Takasaki Advanced Radiation Research Institute

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Takasaki, Japan
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Choi S.,Harvard University | Choi J.,Harvard University | Landig R.,Harvard University | Kucsko G.,Harvard University | And 10 more authors.
Nature | Year: 2017

Understanding quantum dynamics away from equilibrium is an outstanding challenge in the modern physical sciences. Out-of-equilibrium systems can display a rich variety of phenomena, including self-organized synchronization and dynamical phase transitions. More recently, advances in the controlled manipulation of isolated many-body systems have enabled detailed studies of non-equilibrium phases in strongly interacting quantum matter; for example, the interplay between periodic driving, disorder and strong interactions has been predicted to result in exotic 'time-crystalline' phases, in which a system exhibits temporal correlations at integer multiples of the fundamental driving period, breaking the discrete time-translational symmetry of the underlying drive. Here we report the experimental observation of such discrete time-crystalline order in a driven, disordered ensemble of about one million dipolar spin impurities in diamond at room temperature. We observe long-lived temporal correlations, experimentally identify the phase boundary and find that the temporal order is protected by strong interactions. This order is remarkably stable to perturbations, even in the presence of slow thermalization. Our work opens the door to exploring dynamical phases of matter and controlling interacting, disordered many-body systems.


Sawada S.-I.,Takasaki Advanced Radiation Research Institute | Hasegawa S.,Takasaki Advanced Radiation Research Institute | Zhao Y.,Takasaki Advanced Radiation Research Institute | Maekawa Y.,Takasaki Advanced Radiation Research Institute
Journal of Membrane Science | Year: 2017

We prepared proton exchange membranes (PEMs) composed of block-type polymers by a combination of radiation-induced graft polymerization (RIGP) and atom-transfer radical polymerization (ATRP). This process involves the following three steps: (i) RIGP of styrene (St) and chloromethylstyrene (CMS) into poly(ethylene-co-tetrafluoroethylene) (ETFE) films; (ii) the ATRP of ethyl styrene sulfonate (EtSS) starting from the grafted CMS units; and (iii) hydrolysis of the EtSS-grafted film, converting poly(EtSS) to poly(styrene sulfonic acid) (PSSA). The ATRP of EtSS (step (ii)), the key process in our preparation method, was successfully performed by controlling the catalyst concentration at a relatively-low temperature (50 ºC), under the condition of which undesirable thermal polymerization was suppressed. The grafting degree during ATRP could be controlled and ranged from 24% to 240%, resulting in the preparation of PEMs with ion exchange capacities ranging from 0.96 to 2.9 mmol/g. Thus, we have demonstrated that ATRP reactions can be carried out inside solid polymer films. At 30% relative humidity and 80 ºC, the block-type PEMs exhibited higher proton conductivities and water contents than those of the conventional RIGP-PEMs. In the block-type PEMs, the hydrophilic proton-conducting PSSA grafts are separated from the ETFE matrix by the hydrophobic polystyrene grafts. Hence, the PSSA-graft-chain aggregation occurs, creating a well-connected ion channel network, which in turn results in increased proton conduction. © 2017 Elsevier B.V.


Awual M.R.,Kumamoto University | Awual M.R.,Japan National Institute of Materials Science | Jyo A.,Kumamoto University | Ihara T.,Kumamoto University | And 3 more authors.
Water Research | Year: 2011

This study was investigated for the trace phosphate removal at high feed flow rate by ligand exchange fibrous adsorbent. The zirconium(IV) loaded bifunctional fibers containing both phosphonate and sulfonate were used as a highly selective ligand exchange adsorbent for trace phosphate removal from water. The precursory fiber of the bifunctional fibers was co-grafted by polymerization of chloromethylstyrene and styrene onto polyethylene coated polypropylene fiber and then bifunctional fibers were prepared by Arbusov reaction followed by phosphorylation and sulfonation. Phosphate adsorption experimental work was carried out in column approach. Phosphate adsorption increased with decreasing the pH of feed solutions. An increase in the feeds flow rate brings a decrease in both breakthrough capacity and total adsorption. The effect of competing anions on phosphate adsorption systems was investigated. The experimental findings reveal that the phosphate adsorption was not affected in the presence of competing anions such as chloride and sulfate despite the enhancement of the breakthrough points and total adsorption. Due to high selectivity to phosphate species, low concentration level of phosphate (0.22mg/L) was removed at high feed flow rate of 450h -1 in space velocity. The adsorbed phosphate on the Zr(IV) loaded fibrous column was quantitatively eluted with 0.1M NaOH solution and then the column was regenerated by 0.5M H 2SO 4 for the next adsorption operation. During many adsorption-elution-regeneration cycles, no measurable Zr(IV) was found in the column effluents. Therefore, the Zr(IV) loaded bifunctional fibrous adsorbent is to be an effective means to treat wastewater to prevent eutrophication in the receiving water bodies for long time without any deterioration. © 2011 Elsevier Ltd.


