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In the event of an accident at a nuclear fuel handling facility, the wounds of affected workers may be contaminated with plutonium. The current approach for identifying plutonium contamination is by detecting α-particles in the blood stream. However, the applicability of this approach is impeded due to the α-particles being easily shielded by the bodily fluid components. In this study, we investigate a contamination testing method for such cases that involves the collection of blood with a small piece of filter paper, sealing the sample with thin films, and performing x-ray fluorescence analysis. Our previous study on collecting uranium-contaminated blood with filter paper and performing x-ray fluorescence analysis revealed that the effects arising from blood components could be completely removed by peak fitting, and thus water instead of blood was used as a solvent here. Samples containing various amounts of plutonium as well as samples with 150 Bq of plutonium and uranium were prepared with a mass ratio of 0 to 500 times greater than that of plutonium. x-ray fluorescence measurements showed a high linearity and reproducibility of the Pu Lα peak intensity and plutonium radioactivity, and it was clarified that the signal intensity of the Pu Lα peak did not depend on the amount of coexisting uranium. This method will allow for the simple and rapid assessment of plutonium contamination in wounds.

The early Solar System comprised a broad area of abiotically created organic compounds, including interstellar organics which were integrated into planetesimals and parent bodies of meteorites, and eventually delivered to the early Earth. In this study, we simulated interstellar complex organic compounds synthesized by proton irradiation of a gas mixture of CO, NH3, and H2O, which are known to release amino acids after acid hydrolysis on the basis of Kobayashi et al. (1999) who reported that at the first stage of chemical evolution, the main compounds formed abiotically are complex organic compounds with high molecular weights. We examined their possible hydrothermal alteration and stabilities as amino acid precursors under high temperature and pressure conditions simulating parent bodies of meteorites by using an autoclave. We reported that all samples treated at 200–300 °C predominantly released glycine and alanine, followed by α-aminobutyric acid, and serine. After heating, amino acid concentrations decreased in general; however, the recovery ratios of γ-aminobutyric acid increased with temperature. The interstellar complex organic analog could maintain as amino acid precursors after being treated at high temperature (200–300 °C) and pressure (8–14 MPa). However, the molecular structures were altered during heating to form organic compounds that are more stable and can survive in elevated hydrothermal conditions.

Amino acids have been detected in extraterrestrial bodies such as carbonaceous chondrites (CCs), which suggests that extraterrestrial organics could be the source of the first life on Earth, and interplanetary dust particles (IDPs) or micrometeorites (MMs) are promising carriers of extraterrestrial organic carbon. Some amino acids found in CCs are amino acid precursors, but these have not been well characterized. The Tanpopo mission was conducted in Earth orbit from 2015 to 2019, and the stability of glycine (Gly), hydantoin (Hyd), isovaline (Ival), 5-ethyl-5-methylhydantoin (EMHyd), and complex organics formed by proton irradiation from CO, NH

When using a PIG (Penning Ion Gauge) type ion source for production of negative ions, these ions must be extracted from a hole on the side of the anode cylinder, perpendicularly to the magnetic field for plasma confinement. As a result, unnecessary deflection force works on the extracted beam. This study aims to improve the ion extraction efficiency of a cold-cathode PIG negative-ion source. The idea is to reduce the beam loss by cancelling the stray magnetic field from the source by placing small dipole magnets in the extraction electrode. Through the measurement of the magnetic field distribution and beam trajectory calculation, it was numerically confirmed that the beam trajectory can be corrected by this small dipole magnet with a peak magnetic field of about 50 mT under the present experimental condition.

When workers are wounded at a nuclear fuel handling facility, it is difficult to quantify actinide contamination through α‐particle counting because these particles are shielded by blood. To overcome this problem, we used X‐ray fluorescence (XRF) analysis with a handheld‐type device that is useful in cases where sampling is not allowed, such as in this study. In XRF analysis, a primary X‐ray filter made of metal foil is generally inserted between the X‐ray tube and the sample to attenuate the incident X‐ray at the energy region of the XRF signal for the target element. Doing so can reduce the background signal originating from the scattered radiation of the incident X‐ray. In this study, we aimed to optimize a primary X‐ray filter that facilitates simultaneous high‐sensitivity analysis of uranium and plutonium in a wound. For this purpose, XRF measurements were performed for a needle‐puncture wound model contaminated by U and Pu, and the relationship between the filter material/thickness and the detection limit was investigated. Optimizing the filter material/thickness of a given target element was found to improve the detection limit of the measurement by ~10%.

In the event of an accident at a nuclear fuel handling facility, the wounds of affected workers may be contaminated with plutonium. The current approach for identifying plutonium contamination is by detecting α-particles in the blood stream. However, the applicability of this approach is impeded due to the α-particles being easily shielded by the bodily fluid components. In this study, we investigate a contamination testing method for such cases that involves the collection of blood with a small piece of filter paper, sealing the sample with thin films, and performing x-ray fluorescence analysis. Our previous study on collecting uranium-contaminated blood with filter paper and performing x-ray fluorescence analysis revealed that the effects arising from blood components could be completely removed by peak fitting, and thus water instead of blood was used as a solvent here. Samples containing various amounts of plutonium as well as samples with 150 Bq of plutonium and uranium were prepared with a mass ratio of 0 to 500 times greater than that of plutonium. x-ray fluorescence measurements showed a high linearity and reproducibility of the Pu Lα peak intensity and plutonium radioactivity, and it was clarified that the signal intensity of the Pu Lα peak did not depend on the amount of coexisting uranium. This method will allow for the simple and rapid assessment of plutonium contamination in wounds.

