Fission barrier of superheavy nuclei and persistence of shell effects at high spin: cases of 254No and 220Th.

We report on the first measurement of the fission barrier height in a heavy shell-stabilized nucleus. The fission barrier height of 254No is measured to be Bf=6.0±0.

Solvent effect on distribution ratio of Pd(II) in supercritical carbon dioxide extraction and solvent extraction using 2-methyl-8-quinolinol.

The distribution ratio (D(M)) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO(2)) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of logD(M) versus pH plot and logD(M) versus HMQ concentration plot, the extracted species both in the SF-CO(2) extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ)(2). The distribution constant of HMQ (K(D,HMQ)) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ (D(HMQ)) on the pH.

Spectrophotometric measurement of uranium(VI)-tributylphosphate complex in supercritical carbon dioxide.

UV-visible absorption spectra of uranium(VI)-tributylphosphate (U(VI)-TBP) complex dissolved in supercritical CO(2) at 40-60 degrees C and 100-250 kg cm(-2) were recorded. Wavelengths and molar extinction coefficients for the absorption peaks of U(VI)-TBP were determined and confirmed to be in good agreement with those of UO(2)(NO(3))(2)(TBP)(2) complex dissolved in organic solvents such as n-hexane. The absorbance at a given wavelength was proportional to the concentration of U(VI) species in supercritical CO(2), indicating a feasibility of in-situ determination of U(VI) concentration in CO(2) phase.

High-repetition rate 1-J green laser system.

A laser-diode-pumped high-repetition-rate zigzag slab Nd:YAG oscillator-amplifier system is developed as the pumping source of a high-average-power and terawatt Ti:sapphire chirped pulse amplification laser system. This system can produce a greater than 2-J high-energy fundamental laser pulse at a repetition rate of 100 Hz. The frequency-doubled energy with a diffusion-bonded KTP crystal is 1 J at a repetition rate of 100 Hz.

Comparison of mechanically ruled versus holographically varied line-spacing gratings for a soft-x-ray flat-field spectrograph.

Recent progress in the design of aspheric wave-front recording systems has permitted the manufacture of holographic gratings with highly variable groove densities that are suitable for flat-field spectrographs. A holographic grating thus recorded was processed to produce a laminar profile by use of reactive-ion etching. Measurements are reported of the absolute diffraction efficiency of this grating and of a comparable mechanically ruled grating.

RCA/IAEA third external dosimetry intercomparisons in East Asia region.

Several intercomparison exercises were organised by the International Atomic Energy Agency (IAEA) on the determination of operational quantities at the regional or interregional basis. In East Asia region, a third phase of the intercomparison finished in mid 2004. It was organised within the frame of the Regional Cooperation Agreement (RCA) as a follow-up to previous exercises carried out during 1990-1992 and 1995-1996.

Anthropogenic radionuclides in sediment in the Japan Sea: distribution and transport processes of particulate radionuclides.

Distributions of anthropogenic radionuclides ((90)Sr, (137)Cs and (239+240)Pu) in seabed sediment in the Japan Sea were collected during the period 1998-2002. Concentration of (90)Sr, (137)Cs and (239+240)Pu in seabed sediment was 0.07-1.

Quantum-control spectroscopy with exact state selectivity.

A method of exact state-selective spectroscopy is introduced, based on quantum control through four specific short laser pulses. The exact conditions for the two pairs of ultrafast pulses are set by the feedback control for selective excitation to one specific resonance state while the other state is destructively interfered as the shadow pair, leading to a state-selective spectrum.

A small acidic protein 1 (SMAP1) mediates responses of the Arabidopsis root to the synthetic auxin 2,4-dichlorophenoxyacetic acid.

2,4-dichlorophenoxyacetic acid (2,4-D), a chemical analogue of indole-3-acetic acid (IAA), is widely used as a growth regulator and exogenous source of auxin. Because 2,4-D evokes physiological and molecular responses similar to those evoked by IAA, it is believed that they share a common response pathway. Here, we show that a mutant, antiauxin resistant1 (aar1), identified in a screen for resistance to the anti-auxin p-chlorophenoxy-isobutyric acid (PCIB), is resistant to 2,4-D, yet nevertheless responds like the wild-type to IAA and 1-napthaleneacetic acid in root elongation and lateral root induction assays.

