Innovative energy and environmental technologies have an important role in achieving carbon neutrality. However, uncertainties regarding the potential of these technologies still remain. For this ...reason, possible scenarios for such technologies must be developed to facilitate forward-looking decision-making on national energy strategies. This study investigated multiple scenarios of future energy systems in Japan to achieve net-zero CO2 emissions by 2050 using a MARKAL (MARKet ALlocation) energy model. Six cases were configured based on different assumptions of renewable and nuclear power, carbon capture and storage, and hydrogen import, and the CO2 emissions, primary energy supply, final energy consumption, and electricity generation were compared for the different cases. The scenario analysis results suggest that electric power systems in Japan should be fully decarbonized by 2040 in order to achieve carbon neutrality by 2050, implying that renewable power generation should be dominant in the decarbonized electricity sector in Japan. The results also indicate that total energy supply and consumption in 2050 will be between 14.9–15.7 and 9.6–10.2 EJ, respectively, and that 211–256 Mt of CO2 will need to be removed using advanced CO2 removal technologies. The results further imply that CO2 removal technologies will become necessary when industrial decarbonization is difficult.
•We built six scenarios of future energy systems in Japan toward carbon neutrality.•We used a MARKet ALlocation (MARKAL) energy model.•Power sector must reduce CO2 to ∼0 by 2040 to achieve carbon neutrality by 2050.•Total energy supply and consumption in 2050 will be 14.9–15.7 and 9.6–10.2 EJ.•Using advanced CO2 removal technologies, 211–256 Mt of CO2 must be removed.
The masses of ^{246}Es, ^{251}Fm, and the transfermium nuclei ^{249-252}Md and ^{254}No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N=152 neutron shell closure, have ...been directly measured using a multireflection time-of-flight mass spectrograph. The masses of ^{246}Es and ^{249,250,252}Md were measured for the first time. Using the masses of ^{249,250}Md as anchor points for α decay chains, the masses of heavier nuclei, up to ^{261}Bh and ^{266}Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ_{2n} derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N=152 neutron shell closure for Md and Lr.
The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the ...underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in
C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on
C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.
Nuclear size and related topics Ozawa, A.; Suzuki, T.; Tanihata, I.
Nuclear physics. A,
10/2001, Letnik:
693, Številka:
1
Journal Article
Recenzirano
Experimental studies on nuclear sizes and related topics are reviewed. The recent development of radioactive nuclear beams has enabled us to study the nuclear sizes of unstable nuclei. The nuclear ...sizes for unstable nuclei, which are deduced by the interaction cross sections and reaction cross sections, are mainly reviewed. From a theoretical view point, a Glauber-model analysis is important to deduce nuclear sizes. Other related topics, such as halo and skin from a nuclear size point of view are also discussed.
The local compression (LC) technique is used to achieve a straight crack front in weld specimens. However, some interested parties have reported that it results in an excessive underestimation of the ...fracture toughness value. In a previous study, the authors investigated an improved LC condition for securing a straight crack front while maintaining the fracture toughness value through a numerical analysis and fracture toughness tests. As a result, it was found that two local compression conditions which do not apply compression at the future notch tip are superior to the typical LC. However, since these proposed conditions were identified based on the experience of the authors, there may be others that will yield better results. In this study, Bayesian optimization was conducted to identify an improved LC condition. Because the results indicated that the compression area and position are important for improving LC, the conditions for a validation experiment were determined based on these parameters. The proposed LC condition achieved a straight crack front, and the fracture toughness was higher than under the condition recommended in ISO 15653. Therefore, the authors concluded that the condition for improvement of LC was successfully identified by the Bayesian optimization.
We generated a series of harmonics in a xenon gas jet inside a cavity seeded by pulses from a Ti:sapphire mode-locked laser with a repetition rate of 10.8 MHz. Harmonics up to 19th order at 43 nm ...were observed with plateau harmonics at the microW power level. An elaborate dispersion compensation scheme and the use of a moderate repetition rate allowed for this significant improvement in output power of the plateau harmonics of 4 orders of magnitude over previous results. With this power level and repetition rate, high-resolution spectroscopy in the extreme ultraviolet region becomes conceivable. An interesting target would be the 1S-2S transition in hydrogenlike He+ at 60 nm.
The Rare-RI Ring (R3) is a recently commissioned cyclotronlike storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory ...(RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF-^{127}Sn, ^{126}In, ^{125}Cd, ^{124}Ag, ^{123}Pd-were injected in R3. Masses of ^{126}In, ^{125}Cd, and ^{123}Pd were measured whereby the mass uncertainty of ^{123}Pd was improved. This is the first reported measurement with a new storage ring mass spectrometry technique realized at a heavy-ion cyclotron and employing individual injection of the preidentified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF. The impact of the new ^{123}Pd result on the solar r-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction Y_{e}. It is found that the neutron capture cross section on ^{123}Pd increases by a factor of 2.2 and β-delayed neutron emission probability, P_{1 n}, of ^{123}Rh increases by 14%. The neutron capture cross section on ^{122}Pd decreases by a factor of 2.6 leading to pileup of material at A=122, thus reproducing the trend of the solar r-process abundances. The trend of the two-neutron separation energies (S_{2n}) was investigated for the Pd isotopic chain. The new mass measurement with improved uncertainty excludes large changes of the S_{2n} value at N=77. Such large increase of the S_{2n} values before N=82 was proposed as an alternative to the quenching of the N=82 shell gap to reproduce r-process abundances in the mass region of A=112-124.
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•Precision masses of exotic nuclei define the r-process pathway.•A new storage-ring mass spectrometry is proposed.•Individual injection method with the fragment separator is ...invented.•Cyclotron-type isochronous storage ring is designed.•RI beam science will be expanded at RIBF.
Nuclear mass is of fundamental importance, reflecting a variety of structures and interactions formed by constituent nucleons embedded in the nucleus. Precision masses of extremely neutron-rich nuclei define the pathway of r-process nucleosynthesis. The identification of the r-process is one of the unanswered questions in physics in this century. A related challenge is to measure the masses of such short-lived rare isotopes with extremely low production rates. In conjunction with high-energy and high-intensity exotic RI beams available at the RIKEN RI Beam Factory, a new type of storage-ring mass spectrometry is being developed. The novel idea of a cyclotron-like storage ring coupled with an individual injection scheme is introduced in isochronous mass spectrometry.
An electrostatic time-of-flight detector named E-MCP has been developed for quick diagnostics of circulating beam and timing measurement in mass spectrometry at the Rare-RI Ring in RIKEN. The E-MCP ...detector consists of a conversion foil, potential grids, and a microchannel plate. Secondary electrons are released from the surface of the foil when a heavy ion hits it. The electrons are accelerated and deflected by 90∘ toward the microchannel plate by electrostatic potentials. A thin carbon foil and a thin aluminum-coated mylar foil were used as conversion foils. We obtained time resolutions of 69(1) ps and 43(1) ps (standard deviation) for a 84Kr beam at an energy of 170 MeV/u when using the carbon and the aluminum-coated mylar foils, respectively. A detection efficiency of approximately 90% was obtained for both foils. The E-MCP detector equipped with the carbon foil was installed inside the Rare-RI Ring to confirm particle circulation within a demonstration experiment on mass measurements of nuclei around 78Ge produced by in-flight fission of uranium beam at the RI Beam Factory in RIKEN. Periodic time signals from circulating ions were clearly observed. Revolution times for 78Ge, 77Ga, and 76Zn were obtained. The results confirmed successful circulation of the short-lived nuclei inside the Rare-RI Ring.
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