013In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 294, p. 542-546Article in journal (Refereed)
    Abstract [en]

    The application of the radioactive isotope iodine-129 as a tracer of water circulation in the oceans has provided interesting information with respect to sources and mixing of different water masses. We here present results of I-129 distribution in water profiles located in the Nordic Seas and use the isotope to fingerprint water masses in the region. The samples were collected by the US research vessel Knorr in May-June 2002. I-129 signatures along the Norwegian Sea reflect a mixing of I-129-rich surface water along the Scandinavian continental slope and I-129-poor North Atlantic surface water. These two water masses become less segregated along the Fram Strait where apparent I-129 enrichment penetrates the return Arctic flow into the East Greenland Current. The I-129 data further suggest existence of a water mass that is not entirely labeled with respect to origin at the Denmark Strait bottom water. This water parcel probably originates from the Iceland Sea. I-129 data also shed light on the major deep water outflow from the Nordic Seas located at the Faeroe Bank Channel.

  • 11.
    Alfimov, Vasily
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Air and Water Science.
    Measurements of Cl-36 with a gas-filled magnet at the Uppsala tandem laboratory2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 259, no 1, p. 199-203Article in journal (Refereed)
    Abstract [en]

    The performance of a gas-filled magnet combined with a gas ionization detector for measurements of Cl-36 was systematically studied at the Uppsala tandem laboratory. Our tests were conducted at a terminal voltage of 4,6 MV using gas-foil stripping and a 37 MeV Cl-36(+7) ion beam. An optimal suppression of the interfering isobar S-36 in the stand-alone gas-filled magnet (2 mbar N-2 gas pressure) was found to be >= 300, and an additional >= 300 times reduction was achieved by the Eresidual signal of the two-anode gas ionization detector. The overall suppression in the order of >= 10(5) permits analysis of samples with a sulfur content of <= 5 ppm and Cl-36/Cl ratios of >= 10(-15). We have successfully measured samples with Cl-36/Cl ratios in the range of 10(-12)-10(-15) demonstrating the use of a mediumsized tandem accelerator system (similar to 1 MeV/amu) for Cl-36 AMS.

  • 12.
    Apel, Jan
    et al.
    Lund Univ LUX, Dept Archaeol & Ancient Hist, Box 192, Lund, Sweden.;Stockholm Univ, Dept Archaeol & Class Studies, Osteoarchaeol Res Lab, Stockholm, Sweden..
    Wallin, Paul
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Archaeology and Ancient History, Archaeology.
    Stora, Jan
    Stockholm Univ, Dept Archaeol & Class Studies, Osteoarchaeol Res Lab, Stockholm, Sweden..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Early Holocene human population events on the island of Gotland in the Baltic Sea (9200-3800 cal. BP)2018In: Quaternary International, ISSN 1040-6182, E-ISSN 1873-4553, Vol. 465, p. 276-286Article in journal (Refereed)
    Abstract [en]

    The summed probability distribution of 162 radiocarbon dates from Gotland was analysed with reference to archaeological and environmental data in order to evaluate possible variations in settlement intensity on the island. The data indicated variations in demographic development on the island, with probably several different colonization events and external influences; the pioneer settlement reached the island around 9200 cal. BP. After the initial colonization, the radiocarbon dates were rather evenly distributed until around 7700-7600 cal. BP, then there was a drop in the number of dates between 8300 and 8000 cal. BP that may be associated with the 8200 cold event. A marked decline in the number of dates between 7600 and 6000 cal. BP may be associated initially with the Littorina I transgression, but this transgression cannot explain why the Late Mesolithic period is not well represented on Gotland: the climatic development was favourable but did not result in increased human activity. The number of radiocarbon dates indicated that the population size remained low until around 6000 cal. BP, after which there was a gradual increase that reached a first 'threshold' after 5600 cal. BP and a second 'threshold' after 4500 cal. BP. The first apparent population increase was associated with the appearance of the Funnel Beaker Culture (FBC) and the second with Pitted Ware Culture (PWC) complexes. A decline in the number of dates occurred after 4300 cal. BP, i.e. towards the Late Neolithic. There was an association between the frequency distributions of the radiocarbon dates and the number of stray finds from different time periods but any correlation was not straightforward. (C) 2017 Elsevier Ltd and INQUA. All rights reserved.

  • 13.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    10Be in ice - four decades, two ice sheets, 15 deep coring sites2010Conference paper (Other academic)
  • 14.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Haltia-Hovi, E
    Saarinen, T
    Be-10 and climate variability during 1900-2006 AD reflected in varved lake sediments2009Conference paper (Refereed)
  • 15.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Haltia-Hovi, Eeva
    Department of Quaternary Geology, University of Turku, Turku, Finland.
    Saarinen, Timo
    Department of Quaternary Geology, University of Turku, Turku, Finland.
    10Be and solar activity cycles in varved lake sediments, AD 1900–20062010In: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 44, no 2, p. 559-569Article in journal (Refereed)
    Abstract [en]

    Annually resolved terrestrial 10Be archives other than those in polar ice sheets are heretofore unexplored sources of information about past solar activity and climate. Until now, it has proven difficult to find natural archives that have captured and retained a 10Be production signal, and that allow for annual sampling and contain sufficient 10Be for AMS measurement. We report the first annually resolved record of 10Be in varved lake sediments. The record comes from Lake Lehmilampi, eastern Finland, which lies at 63°37′N, 29°06′E, 95.8 m a. s. l. The focus on the last 100 years provided an unprecedented opportunity to compare sediment 10Be data with annual ice core, neutron monitor and sunspot number data. Results indicate successful recovery of 10Be atoms from as little as 20 mg sediment. Sediment 10Be accumulation rates suggest control by solar activity, manifested as a reflection of the 11-year Schwabe solar cycle and its amplitude variations throughout the investigated period. These results open the possibility of using varved lake sediment 10Be records as a new proxy for solar activity, thus providing a new approach for synchronization of paleoclimate events worldwide.