ガフクロミックフィルムを使用して低エネルギーX線発生装置から発生するX線による空気カーマの積算値を測定し、シリコンドリフト検出器によって測定したエネルギースペクトルに基づいて、各エネルギービンの空気カーマを評価した。エネルギービンごとに70 µm線量当量の換算係数を掛け合わせ、低エネルギーX線による皮膚線量を評価した。 キーワード：X線，線量評価，ガフクロミックフィルム，エネルギースペクトル測定 1. 緒言 50 keV程度までの低エネルギーX線は工業製品の非破壊検査や環境試料・美術品等のX線分析などに広く活用されている。これらのX線発生装置にはインターロックシステムが設けられており、X線の漏えいを防止しているが、装置の不備や誤った使用などによりX線が漏えいすると、作業者がX線に被ばくする恐れがある[1]。しかし、このような低エネルギーX線による被ばくに対する線量評価は容易ではない。そこで、本研究ではX線発生装置から放出される低エネルギーX線による被ばく線量評価法の確立を目指した。 2. 実験 最も普及しているWターゲットの小型X線発生装置から発生するX線のエネルギースペクトルを、シリコンドリフト検出器 (SDD) で測定した。管電圧は40 kV、管電流は10 μAとし、SDDユニットに直径25 μmのW製ピンホールを設置した。測定したスペクトルとCuの質量減弱係数を基に計算したCu 100 μmフィルタを設置した場合として予想されるスペクトルは、Cu 100 μmフィルタを設置して実測したスペクトルと一致し、任意のX線フィルタを介した場合のX線スペクトルが再現できることを確認した。次に、各種厚さのCuフィルタを設置した場合の空気カーマを低エネルギーX線用ガフクロミックフィルム (XR-QA2) で測定した。ガフクロミックフィルムの黒化度と空気カーマには正の相関があるため、予め二次標準場で較正した。ガフクロミックフィルムで測定される空気カーマはX線の全エネルギーに対する積算値であるため、フルエンスから空気カーマへの換算係数[2]及び計算したエネルギースペクトルに基づいて各エネルギービンの空気カーマを評価し、それらに70 µm線量当量への換算係数[2]を掛け合わせて皮膚線量を評価した。 3. 結論 本研究では、管電圧を40 kVに設定したWターゲットX線管について、任意のX線フィルタに対するエネルギースペクトルの計算が可能となった。また、これに基づく低エネルギーX線による皮膚線量の評価法を示した。 4. 謝辞 ガフクロミックフィルムの較正は茨城県立医療大学の二次標準場で行った。ご協力いただいた佐藤斉先生、中島絵梨華先生に深く感謝いたします。 参考文献 [1] Suzuki et al., Health Phys. 91 (2006) S35-S38. [2] ICRP publication 74 「外部放射線に対する放射線防護に用いるための換算係数」日本アイソトープ協会, 日本原子力学会2020春の年会

This study conducted an evaluation of elemental composition of concrete in an old nuclear reactor facility using the particle-induced X-ray emission (PIXE) technique. Given that the physical volume of the concrete is huge, easy, and quick analysis of many samples via the PIXE method can expedite the decommissioning work. The result of this study confirmed that it is possible to use the PIXE method for detecting light and medium-heavy elements (from Na to Fe) in concrete without the complicated chemical treatment. Some of these elements contain parent nuclides of Na-24, Al-28, and Fe-55, which are dominant components with residual radioactivity for a period of up to 10 years after facility shutdown.

我々はこれまでに、核燃料取扱作業中の事故で創傷部にアクチニド汚染の可能性がある際に、創傷部の血液を拭き取り蛍光X線分析により定量する方法を提案してきた。今回は、プルトニウムに対してウランが非常に多い混在汚染の場合に、プルトニウムの蛍光X線の信号が受ける影響について検討した。その結果、ウラン質量がプルトニウムの約100倍を超える場合でもプルトニウムを定量できる可能性が示された。 キーワード：創傷部，ウラン，プルトニウム，蛍光X線分析 1. 緒言 核燃料取扱施設では、作業者がウランやプルトニウム等のアクチニドによる汚染を伴う創傷を負うリスクがある。このような事故では、汚染核種や汚染量を迅速に把握し、これに基づく治療を行う必要がある。通常、アクチニドの検出はα線計測によって行われる。しかし、創傷部汚染の場合、血液等によってα線が遮蔽され、検出が困難になる場合があり得る。そこで、我々は創傷部のアクチニドを検出するために、創傷部の血液をろ紙で捕集し、これを蛍光X線分析で元素分析する手法を開発してきた[1,2]。これまでに、この手法がウラン汚染血液及びプルトニウム汚染血液に適用できることが明らかとなっている。一方、核燃料中ではその質量の大部分をウランが占めており、プルトニウムはごく少量である。本研究では、このようなウランの質量存在比が大きい場合にプルトニウムの蛍光X線の信号が受ける影響について検討した。 2. 実験 使用済み核燃料中のウランとプルトニウムの質量比 (100倍程度) を参考に、ウランの質量がプルトニウムの質量の100～500 倍程度になるよう、各種濃度の硝酸ウラン溶液 10 µLと150 Bqの硝酸プルトニウム溶液10 µLを5.5 mm径に切り出したろ紙 (5A, Advantec) に滴下、乾燥させた。これをポリプロピレンフィルムで密封し、汚染拡大を防止した後、蛍光X線分析を行った。蛍光X線分析装置はEpsilon4 (マルバーンパナリティカル) を用いた。 3. 結果、考察 試料中のウランの質量がプルトニウムの質量の約100 倍である場合の蛍光X線スペクトルを図1に示す。U Lα線 (13.6 keV) とPu Lα線 (14.3 keV) が観測され，信号強度に大きな差があるが，ピークは十分離れている。よってこの場合でもプルトニウムの定量は可能であることが示された。 参考文献 [1] Y. Izumoto et al., J. Radiol. Prot. 38 (2018) 1384-1392 [2] Y. Izumoto et al., X-ray spectrometry (2019), in press, 日本原子力学会2019年秋の大会