Japanese adult male voxel phantom constructed on the basis of CT images.

A Japanese adult male voxel (volume pixel) phantom (hereinafter referred to as the JM phantom) was constructed on the basis of CT images of a healthy Japanese adult male volunteer. Body characteristics of the JM phantom were compared with those of a voxelised MIRD5 type phantom and a Japanese adult male voxel phantom which was previously developed. The voxel size of the JM phantom is 0.

The roles of specific glycosylases in determining the mutagenic consequences of clustered DNA base damage.

The potential for genetic change arising from specific single types of DNA lesion has been thoroughly explored, but much less is known about the mutagenic effects of DNA lesions present in clustered damage sites. Localized clustering of damage is a hallmark of certain DNA-damaging agents, particularly ionizing radiation. We have investigated the potential of a non-mutagenic DNA base lesion, 5,6-dihydrothymine (DHT), to influence the mutagenicity of 8-oxo-7,8-dihydroguanine (8-oxoG) when the two lesions are closely opposed.

Structural kinetics studies on phase transitions of the Bi UPD layer between the (2 x 2) and (p x square root[3]) structures using surface X-ray diffraction.

The kinetics of the phase transition between the (2 x 2) and (p x square root[3])-Bi structures on Au(111) was investigated using electrochemical methods and time-resolved surface X-ray diffraction. The temporal changes in the current value and the diffracted X-ray intensity that originated from the (2 x 2)-Bi overlayer were monitored during the phase transitions at various over-potentials. The phase transition models and kinetics parameters were deduced from each of the current and X-ray intensity transient curves.

Concentration and daily excretion of uranium in urine of Japanese.

A study was undertaken to investigate uranium concentrations in urine samples for unexposed Japanese individuals and to evaluate uranium daily excretion. Uranium concentrations were measured with inductively coupled plasma mass spectrometry after microwave-assisted digestion and online separation using the UTEVA extraction chromatographic resin. The concentrations ranged from 0.

Quasi-Kondo phenomenon due to the dynamical Jahn-Teller effect.

A mechanism of the nonmagnetic Kondo effect is proposed on the basis of a multiorbital Anderson model coupled with dynamical Jahn-Teller (JT) phonons. An electron system coupled dynamically with JT phonons has a vibronic ground state with double degeneracy due to clockwise and anticlockwise rotational modes with entropy of log2. When a temperature is lower than a characteristic energy to turn the rotational direction, the rotational degree of freedom is eventually suppressed and the corresponding entropy is released, leading to quasi-Kondo behavior.

Soft X-ray beamline specialized for actinides and radioactive materials equipped with a variably polarizing undulator.

This report presents the design of an undulator beamline at SPring-8 to be used for soft X-ray spectroscopy focused on radioactive materials. Photoemission spectroscopy experiments are carried out in a radioisotope (RI)-controlled area where actinide compounds as well as unsealed radioactive materials are usable. Intrusion of the radioactive materials into the electron storage ring or to the outside of the evacuated beamline components can be avoided by a specially devised RI protection/inspection mechanism.

Characterisation of radionuclides formed by high-energy neutron irradiation.

The physicochemical properties of radionuclides suspended in the air are important parameters in order to evaluate internal doses due to the inhalation of the airborne radionuclides and to develop the air-monitoring system in high-energy proton accelerator facilities. This study focuses on the property of radioactive airborne chlorine (38Cl and 39Cl) and sulphur (38S) produced in Ar gas by irradiation with high-energy neutrons. As a result of the irradiation of a mixture of Ar gas and dry air, 38Cl and 39Cl existed as non-acidic gas and 38S was present as acidic gas.

Comparison of thermal neutron distributions within shield materials obtained by experiments, SN and Monte Carlo code calculations.

Benchmark experiments of thermal neutron distributions within the shield materials, graphite pile and pure water, were performed by using 252Cf fission neutrons and gold foil activation detectors, and, to these results, the estimates obtained by using the discrete ordinate code ANISN and the Monte Carlo code MCNP5 with two different cross-section libraries, ENDF/B-VI and the Japanese new version of JENDL-3.3, were compared. The results revealed that the MCNP5 calculations with the two libraries closely agree with the experiments and that there are slight differences between the MCNP5 and the ANISN calculations.