  • 16.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Haltia-Hovi, Eeva
    Saarinen, Timo
    Linking ice sheet and lake sediment archives of Be-10, 1468-1980 CE2013In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 294, p. 524-529Article in journal (Refereed)
    Abstract [en]

    As part of understanding and reconstructing our climate history it is important to investigate the link between climate and solar activity. Ice cores and ocean sediments have provided information on a range of timescales on atmospheric Be-10 production, which is a proxy for past solar activity due to its cosmogenic nature of production. We here present results from the first, to our knowledge, multi-centennial and annual resolution study of Be-10 in varved lake sediments. Varves were sampled over an interval covering the period 1468-2006 CE in sediment cored from Lake Lehmilampi in eastern Finland. The measured concentrations were converted into annual Be-10 deposition rates by using the weights of dried samples as an estimation of sedimentation rates and scaling the result from sampling to catchment area size. We compare the lake catchment Be-10 deposition rates to those derived from the Greenlandic ice cores NGRIP and Dye-3 along with past solar activity. Sediment Be-10 concentrations range 2.1-17.6 x 10(8) atoms g(-1). The high end of this range is represented by a limited number of samples, and the average is near the lower end at 4.1 x 10(8) atoms g(-1). The deposition rates range 0.5-3.9 x 10(6) atoms cm(-2) year(-1), with an average of 1.8 x 10(6) atoms cm(-2) year (0.057 atoms cm(-2) s(-1)). We note higher Be-10 deposition during the Sporer (similar to 1415-1535 CE) and Maunder (similar to 1645-1715 CE) solar minima, and also at the onset of the Dalton (similar to 1790-1830 CE) minimum. Equally high Be-10 values in the 1840s and lower deposition during the Dalton minimum are not consistent with contemporaneous solar activity. Although this may in part be a result of incomplete measurements in the 19th century, it also shows the complexity of deposition and the intricacy of reconstructing past solar activity from sediment Be-10 data. A comparison with ice core data reveals particularly good agreement between sediment and Dye-3 Be-10 flux around 1500-1750 CE.

  • 17.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Haltia-Hovi, Eeva
    Saarinen, Timo
    Six centuries of annually resolved 10Be in varved lake sediments and its relation to production rates2010Conference paper (Other academic)
  • 18.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics.
    Haltia-Hovi, Eeva
    University of Turku, Finland.
    Saarinen, Timo
    University of Turku, Finland.
    Solar cycle variations reflected in 10Be in varved lake sediments, 1900-2006 AD2009Manuscript (preprint) (Other academic)
  • 19.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Hansson, M.
    Steen-Larsen, H. C.
    Storm, Anna Sturevik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Morth, C. -M
    Murad, A.
    Variability of Be-10 and delta O-18 in snow pits from Greenland and a surface traverse from Antarctica2013In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 294, p. 568-572Article in journal (Refereed)
    Abstract [en]

    To examine temporal variability of Be-10 in glacial ice, we sampled snow to a depth of 160 cm at the NEEM (North Greenland Eemian Ice Drilling) drilling site in Greenland. The samples span three years between the summers of 2006 and 2009. At the same time, spatial variability of Be-10 in glacial ice was explored through collection of the upper similar to 5 cm of surface snow in Antarctica during part of the Swedish-Japanese traverse from Svea to Syowa station during the austral summer in 2007-2008. The results of the Greenlandic 1 Be snow suggested variable concentrations that apparently do not clearly reflect the seasonal change as indicated by the delta O-18 data. The Be-10 concentration variability most likely reflects also effects of aerosol loading and deposition pathways, possibly in combination with post-depositional processes. The Antarctic traverse data expose a negative correlation between Be-10 and delta O-18, while there are weaker but still significant correlations to altitude and distance to the coast (approximated by the distance to the 70th latitude). These relationships indicate that geographical factors, mainly the proximity to the coast, may strongly affect 1 Be concentrations in snow in Queen Maud Land, Antarctica.

  • 20.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Sturevik Storm, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Surface and snow pit 10Be from the NEEM drill site, Greenland2010Conference paper (Other academic)
  • 21.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Beer, Juerg
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Kubik, Peter
    ETH, Zurich, Switzerland.
    Christl, Marcus
    ETH, Zurich, Switzerland.
    Johnsen, Sigfús J.
    Niels Bohr Institute, Copenhagen, Denmark.
    Abreu, José
    Eawag, Zurich, Switzerland.
    Vinter, Bo M.
    Niels Bohr Institute, Copenhagen, Denmark.
    A 600-year annual 10Be record from the NGRIP ice core, Greenland2009In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, p. L11801-Article in journal (Refereed)
    Abstract [en]

    Despite the extensive use of 10Be as the most significant information source on past solar activity, there has been only one record (Dye-3, Greenland) providing annual resolution over several centuries. Here we report a new annual resolution 10Be record spanning the period 1389-1994 AD, measured in an ice core from the NGRIP site in Greenland. NGRIP and Dye-3 10Be exhibits similar long-term variability, although occasional short term differences between the two sites indicate that at least two high resolution 10Be records are needed to assess local variations and to confidently reconstruct past solar activity. A comparison with sunspot and neutron records confirms that ice core 10Be reflects solar Schwabe cycle variations, and continued 10Be variability suggests cyclic solar activity throughout the Maunder and Spörer grand solar activity minima. Recent 10Be values are low; however, they do not indicate unusually high recent solar activity compared to the last 600 years.

  • 22.
    Berggren, Ann-Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Enhanced beam currents with co-precipitated niobium as a matrix for AMS measurements of 10Be2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 7-8, p. 795-798Article in journal (Refereed)
    Abstract [en]

    When dealing with small amounts of 10Be, it is challenging to achieve the good performance in the ion source that is needed to enable a reliable AMS measurement. We have co-precipitated beryllium with dissolved NbCl5, using a range of mixing ratios, to establish an optimal and practical procedure. 9Be16O beam currents for co-precipitated samples of 9Be-Nb are often higher, but show a slower rise than for samples either co-precipitated or mixed with silver. However, while the Ag sample currents soon deteriorate, Nb sample currents stay high for an extended time, leading to higher measuring performance and better statistics. Although co-precipitated Be-Nb mixtures do not reach such high beam currents as BeO mechanically mixed with Nb powder, we prefer co-precipitation as it provides enough material for handling and an additional mixing step is avoided. We recommend use of NbCl5 as an alternative to AgNO3 on account of the much lower boron association of niobium compared to silver. No critical limit in the matrix:Be mixing ratio was observed, but we note a steady decline of maximum currents reached with increasing mixing ratio.

