Whole-body counter surveys of over 2700 babies and small children in and around Fukushima Prefecture 33 to 49 months after the Fukushima Daiichi NPP accident

BABYSCAN, a whole-body counter (WBC) for small children was developed in 2013, and units have been installed at three hospitals in Fukushima Prefecture. Between December, 2013 and March, 2015, 2707 children between the ages of 0 and 11 have been scanned, and none had detectable levels of radioactive cesium. The minimum detectable activities (MDAs) for ¹³⁷Cs were ≤3.5 Bq kg⁻¹ for ages 0–1, decreasing to ≤2 Bq kg⁻¹ for ages 10–11. Including the ¹³⁴Cs contribution, these translate to a maximum committed effective dose of ∼16 µSv y⁻¹ even for newborn babies, and therefore the internal exposure risks can be considered negligibly small.Analysis of the questionnaire filled out by the parents of the scanned children regarding their families’ food and water consumption revealed that the majority of children residing in the town of Miharu regularly consume local or home-grown rice and vegetables, while in Minamisoma, a majority avoid tap water and produce from Fukushima. The data show, however, no correlation between consumption of locally produced food and water and the children’s body burdens.     

Estimation of the Optimum Concentration Interval of the Contents of Praseodymium, Neodymium, Europium, Holmium, and Erbium in a Solution

Based on the electronic absorption spectra of Pr³⁺, Nd³⁺, Eu³⁺, Ho³⁺, and Er³⁺ ions in 1 M aqueous solutions of chloric acid, calibration graphs have been constructed in a concentration of metals–optical density of a solution format for different frequencies. The band for praseodymium was used at 22,520 cm^–1, for neodymium at 17,380, 13,480, and 12,560 cm^–1, for europium at 25,380 cm^–1, for holmium at 18,580 and 15,580 cm^–1, and for erbium at 39,160, 26,480, and 19,160 cm^–1. The errors in determining the concentration of the indicated elements as a function of their content have been calculated. It is shown that for perchloric solutions of praseodymium it is possible to correctly determine its contents within the concentration range 0.1–1.5% at a frequency of 22,520 cm^–1; for neodymium the ranges are 0.4–1.0, 0.3–1.0, and 0.5–1.0% at 17,380, 13,480, and 12,560 cm^–1, respectively; for europium 0.4–1.5% at 25,380 cm^–1; for holmium — 0.2–1.5 and 0.4–1.5% at 15,580 and 18,580 cm^–1, and for erbium the range is 0.4–1.0% at frequencies of 39,160, 26,480, and 19,160 cm^–1.     

Laser investigations at 269 nm for XeF(D-X) in Ne crystals

From line narrowing in amplified spontaneous emission at the D-X transition (269nm) of XeF in solid Ne a gain coefficient of 3.4 cm^–1 has been derived and ground-state losses of 2.8 cm^–1 have been determined by variation of the absorption length. A dielectric laser cavity has been optimized with the reflectivities R₁=100% and R₂=70% for 1 cm long crystals; laser action has been achieved.     

Strangeness Nuclear Physics at J-PARC

After the big earthquake in the east part of Japan on March 11, 2011, the beams in the hadron experimental hall at J-PARC have been successfully recovered in February, 2012. The experimental program using pion beams is now on-going with the primary proton beam power of ~5 kW. Before a long summer shutdown scheduled in 2013, several experiments in strangeness nuclear physics are going to take data. In this period, we anticipate the beam power would exceed 10 kW and the experiments to use K ^? beams will start. The experimental program is explained briefly.     

Superconductivity and processing of single Bi−O layered cuprates in the (Bi,Pb)−Sr−(Ca,Y)−Cu−O system

The effects of improved materials processing on single Bi–O layered cuprates in the (Bi, Pb)–Sr–(Ca, Y)–Cu–O system have been investigatged. For Bi-1212 we have improvedT _c to 102 K. The bulk nature of superconductivity is confirmed by the presence of superconducting volume fractions ( ZFC) around 30–40%. The critical current density is 2×10⁶ Acm^–2 at 5 K and 0 T. Moreover, indications for the presence of a second phase probably Bi-1223 with a transition to superconductivity in the range of 115–150 K have been found.     

Tunnett

Conclusion The p⁺–n⁺–i(v)–n⁺ GaAs Tunnett diodes have been fabricated with control of the growing diffusion technique in TDM CVP liquid phase epitaxial growth. The threshold current density (J_th) of 2.8×10⁴ A/cm², the threshold voltage (V_th) of 5.3V for the oscillation and the 1% duty cycle operation have been succeeded. The more reduction of J_th and V_th will be able to realize the CW operation.     