Workers in nuclear fuel handling facilities have a finite risk of injury and wound contamination from actinides such as uranium (U) and plutonium (Pu). When such contamination occurs, medical doctors determine the appropriate course of treatment (surgical resection of tissue in the contaminated wound, administration of a decontamination agent, or other regimen). Their decision is based on the types and amounts of α-emitting actinide contaminants, which can lead to serious internal exposure when accidentally intake take place. Although surgically resecting the tissue in the contaminated wound can suppress additional actinide intake, rapid quantification of the actinides in the wound may be useful to avoid unnecessary surgeries. The rapid detection of actinides is usually performed by the α-particle counting method. However, in cases of wound contamination, most of the α-particles cannot pass through the blood oozing from the wound. In our previous study, we developed a new method that rapidly detects U in wounds based on X-ray fluorescence analysis of contaminated blood collected by a filter paper [1]. In our preliminary experiment, we showed that this technique is also applicable to blood contaminated with Pu. However, in facilities such as spent nuclear fuel reprocessing plants, Pu and U are often handled together, and the concentration ratio of the two elements depends on the work process. Therefore, the simultaneous quantification of U and Pu in wounds is required for radiation emergency medicine in these nuclear facilities. The energy difference between the U Lα (13.6 keV) and Pu Lα (14.3 keV) peaks is larger than the energy resolution of the detector (~275 eV at Mo Kα); moreover, these peaks little affect each other when the concentrations of their causative elements are comparable. However, when the U concentration is much higher than the Pu concentration, the background in the energy region of the Pu Lα peak may increase. In addition, as U and Pu are excited by incident X-rays of the similar energy, the peak intensity of Pu Lα can be lower in a sample containing a large amount of U and a small amount of Pu than in a sample containing the same amount of Pu alone. In this study, the model samples for X-ray spectrometry analysis were contaminated with U and Pu over a wide range of concentration ratios. The samples were prepared by mixing uranium- and plutonium nitrate solutions of various mixing ratios and dropping them onto filter papers. We discuss not only the minimum detection limits for U and Pu, but also the range of Pu/U ratios that can be adequately determined by the above method. [1] Izumoto et al., X-ray spectrometry, in press., 68th Annual Denver X-ray Conference

It is known that the peak of Uranium (U) Lα line (13.6 keV) overlaps with that of Rubidium (Rb) Kα line (13.4 keV) in XRF spectrum. Rb is, unfortunately, one of the abundant elements in natural environment. Our previous studies [1,2] showed that multiple Gaussian fitting could separate these lines when the sample contains comparable amounts of U and Rb. On the other hand, if the amount of Rb is much larger than that of U, the fitting may give incorrect results. In this case, U quantification using U Lβ lines (mainly U Lβ1 (17.2 keV) and Lβ2 (16.4 keV) lines) might be useful. In the present study, a new portable TXRF device was built to verify this idea. We prepared the new device by modifying a 200TX portable TXRF spectrometer (Ourstex Co., Ltd.), which was originally equipped with an X-ray tube with a tungsten (W) anode [1]. The anode material was changed to silver (Ag), whereas the other parts including the incident X-ray collimating system stayed as before. Since Ag has lower atomic number than W, background signal derived from bremsstrahlung X-ray is lower in our new device than that in an original 200TX. Moreover, strong Ag Kα line can excite L3 and L2 shell electrons of U more efficiently. Sample solutions were prepared by mixing a multi-element standard solution (XSTC-1407, Spex CertiPrep Inc.), which contains same concentrations of cobalt, cesium, cupper, thorium (Th), and U with dilution series of a Rb standard solution. In the measured TXRF spectra of the sample solution with low rubidium concentration, the U Lα peak can be clearly found and the intensity of the peak was much higher than that of U Lβ lines. Therefore, if the Rb concentration is low, quantification using the U Lα peak is favorable. On the other hand, for sample solutions with high Rb concentrations, the peak of U Lα was buried in that of Rb Kα. In this case, Gaussian fitting using the peaks of U Lβ lines along with that of the U Lα line was useful to U quantification. It should be noted that, however, the peak of U Lβ2 line overlapped with that of Th Lβ1 line (16.4 keV) originating from thorium contained in XSTC-1407. Since concentration of Th in environmental samples is usually similar to that of U, quantification based on U Lβ2 line can be less accurate than that using U Lβ1 line. This research has been conducted as regulatory supporting research funded by Secretariat of Nuclear Regulation Authority (S/NRA/R), Japan. [1] T. Matsuyama et al., J. Nucl. Sci. Technol. 54, (2017), 940. [2] T. Matsuyama et al., Spectrochim. Acta Part B 149, (2018), 35., 18th International Conference on Total Reflection x-ray Fluorescence Analysis and Related Methods (TXRF2019)

The analysis of uranium in environmental samples, quantified using total reflection X-ray fluorescence (TXRF) analysis, would be adversely affected by the presence of rubidium and strontium in larger amounts than uranium as coexisting elements. This is because the U Lα line at 13.61 keV is close to the Rb Kα line at 13.40 keV and the Sr Kα line at 14.17 keV. Using the U Lβ1 line (instead of the U Lα line), which does not overlap with the peaks of coexisting elements, we will be able to avoid these adverse effects. Since there is no TXRF device that can perform a quantitative analysis of uranium by using the U Lβ1 line, the following modifications were made to the existing device with the intention of rapid on-site analysis. The X-ray tube of the new device has a silver anode instead of a tungsten anode, and the sensitive area of the detector was expanded. In addition, the mechanism for adjusting the position of the sample stage was changed from manual to computerized control. These changes made it possible to screen uranium in environmental samples rapidly on site without chemical separation.