  • 23. Bergsaker, H.
    et al.
    Bykov, I.
    Petersson, P.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Likonen, J.
    Koivuranta, S.
    Coad, J. P.
    Van Renterghem, W.
    Uytdenhouwen, I.
    Widdowson, A. M.
    Microscopically nonuniform deposition and deuterium retention in the divertor in JET with ITER-like wall2015In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 463, p. 956-960Article in journal (Refereed)
    Abstract [en]

    The divertor surfaces in JET with ITER-like wall (ILW) have been studied using micro ion beam analysis (mu-IBA) methods and scanning electron microscopy (SEM). Deposited layers with beryllium as main constituent had been formed during plasma operations through 2011-2012. The deuterium trapping and impurity deposition were non-uniform, frequently enhanced within pits, cracks and valleys, regions reaching in size from 10 mu m to 200 mu m. The impurity deposition and fuel retention were correlated with the surface slope with respect to the direction of ion incidence. Typically more than 70% of the total measured areal density of trapped D was found in less than 30% of the surface area. This is of consequence for the interpretation of other surface analyses and in extrapolation from fuel retention in JET with ITER-like wall and rough divertor surfaces to ITER with smoother surfaces.

  • 24. Bergsaker, H.
    et al.
    Bykov, I.
    Petersson, P.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Likonen, J.
    Koivuranta, S.
    Coad, J. P.
    Widdowson, A. M.
    Microstructure and inhomogeneous fuel trapping at divertor surfaces in the JET tokamak2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 266-270Article in journal (Refereed)
    Abstract [en]

    The plasma deposited layers at divertor surfaces in the JET tokamak with carbon wall have been studied post mortem, using micro ion beam analysis (mu-IBA) methods, optical microscopy and scanning electron microscopy (SEM). The layers were formed during plasma operations over different periods through 1998-2009. They frequently have a columnar structure. For mu-IBA a 3 MeV He-3 beam was used, focused to about 5-15 mu m size. Nuclear reaction analysis was used to measure D, Be and C. Elemental mapping was carried out both at the original surface and on polished layer cross sections. Trapped deuterium is predominantly found in remote areas on the horizontal bottom divertor tiles and in regions with locally enhanced deuterium concentration on the vertical tiles. Pockets with enhanced deuterium concentration are found in the carbon fibre composite (CFC) substrate. Areas with dimensions of about 100 mu m with enhanced deuterium concentration are also found inside the deposited layers. The inhomogeneous fuel trapping is tentatively explained with co-deposition in partly protected pits in the substrate and by incorporation of dust particles in the growing layers.

  • 25.
    Bergsaker, H.
    et al.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;KTH Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, SE-10405 Stockholm, Sweden..
    Bykov, I.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;KTH Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, SE-10405 Stockholm, Sweden..
    Zhou, Y.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;KTH Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, SE-10405 Stockholm, Sweden..
    Petersson, P.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;KTH Royal Inst Technol, Sch Elect Engn, Dept Fus Plasma Phys, SE-10405 Stockholm, Sweden..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Likonen, J.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;VTT Tech Res Ctr Finland, POB 1000, FI-02044 Espoo, Finland..
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Koivuranta, S.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;VTT Tech Res Ctr Finland, POB 1000, FI-02044 Espoo, Finland..
    Widdowson, A. M.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.;CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Deep deuterium retention and Be/W mixing at tungsten coated surfaces in the JET divertor2016In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T167, article id 014061Article in journal (Refereed)
    Abstract [en]

    Surface samples from a full poloidal set of divertor tiles exposed in JET through operations 2010-2012 with ITER-like wall have been investigated using SEM, SIMS, ICP-AES analysis and micro beam nuclear reaction analysis (mu-NRA). Deposition of Be and retention of D is microscopically inhomogeneous. With careful overlaying of mu-NRA elemental maps with SEM images, it is possible to separate surface roughness effects from depth profiles at microscopically flat surface regions, without pits. With (He-3, p) mu-NRA at 3-5 MeV beam energy the accessible depth for D analysis in W is about 9 mu m, sufficient to access the W/Mo and Mo/W interfaces in the coatings and beyond, while for Be in W it is about 6 mu m. In these conditions, at all plasma wetted surfaces, D was found throughout the whole accessible depth at concentrations in the range 0.2-0.7 at% in W. Deuterium was found to be preferentially trapped at the W/Mo and Mo/W interfaces. Comparison is made with SIMS profiling, which also shows significant D trapping at the W/Mo interface. Mixing of Be and W occurs mainly in deposited layers.

  • 26. Bergsaker, H.
    et al.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Bykov, I.
    Heinola, K.
    Petersson, P.
    Miettunen, J.
    Widdowson, A.
    Riccardo, V.
    Nunes, I.
    Stamp, M.
    Brezinsek, S.
    Groth, M.
    Kurki-Suonio, T.
    Likonen, J.
    Coad, J. P.
    Borodin, D.
    Kirschner, A.
    Schmid, K.
    Krieger, K.
    First results from the Be-10 marker experiment in JET with ITER-like wall2014In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 54, no 8, p. 082004-Article in journal (Refereed)
    Abstract [en]

    When the ITER-like wall was installed in JET, one of the 218 Be inner wall guard limiter tiles had been enriched with Be-10 as a bulk isotopic marker. During the shutdown in 2012-2013, a set of tiles were sampled nondestructively to collect material for accelerator mass spectroscopy measurements of Be-10 concentration. The letter shows how the marker experiment was set up, presents first results and compares them to preliminary predictions of marker redistribution, made with the ASCOT numerical code. Finally an outline is shown of what experimental data are likely to become available later and the possibilities for comparison with modelling using the WallDYN, ERO and ASCOT codes are discussed.

  • 27. Bykov, I.
    et al.
    Bergsaker, H.
    Petersson, P.
    Likonen, J.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Widdowson, A.
    Combined ion micro probe and SEM analysis of strongly non uniform deposits in fusion devices2015In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 342, p. 19-28Article in journal (Refereed)
    Abstract [en]

    Conventional ion beam analysis (IBA) of deposited layers from fusion devices may have insufficient accuracy due to strongly uneven appearance of the layers. Surface roughness and spatial variation of the matrix composition make interpretation of broad beam spectra complex and non obvious. We discuss complications of applied IBA arising for fusion-relevant surfaces and demonstrate how quantification can be improved by employing micro IBA methods. The analysis is bound to pre-defined regions on the sample surface and can be extended by employing beams of several types, scanning electron microscopy (SEM) and stereo SEM techniques. (C) 2014 Elsevier B.V. All rights reserved.

