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Johansen, M. P.*; Carpenter, J. G.*; Charmasson, S.*; Gwynn, J. P.*; McGinnity, P.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*
Journal of Environmental Radioactivity, 268-269, p.107243_1 - 107243_10, 2023/11
被引用回数:1 パーセンタイル:0(Environmental Sciences)Po has been identified as one of the main contributors to ingestion doses to humans, particularly from the consumption of seafood. The amount of Po activity concentration data for various types of seafood has increased greatly in recent times. However, to provide realistic seafood dose assessments, most Po data requires correction to account for losses that can occur before the seafood is actually consumed. We develop generic correction factors for the main processes associated with reduction of Po in seafood - leaching during cooking, radioactive decay between harvest and consumption, and sourcing from mariculture versus wild-caught. When seafood is cooked, the overall mean fraction of Po retained is 0.74 for all cooking and seafood types, with the means for various seafoods and cooking categories ranging from 0.56 to 1.03. When considering radioactive decay between harvest and consumption, the overall mean fraction remaining is 0.81 across all seafood preservation/packaging types, with estimates ranging from 0.50 (canned seafood) to 0.98 (fresh seafood). Regarding mariculture influence, the available limited data suggest marine fish and crustaceans raised with processed feed have about one order of magnitude lower Po muscle content than wild-caught seafood of the same or similar species, although this ratio varies. Overall, this study concludes that Po activity concentrations in seafood at the time of ingestion may be reduced to only about 55% compared to when it was harvested. Therefore, correction factors must be applied to any data derived from environmental monitoring in order to achieve realistic dose estimates. The data also suggest lower Po ingestion doses for consumers who routinely favour cooked, long shelf-life and farmed fish/crustaceans. However, more data is needed in some categories, especially for cooking of molluscs and seaweed, and for the Po content in all farmed seafood.
Nowak, K.*; Wimmer, K.*; Hellgartner, S.*; Mcher, D.*; Bildstein, V.*; Diriken, J.*; Elseviers, J.*; Gaffney, L. P.*; Gernhuser, R.*; Iwanicki, J.*; et al.
Physical Review C, 93(4), p.044335_1 - 044335_10, 2016/04
被引用回数:18 パーセンタイル:77.39(Physics, Nuclear)The Ar()Ar two-neutron transfer reaction at 2.16 MeV/u was studied at CERN using a Ar radioactive beam and a tritium loaded radioactive target. Angular distributions for three final states were measured and based on the shape of the differential cross section an excited state at 3695 keV was identified as the first excited 0 state. The differential cross-sections for the 0-ground state, and first excited 2 and 0 states are compared to DWBA calculations including two-step reactions through the intermediate nucleus Ar. By comparison large scale shell model calculations using state-of-the-art effective interactions, with and without the tensor components of the interactions, it was observed that the cross-shell proton-neutron tensor interaction has measurable effects on the observables at low excitation energy in Ar.
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
Physics Letters B, 740, p.298 - 302, 2015/01
被引用回数:29 パーセンタイル:85.36(Astronomy & Astrophysics)Single-neutron states in Zn have been populated using the reaction Zn(d,p) at REX-Isolde, CERN. The analysis reveals that the lowest excited states in Zn lie at approximately 1 MeV, and involve neutron orbits above the N=50 shell gap. A 5/2 configuration was assigned to the 983-keV state. Comparison with large-scale shell model calculations supports a robust neutron N=50 shell closure for Ni. These data constitute an important step towards the understanding the magicity of Ni and the structure of nuclei in the region.
Terry, J. R.*; Brown, B. A.*; Campbell, C. M.*; Cook, J. M.*; Davies, A. D.*; Dinca, D.-C.*; Gade, A.*; Glasmacher, T.*; Hansen, P. G.*; Sherrill, B. M.*; et al.