In radiation emergency situations involving persons having plutonium (Pu)-contaminated wounds, rapid assessment of the degree of Pu contamination is required to determine the appropriate course of treatment. Currently, rapid on-site detection of Pu is usually performed by analysis of α-particles emitted from the adhesive tape peeled off the wound. However, the detection of α-particles is difficult, especially in traumatic skin lesions with oozing blood, because of the low permeability of α-particles in blood. Therefore, we focused on x-ray fluorescence (XRF) analysis because x-rays easily pass through several millimetres of blood. In this study, we developed a new methodology for the rapid detection of heavy elements in wounds based on XRF analysis of the contaminated blood collected by gauze patch and filter paper, using stable lead (Pb) as a model contaminant substitute for Pu. Mouse blood samples contaminated with Pb were dropped on gauze patches or absorbed by filter papers and were subjected to XRF measurement. Small pieces of filter paper served as more suitable extraction materials than gauze patches because the entire amount of blood absorbed could be measured. When we used filter paper, the signal intensity of the Pb Lα peak was proportional to the Pb concentration in the blood. With a measurement time of 30 s, the minimum detection limit of Pb in blood collected by filter paper was 2.4 ppm.

原子力施設で働く作業員が創傷を負い、患部にウランは付着していることが疑われる場合の検査方法として、ろ紙で患部の血液を吸い取り、蛍光X線分析を行う方法を新たに開発したので報告する。ろ紙小片にウラン含有実験用血液を滴下し、マイラとフィルムで密封して、卓上型蛍光X線分析器で分析した。スペクトルにはウランのピークの他に、血液に由来する臭素やルビジウムのピークも観測され、ピークフィッティングによりこれらを分離した。, European Conference on X-ray Spectrometry(EXRS2018)

The precise estimation of stopping power is crucial to predict the beam energy loss in the target for heavy-ion fusion and heavy-ion-driven high-energy density physics experiments. The electromagnetic shock wave has been proposed to generate a well-defined atomic hydrogen target for the stopping power measurement with dissociation effects. We measured the angular distribution profile of the discharge plasma and the plasma velocity in the electromagnetic shock tube by high-speed framing cameras. To improve the uniformity of the discharge plasma and the velocity, an external magnetic field was applied in the electromagnetic shock tube. The plasma velocity was up to approximately 40 km/s for an initial hydrogen gas pressure of 100 Pa and the velocity decreased with the initial pressure and the propagation length. The framing cameras showed that angular distributions of the discharge plasmas were not uniform and the initial angular distributions were important for the development of plasma profiles. The interaction of the plasma with the external magnetic field was estimated using the ratio of the plasma dynamic pressure to the magnetic pressure. The estimations offer more magnetic fields to improve the discharge uniformity due to the interaction.

The equation of state (EOS) of fissile materials under extreme thermodynamic conditions is of great importance to assess the safety of nuclear energy systems related to extremely severe nuclear accidents and intentional nuclear terrorism. In this study, for a simple, safe, and precise measurement of these properties, we propose an experimental setup in which a small amount of fissile material sample is homogeneously heated by an intense short-pulsed heavy-ion beam, and subsequent hydrodynamic motion is examined. As an example, we investigated the response of a slab of uranium foam (density = 5% of solid density) to a pulsed 23 Na + beam with a duration of 2 ns and peak irradiation flux of 5 GW/mm 2 . The target thickness and incident beam energy were adjusted to 80 μm and 1.5 MeV/u, respectively, for the beam-energy deposition to occur almost at the top of the Bragg peak and inhomogeneity in the stopping power to be ±2.5%. The hydrodynamic motion of the target during and after irradiation was calculated with a one-dimensional radiation hydrodynamic code. To calculate beam-energy deposition in the target, we used density- and temperature-dependent projectile stopping data obtained with a finite-temperature Thomas-Fermi target atomic model and degeneracy-dependent dielectric response functions. The numerical results showed that the target was almost isometrically heated up to ≈ 10 5 K well before the rarefaction wave reached the center of the target, and fairly homogeneous temperature and density distributions were obtained at the end of the pulse duration. We discuss the feasibility of experimental EOS studies, such as the evaluation of pressures at off-Hugoniot conditions as a function of internal energy from the measurements of the target expansion velocity.

Heavy ion fusion sciences and heavy-ion-driven high energy density physics experiments require evaluations of the stopping power with dependences on target density and temperature. We are interested in effects of dissociation of the target molecules which have not been experimentally investigated. The electro-magnetically driven shock wave has been proposed to produce well-defined dissociated target which is required to measure the stopping power with the dissociated effect. We have velocity measurements in the electro-magnetic shock tube to understand the target physical condition. The velocity measurement by laser refraction gives reliable experimental results, which shows that the shock velocity is not enough to dissociate hydrogen completely. The experiments indicate that input energy does not convert to the piston plasma in electro-magnetic shock tube efficiently.

As a method to evaluate high-temperature equation of state (EOS) data of fissile materials precisely and safely, we numerically examined an experimental setup based on a sub-range fissile target and a high-intensity short-pulsed heavy-ion beam. As an example, we calculated one-dimensional hydrodynamic motion of a uranium target with ρ = 0.03ρsolid (ρsolid ≡ solid density = 19.05 g/cm3) induced by a pulsed 23Na+ beam with a duration of 2 ns and a peak power of 5 GW/mm2. The projectile stopping power was calculated using a density- and temperature-dependent dielectric response function. To heat the target uniformly, we optimized the experimental condition so that the energy deposition could occur almost at the top of the Bragg peak. The energy deposition inhomogeneity could be reduced to ±5% by adjusting the incident energy and the target thickness to be 2.02 MeV/u and 180 μm, respectively. The target could be heated homogeneously up to kT =7 eV well before the arrival of the rarefaction waves at the center of the target. In principle, the EOS data can be evaluated by iteratively adjusting the data embedded in the hydro code until the measured hydrodynamic motion is reproduced by the calculation. This method is consistent with the conditions of nuclear nonproliferation, because a very small amount of fissile material is enough to perform the experiment, and no shock compression occurs in the target.