  • 28. Bykov, I.
    et al.
    Bergsaker, H.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Heinola, K.
    Miettunen, J.
    Groth, M.
    Petersson, P.
    Widdowson, A.
    Likonen, J.
    Materials migration in JET with ITER-like wall traced with a Be-10 isotopic marker2015In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 463, p. 773-776Article in journal (Refereed)
    Abstract [en]

    The current configuration of JET with ITER-like Wall (ILW) is the best available proxy for the ITER first wall. Beryllium redistribution in JET-ILW can be used for estimates of its migration in ITER. To trace it, a localized isotopic Be marker has been implemented. A bulk Be-9 tile has been enriched with Be-10 up to atomic concentrations of 1.7 x 10(-9) and installed at the inner midplane of JET before the campaign. During the 2012 shutdown over 100 surface samples were taken non destructively from surfaces of two toroidally opposite limiter beams. The absolute areal densities of the marker were inferred from Be-15 atomic concentration in each sample, measured with Accelerator Mass Spectrometry with sensitivity <10(-14). The results of marker mapping are compared with predictions made with the ASCOT orbit following code.

  • 29.
    Bykov, I.
    et al.
    Royal Inst Technol KTH, Div Fus Plasma Phys, Stockholm, Sweden..
    Bergsåker, H.
    Royal Inst Technol KTH, Div Fus Plasma Phys, Stockholm, Sweden..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Zhou, Y.
    Royal Inst Technol KTH, Div Fus Plasma Phys, Stockholm, Sweden..
    Heinola, K.
    Univ Helsinki, Dept Phys, POB 64, Helsinki 00560, Finland..
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Likonen, J.
    VTT, POB 1000, Espoo 02044, Finland..
    Petersson, P.
    Royal Inst Technol KTH, Div Fus Plasma Phys, Stockholm, Sweden..
    Widdowson, A.
    EUROfus Consortium, JET, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Studies of Be migration in the JET tokamak using AMS with Be-10 marker2016Conference paper (Refereed)
    Abstract [en]

    The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a Be-10 enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm(2) sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The Be-10/Be-9 ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the B-10 isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.

  • 30. Bykov, I.
    et al.
    Petersson, P.
    Bergsåker, H.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Investigation of tritium analysis methods for ion microbeam application2012In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 273, p. 250-253Article in journal (Refereed)
    Abstract [en]

    The trapping and retention of tritium in deposited layers on plasma-facing components is a critical issue for the international tokamak experimental reactor (ITER) and for future power producing tokamak fusion reactors. Cross sections of deposited layers at surfaces in the JET tokamak divertor are being investigated using ion microbeam analysis. To include tritium analysis with high spatial resolution, a number of plausible ion beam techniques have been investigated. Calibration samples with 150 nm tritiated titanium films were used. Absolute concentrations were determined with classical ERD using 2.5-3.5 MeV C-12(+). Cross sections for non-Rutherford ERD and for the T(C-12,p)C-14 and T(C-12,alpha)B-11 nuclear reactions were measured for different angles in the energy range 2.5-15 MeV. Background spectra were collected from pure carbon, beryllium and deuterium enriched samples and the sensitivity for microbeam NRA measurements of the tritium concentration in thick targets with predominantly Be-C-D matrix was estimated.

  • 31. Bykov, Igor
    et al.
    Bergsaker, Henric
    Petersson, Per
    Likonen, Jari
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Quantitative plasma-fuel and impurity profiling in thick plasma-deposited layers by means of micro ion beam analysis and SIMS2014In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, p. 280-285Article in journal (Refereed)
    Abstract [en]

    The operation of the Joint European Torus (JET) with full-carbon wall during the last decades has proven the importance of material re-deposition processes in remote areas of the tokamak. The thickness of the deposits in shadowed areas can reach 1 mm. The main constituent is carbon, with little inclusion of Inconel components. Atomic fractions Be/C and D/C can locally reach 1. Three methods were used to study thick deposits on JET divertor surfaces: (i) NRA analysis with a 15 mu m wide, 3 MeV He-3 ion microbeam on a polished cross section of the layer to determine the concentration distribution of D, Be and C and the distribution of Ni by particle induced X-ray emission; (ii) elastic proton scattering (EPS) from the top of the layers with a broad proton beam at 3.5 and 4.6 MeV. These methods were absolutely calibrated using thick elemental targets. (iii) Depth profiling of D, Be and Ni was done with secondary ion mass spectrometry (SIMS), sputtering the layers from the surface. The three methods are complementary. The thickest layers are accessible only by microbeam mapping of the cross sections, albeit with limited spatial resolution. The SIMS has the best depth resolution, but is difficult for absolute quantification and is limited in accessible depth. The probed depth with proton backscattering is limited to about 30 mu m. The combination of all three methods provided a coherent picture of the layer composition. It was possible to correlate the SIMS profiling results to quantitative data obtained by the microbeam method.

  • 32.
    Chen, P.
    et al.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Yu, Z. B.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. United Arab Emirates Univ, Dept Geol, Al Ain, U Arab Emirates..
    Yi, P.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Mugwaneza, Vincent de Paul
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul, Nanjing 210098, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Peoples R China..
    Comparison of measurement and modeling results of the global Be-10 flux in topsoil2017In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 311, no 3, p. 2039-2045Article in journal (Refereed)
    Abstract [en]

    Soils are among the major terrestrial reservoirs of atmospheric Be-10 isotope and provide information of landscape evolution history. Despite this importance, there is no overview of the global soil Be-10 fluxes in topsoil that is linked with atmospheric flux models. A comparison between measured (in topsoil) and atmospherically modeled Be-10 fluxes is presented here. The data show relatively good agreement in the latitudinal trends. This feature demonstrates the potential to use the modeling data in estimating soil development/erosion rates in large scale basins where extensive Be-10 measurements can be limited.