Spectrophotometric Determination of Sm(III) Content in Hydrochloric Acid Solution

On the basis of the electronic absorption spectra of Sm³⁺ ions in aqueous solutions of hydrochloric and perchloric acids (1M) calibration plots of samarium content against the optical density of the solutions have been constructed for frequencies 47,800, 31,460, 29,140, 27,760, 26,740, 24,940, 24,020, 21,580, and 20,900 cm^–1 corresponding to the optical density maxima. The results of the calculation of errors in determining the metal concentration are presented. It has been shown that for hydrochloric acid solutions of samarium correct determination of its content is possible at frequencies 24,940, 21,580, and 20,900 cm^–1 in the concentration ranges 1.0–3.5, 2.5–5.0, and 0.08–5.00%, respectively. For perchloric acid solutions of samarium, correct determination of its content is possible at the 24,940 cm^–1 frequency in the concentration range from 1.0 to 3.5%.     

Rotating-disk diode-pumped continuous-wave Nd:YAG laser

Continuous-Wave (CW) diode-laser-pumped experiments using rotating Nd: YAG disk(s) have been performed in the input-power range of 1–6 W and rotation-speed range of 0–25 Hz. With a single Nd: YAG disk in the laser cavity, about 1.56 W of output power at 1.06 µm due to the Nd³⁺ (⁴ F _3/2–⁴ I _11/2) transition at an absorbed input power of 4.2 W has been observed, leading to an optical-to-optical conversion efficiency of over 37% and slope efficiency of 52% using 7.5% transmission output coupler. The laser output power has been observed to decrease by either increasing the number of Nd:YAG disks in the cavity or increasing the rotation speed of the disk(s).     

Practical separation of silicon isotopes by IRMPD of Si2F6

Large-scale silicon isotope separation based on the IRMPD of natural Si₂F₆ has been carried out using a commercially available high power CO₂ TEA laser and a flow reaction system. The decomposition product SiF₄ containing 19–33% of ³⁰Si was obtained at a production rate of 1.5×10^–2–2.6×10^–2 mol·h^–1, depending on experimental parameters such as laser wavelength, laser fluence, pressure, and flow rate. SiF₄ containing 12% of ²⁹Si was obtained under slightly different conditions, i.e., at a shorter wavelength than that for ³⁰Si. When 39% of Si₂F₆ was decomposed at a slow flow rate, residual Si₂F₆ was found to have 99.7% of ²⁸Si. The production rate was 4.2×10^–2 mol·h^–1.     

Optical Thin-Film Sensors for the Determination of Aqueous Halide Ions

Fourteen thin-film optical sensors in which halide-sensitive fluorophores are immobilized in a thin copolymer film (50 m, dry) have been developed and characterized. The sensor films use rhodamine, 6-methoxyquinoline, and harmane dyes which have been functionalized and bound to a hydrophilic copolymer. The sensor films are reversibly capable of determining aqueous bromide and iodide with 4 and 2% accuracy, respectively, at concentrations of around 10^–3 mol dm^–3, and are more sensitive than previous plastic sensor fabrications. The 90% response time to molar iodide is 30–60 s. A combination of sensor films allows the simultaneous determination of both I^– and Br^– in a mixed-halide solution. The interference of several ions, including pseudo-halides, on the sensor films has been studied.     

Relaxation during short-range-ordering in Cu-30% Zn alloy

The internal friction measured in a vacuum torsion pendulum has been used to determine the kinetics of short range ordering in an Cu-30% Zn alloy. Curves of relative internal friction (Q^–1/Q ₀ ^–1 ) against annealing time have been determined for various annealing temperatures. Average activation energy of 1·7 eV was found for the ordering process, which equals to that derived for zinc diffusion in coarse grained copper.     

Torsion-rotation far-infrared spectrum of O-18 methanol

High-resolution Fourier transform spectra have been recorded from 15–470 cm^–1 for the far-infrared trosion-rotation band of O-18 methanol in the vibrational ground state. So far, 57 subbands have been assigned in the 15–220 cm^–1 region for a wide range of rotational and torsional states, and their J-independent origins have been determined to an estimated accuracy of ±0.01 cm^–1. The observed origins were found to deviate in many cases by several tenths of a cm^–1 from the values calculated with the previous molecular parameters. Together with 4 known microwave origins, the new data have been fitted to a model torsion-rotation Hamiltonian in order to refine the set ofb-type molecular constants for the ground state. With the new parameter set, the experimental subband origins are reproduced with an rms error of ±0.02 cm^–1, representing a substantial improvement over the earlier situation. The spectroscopic results have also been of great assistance with our assignments of optically-pumped FIR laser emission in CH₃ ¹⁸OH, in providing FIR data for checking the identification of the IR-pump/FIR-laser transition systems through combination loop relations.     