Beam focusing properties of cone optics were systematically investigated by Monte Carlo simulations under various combinations of beam and cone parameters. To optimize the cone optic design for accelerator-driven WDM experiments, the beam intensity gains after cone focusing were evaluated from the simulation results as functions of cone wall material and shape parameters such as taper angle and wall curvature. The uniformity of the cone-focused beam was also examined by considering not only various cone parameters but also the cases involving the misalignment of the cone optic. From the results, a parabolic gold cone was found to be the best choice at least for relatively light ions such as lithium having MeV energies. It is also found that although smaller taper angle improves the total beam transport efficiency in the optic, it brings more difficulties in the alignment of the optic because the alignment accuracy should be less than a half of the taper angle to obtain acceptable uniformity in the beam energy deposition on the target.

Heavy-ion stopping in foam targets with subcell-scale hydro motions was numerically investigated in relation to ion-driven warm dense matter experiments. To simulate porous foam targets, we employed a simple 1D periodic multilayer model consisting of thin solid slabs and gaps between them. The averaged pore diameter and cell-wall thickness of the foam were represented by the gap width between the slabs and the slab thickness, respectively. The density- and temperature-dependent projectile stopping cross-sections were evaluated using a binary encounter model taking into account the electronic state of target atoms during heating and expansion. We employed a combination of 11Na projectiles and subrange 13Al foam targets with ρ=0.05ρsolid. The hydrodynamic motion of the target was calculated with a 1D code. During homogenization, hot dense spots appeared at the original gap positions, owing to stagnation of the jets. As a result, even after the pores were filled with blow-off materials, the initial inhomogeneity was not completely smeared out, and the total energy loss was still not equal to that in the homogeneous equivalent, especially for large pore sizes.

The dependence of the MeV ion focusing ability of tapered capillary optics on the capillary wall material was investigated using tapered glass capillaries made of two different glass materials: borosilicate glass and lead glass. The energy spectrum measurement of capillary-focused proton beams showed that the beam focusing ratio for the lead glass capillary was slightly higher than that for the borosilicate glass capillary, but the enhancement was much lower than expected from the target atomic number dependence of the Rutherford scattering cross section. Three-dimensional Monte Carlo simulations were performed to examine the effect of the capillary wall shape as well as that of the wall material. When a constant taper angle capillary was used, the beam focusing ratio was found to be enhanced by a factor of 2 compared to when the conventional tapered capillary having a convex inner wall was used. These results indicated that the probability of the scattered ion escaping from the capillary wall plays a predominant role in the MeV ion transmission in the tapered capillary optics.

A design study of electro-magnetic shock tube for dissociated gas targets is presented. Behind the shock front, there is a dissociated gas region without ionization. That is suitable target for the stopping power measurement when we have an appropriate shock velocity. The previous experiments showed that the dissociated target duration with uniform density and temperature profiles as long as microsecond was required for synchronization with projectile. A new shock tube with long drift section is proposed. The duration of shock heated region can be estimated to be 2 μ s in this design. This configuration enables us to measure the difference of the stopping power between molecules and dissociated atoms for heavy ion beams more reliably.

A precise target positioning system based on a laser position sensor was developed for a high-efficiency wavelength dispersive PIXE analysis. The absolute position and the target surface profile were clearly observed using this position sensor, which was rigidly connected to the target vacuum chamber. By using a thin proton beam ( width = 2 mm ) and a small target (width = 1 mm), the optimum target position for the measurement of chlorine ( Cl ) Kβ X-ray could be determined from X-ray detection yields measured at various target positions. We found that the relationship between the X-ray detection yield and the target position can be explained by the target size as well as the incident proton beam width. After precise adjustment of the target position using the above system, target samples with two different Cl compounds, NaCl and NH 4 Cl , were successfully distinguished from the difference in the measured profiles of Kβ X-ray spectra.

The chemical speciation of phosphorus and sulfur in lake sediment was performed by analyzing Kα X-ray spectra recorded with a high-resolution wavelength-dispersive particle-induced X-ray emission (WD-PIXE) system. The concentrations of phosphorus and sulfur in the sediment were 2500 and 7000 ppm, respectively. To measure both minor elements in a reasonable measurement time, a 2-MeV proton beam with a high current density (6 nA/mm2) was used for the chemical speciation. The possible chemical state change caused by the proton irradiation was studied in order to determine the maximal irradiation time without significant change. We found that the chemical states of phosphorus and sulfur were stable under a beam current density of 6 nA/mm2 and a measurement time of 60 min (phosphorus) and 90 min (sulfur). The chemical states of phosphorus and sulfur were determined to be P5+ and a mixture of S2− and S6+, respectively.

Electromagnetically driven shock tubes compatible with in-beam experiments have been developed to examine the stopping power of hot or warm matter over a wide temperature range. The beam–plasma coupling constant γ was calculated under various operating conditions of the shock tube. We found that γ ∼0.1 is achievable with 10 keV/u Pb ions and a fully ionized plasma produced by a shock wave with 70–80 km/s in a hydrogen gas of 6–9 kPa. The dissociation effect on the hydrogen stopping power for low-energy protons was also evaluated and a 40–50% increase in the stopping cross-section of dissociated hydrogen was predicted in a projectile energy region of 10–40 keV. For the demonstration of the energy loss measurement using shock-heated gas targets, the developed shock tube was embedded into the beam line and tested on its shock-production abilities. In the preliminary experiment using 375 keV/u carbon projectiles, we successfully detected the signal of a carbon ion penetrating a shock-heat hydrogen target and observed a decrease in the signal height, which probably corresponds to the energy loss.