  • 33.
    Chen, Xuegao
    et al.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Jiangsu, Peoples R China..
    Gong, Meng
    Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Jiangsu, Peoples R China..
    Yi, Peng
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Jiangsu, Peoples R China..
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. United Arab Emirates Univ, Dept Geol, Al Ain, U Arab Emirates..
    Yu, Zhongbo
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Jiangsu, Peoples R China..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Chen, Li
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing 210098, Jiangsu, Peoples R China..
    Distribution of I-129 in terrestrial surface water environments2015In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 361, p. 604-608Article in journal (Refereed)
    Abstract [en]

    The global distribution of the radioactive isotope iodine-129 in surface waters (lakes and rivers) is presented here and compared with the atmospheric deposition and distribution in surface marine waters. The results indicate relatively high concentrations in surface water systems in close vicinity of the anthropogenic release sources as well as in parts of Western Europe, North America and Central Asia. I-129 level is generally higher in the terrestrial surface water of the Northern hemisphere compared to the southern hemisphere. The highest values of I-129 appear around 50 degrees N and 40 degrees S in the northern and southern hemisphere, separately. Direct gaseous and marine atmospheric emissions are the most likely avenues for the transport of 1291 from the sources to the terrestrial surface waters. To apply iodine-129 as process tracer in terrestrial surface water environment, more data are needed on I-129 distribution patterns both locally and globally.

  • 34.
    Chen, Xuegao
    et al.
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing, Jiangsu, Peoples R China..
    Liu, Xue
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing, Jiangsu, Peoples R China..
    Yi, Peng
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing, Jiangsu, Peoples R China..
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. United Arab Emirates Univ, Dept Geol, Al Ain, U Arab Emirates..
    Yu, Zhongbo
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Hohai Univ, Coll Hydrol & Water Resources, Nanjing, Jiangsu, Peoples R China..
    Chen, Li
    Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China.;Desert Res Inst, Div Hydrol Sci, Las Vegas, NV USA..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Estimation of I-129 inventory in the oceans2016In: Journal of Radioanalytical and Nuclear Chemistry, ISSN 0236-5731, E-ISSN 1588-2780, Vol. 308, no 1, p. 59-65Article in journal (Refereed)
    Abstract [en]

    Spatial distribution of oceanic I-129 inventory presented here is based on collection of data from published literatures coupled with model calculation using ArcGIS software tools. A total of 363 thiessen polygons were created for the oceans in order to cover the tremendous variability in distribution of I-129 data range. The results indicate that total I-129 oceanic inventory is approximately 7310 kg, which is mainly stored in the region of the North Atlantic and the Arctic Oceans. The concentrations of I-129 in the oceans are 3-4 orders of magnitude higher than the pre-anthropogenic level reflecting effects of post 1945 anthropogenic activities.

  • 35.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Suvanam, Sethu Saveda
    Royal Institute of Technology (KTH), School of Information and Communication Technology, PO Box Electrum 229, SE-16440 Kista, Sweden.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    Impact of H-Uptake from Forming Gas Annealing and Ion Implantation on the Photoluminescence of Si Nanoparticles2018In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 3, article id 1700444Article in journal (Refereed)
    Abstract [en]

    Silicon nanoparticles (SiNPs) are formed by implanting 70keV Si+ into a SiO2-film and subsequent thermal annealing. SiNP samples are further annealed in forming gas. Another group of samples containing SiNP is implanted by 7.5keV H+ and subsequently annealed in N-2-atmosphere at 450 degrees C to reduce implantation damage. Nuclear reaction analysis (NRA) is employed to establish depth profiles of the H-concentration. Enhanced hydrogen concentrations are found close to the SiO2 surface, with particularly high concentrations for the as-implanted SiO2. However, no detectable uptake of hydrogen is observed by NRA for samples treated by forming gas annealing (FGA). H-concentrations detected after H-implantation follow calculated implantation profiles. Photoluminescence (PL) spectroscopy is performed at room temperature to observe the SiNP PL. Whereas FGA is found to increase PL under certain conditions, i.e., annealing at high temperatures, increasing implantation fluence of H reduces the SiNP PL. Hydrogen implantation also introduces additional defect PL. After low-temperature annealing, the SiNP PL is found to improve, but the process is not found equivalently efficient as conventional FGA.

  • 36.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Moro, Marcos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    Luminescence of Silicon Nanoparticles from Oxygen Implantated SiliconIn: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081Article in journal (Refereed)
  • 37.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Suvanam, Sethu Saveda
    Royal Institute of Technology (KTH), School of Information and Communication Technology, PO Box Electrum 229, SE-16440 Kista, Sweden.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    Influence of Swift Heavy Ion Irradiation on the Photoluminescence of Si-nanoparticles and Defects in SiO22017In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 37, article id 375603Article in journal (Refereed)
    Abstract [en]

    The influence of swift heavy ion (SHI) irradiation on the photoluminescence (PL) of silicon nanoparticles (SiNPs) and defects in SiO2-film is investigated. SiNPs were formed by implantation of 70 keV Si+ and subsequent thermal annealing to produce optically active SiNPs and to remove implantation-induced defects. Seven different ion species with energy between 3-36 MeV and fluence from 10(11)-10(14) cm(-2) were employed for irradiation of the implanted samples prior to the thermal annealing. Induced changes in defect and SiNP PL were characterized and correlated with the specific energy loss of the employed SHIs. We find that SHI irradiation, performed before the thermal annealing process, affects both defect and SiNP PL. The change of defect and SiNP PL due to SHI irradiation is found to show a threshold-like behaviour with respect to the electronic stopping power, where a decrease in defect PL and an anticorrelated increase in SiNP PL after the subsequent thermal annealing are observed for electronic stopping exceeding 3-5 keV nm(-1). PL intensities are also compared as a function of total energy deposition and nuclear energy loss. The observed effects can be explained by ion track formation as well as a different type of annealing mechanisms active for SHI irradiation compared to the thermal annealing.