Physical Review C, 77(1), p.014316_1 - 014316_12, 2008/01
被引用回数:77 パーセンタイル:95.33(Physics, Nuclear)ミシガン州立大学サイクロトロンにて、中性子過剰核Mgビームからの一粒子ノックアウト反応の断面積を測定した。その結果、Mgからのノックアウト反応によりMgの状態が多数観測され、負パリティ状態と考えられている状態を直接生成する断面積が大きいことがわかった。このことは、Mgの基底状態の波動関数に負パリティを持つpf軌道に中性子が励起した状態が相当含まれていないと説明されないことを意味し、モンテカルロ殻模型などが予言する2粒子2空孔励起の描像を強く支持するものである。さらに、この実験結果からスペクトロスコピック因子を引き出し、原子力機構でなされたモンテカルロ殻模型計算と比較したところ、両者の良い一致が得られた。すなわち、この「逆転の島」領域における殻模型の妥当性が示された。
Terry, J. R.*; Basin, D.*; Brown, B. A.*; Campbell, C. M.*; Church, J. A.*; Cook, J. M.*; Davies, A. D.*; Dinca, D.-C.*; Enders, J.*; Gade, A.*; et al.
Physics Letters B, 640(3), p.86 - 90, 2006/09
被引用回数:59 パーセンタイル:93.15(Astronomy & Astrophysics)アメリカ・ミシガン州立大学にある超伝導サイクロトロンを用いて生成された、中性子過剰核Neの一中性子ノックアウト反応により、Neの低励起状態を探索した。その結果、885keVの765keVの二つの励起状態が見つかった。中性子数20の魔法数が良いと仮定したsd殻模型計算では、この原子核では中性子分離エネルギーまでに一つしか励起状態がないとされるため、少なくともこれらのうち一つは魔法数を規定する20の殻ギャップを超えて中性子が励起した状態と結論づけられる。原子力機構で行ったモンテカルロ殻模型計算によると、中性子数20の殻ギャップがNe同位体ではかなり縮まるため、1粒子1空孔励起した配位が主である負パリティ状態が1MeV以下の低い励起エネルギーに出現することが予言されている。この実験結果はまさにそのような状態が存在することを示したものであり、Neにおける殻ギャップについて大きな知見を与えた。
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
no journal, ,
Single-neutron states in the = 49 isotope Zn were populated in the Zn(d,p)Zn transfer reaction at REX-ISOLDE, CERN. The combined detection of protons ejected in the reaction and of rays emitted by Zn permitted the identification of the lowest-lying 5/2 and 1/2 excited states. The analysis of proton angular distributions links these states to a significant amount of single-particle strength around 1 MeV, and specifically to the d and s neutron orbits, which lie above the = 50 neutron shell gap. Comparison with large-scale-shell-model calculations supports a robust = 50 shell-closure for Ni. These data constitute a considerable step towards the understanding of the magicity of Ni and of the structure of isotopes in the region.
Johansen, M. P.*; Carpenter, J. G.*; Charmasson, S.*; Gwynn, J. P.*; McGinnity, P.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*
no journal, ,
Artificial and natural radionuclides are known to accumulate in seafood worldwide and cause internal dose to seafood consumers. It has been nearly 30 years since the IAEA MARDOS global seafood dose assessment was published. Since then, world seafood consumption has increased, diet patterns have changed, and new inputs of radionuclides into marine systems have occurred. A new global assessment of seafood dose is being conducted that uses a much-expanded global database on radionuclides in seafood (Marine Radioactivity Information System -MARIS) as well as global diet data and updated parameters for dose calculation. The new assessment: (i) Evaluates 16 natural and anthropogenic radionuclides. (ii) Draws from more than 84,856 global data for biota in MARIS, from which 31,665 final activity concentration data passed quality assurance screening. (iii) Uses seafood consumption data from diet studies representing approximately 35% of the world population. (iv) Develops new correction factors for the loss of Po-210 from cooking and radiological decay as well as the decreases in Po-210 in maricultured seafood. (v) Implements a bespoke Monte Carlo application for calculating seafood dose distributions. (vi) Compiles and evaluates + 150 seafood ingestion dose estimates published in the past 30 years. The results provide well-supported estimates on the mean and distribution of background seafood dose for world consumers. This important new result provides a comparative reference for local, regional and national dose assessments; for the dose rates resulting from facility and accident releases, and for quantifying the global changes in ingestion dose from seafood over time. The assessment is being conducted within the IAEA Coordinated Research Project "Behaviour and Effects of Natural and Anthropogenic Radionuclides in the Marine Environment and their Use as Tracers for Oceanography Studies."