Recent research activities in Japan relevant to heavy ion fusion (HIF) are presented. During the past two years, significant progress in HIF and high energy density (HED) physics research has been made by a number of research groups in universities and accelerator facilities. Evolutions in phase space during the longitudinal compression of intense beams were investigated at UU–NUT–TIT. Beam–plasma interaction experiments and related theoretical studies are in progress at RLNR-TIT. In the study, shock-heated hydrogen was used for the interaction experiments as a well-defined non-ideal-plasma target. In the beam–plasma interaction experiments, a special emphasis is placed on an evaluation of non-linear effects on the stopping power in a beam-heated plasma target. A direct–indirect hybrid scheme of a beam-driven ICF target has been proposed and discussed at UU. In the same group, a method for controlling the Rayleigh–Taylor instability in imploding fuel target has been proposed using oscillating heavy ion beams (HIBs). Core dynamics of the impact ignition has been investigated both experimentally and numerically at ILE—Osaka. Dense plasmas driven by intense ion beams and/or a pulse powered device, were evaluated by a group of DES-TIT, concerning the researches on HED and warm dense matter (WDM) physics. A quasi-statically tamped target was proposed to make a well-defined, warm dense state for equation-of-state (EOS) studies based on ion accelerators. The potentiality of the new facility planned at KEK was evaluated by a collaborating group of TIT–UU–KEK, which can extend the parameter regime for laboratory experiments to study the properties of matter under extreme conditions. A possible method to make a high-pressure condition for study of the planetary science was discussed as a short-term subject of intense HIBs.

Change of fine structures of K x-ray spectra for sulfur compound targets during MeV proton irradiation was observed in-situ using a high-resolution wavelength-dispersive (WD) x-ray spectrograph. Five standard samples of sulfur with different chemical states (MoS 2 , Na 2 SO 3 , (NH 4 ) 2 SO 4 , Na 2 SO 4 , and Na 2 S 2 O 3 ) were prepared for this measurement. The proton energy, beam current, and beam spot diameter were 2 MeV, 25-120 nA, and 16 mm 2 , respectively. We found that the sulfur Kα 1 line energy for the Na 2 SO 3 sample (originally s 4+ ) became higher with increase of the proton dose. After irradiation of more than 10 8 Gy, the Kα 1 energy for the Na 2 SO 3 sample was nearly equal to that for the Na 2 SO 4 sample (originally s 6+ ). This result indicates that most of the s 4+ on the Na 2 SO 3 target surface has changed into s 6+ through the irradiation. Dependence of the chemical state change on the absorption dose and beam current density is also discussed.

The chemical speciation of sulfur in activated carbon has been performed by analyzing Kα1 x-ray spectra of sulfur recorded with a home-made wavelength-dispersive, particle-induced x-ray emission spectrometry system (WD-PIXE). MoS2, S, Na2SO3, and (NH4)2SO4 were used as reference materials to determine the chemical shift of sulfur Kα1 x-ray energy. The energy resolution defined by the full width at the half maximum was 0.6 eV or 0.03% for sulfur Kα1 x-ray. This was sufficiently high for speciation of sulfur in solid materials. The chemical shift of sulfur in activated carbon clearly showed that sulfur resides as elemental sulfur. This new speciation technique for solid materials successfully demonstrated that sulfate ions in aqueous solution was reduced to form elemental sulfur on an activated carbon under low applied voltage of < 5 V and current of < 1 mA. Copyright © 2009 John Wiley & Sons, Ltd.

Chemical state changes of phosphorus induced by proton irradiation were measured by a high-resolution wavelength-dispersive (WD) PIXE system. Six standard samples of phosphorus with different chemical states ( Ca ( H 2 PO 4)2• H 2 O ( P 5+), CaHPO 4•2 H 2 O ( P 5+), NaH 2 PO 4 ( P 5+), CaHPO 3• H 2 O ( P 3+), Ca ( H 2 PO 2)2 ( P 1+), and NaH 2 PO 2• H 2 O ( P 1+)) were prepared for the measurements. The P - K α1 peak energy for the sample of P 3+ increased after the irradiation. The peak energy of the P 3+ sample became nearly same as that of P 5+ after irradiation with more than 2 ×107 Gy . This result indicates that P 3+ in the sample has changed to P 5+ due to proton irradiation. On the other hand, the P - K α X-ray spectra for the samples of P 5+ didn't show any interesting changes even for much higher proton dose (3.4 × 108 Gy ). Also, P - K α peaks which correspond to chemical states ( P 5+ and P 3-) other than original state were observed for the sample of P 1+ in the region of more than 107 Gy .

Concerning the PIXE analysis of Cr ( VI ) in water using ion-exchange filters, the limit of detection (LOD) and the influence of matrix anions were investigated. In order to look for the experimental condition for obtaining the minimum LOD, we measured the Cr - K α X-ray counts and background counts under the K α X-ray peak as a function of the incident proton energy and the thickness of the Mylar absorber foil in front of the detector. To investigate the interference by coexisting anions, each of PO 43-, SO 42-, NO 3-, Cl -, and F - ions and Cr ( VI ) ions were mixed in aqueous solutions and adsorbed on DE81-DEAE cellulose paper, a weakly basic anion exchanger with diethylaminoethyl functional groups. Then the filter samples were measured by PIXE using 2.5 MeV proton beams. We obtained a LOD of 0.16 µg or 8 ppb for 20 mL samples at a proton energy of 2.5 MeV and a Mylar film thickness of 50 or 100 µm. The experimental results on the mixed solutions indicated that NO 3-, Cl -, and F - as coexisting ions didn't interfere significantly with determination of a 50 µ g / L Cr ( VI ) concentration for 40 mL total solution volume, despite the total amount of anions was about 90% of ion exchange capacity of a filter. On the other hand, slight interferences by PO 43- ions were observed. However, under the same condition, we found that if the total amount of SO 42- ions was higher than 20% of ion exchange capacity, they induced significant interferences in determining Cr ( VI ).