Shielding analysis at the upper section of the accelerator-driven system.

The proton beam duct of the accelerator-driven system (ADS) acts as a streaming path for spallation neutrons and photons and causes the activation of the magnets and other devices above the subcritical core. We have performed a streaming analysis at the upper section of the lead-bismuth target/cooled ADS (800 MWth). MCNPX was used to calculate the radiation dose from streamed neutrons and photons through the beam duct.

Dose calculation system for remotely supporting radiotherapy.

The dose calculation system IMAGINE is being developed keeping in mind remotely supporting external radiation therapy using photon beams. The system is expected to provide an accurate picture of the dose distribution in a patient body, using a Monte Carlo calculation that employs precise models of the patient body and irradiation head. The dose calculation will be performed utilising super-parallel computing at the dose calculation centre, which is equipped with the ITBL computer, and the calculated results will be transferred through a network.

Shielding design of the ITER NBI duct for nuclear and bremsstrahlung radiation.

Three-dimensional Monte Carlo shielding analyses are conducted on the ITER Neutral Beam Injection (NBI) duct for the nuclear and bremsstrahlung radiation. The detailed distribution is evaluated about the nuclear heating rate and surface heat load of the NBI duct wall by the neutron and photon transport calculation. The analytical representations of these nuclear responses are established as a function of the distance from the blanket surface.

Element-specific surface X-ray diffraction study of GaAs(001)-c(4 x 4).

In situ structure analysis of GaAs(001)-c(4 x 4) has been carried out by synchrotron surface x-ray diffraction, which is sensitive to the three-dimensional structure and the atomic species. On the basis of 98 independent in-plane diffractions and 11 fractional-order rod profiles, the atomic coordinates and thermal vibration parameters were determined. X-ray diffraction results show the buckling of surface dimers and a strain field extending up to the sixth layer from the surface.

Method for detecting DNA strand breaks in mammalian cells using the Deinococcus radiodurans PprA protein.

In a previous study, we identified the novel protein PprA that plays a critical role in the radiation resistance of Deinococcus radiodurans. In this study, we focussed on the ability of PprA protein to recognize and bind to double-stranded DNA carrying strand breaks, and attempted to visualize radiation-induced DNA strand breaks in mammalian cultured cells by employing PprA protein using an immunofluorescence technique. Increased PprA protein binding to CHO-K1 nuclei immediately following irradiation suggests the protein is binding to DNA strand breaks.

Development of lung and soft tissue substitutes for photons.

The use of solid tissue substitutes is a well-accepted and common practice in dosimetric studies and in the production of counting standards for radiological protection. However, only a few solid tissue substitutes simulating a particular body tissue with respect to a set of physical characteristics are commercially available. Hence, we have developed polyurethane-based tissue substitutes simulating soft tissue, muscle, muscle-adipose mixture tissue (90% muscle + 10% adipose), brain, cartilage, larynx, thyroid, trachea, liver, kidney, skin and lungs.

Calculations for the availability of photoneutron using synchrotron radiation.

The availability of the neutrons due to photonuclear reactions has been discussed by using synchrotron radiation with the beryllium targets. The superconducting wiggler with the magnetic field of approximately 10 T, which is installed into an 8 GeV class storage ring, can emit intense and high-energy photons to produce neutrons. By using MCNPX, the simulations were performed for the conceptual design of the neutron beamline to estimate the available intensity and to investigate the shield conditions.

High Intensity Proton Accelerator Project in Japan (J-PARC).

The High Intensity Proton Accelerator Project, named as J-PARC, was started on 1 April 2001 at Tokai-site of JAERI. The accelerator complex of J-PARC consists of three accelerators: 400 MeV Linac, 3 GeV rapid cycle synchrotron and 50 GeV synchrotron; and four major experimental facilities: Material and Life Science Facility, Nuclear and Particle Physics Facility, Nuclear Transmutation Experiment Facility and Neutrino Facility. The outline of the J-PARC is presented with the current status of construction.