| 1. |
- Power, M. J., et al.
(författare)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Tidskriftsartikel (refereegranskat)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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| 2. |
- Marcouille, O., et al.
(författare)
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Production of high energy photons with in vacuum wigglers : From SOLEIL wiggler to MAXIV wiggler
- 2019
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Ingår i: Proceedings of the 13th International Conference on Synchrotron Radiation Instrumentation, SRI 2018. - : Author(s). - 9780735417823 ; 2054
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Konferensbidrag (refereegranskat)abstract
- Small gap wigglers become more and more attractive to produce high photon fluxes in the hard X-ray photon range. They use magnet blocks of high magnetization which resists much better to heating (baking, synchrotron radiation) than in the past, produce high magnetic field with numerous periods and are very compact. They also are a very good alternative to superconducting technology which requires special infrastructure, heavy maintenance and is not running cost free. SOLEIL, operating presently at 2.75 GeV has designed and built an in-vacuum wiggler of 38 periods of 50 mm producing 2.1 T at a minimum gap of 5.5 mm to delivered photon beam between 20 keV and 50 keV. Already in operation, further improvements are presently in progress to push photons towards higher energy, in particular thanks to the operation at lower gap (4.5 mm). MAX IV and SOLEIL, in the frame of collaboration, ave built an upgraded version of the existing SOLEIL wiggler with the target to extend the spectral range at high energy (above 50 keV) but also at low energy (4 keV) with the same insertion device. The design of the existing magnetic system has been modified to reach 2.4 T at a minimum gap of 4.2 mm and includes taper operation to avoid undulator structure in the radiated spectrum at low energy.
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| 3. |
- Baudin, K, et al.
(författare)
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Sputtering of large size clusters from solids bombarded by high energy cluster ions and fullerenes
- 1996
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Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS. - : ELSEVIER SCIENCE BV. - 0168-583X. ; 112:1-4, s. 59-63
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- It is shown that polyatomic ions at high energy (MeV) are able to emit large size cluster ions with a high yield when they bombard solid surfaces. Results on sputtering of clusters ejected from inorganic and organic targets as well as sputtering of C-n(-)
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| 4. |
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| 5. |
- Daya, DDNB, et al.
(författare)
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Radiation damage features on mica and L-valine probed by scanning force microscopy
- 1995
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Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS. - : ELSEVIER SCIENCE BV. - 0168-583X. ; 106:1-4, s. 38-42
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The radiation damage tracks on the surface of muscovite mica due to single 78.2 MeV I-127 ions from the Uppsala EN tandem accelerator have been studied using tapping mode scanning force microscopy (TM-SFM). Conically-shaped hillocks having nearly circular
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| 6. |
- Della-Negra, S., et al.
(författare)
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Orion project : Acceleration of cluster ions and highly charged biomolecules from 10 MeV to 1 GeV
- 1992
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Konferensbidrag (refereegranskat)abstract
- Cluster ions-projectiles have been revealed to be very efficient to drive energy or momentum on a solid surface. The impact of massive cluster is able to produce high energy density on a narrow area. Astonishing non linear effect has been observed [1] in the yield of secondary ions emission desorbed from a surface bombarded by molecular or clusters ions. The ORION project consists in accelerating with the Orsay Tandem, cluster ions and in a further step, charged biomolecules, in order to investigate these processes in a velocity range which correspond to their maximum of efficiency (a few keV per mass unit). This paper presents preliminary attemps and first results in creating C 60 and C 70 molecular ion beams using the Orsay Tandem accelerating structure.
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| 7. |
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