  • 38.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Suvanam, Sethu Saveda
    Royal Institute of Technology (KTH), School of Information and Communication Technology, PO Box Electrum 229, SE-16440 Kista, Sweden.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    MeV Ion Irradiation Effects on the Luminescence Properties of Si-implanted SiO2-thin Films2016In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 13, no 10-12, p. 921-926Article in journal (Refereed)
    Abstract [en]

    The effects of MeV heavy ion irradiation at varying fluence and flux on excess Si, introduced in SiO2 by keV ion implantation, are investigated by photoluminescence (PL). From the PL peak wavelength (lambda) and decay lifetime (t), two PL sources are distinguished: i) quasi-direct recombination of excitons of Si-nanoparticles (SiNPs), appearing after thermal annealing (lambda > 720 nm, tau similar to mu s), and ii) fast-decay PL, possibly due to oxide-related defects (lambda similar to 575-690 nm, tau similar to ns). The fast-decay PL (ii) observed before and after ion irradiation is induced by ion implantation. It is found that this fast-decay luminescence decreases for higher irradiation fluence of MeV heavy ions. After thermal annealing (forming SiNPs), the SiNP PL is reduced for samples irradiated by MeV heavy ions but found to stabilize at higher level for higher irradiation flux; the (ii) band vanishes as a result of annealing. The results are discussed in terms of the influence of electronic and nuclear stopping powers.

  • 39.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Suvanam, Sethu Saveda
    Royal Institute of Technology (KTH), School of Information and Communication Technology, PO Box Electrum 229, SE-16440 Kista, Sweden.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Wolff, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    Si-nanoparticle Synthesis Using Ion Implantation and MeV Ion Irradiation2015In: Physica Status Solidi C: Current Topics In Solid State Physics, Vol 12, No 12 / [ed] Mascher, P; Moreels, I; Climente, JI; Andre, P; Reece, P; Ribierre, JC; Pereira, L; Philippe, L; Pellicer, E, 2015, no 12, p. 1301-1305Conference paper (Refereed)
    Abstract [en]

    A dielectric matrix with embedded Si-nanoparticles may show strong luminescence depending on nanoparticles size, surface properties, Si-excess concentration and matrix type. Ion implantation of Si ions with energies of a few tens to hundreds of keV in a SiO2 matrix followed by thermal annealing was identified as a powerful method to form such nanoparticles. The aim of the present work is to optimize the synthesis of Si-nanoparticles produced by ion implantation in SiO2 by employing MeV ion irradiation as an additional annealing process. The luminescence properties are measured by spectrally resolved photoluminescence including PL lifetime measurement, while X-ray reflectometry, atomic force microscopy and ion beam analysis are used to characterize the nanoparticle formation process. The results show that the samples implanted at 20%-Si excess atomic concentration display the highest luminescence and that irradiation of 36 MeV 127I ions affects the luminosity in terms of wavelength and intensity. It is also demonstrated that the nanoparticle luminescence lifetime decreases as a function of irradiation fluence.

  • 40.
    Chulapakorn, Thawatchart
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sychugov, Ilya
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Suvanam, Sethu Saveda
    Royal Institute of Technology (KTH), School of Information and Communication Technology, PO Box Electrum 229, SE-16440 Kista, Sweden.
    Xie, Ling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    LEIFER, KLAUS
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Linnros, Jan
    Royal Institute of Technology (KTH), Department of Materials and Nano Physics, SE-164 40 Kista, Sweden.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. Royal Institute of Technology, School of Information & Communication Technology, SE-16440 Kista, Sweden.
    Ion Beam Synthesis of Luminescent Silicon NanoparticlesManuscript (preprint) (Other academic)
  • 41.
    Czymzik, Markus
    et al.
    Lund Univ, Dept Geol, Quaternary Sci, S-22362 Lund, Sweden..
    Adolphi, Florian
    Lund Univ, Dept Geol, Quaternary Sci, S-22362 Lund, Sweden..
    Muscheler, Raimund
    Lund Univ, Dept Geol, Quaternary Sci, S-22362 Lund, Sweden..
    Mekhaldi, Florian
    Lund Univ, Dept Geol, Quaternary Sci, S-22362 Lund, Sweden..
    Martin-Puertas, Celia
    GEZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, D-14473 Potsdam, Germany..
    Aldahan, Ala
    United Arab Emirates Univ, Dept Geol, Al Ain 15551, U Arab Emirates..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Brauer, Achim
    GEZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, D-14473 Potsdam, Germany..
    A varved lake sediment record of the Be-10 solar activity proxy for the Lateglacial-Holocene transition2016In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 153, p. 31-39Article in journal (Refereed)
    Abstract [en]

    Solar modulated variations in cosmogenic radionuclide production provide both information on past changes in the activity of the Sun and a global synchronization tool. However, to date the use of cosmogenic radionuclides for these applications is almost exclusively based on Be-10 records from ice cores and C-14 time-series from tree rings, all including archive-specific limitations. We present the first Be-10 record from annually laminated (varved) lake sediments for the Lateglacial-Holocene transition from Meerfelder Maar. We quantify environmental influences on the catchment and, consequently, Be-10 deposition using a new approach based on regression analyses between our Be-10 record and environmental proxy time-series from the same archive. Our analyses suggest that environmental influences contribute to up to 37% of the variability in our Be-10 record, but cannot be the main explanation for major Be-10 excursions. Corrected for these environmental influences, our Be-10 record is interpreted to dominantly reflect changes in solar modulated cosmogenic radionuclide production. The preservation of a solar production signal in Be-10 from varved lake sediments highlights the largely unexplored potential of these archives for solar activity reconstruction, as global synchronization tool and, thus, for more robust paleoclimate studies.

  • 42.
    Czymzik, Markus
    et al.
    Lund Univ, Dept Geol, Lund, Sweden..
    Muscheler, Raimund
    Lund Univ, Dept Geol, Lund, Sweden..
    Brauer, Achim
    GFZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, Potsdam, Germany..
    Adolphi, Florian
    Lund Univ, Dept Geol, Lund, Sweden..
    Ott, Florian
    GFZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, Potsdam, Germany..
    Kienel, Ulrike
    GFZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, Potsdam, Germany.;Ernst Moritz Arndt Univ Greifswald, Inst Geog & Geol, Greifswald, Germany..
    Draeger, Nadine
    GFZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Evolut 5 2, Potsdam, Germany..
    Slowinski, Michal
    Polish Acad Sci, Inst Geog & Spatial Org, Dept Environm Resources & Geohazards, Torun, Poland..
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. United Arab Emirates Univ, Dept Geol, Al Ain, U Arab Emirates..
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Solar cycles and depositional processes in annual Be-10 from two varved lake sediment records2015In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 428, p. 44-51Article in journal (Refereed)
    Abstract [en]

