Japan Atomic Energy Agency

About: Japan Atomic Energy Agency is a government organization based out in Tōkai-mura, Japan. It is known for research contribution in the topics: Neutron & Laser. The organization has 7151 authors who have published 17791 publications receiving 259118 citations. The organization is also known as: JAEA & Nihon genshiryoku kenkyū kaihatsu kikō.

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

Abstract: We demonstrate a novel pathway to control and stabilize oxygen vacancies in complex transition-metal oxide thin films. Using atomic layer-by-layer pulsed laser deposition (PLD) from two separate targets, we synthesize high-quality single-crystalline CaMnO3 films with systematically varying oxygen vacancy defect formation energies as controlled by coherent tensile strain. The systematic increase of the oxygen vacancy content in CaMnO3 as a function of applied in-plane strain is observed and confirmed experimentally using high-resolution soft X-ray absorption spectroscopy (XAS) in conjunction with bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES). The relevant defect states in the densities of states are identified and the vacancy content in the films quantified using the combination of first-principles theory and core–hole multiplet calculations with holistic fitting. Our findings open up a promising avenue for designing and controlling new ionically active properties and functionalities of com...

Fluence-to-dose conversion coefficients for neutrons and protons calculated using the PHITS code and ICRP/ICRU adult reference computational phantoms.

Abstract: The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation and tissue weighting factors, w(R) and w(T), respectively, as revised in ICRP Publication 103 were employed. The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of the absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. By comparing these data with the corresponding data for the effective dose, we found that the numerical compatibilities of the revised w(R) with the Q(L) and Q(y) relationships are fairly established. The calculated data of these dose conversion coefficients are indispensable for constructing the radiation protection systems based on the new recommendations given in ICRP103 for aircrews and astronauts, as well as for workers in accelerators and nuclear facilities.

Isolated electron spins in silicon carbide with millisecond-coherence times

Abstract: The elimination of defects from SiC has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. Here, we show that individual electron spin states in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled. Bound to neutral divacancy defects, these states exhibit exceptionally long ensemble Hahn-echo spin coherence, exceeding 1 ms. Coherent control of single spins in a material amenable to advanced growth and microfabrication techniques is an exciting route to wafer-scale quantum technologies.

Mutagenic effects of ion beam irradiation on rice

Abstract: We investigated the usefulness of ion beams for mutation breeding in rice (Oryza sativa L.) by comparing the efficiency (i.e., the ratio of desirable mutations to plant damage such as lethality and sterility), mutation rate, spectrum, and optimum dose to that of gamma rays. Rice seeds were irradiated with carbon ions (mean linear energy transfer = 76 and 107 keV/μm), helium ions (9 keV/μm), and gamma rays, and their survival and fertility were examined in the M1 generation. The frequency of chlorophyll mutations and their types (albina, xantha, and viridis) were examined in the M2 generation, using the M1-plant progeny method. The efficiency of ion beams either equaled or exceeded that of gamma rays. In addition, the mutation rate of ion beams was higher than that of gamma rays. Thus, ion beams appeared to efficiently induce mutants with little radiation damage. No remarkable difference was observed in the relative frequencies of each type of mutation among 3 types of ion beams and gamma rays, thus suggesting that there was no difference in the spectrum. A shoulder dose, which hardly affected survival, was sufficient to efficiently obtain mutants for both types of radiation.