Ishii Y.,Takasaki Advanced Radiation Research Institute | Ohkubo T.,Takasaki Advanced Radiation Research Institute | Kojima T.,Takasaki Advanced Radiation Research Institute | Kamiya T.,Takasaki Advanced Radiation Research Institute
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2011

A compact focusing lens system with high demagnification over 1500 was designed to form an ion nanobeam with 346 keV energy by adding a short distance acceleration tube for beam acceleration and focusing downstream of the existing double acceleration lens system. The demagnification, focusing points and aberrations of the acceleration tube were studied using beam trajectory calculation. The acceleration tube was designed to have a length of 140 mm and a demagnification of 2 at its acceleration tube voltage of 300 kV, which resulted in a new compact focusing lens system with a total length of about 640 mm. In addition, the maximum voltage and electric-field of the acceleration tube were confirmed experimentally on the built device to be 300 kV and 30 kV/cm, respectively. The final beam size formed by the system was estimated to be 130 nm in diameter using the design parameters. The result suggests that an ion nanobeam of 346 keV can be formed by an apparatus having the reasonable length of 2 m, which permits us to develop a system for 1 MV by elongating its tube length.


Ohkubo T.,Takasaki Advanced Radiation Research Institute | Ishii Y.,Takasaki Advanced Radiation Research Institute | Miyake Y.,Beam Inc | Kamiya T.,Takasaki Advanced Radiation Research Institute
AIP Conference Proceedings | Year: 2013

A new 300 kV compact focused gaseous ion beam (gas-FIB) system with three-stage acceleration lens was constructed at JAEA. The preliminary experiments of formation of the focused gaseous ion beams were carried out to show the availability of the gas-FIB system as a writing tool for 3D proton lithography. As a result of the experiments, it was proved that the focal point was kept at the same position under changing the kinetic energy but with keeping the kinetic energy ratio constant, which was defined as the ratio of kinetic energy in object side to that in image side for the third acceleration lens. This characteristic of the gas-FIB is a good point to advance the 3D proton lithography changing penetration depth in a sample by varying the beam energy. © 2013 AIP Publishing LLC.


Kitamura A.,Takasaki Advanced Radiation Research Institute | Satoh T.,Takasaki Advanced Radiation Research Institute | Koka M.,Takasaki Advanced Radiation Research Institute | Kobayashi T.,RIKEN | Kamiya T.,Takasaki Advanced Radiation Research Institute
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2013

Polytetrafluoroethylene (PTFE) is a typical fluoropolymer and it has several desirable technological properties such as electrical insulation, solid lubrication etc. However, the conventional microstructuring methods have not been well applied to PTFE due to its chemical inertness. Some effective micromachining using synchrotron radiation or ion beam irradiation has been reported. In this study, we create micro-prominences by raising the original surface using proton beam writing (PBW) without chemical etching. A conical prominence was formed by spiral drawing from the center with a 3 MeV proton beam. The body was porous, and the bulk PTFE below the prominence changed to fragmented structures. With decreasing writing speed, the prominence became taller but the height peaked. The prominence gradually reduced in size after the speed reached the optimum value. We expect that these porous projections with high aspect ratio will be versatile in medical fields and microelectromechanical systems (MEMS) technology. © 2013 Elsevier B.V. All rights reserved.