    Beryllium 10 concentrations (Be-10(con)) were measured at annual resolution from varved sediment cores of Lakes Tiefer See (TSK) and Czechowskie (JC) for the period 1983-2009 (similar to solar cycles 22 and 23). Calibrating the Be-10(con) time-series against complementing proxy records from the same archive as well as local precipitation and neutron monitor data, reflecting solar forced changes in atmospheric radionuclide production, allowed (i) identifying the main depositional processes and (ii) evaluating the potential for solar activity reconstruction. Be-10(con) in TSK and JC sediments are significantly correlated to varying neutron monitor counts (TSK: r = 0.5, p = 0.05, n = 16; JC: r = 0.46, p = 0.03, n = 22). However, the further correlations with changes in organic carbon contents in TSK as well as varying organic carbon and detrital matter contents in JC point to catchment specific biases in the 10Be(con) time-series. In an attempt to correct for these biases multiple regression analysis was applied to extract an atmospheric Be-10 production signal (Be-10(atmosphere)). To increase the signal to noise ratio a Be-10 composite record (Be-10(composite)) was calculated from the TSK time-series. Be-10(composite) and JC Be-10(atmosphere) is significantly correlated to variations in the neutron monitor record (r = 0.49, p = 0.01, n = 25) and matches the expected amplitude changes in 10Be production between solar cycle minima and maxima. This calibration study on 10Be from two sites indicates the large potential but also, partly site-specific, limitations of Be-10 in varved lake sediments for solar activity reconstruction.

  • 43. Dahl-Jensen, D.
    et al.
    Albert, M. R.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Azuma, N.
    Balslev-Clausen, D.
    Baumgartner, M.
    Berggren, Ann-Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Bigler, M.
    Binder, T.
    Blunier, T.
    Bourgeois, J. C.
    Brook, E. J.
    Buchardt, S. L.
    Buizert, C.
    Capron, E.
    Chappellaz, J.
    Chung, J.
    Clausen, H. B.
    Cvijanovic, I.
    Davies, S. M.
    Ditlevsen, P.
    Eicher, O.
    Fischer, H.
    Fisher, D. A.
    Fleet, L. G.
    Gfeller, G.
    Gkinis, V.
    Gogineni, S.
    Goto-Azuma, K.
    Grinsted, A.
    Gudlaugsdottir, H.
    Guillevic, M.
    Hansen, S. B.
    Hansson, M.
    Hirabayashi, M.
    Hong, S.
    Hur, S. D.
    Huybrechts, P.
    Hvidberg, C. S.
    Iizuka, Y.
    Jenk, T.
    Johnsen, S. J.
    Jones, T. R.
    Jouzel, J.
    Karlsson, N. B.
    Kawamura, K.
    Keegan, K.
    Kettner, E.
    Kipfstuhl, S.
    Kjaer, H. A.
    Koutnik, M.
    Kuramoto, T.
    Koehler, P.
    Laepple, T.
    Landais, A.
    Langen, P. L.
    Larsen, L. B.
    Leuenberger, D.
    Leuenberger, M.
    Leuschen, C.
    Li, J.
    Lipenkov, V.
    Martinerie, P.
    Maselli, O. J.
    Masson-Delmotte, V.
    McConnell, J. R.
    Miller, H.
    Mini, O.
    Miyamoto, A.
    Montagnat-Rentier, M.
    Mulvaney, R.
    Muscheler, R.
    Orsi, A. J.
    Paden, J.
    Panton, C.
    Pattyn, F.
    Petit, J. -R
    Pol, K.
    Popp, T.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Prie, F.
    Prokopiou, M.
    Quiquet, A.
    Rasmussen, S. O.
    Raynaud, D.
    Ren, J.
    Reutenauer, C.
    Ritz, C.
    Rockmann, T.
    Rosen, J. L.
    Rubino, M.
    Rybak, O.
    Samyn, D.
    Sapart, C. J.
    Schilt, A.
    Schmidt, A. M. Z.
    Schwander, J.
    Schuepbach, S.
    Seierstad, I.
    Severinghaus, J. P.
    Sheldon, S.
    Simonsen, S. B.
    Sjolte, J.
    Solgaard, A. M.
    Sowers, T.
    Sperlich, P.
    Steen-Larsen, H. C.
    Steffen, K.
    Steffensen, J. P.
    Steinhage, D.
    Stocker, T. F.
    Stowasser, C.
    Sturevik, A. S.
    Sturges, W. T.
    Sveinbjornsdottir, A.
    Svensson, A.
    Tison, J. -L
    Uetake, J.
    Vallelonga, P.
    van de Wal, R. S. W.
    van der Wel, G.
    Vaughn, B. H.
    Vinther, B.
    Waddington, E.
    Wegner, A.
    Weikusat, I.
    White, J. W. C.
    Wilhelms, F.
    Winstrup, M.
    Witrant, E.
    Wolff, E. W.
    Xiao, C.
    Zheng, J.
    Eemian interglacial reconstructed from a Greenland folded ice core2013In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 493, no 7433, p. 489-494Article in journal (Refereed)
    Abstract [en]

    Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.

  • 44. Emmoth, B.
    et al.
    Kreter, A.
    Hallén, A.
    Jakubowski, M.
    Lehnen, M.
    Litnovsky, A.
    Petersson, Patrick
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Philipps, V.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Rubel, M.
    Schweer, B.
    Sundelin, P.
    Unterberg, B.
    Wienhold, P.
    In-situ measurements of carbon and deuterium deposition using the fast reciprocating probe in TEXTOR2009In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 390-91, no 1, p. 179-182Article in journal (Refereed)
    Abstract [en]

    Silicon samples were exposed in the scrape-off layer of the TEXTOR plasma using a fast reciprocating probe, with the aim of studying carbon deposition and deuterium retention during Dynamic Ergodic Divertor (DED) operation. Separate samples were exposed for 300 ms at the flat-top phase of neutral beam heated discharges. The exposure conditions were varied on a shot-to-shot basis by external magnetic perturbations generated by the DED in the m/n = 3/1, DC regime, base configuration. Nuclear Reaction Analysis (NRA) was used to characterise collector sample surfaces after their exposure. Enhanced concentrations of both carbon and deuterium (C 3-10 x 10(16) at./cm(2), D 8-60 x 10(15) at./cm(2)) were found. The D/C ratio was less than unity which indicates that most of the carbon and deuterium were co-deposited. Carbon e-folding lengths of about 2 cm were found on both toroidal sides of the probe independent of DED perturbations.

