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We studied lethal and mutagenic bystander effects in normal human fibroblasts irradiated with low-energy-carbon ions. After cells reached confluence, cells were irradiated with initial energies of 6 MeV/n carbon ions. The residual energy and LET value were 4.6 MeV/n and 309 keV/µm. The doses used for survival and mutational studies were 0.082 and 0.16 Gy. Irradiation was carried out using 4 different irradiation conditions and plating conditions: (1) The entire cell area on the Mylar film was irradiated (We abbreviate as 'all irradiation'); (2) Irradiated and unirradiated cells were pooled in a 1:1 ratio and plated as a single culture until the plating for lethal and mutagenic experiments (We abbreviate as 'mixed population'); (3) Only half of the area on the Mylar film were irradiated using an ion-beam stopper (We abbreviate as 'half irradiation'); and (4) Only half of the area of the cells were irradiated, and a specific inhibitor of gap junctions was added to the culture (We abbreviate as 'half irradiation with inhibitor'). Cell samples were analyzed for lethal and mutagenic bystander effects, including a PCR evaluation of the mutation spectrum. The surviving fraction of all irradiation was the same as the half irradiation case. The surviving fractions of both mixed population and the half irradiation with inhibitor were the same level and higher than those of all irradiation and half irradiation. The mutation frequencies at the (the hypoxanthine-guanine phosphoribosyl transferase) locus of all irradiation and half irradiation were at the same level and were higher than those of mixed population and half irradiation with inhibitor, respectively. There is evidence that the bystander effects for both lethality and mutagenicity occurred in the unirradiated half of the cells, in which only half of the cells were irradiated with the carbon ions. These results suggest that the bystander cellular effects via gap-junction-mediated cell-cell communication are induced by high-LET-carbon ions.

The total and the partial charge-changing cross sections of 40Ar fragmentation on CH2, C, Al, Cu and Pb targets at the highest energy of 495 A MeV were investigated using CR-39 plastic nuclear track detector. The total charge-changing cross-section for hydrogen target was calculated based on the results of polyethylene and carbon targets. It was found that the total charge-changing cross sections for fragmentation of 40Ar on H, C, Al, Cu and Pb targets were independent on the beam energy in our studied energies, and were consistent with the predictions of Bradt-Peters semi-empirical formula. Nilsen semi-empirical formula, NUCFRG2 and PHITS simulation codes given an underestimation of experimental data. The partial cross sections for projectile fragment production were independent on the beam energy in our studied energies for each target and do not show a significant odd-even effect. The partial cross sections for projectile fragment production were also compared with different empirical parametrization formulas, such as different version of Cummings, Nilsen, FRACS and EPAX3. Generally, EPAX3 and FRACS empirical parametrization can give a reasonable estimation of data within 25% relative errors.

The system used to analyze the process of the formation of latent image specks (LISs) in silver-salt photographic materials due to radiation exposure to obtain the dispersion index, which is the number of LISs in a silver halide grain formed by one impact of high-energy particle, was improved. By using the electron beam from a transmission electron microscope, electrons of uniform energy could be produced for irradiation purposes. The number of electrons impacting a single silver halide grain along with the energy of each electron was controlled by varying the current density and the applied voltage. A new analysis method which included the probability that LIS may not be formed despite an impact of high-energy particle was proposed. The number of LISs was counted by the arrested development method. The probability and the dispersion index were estimated at approximately 0.5 and 1, respectively, for an unsensitized emulsion with cubic grains. This method will be useful in the design of new nuclear emulsion plates.

Our interests for years lay to investigate the reason why CR-39 polymer has such high sensitivity as plastic nuclear track detector(PNTD) on chemical structural aspects. We developed three PNTDs from three diacrylate compounds as monomers bearing different molecular length as well as different numbers of internal ether bonds. The polymer products obtained were colorless and transparent with 3-D molecular structures as CR-39 and different lattice each other. Our purpose of the current study was to investigate structural damages caused in newly prepared PNTD s and CR-39 by irradiation of Nitrogen ion (6 MeV/n, fluence of 5×10 11 cm-2). The structural damage by irradiation was analyzed by the magnitude of the relative absorbance of specific functional groups such as ester, C-O, ether and C-H bonds by means of FT-IR (ATR) method. The correlation between the relative absorbance and the molecular length of the monomers were discussed.

The emission angle distribution of projectile fragments (PFs) and the temperature of PF emission sources for fragmentation of 56Fe on polyethylene, carbon, and aluminum targets at the highest energy of 497 A MeV are investigated on the basis of corrected data, using a CR-39 plastic nuclear track detector. It is found that the average emission angle of PFs increases with the decrease in PF charge for the same target, and no obvious dependence of angular distribution on the mass of the target nucleus is found for the same PF. The cumulative squared transverse momentum distribution of PFs can be well represented by a single Rayleigh distribution. The temperature of PF emission sources is extracted from the distribution, and it is about 1.0–8.0 MeV and does not depend on the mass of the target for PFs with charges of 9