Anti-Stokes Raman laser investigations on atomic Tl and Sn

Anti-Stokes Raman laser experiments using metastable atomic Tl and Sn have been performed. The required metastable population inversion is generated by photodissociation of TlI and SnBr₂ with KrF laser radiation. The Tl(Sn) system permits frequency up-conversion by 7793 cm^–1 (17,163 cm^–1). By optimization of system parameters, uv output energies up to 2.5 mJ (377 nm) and conversion efficiencies of more than 25% have been achieved for Tl. Further improvements and principal limitations will be discussed.     

Internal radiocesium contamination of adults and children in Fukushima 7 to 20 months after the Fukushima NPP accident as measured by extensive whole-body-counter surveys

The Fukushima Dai-ichi NPP accident contaminated the soil of densely-populated regions in Fukushima Prefecture with radioactive cesium, which poses significant risks of internal and external exposure to the residents. If we apply the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv/y would be expected to be frequent in Fukushima.Extensive whole-body-counter surveys (n = 32,811) carried out at the Hirata Central Hospital between October, 2011 and November, 2012, however show that the internal exposure levels of residents are much lower than estimated. In particular, the first sampling-bias-free assessment of the internal exposure of children in the town of Miharu, Fukushima, shows that the ¹³⁷Cs body burdens of all children (n = 1,383, ages 6–15, covering 95% of children enrolled in town-operated schools) were below the detection limit of 300 Bq/body in the fall of 2012. These results are not conclusive for the prefecture as a whole, but are consistent with results obtained from other municipalities in the prefecture, and with prefectural data.     

Far infrared emission spectra from stratospheric hydrogen peroxide

Synthetic emission spectra from two stratospheric altitude observations have been analyzed for the presence of H₂O₂ in the far infrared region. The calculations are made with a high spectral resolution (10^–3 cm^–1 or 10^–4 cm^–1) greater than those in experimental measurements which are in the region of 3.10^–3 cm^–1. Spectra cover a spectral interval between 40 and 120 cm^–1 showing the best features of H₂O₂ susceptible to observation in a stratospheric spectrum. The optimum conditions for identification have been considered. Using the variations in H₂O₂ abundance in the measurement data and photochemical models, the H₂O₂ features detection limits have been studied.     

High brightness operation of a XeCl laser with negative branch unstable resonators

Confocal and non-confocal negative branch unstable resonators with an intracavity spatial filter have been applied to a high-gain short-pulse UV preionized XeCl laser. The near- and far-field radiation characteristics have been investigated in both configurations. Laser beams of larger brightness have been obtained with non-confocal schemes. A maximum beam brightness of 1.3×10¹⁴ Wcm^–2Sr^–1 has been achieved.     

A superheated Na cell for X-ray photoionization experiments

The performance of a superheated alkali vapor cell, with a geometry suitable for x-ray photoionization experiments, is described. An internal heater was used to superheat sodium vapor in a split-wick heat pipe. At a Na pressure of 20 Torr, the transmission through the cell in the region of theC–X molecular band of Na₂ increased to 50% from the 5% observed when the cell was operated in a conventional heat-pipe mode. In the presence of a Na atom density of 2×10¹⁷ cm^–3, the average molecule density over the length of the cell was measured to be 2.5×10¹⁵ cm^–3. In the hot central region of the superheated cell, the molecule density was predicted to have been reduced by a factor of 50 to 3×10¹⁴ cm^–3.     

Gain and saturation measurements in a discharge excited F2 laser using an oscillator amplifier configuration

The small-signal gain coefficient and the saturation intensity of a F₂ pulsed discharge molecular laser at 157 nm have been measured using two discharge devices in an oscillator-amplifier configuration. The small signal gain coefficient was measured to be 5.2±0.4% cm^–1 at 3 atm total pressure and 1.5 cm electrode spacing and 4.1±0.4% cm^–1 at 2 atm total pressure and 2 cm electrode spacing while the values of the saturation intensity were 5 MW/cm² and 4.6 MW/cm², respectively.     

Analysis of the high resolution spectrum of the fundamental bandsv2 andv5 of12CH3F and their interactions

Thev ₂(A₁) andv ⁵(E) fundamental vibration-rotation bands of¹²CH₃F have been recorded under high resolution (0.015 to 0.020 cm^–1) in the spectral range of 1460 cm^–1. About 1100 transitions have been assigned. The Coriolis interaction between v₂=1 and v₅=1, and the l(2,-1) interaction in v₅=1 have been rigorously treated. Sixteen molecular constants have been determined from a least squares analysis. They reproduce the observed data with an overall standard deviation of 0.0037 cm^–1.