  • 45.
    Englund, Edvard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hou, X. L.
    Petersen, R.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Speciation of iodine (127I and 129I) in lake sediments2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 7-8, p. 1102-1105Article in journal (Refereed)
    Abstract [en]

    Fallout of anthropogenic I-129 at northern Europe has been occurring since the early 1950. Nevertheless, it is still unclear where and how this radioactive iodine is incorporated in the surface environment. In order to elucidate part of this problem, we here present an investigation of the occurrence modes of I-129 in varved lake sediments, collected in central Sweden and cover the period 1941-2007. Using a sequential extraction method, the results of I-129 and I-127 indicate that the partitioning of the two isotopes were more or less similar, despite the large gradient of I-129 within the sediment. Organic bound iodine was the dominant form over other fractions, while iodine bound to metal oxides was negligible. The leachable part constituted 5-6% of the iodine. Diagenetic influence seems to exert a limited effect on distribution of iodine in the examined sediment section.

  • 46.
    Englund, Edvard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hou, X. L.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Söderström, C.
    Iodine (129I and 127I) in aerosols from northern Europe2010In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 268, no 7-8, p. 1139-1141Article in journal (Refereed)
    Abstract [en]

    Huge amount of I-129 has been emitted to the environment during the last decades from a variety of anthropogenic nuclear activities. Aerosols represent a carrier of iodine in the atmosphere in addition to gaseous forms for which data are lacking in Sweden. In this study the first time series of iodine isotopes (I-129 and I-127) in aerosols covering the period of 1983 to 2008 from two sites in Sweden are presented. The results show that both I-129 and I-127 concentrations are considerably higher in southern compared to northern Sweden. Furthermore there is a significant difference in the relative concentrations between the sites being similar to 6 times higher for I-129 compared to similar to 3 times for I-127. The portion of the I-129 related to dry deposition, based on aerosol data, represents only a minor amount of the total fallout which is dominated by wet deposition.

  • 47.
    Englund, Edvard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Tracing anthropogenic nuclear activity with I-129 in lake sediment2008In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 99, no 2, p. 219-229Article in journal (Refereed)
    Abstract [en]

    This study reports the first data of I-129 fallout in Scandinavia, covering the last 80 years. The investigation is based on sediment sections from a lake in central Sweden. In addition to analysis of I-129, a combination of several radionuclides (Pb-210, Cs-137 and C-14) was used to establish an accurate chronology of the sediment profile. The concentration of I-129 exhibits an increasing trend (similar to 10(7) to similar to 10(9) atoms/g) during the last 40 years, suggesting a significant atmospheric input from the nuclear reprocessing facilities in Sellafield (UK) and La Hague (France). A peak corresponding to fallout from the Chernobyl accident (1986) is clearly distinguishable, whereas the impact of fallout from the nuclear weapons' tests since the early 1950s is not distinguished.

  • 48.
    Englund, Edvard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Alfimov, V.
    A routine preparation method for AMS measurement of 129I in solid material2007In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 259, no 1, p. 365-369Article in journal (Refereed)
    Abstract [en]

    Here we present results of an 129I extraction procedure applied to solid matrices (soils and organic matters), which is based on combustion of samples in an oxygen atmosphere. Stepwise heating and continuous warming of the whole system were critical points in order to achieve relatively satisfactory yields of iodine from samples ranging up to 1.5 g. Repeated combustions of blanks show both stable background levels and no significant memory effects. We have processed a series of different types of sample materials including standard soil, maple leaves and surface soil from Uppsala in Central Sweden. The results show analytical reproducibility and agreement with reported values.

  • 49.
    Englund, Edvard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Hou, Xiaolin
    Renberg, Ingmar
    Saarinen, Timo
    Modeling fallout of anthropogenic I-1292008In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 42, no 24, p. 9225-9230Article in journal (Refereed)
    Abstract [en]

    Despite the relatively well-recognized emission rates of the anthropogenic 128I, there is little knowledge about the temporal fallout patterns and magnitude of fluxes since the start of the atomic era at the early 1940s.We here present measurements of annual 129I concentrations in sediment archives from Sweden and Finland covering the period 1942-2006. The results revealed impression of 129I emissions from the nuclear reprocessing facility at Sellafield and La Hague and a clear Chernobyl fallout enhancement during 1986. In order to estimate relative contributions from the different sources, a numerical model approach was used taking into accountthe emission rates/ estimated fallout, transport pathways, and the sediment system. The model outcomes suggest a relatively dominating marine source of 129I to north Europe compared to direct gaseous releases. A transfer rate of 129I from sea to atmosphere is derived for pertinent sea areas (English Channel, Irish Sea, and North Sea), which is estimated at 0.04 to 0.21 y-1.

  • 50. Gasior, P.
    et al.
    Irrek, F.
    Petersson, Patrick
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Penkalla, Hj.
    Rubel, M.
    Schweer, B.
    Sundelin, P.
    Wessel, E.
    Linke, J.
    Philipps, V.
    Emmoth, B.
    Wolowski, J.
    Hirai, T.
    Laser-induced removal of co-deposits from graphitic plasma-facing components: Characterization of irradiated surfaces and dust particles2009In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 390-91, no 1, p. 585-588Article in journal (Refereed)
    Abstract [en]

    Laser-induced fuel desorption and ablation of co-deposited layers on limiter plates from the TEXTOR tokamak have been studied. Gas phase composition was monitored in situ, whereas the ex situ studies have been focused on the examination of irradiated surfaces and broad analysis of dust generated by ablation of co-deposits. The size of the dust grains is in the range of few nanometers to hundreds of micrometers. These are fuel-rich dust particles, as determined by nuclear reaction analysis. The presence of deuterium in dust indicates that not all fuel species are transferred to the gas phase during irradiation. This also suggests that photonic removal of fuel and the ablation of co-deposit from plasma-facing components may lead to the redistribution of fuel-containing dust to surrounding areas.

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