We present charge‐state evolution studies for Pb54+ ion beams passing through stripper foils at relativistic energies of 5.9 GeV/u. The purpose of this investigation is to determine the optimum ...target material and non‐equilibrium thickness for the efficient production of few‐electron lead ions, that is, Pb80+ and Pb81+, at the present European Organization for Nuclear Research, CERN, accelerator facility at energies as high as 5.9 GeV/u. Based on these predictions, an Al stripper foil has been selected for a proof‐of‐principle measurement in the frame of the Gamma Factory study group. The experimental data confirms a substantial yield of non‐bare Pb ions. In addition, a charge‐state evolution study for the production of Li‐like lead ions Pb79+ is presented, which will be subject of a follow‐up experiment in the near future.
The timing of petroleum charge, especially in structurally complex basins, is often poorly defined, with few data to constrain petroleum systems models. In this study we reconstruct in detail the ...evolution of the >6 Tcf Maui Field, a mature gas-condensate field in the southern Taranaki Basin, northwestern New Zealand. Structural restoration suggests that closure developed between 6 and 5.3 Ma. Maturation modelling shows that charge of the main gas reservoir is only feasible from the nearby Maui sub-basin kitchen, across a major fault zone, the Cape Egmont Fault Zone (CEFZ). We apply petroleum systems modelling to predict timing and amount of charge using a reconstructed distribution of shaly fault rock as an approximation of fault permeability. Models reproducing the variable oil and gas accumulations in different areas of the field suggest that the field was charged within 4 Myr. This supports the notion that connected permeability exists even across large fault zones, allowing charge in geologically short times frames. Models using a range of fault and carrier bed properties suggest that presence of connected sandy carrier beds linking the fault zone with reservoirs is essential for petroleum migration. Predicted migration pathways occur through outer parts of the CEFZ characterized by greater architectural complexity as well as through the central area of the CEFZ with the largest offset. This suggests that the impact of shale-rich fault rock on petroleum migration across large fault zones is smaller than commonly expected. In particular, in deeper parts of the basin, a major fault zone can provide sufficient permeability to be the preferred pathway for vertical migration. These results illustrate that despite the complexity of migration pathways, petroleum migration can occur in geologically short time.
•The giant Maui gas-condensate field in New Zealand was charged within less than 4 Myrs.•Charge occurred across a major fault zone.•A variable shale gouge ratio model best reproduces petroleum migration.•Major fault zones can provide migration pathways in deep strata while sealing in shallow strata.
Commercial silicon heterojunction photovoltaic modules, known as amorphous-silicon-based heterojunction with intrinsic thin-film layer (HIT) modules, show average degradation after 10 years in the ...field. HIT modules weathered outdoors in Colorado and Florida display mostly uniform decreases in intensity when mapped with photoluminescence (PL) imaging compared to a control module. Flash-table-based current-voltage curves show that degradation is dominated by voltage loss. Samples are cored from each of the modules, and deep level transient spectroscopy (DLTS) detects three electron-trap defect states in all modules with activation energies of electron emission from the defects of 0.07, 0.16, and 0.50 eV. DLTS measurements on the weathered modules show an additional deep-level, electron-trap defect state with an activation energy of 0.51 eV and a trap density of approximately 1012 cm−3. The capture rate is measured using varying short filling pulse times, and the resulting capture cross section is estimated to be 1.1x10−16 cm2. The development of the weathering-related defect level correlates to decreases in carrier lifetime, PL intensity, and module voltage. Various depths of the space charge region are probed with increments in applied reverse bias and filling-pulse bias. This DLTS depth profiling shows a trend of trap density increasing with less applied reverse bias, suggesting that the weathering-related defect increases carrier recombination toward the interface between the bulk silicon wafer and the junction-forming amorphous-silicon passivation layers.
•Characterize degraded silicon heterojunction modules when weathered outdoors.•Deep level transient spectroscopy detects degradation related defect level.•Samples prepared by ultrashort pulse laser micromachining.•Defect states near hydrogenated amorphous silicon and crystalline silicon interface.•Defect correlates to decreased photoluminescence intensity and carrier lifetime.
► A barrier island freshwater lens is an extremely dynamic and vulnerable system. ► Age distribution, recharge patterns, hydrochemical evolution of a freshwater lens. ► Groundwater age allows for ...estimating groundwater recharge rate. ► Stable isotopes as indicator for changed recharge patterns or temperature increase. ► Conceptual model from recharge to discharge of a barrier island freshwater lens.