The most important species of chromium (VI) formed in water are anions such as CrO 42-, whereas chromium (III) is mainly present in the form of cationic species such as Cr ( OH )2+. Pure water and tap water samples were artificially contaminated with mixture of chromium (VI) and chromium (III) standard solutions. Sequential filtration through commercially available Whatman P81 cellulose phosphate paper and Whatman DE81 DEAE cellulose paper was employed for separation and preconcentration of chromium (III) and chromium (VI) in these water samples, respectively. The PIXE measurements of these filter paper samples were performed using 2-MeV proton beams delivered by a tandem pelletron accelerator at Research Laboratory for Nuclear Reactors, Tokyo Tech. The beam current and the measuring time for each sample were 1 nA and 10 minutes, respectively. Instrumental detection limits were 60 ng for chromium (VI) and 120 ng for chromium (III). Detectable range for chromium (VI) and chromium (III) in water were ≧ 10 ppb and ≧ 50 ppb, respectively. For chromium (VI), the detectable range was considerably lower than the maximum allowed concentration of 50 ppb for chromium (VI) in both the drinking water standards and the environmental quality standards in many countries.

A high-efficiency high-resolution wavelength-dispersive spectrograph with a von-Hamos configuration was developed for chemical state identification of elements in environmental samples using PIXE analysis. To evaluate the performance of this system, chlorine K X-ray spectra for NaCl, NH 4 Cl and polyvinylchloride (PVC) targets were measured and compared. Also, to study the applicability to environmental mixed samples, mixtures of NaCl and NH 4 Cl with different mixing ratios were measured. Through observation of Cl Kα 1 X-ray from NaCl, the energy resolution of the system was determined to be 1.1 eV. For the NaCl sample, a Kβ x line was observed at an energy, which is higher than that of the Kβ main peak by 2 eV, whereas no Kβ x emission was observed for the NH 4 Cl sample. The chemical shift of the Kβ main peak for PVC relative to that for NaCl was about 1.2 eV. For NaCl–NH 4 Cl mixture targets, the relative intensity of Kβ x satellite to the Kβ main line provided an indication of mixing ratio. Energies and relative intensity of Cl Kβ X-ray satellites for NaCl and NH 4 Cl samples calculated by a simple molecular-orbital method agreed only qualitatively with the experimental results.

A coaxial electromagnetic shock tube was developed to produce a non-ideal plasma target with Γ ∼ 0.1 (Γ: Plasma coupling constant) for non-linear interaction experiments between ion beams and plasmas. To evaluate the shock velocity, we photographed the trajectory of the shock front along the tube by a streak camera. From these measurements, we found that the shock waves are strong enough to produce a non-ideal plasma in the tube. To reduce the plasma thickness for the stopping power measurements, the effective diameter of the tube was reduced by using a tapered section. The effects of the tapered section on the shock velocity and the shape of the shock front were examined. Using a 30 tapered section, the shock velocity was increased up to 54 km/s compared with 47 km/s for a straight tube.

We tested an experimental setup for measurement of non-linear stopping of low-energy heavy ions in non-ideal plasmas. In this setup, we used a silicon surface-barrier charged-particle detector (SSBD), which could measure the energy of single ions. For synchronization between the plasma production and the injection of single projectiles, a fast beam kicker was installed in front of the plasma target. In order to test this setup, we used a laser-produced polyethylene plasma target instead of a shock-driven plasma device, which is under R&D process. Results of a preliminary energy loss measurement for low-speed heavy ions in the laser plasma are reported. Performance on the time resolution evaluated by using a carbon-foil target is also presented.

In this paper, significant progresses of Japanese research activities are presented in heavy ion fusion (HIF) and high energy density physics (HEDP). Heavy ion beam (HIB) is a prominent tool to study HEDP and HIF, and HIBs may be a promising inertial fusion driver. HIB accelerators have been studied intensively for a long time; HIB pulse profile, a particle energy and a HIB quality are controllable. A HIB energy deposition profile is also well defined, and HIB energy is deposited inside a material. By focusing and using the HIB excellent properties, Japanese HIF and HEDP activities have covered a wide variety of subjects ranging from new accelerators to future HIF studies: ion source, new inductive accelerator, beam physics, beam bunching, beam instabilities, HIB interactions with gas or materials, laser ion acceleration, HIB transport, HIB-based warm dense (WD) state generation, new measurement of HED or WD matters, HIB stopping power, atomic physics, multi-HIBs illumination on a target, HIF target implosion, impact ignition scheme, HIB-radiation conversion, radiation confinement and transport in HED matter or in HIF, and so on.

We developed an experimental apparatus for the study of non-linear stopping of low-energy heavy ions in non-ideal plasmas. The target plasma was produced by an electromagnetically driven shock tube. A pair of 50- μ m -diameter beam apertures was attached to the shock tube wall. These apertures confined hydrogen gas of ≈ 5 Torr in the tube and sustained the pressure difference ( ∼ 10 5 – 10 6 ) between the tube and the beam line. In order to measure the energy loss in the plasma in the tube, we used a semiconductor charged-particle detector, which could directly measure the kinetic energy of single particles, since the beam transmission through these apertures was very small. To synchronize the plasma production in the shock tube and the injection of projectiles, a fast beam kicker was installed in front of the plasma target. Results of preliminary experiments using thin carbon foil targets showed that the measured energy loss of single projectiles after passing through the target was in agreement with other data. The time resolution of the energy-loss measurement system was ≈ 150 ns , which is enough to measure the projectile energy loss during the life time of the target plasma.