Ohkubo T.,Takasaki Advanced Radiation Research Institute | Ishii Y.,Takasaki Advanced Radiation Research Institute | Kamiya T.,Takasaki Advanced Radiation Research Institute
AIP Conference Proceedings | Year: 2011

The focused gaseous ion beam (gas-FIB) system composed of a series of electrostatic lenses, called "acceleration lens system", has been developed to form nanobeams using gaseous ions generated from a plasma ion source. Ion beams are accelerated and focused simultaneously by a pair of electrodes. A new all-in-one compact acceleration system including an acceleration tube is now under development to form 300 keV ion nanobeam. Chromatic and spherical aberrations are, however, hindrance to form nanobeams with their smaller sizes in diameter. A deceleration lens, which performs like a defocusing lens, was theoretically introduced to downstream of the present acceleration lens system to reduce the aberrations. Ion beam optics simulations were carried out to show that this aberration reduction technique is effective to reduce chromatic and spherical aberrations. As a result, we reduced the chromatic aberration coefficient by 26%, the spherical aberration coefficient by 17% and a beam diameter by 17%, with the deceleration energy of 15 keV. In case of using an electrostatic acceleration tube with 100 mm length, the final beam diameter of 103 nm at 300 keV is obtained by the all-in-one acceleration lens system with the total acceleration length of only 650 mm. © 2011 American Institute of Physics.


Satoh T.,Takasaki Advanced Radiation Research Institute | Koka M.,Takasaki Advanced Radiation Research Institute | Kada W.,Gunma University | Yokoyama A.,Takasaki Advanced Radiation Research Institute | Kamiya T.,Takasaki Advanced Radiation Research Institute
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2014

We have developed a real-time single-ion hit position detecting system to replace a CR-39 solid-state nuclear-track detector for cell irradiation experiments because the CR-39 takes several minutes for off-line etching. The new real-time system consists of a 500-μm-thick CaF2(Eu) scintillator, an optical microscope with a 10× objective lens, and a high-gain charge-coupled device camera. Each of the 260-MeV neon ions passing through a 100-μm-thick CR-39 sheet was detected using the real-time system in a performance test for the spatial resolution. The full width at half maxima (FWHMs) of the distances between positions detected by the real-time system and the centers of the etch pits on CR-39 were 6.5 and 6.9 μm in the x and y directions, respectively. The result shows that the system is useful for typical cultured cells of a few tens of micrometers in size. © 2014 Elsevier B.V. All rights reserved.


Kada W.,Gunma University | Satoh T.,Takasaki Advanced Radiation Research Institute | Yokoyama A.,Takasaki Advanced Radiation Research Institute | Koka M.,Takasaki Advanced Radiation Research Institute | Kamiya T.,Takasaki Advanced Radiation Research Institute
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2014

Confocal optics for ion luminescence (IL) was developed for the precise analysis of the chemical composition of microscopic targets with an external proton microbeam probe. Anti-reflection-coated confocal micro-lens optics with an effective focus area of approximately 800 × 800 μm was installed on the microbeam line of a single-ended accelerator. Chromatic aberrations of the confocal optics were examined at wavelengths of 300-900 nm. An electrically-cooled back-thinned charge coupled device spectrometer with a wavelength resolution of 0.5 nm was used for the microscopic spectroscopy and IL imaging of microscopic mineral targets. Simultaneous microscopic IL and micro-PIXE analysis were performed using an external 3 MeV H+ microbeam with a current of less than 100 pA. A spectral resolution of 3 nm was achieved for a single IL peak which corresponded to Cr3+ impurities in a single-crystal of aluminum oxide. The use of IL spectroscopy and imaging for aerosol targets revealed microscopic distributions of the chemical and elemental composition in the atmosphere. © 2013 Elsevier Ltd. All rights reserved.


Ohkubo T.,Takasaki Advanced Radiation Research Institute | Ishii Y.,Takasaki Advanced Radiation Research Institute
Review of Scientific Instruments | Year: 2015

A compact focused gaseous ion beam system has been developed to form proton microbeams of a few hundreds of keV with a penetration depth of micrometer range in 3-dimensional proton beam writing. Proton microbeams with kinetic energies of 100-140 keV were experimentally formed on the same point at a constant ratio of the kinetic energy of the object side to that of the image side. The experimental results indicate that the beam diameters were measured to be almost constant at approximately 6 μm at the same point with the kinetic energy range. These characteristics of the system were experimentally and numerically demonstrated to be maintained as long as the ratio was constant. © 2015 AIP Publishing LLC.

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