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- Murin, Yu., et al.
(författare)
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A detector system for studying nuclear reactions relevant to Single Event Effects
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 578:2, s. 385-398
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Tidskriftsartikel (refereegranskat)abstract
- We describe a device to study reactions relevant for the Single Event Effect (SEE) in microelectronics by means of 200A and 300AMeV, inverse kinematics, Si + H and Si + D reactions. The work is focused on the possibility to measure Z = 2-14 projectile fragments as efficiently as possible. During commissioning and first experiments the fourth quadrant of the CELSIUS storage ring acted as a spectrometer to register fragments in two planes of Si strip detectors in the angular region 0 degrees-0.6 degrees. A combination of ring-structured and sector-structured Si strip detector planes operated at angles 0.6 degrees-1.1 degrees. For specific event tagging a Si+ phoswich scintillator wall operated in the range 3.9 degrees-11.7 degrees and Si Delta E-E telescopes of CHICSi type operated at large angles.
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| 6. |
- Jaderstrom, H., et al.
(författare)
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200 and 300 MeV/nucleon nuclear reactions responsible for single-event effects in microelectronics
- 2008
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 77:4, s. 44601-
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Tidskriftsartikel (refereegranskat)abstract
- An experimental study of nuclear reactions between Si-28 nuclei at 200 and 300 MeV/nucleon and hydrogen or deuterium target nuclei was performed at the CELSIUS storage ring in Uppsala, Sweden, to collect information about the reactions responsible for single-event effects in microelectronics. Inclusive data on Si-28 fragmentation, as well as data on correlations between recoils and spectator protons or alpha particles are compared to predictions from the Dubna cascade model and the Japan Atomic Energy Research Institute version of the quantum molecular dynamics model. The comparison shows satisfactory agreement for inclusive data except for He fragments where low-energy sub-barrier fragments and recoiling fragments with very large momenta are produced much more frequently than predicted. The yield of exclusive data are also severely underestimated by the models whereas the charge distributions of recoils in these correlations compare well. The observed enhancement in He emission, which may well be important for the description of single-event effects, is most likely to be attributed to alpha clustering in Si-28 nuclei.
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| 7. |
- Mitra, Aditee, et al.
(författare)
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The role of mixotrophic protists in the biological carbon pump
- 2014
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 11, s. 995-1005
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Tidskriftsartikel (refereegranskat)abstract
- The traditional view of the planktonic foodweb describes consumption of inorganic nutrientsby photo-autotrophic phytoplankton, which in turn supports zooplankton and ultimately higher trophic levels. Pathways centred on bacteria provide mechanisms for nutrient recycling. This structure lies at the foundation of most models used to explore biogeochemical cycling, functioning of the biological pump, and the impact of climate change on these processes. We suggest an alternative paradigm, which sees the bulk of the base of this foodweb supported by protist plankton (phytoplankton and microzooplankton) communities that are mixotrophic – combining phototrophy and phagotrophy within a single cell. The photoautotrophic eukaryotic plankton and their heterotrophic microzooplankton grazers dominate only within immature environments (e.g., spring bloom in temperate systems). With their flexible nutrition, mixotrophic protists dominate in more mature systems (e.g., temperate summer, established eutrophic systems and oligotrophic systems); the more stable water columns suggested under climate change may also be expected to favour these mixotrophs. We explore how such a predominantlymixotrophic structure affects microbial trophic dynamics and the biological pump. The mixotroph dominated structure differs fundamentally in its flow of energy and nutrients, with a shortened and potentially more efficient chain from nutrient regeneration to primary production. Furthermore, mixotrophy enables a direct conduit for the support of primary production from bacterial production. We show how the exclusion of an explicit mixotrophic component in studies of the pelagic microbial communities leads to a failure to capture the true dynamics of the carbon flow. In order to prevent a misinterpretation of the full implications of climate change upon biogeochemical cyclingand the functioning of the biological pump, we recommend inclusion of multi-nutrient mixotroph models within ecosystem studies.
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| 8. |
- Murin, Y, et al.
(författare)
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SEE-Related Studies at CELSIUS
- 2005
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Ingår i: Proc. 6th Int. Conf. on Nuclear Physics at Storage Rings (STORI’05), Bonn. ; , s. 153-
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Konferensbidrag (refereegranskat)
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| 9. |
- Zubkov, V. G., et al.
(författare)
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Structural, vibrational, electronic, and luminescence properties of the cyclotetravanadates A(2)M(VO3)(4) (A=Na,Ag; M=Ca,Sr)
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77, s. 174113-
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Tidskriftsartikel (refereegranskat)abstract
- The physical properties of the family of cyclotetravanadates A(2)M(VO3)(4), where A=Na,Ag and M=Ca,Sr, have been studied by means of x-ray powder diffraction, neutron diffraction, electron diffraction, infrared, Raman, NMR, photoexcitation and pulse cathode beam excitation, and x-ray photoelectron spectroscopies, and band structure calculations. The differences between the structural, vibrational, luminescence, and electronic properties of the alkali metal-containing [Na2Ca(VO3)(4) and Na2Sr(VO3)(4)] and the d metal-containing cyclotetravanadates [Ag2Ca(VO3)(4) and Ag2Sr(VO3)(4)] are analyzed. Na2Ca(VO3)(4), Ag2Ca(VO3)(4), Na2Sr(VO3)(4), and Ag2Sr(VO3)(4) have tetragonal structures, P4/nbm, with a=10.438 49(6), 10.445 24(5), 10.634 49(4), and 10.625 74(6), and c=4.938 73(5), 4.968 45(5), 4.962 05(4), and 4.979 30(4) angstrom, respectively. The main structural feature of A(2)M(VO3)(4) is the tetracyclic [V4O12] units. The hybridized O 2p-V 3d states of the tetracyclic [V4O12] units have a dominant influence on the electronic structure of these compounds. The compounds are semiconducting with a local density approximation band gap increasing, from 1.85 eV for Ag2Ca(VO3)(4) to 3.02 eV for Na2Ca(VO3)(4). The prospects of these compounds as advanced materials for detectors of photon and corpuscular radiation as well as for color correction of light emission sources such as lamp and light emitting diode sources are discussed.
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| 10. |
- Tyutyunnik, A. P., et al.
(författare)
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CRYSTAL STRUCTURE AND VIBRATIONAL SPECTRA OF M[VO(2)(SeO(4))(H(2)O)(2)]center dot H(2)O (M = K, Rb, NH(4))
- 2011
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Ingår i: Journal of Structural Chemistry. - 0022-4766 .- 1573-8779. ; 52:2, s. 350-357
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Tidskriftsartikel (refereegranskat)abstract
- By the hydration of MVO(SeO(4))(2) with saturated water vapors at room temperature a series of isostructural complex compounds of vanadium(V) of the composition M[VO(2)(SeO(4))(H(2)O)(2)]center dot H(2)O (K, Rb, NH(4)) are synthesized and their physicochemical properties are studied. Based on the X-ray and neutron diffraction data, it is found that their crystal structure is composed of VO(6) octahedra linked in infinite chains by bridging SeO(4) tetrahedra. Each of the VO(6) octahedra has two short terminal V-O bonds forming a bent dioxovanadium group VO(2)(+). Two water molecules are coordinated by vanadium and one molecule is out of the first coordination sphere in the interchain space. The vibrational spectra of the studied compounds are completely consistent with their structural features.
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