Freshwater lenses below barrier islands are dynamic systems affected by changes in morphodynamic patterns, groundwater recharge and discharge. They are also vulnerable to pollution and overabstraction of groundwater. Basic knowledge on hydrogeological and hydrochemical processes of freshwater lenses is important to ensure a sustainable water management, especially when taking into account possible effects of climate change. This is the first study which gives a compact overview on the age distribution, recharge conditions and hydrochemical evolution of a barrier island freshwater lens in the southern North Sea (Spiekeroog Island, Eastfrisian Wadden Sea). Two ground- and surface water sampling campaigns were carried out in May and July 2011, supplemented by monthly precipitation sampling from July to October. 3H–3He ages, stable oxygen and hydrogen isotopes and major ion concentrations show that the freshwater lens reaches a depth of 44mbsl, where an aquitard constrains further expansion in vertical direction. Groundwater ages are increasing from 4.4years in 12mbsl up to >70years at the freshwater–saltwater interface. Stable isotope signatures reflect average local precipitation signatures. An annual recharge rate of 300–400mm was calculated with 3H–3He data. Freshwater is primarily of Na–Ca–Mg–HCO3– and Ca–Na–HCO3–Cl type, while lowly mineralized precipitation and saltwater are of Na–Cl types. A trend towards heavier stable isotope signatures and higher electric conductivities in the shallower, younger groundwater within the freshwater lens may indicate increasing atmospheric temperatures in the last 30years.
Oceanic ⁸⁷Sr/⁸⁶Sr-isotope ratios are strongly influenced by rates of silicate weathering and therefore linked not only to glaciation but also to sea-level change. The present study combines analysis ...of sequence stratigraphy and basin architecture with Sr-isotope stratigraphy in Miocene shallow-water sediments in southern Portugal and Crete (Greece). The common method is to use smoothed global sea water Sr-isotope reference curves but here a different approach is chosen. Instead, measured Sr-isotope curves are correlated with unsmoothed reference curves by identification of similar fluctuations in the order of several 100 kyr. Transgressive intervals are characterized by increasing Sr-isotope ratios interpreted as corresponding to intensified silicate weathering as a consequence of deglaciation, while lowstand deposits have low Sr-isotope ratios. Comparison of Sr-isotope curves and sedimentary sequences in the studied basins with independent global δ¹⁸O data and data on global sea-level might suggest a general relationship, supporting a connection to global climate change. Because of these relationships, the method presented herein has a high potential for use in high-resolution age dating and is also applicable in shallow-water sediments.
New Zealand’s offshore sedimentary basins Bland, Kyle J.; Strogen, Dominic P.; Arnot, Malcolm J. ...
New Zealand journal of geology and geophysics,
02/2024
Journal Article
Commercial silicon heterojunction modules known as heterojunction with intrinsic (amorphous silicon) thin-film layer (HIT) modules show average degradation after 10 years in the field. HIT modules ...weathered outdoors in Colorado and Florida have reduced photoluminescence intensity compared to a control module and have degradation dominated by voltage loss. Deep level transient spectroscopy (DLTS) detects three electron-trap defect states in all modules with activation energies of 0.07, 0.16, and 0.50eV. DLTS on the weathered modules shows an additional deep-level, electron-trap defect state with an activation energy of 0.52eV.
Modern scleractinian corals are classical components of marine shallow warm water ecosystems. Their occurrence and diversity patterns in the geological record have been widely used to infer past ...climates and environmental conditions. Coral skeletal composition data reflecting the nature of the coral environment are often affected by diagenetic alteration. Ghost structures of annual growth rhythms are, however, often well preserved in the transformed skeleton. We show that these relicts represent a valuable source of information on growth conditions of fossil corals. Annual growth bands were measured in massive hemispherical Porites of late Miocene age from the island of Crete (Greece) that were found in patch reefs and level bottom associations of attached mixed clastic environments as well as isolated carbonate environments. The Miocene corals grew slowly, about 2–4 mm yr−1, compatible with present‐day Porites from high‐latitude reefs. Slow annual growth of the Miocene corals is in good agreement with the position of Crete at the margin of the Miocene reef belt. Within a given time slice, extension rates were lowest in level bottom environments and highest in attached inshore reef systems. Because sea surface temperatures (SSTs) can be expected to be uniform within a time slice, spatial variations in extension rates must reflect local variations in light levels (low in the level bottom communities) and nutrients (high in the attached reef systems). During the late Miocene (Tortonian–early Messinian), maximum linear extension rates remained remarkably constant within seven chronostratigraphic units, and if the relationship of SSTs and annual growth rates observed for modern massive Indo‐Pacific Porites spp. applies to the Neogene, minimum (winter) SSTs were 20°–21°C. Although our paleoclimatic record has a low resolution, it fits the trends revealed by global data sets. In the near future we expect this new and easy to use Porites thermometer to add important new information to our understanding of Neogene climate.
Laser cutting and micromachining can be applied to solar cell materials for processing and characterization applications. An ultrashort pulse (USP) laser with sub-picosecond pulse width can remove ...material with minimal thermal effects or damage, which is termed `cold ablation'. Such USP laser cutting and scribing can be implemented for isolating areas within a larger cell while maintaining electrical performance and preventing laser-induced damage and shunting. Laser micromachining has been used to isolate a shunt to improve cell performance and to isolate a small, selected area to define a sample suitable for deep level transient spectroscopy.
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