A shock-driven plasma target was developed to examine non-linear interactions between low-energy heavy ions and cold-dense plasmas. MD calculations predicted that beam–plasma coupling constant γ ∼ 0.1 must be achieved to observe the non-linearity, which corresponds to the plasma coupling constant Γ ≈ 0.2 for projectiles of v proj ≈ 10 keV / u and q ≈ 2 . One-dimensional numerical estimations using SESAME equation of state showed that a shock wave propagating in 5-Torr H 2 gas with 47 km/s must be produced to satisfy Γ ≈ 0.2 . Utilizing an electromagnetic shock tube with a peak current of 50 kA and a current rise time of 800 ns, we achieved a shock speed of 45 km/s. The electron density distribution of the shock-produced plasma along the beam axis was measured by a Mach–Zehnder interferometer. From this measurement we confirmed that the electron density was over 10 17 cm - 3 and the homogeneity was acceptable during several hundred nanoseconds. The electron temperature was also determined by optical spectroscopic measurements. The Coulomb coupling constant was evaluated using these experimental data to investigate feasibility of the beam–plasma interaction experiments.

Low-velocity (

Plasmas at high density and/or high-temperature state are produced using pulse power devices. Dense, cylindrically evolving plasmas are produced using pulse- power-driven exploding discharges in water. Shock-heated, high-temperature plasmas are produced also in a compact pulse power device. In contrast to the pulse-powered plasmas, properly moderated high-power ion beams can make a well-defined plasma over a wider range of density–temperature space. Their advantages and attainable parameter region are comparatively discussed as a driver for making the high-energy-density states.

In this study we present an eminent enhancement of magnetoresistance (MR) effect in FeCo alloy nanocomposite prepared by sequential implantation of 100 keV 57 Fe and 59 Co ions into Al 2 O 3 matrices. We investigated the MR effect in the granules with changing the relative amount of Fe and Co implanted to total fluences of (1.0–1.2) × 10 21 ions/m 2 and found a systematic change of MR ratio with a maximum effect around Co concentration of 25 at.%. The obtained MR ratio at room temperature and at external field H = 8.8 ×10 5 A/m is 13.2% and it is the highest value reported among the Fe, Co and FeCo granular films.

Stopping power of low-energy, highly charged projectiles in cold dense plasmas was numerically investigated to search realistic parameters for beam–plasma interaction experiments using ≈10–100 keV/u projectiles delivered by a 1.7 MV electrostatic accelerator. In order to evaluate the energy loss, a simple Molecular Dynamics (MD) computer code was applied. If the projectile velocity was as low as the thermal velocity of plasma electrons, and the projectile charge was sufficiently high, nonlinear stopping was observed even for weakly nonideal plasma targets with Γ ≈ 0.1 . According to a numerical analysis on the charge state distribution coupled with an energy loss calculation, projectiles with such a high charge state are rapidly lost by the strong recombination owing to electrons loosely trapped by the projectile, as well as the residual hydrogen atoms in the plasma.

Quasi-monochromatic X-ray emission induced by MeV-proton bombardment onto metallic targets was applied to radiography of small samples. The X-ray energy was adjusted in the range of ≈4–23 keV by changing the target material. The radiograms were recorded on an imaging plate. A small phantom made of Lucite was prepared for the test of photography using a contrast medium (RuCl3·H2O; ruthenium chloride). To clearly observe the image of the contrast agent, the photon energy was chosen to be 23.17 keV (Cd Kα) which is slightly above the K-absorption edge of Ru at 22.12 keV. Only the image of the contrast agent was successfully extracted by subtracting the image taken by 21.18-keV X-rays (Pd Kα) from that obtained by the 23.17-keV photons. Also images of a small fish sample were taken using a point-like X-ray source excited by a proton microbeam with a diameter of ≈10 μm. In this experiment, the X-ray energy was adjusted to 4.51 keV (Ti Kα) to obtain a strong attenuation by Ca in the bones. A fine structure of the bones in the thin caudal fin (

Thick-target PIXE analysis was applied to the study of electrokinetic soil remediation technique. In order to simulate radioactive soil contamination by 137 Cs , salt of stable cesium was mixed with soil samples. These soil samples were subjected to electrolysis for up to 36 hours with a field gradient of ≈ 1-3 V/cm. After the electrolysis, we measured the distribution of Cs concentration in the soil along the electrolysis cell by PIXE analysis. LX-rays of cesium were used for the analysis. The Cs concentrations in the drain water sampled from the cathode well were also evaluated. After the electrolysis the migration of cesium from the anode to the cathode was clearly observed. Water supply into the anode well enhanced the removal rate. We found that the main driving force of the migration of Cs + observed in this work was not electrophoretic migration, but electroosmotic flow in the soil samples. Owing to the spectral interference by major metallic elements in the soil, the minimum detectable concentration of cesium by the present method was limited to ≈ 800 ppm.

An ion source for generation of low-charged heavy ions has been developed using low-power KrF excimer and frequency-doubled Nd:YAG lasers. The ion source was examined with two experimental modes of low-voltage DC extraction at ∼20 kV and high-voltage pulse extraction at 150 kV. Normalized emittance of extracted beams composed of Cu+ and Cu2+ ions was measured to be about 0.05 and 0.8 πmm-mrad for the DC extraction and the pulse extraction, respectively. Electron temperature was observed by means of a single probe method to be 0.8 to 2.5 eV, depending on the intensity of the KrF laser.

The interaction process between fast heavy ions and dense plasma was experimentally investigated. We injected 4.3-MeV/u or 6.0-MeV/u iron ions into a z-pinch-discharge helium plasma and measured the energy loss of the ions by the time of flight method. The energy loss of 4.3-MeV/u ions fairly agreed with theoretical prediction when the electron density of the target was on the order of 1018 cm−3. With increasing electron density beyond 1019 cm−3, the difference between the experiment and the theory became remarkable; the experimental energy loss was 15% larger than the theoretical value at the peak density. For 6.0-MeV/u ions, the deviation from the theory appeared even at densities below 1019 cm−3. These discrepancies indicated that density effects such as ladderlike ionization caused the enhancement of the projectile mean charge in the target.