第26回固体中核飛跡に関する国際会議（ICNTS26)(2014年9月15日-19日, 神戸）, 26th International Conference on Nuclear Tracks in Solids (ICNTS26) (September 15-19 2014. Kobe, Japan), As a part of the Alteino Long Term Cosmic Ray measurements on board the International Space Station (ALTCRISS) project, the shielding effect of polyethylene (PE) were evaluated in the Russian segment of the ISS, using active and passive dosimeter systems covered with or without PE shielding. For the passive dosimeter system, PADLES (Passive Dosimeter for Life-Science and Experiments in Space) was used in the project, which consists of a Thermo-Luminescent Dosimeters (TLD) and CR-39 Plastic Nuclear Track Detectors (PNTDs) attached to a radiator. Not only CR-39 PNTD itself but also a tissue equivalent material, NAN-JAERI, were employed as the radiator in order to investigate whether CR-39 PNTD can be used as a surrogate of tissue equivalent material in space dosimetry or not. The agreements between the doses measured by PADLES with CR-39 PNTD and NAN-JAERI radiators were quite satisfactorily, indicating the tissue-equivalent dose can be measured by conventional PADLES even though CR-39 PNTD is not perfect tissue-equivalent material. It was found that the shielding effect of PE varies with location inside the spacecraft: it became less significant with an increase of the mean thickness of the wall. This tendency was also verified by Monte Carlo simulation using the PHITS code. Throughout the flight experiments, in a series of four phases in the ALTCRISS project from December 2005 to October 2007, we assessed the ability of PE to decrease radiation doses in Low Earth Orbit(LEO)., 形態: 図版あり, Physical characteristics: Original contains illustrations, 資料番号: PA1610040000

The sensitization effect of carbon dioxide treatments with 0.6 MPa on poly(allyl diglycol carbonate) (PADC) etched track detectors is confirmed for protons and He, C, and Fe ions, where the stopping powers range from 10 to 600 keV/mm. Based on the FT-IR study for the PADC films that were maintained at room temperature and at elevated temperatures, the diffusion coefficient of carbon dioxide, is determined as D ¼ 14,670exp(9030/T(K)) cm2/s. The sensitivity is enhanced when carbon dioxide is released toward the chemical etching solution that passes through the detector surface. Segmented PADC polymer chains are washed away by the flow of carbon dioxide along the latent tracks in PADC, which results in a higher track etch rate.

Chemical modification along ion tracks in Poly (allyl diglycol carbonate), PADC, films has been studied by means of Fourier transform infrared (FT-IR) spectrometry, which has exposed to protons and heavy ions in air. Chemical damage parameters, namely, radial size of the track core, in which the considered chemical groups are lost, damage density, which is the number of losses of considered functional groups per unit length of tracks, and radiation chemical yields, G values, for each group are evaluated as a function of the stopping power. The radiation chemical yields are higher at lower stopping powers for each ion and greater with increasing charge at the same stopping powers. Secondary electrons with higher energy should play a significant role to increase the yields by producing damage at a relatively distant place from the ion trajectories.

More than 15 years have been passed since the discovery of the sensitization effect by CO2 treatment on PADC detectors. The effect has strong relation with the dissolving process of CO2 into etching solution through the renewing surface of the detector during etching. In this study, releasing behavior of CO2 from the treated PADC is examined by means of FT-IR spectrometry and discussed based on the diffusion theory of Fick. We have succeeded to produce bending-etch pits, in which the pit walls have differed slope, depending on the applied etching conditions with the CO2 treatment or not.

desorption ionization-mass spectrometry (MALDI-MS) have been applied to analyze etch products of CR-39 plastic (one of the most frequently used solid states nuclear track detector) for the understanding of track formation and etching mechanisms by heavy ion irradiation. The etch products of irradiated CR-39 dissolved in sodium hydroxide solution (NaOH) contain radiation-induced fragments. For the GC-MS analysis, we found peaks of diethylene glycol (DEG) and a small but a definitive peak of ethylene glycol (EG) in the etch products from CR-39 irradiated by 60 MeV N ion beams. The etch products of unirradiated CR-39 showed a clear peak of DEG, but no other significant peaks were found. DEG is known to be released from the CR-39 molecule as a fragment by alkaline hydrolysis reaction of the polymer. We postulate that EG was formed as a result of the breaking of the ether bond (C-O-C) of the DEG part of the CR-39 polymer by the irradiation. The mass distribution of polyallylalcohol was obtained from the etch products from irradiated and unirradiated CR-39 samples by MALDI-MS analysis. Polyallylalcohol, with the repeating mass interval of m/z = 58 Da (dalton) between m/z = 800 and 3500, was expected to be produced from CR-39 by alkaline hydrolysis. We used IAA as a matrix to assist the ionization of organic analyte in MALDI-MS analysis and found that peaks from IAA covered mass spectrum in the lower m/z region making difficult to identify CR-39 fragment peaks which were also be seen in the same region. The mass spectrometry analysis using GC-MS and MALDI-MS will be powerful tools to investigate the radiation-induced polymeric fragments and helping to understand the track formation mechanism in CR-39 by heavy ions.

Charge identification of trans-iron nuclei (nuclear charge: Z>=30) using CR-39 plastic nuclear track detector (PNTD) is essential as a part of an effort to our future measurements of the projectile charge changing cross sections for galactic cosmic ray nuclei, but extremely hard. Therefore, an improvement method of the charge resolution (sZ) for 350 MeV/n Ge in CR-39 PNTD using the trajectory tracing technique with averaging the signals of nuclear tracks for each ion was studied. Eight sheets of CR-39 PNTDs were aligned and exposed to Ge beam behind a graphite target to produce projectile fragments. Average of the nuclear track data was taken over 16 detector surfaces for each ion, then the sZ of Ge was successfully improved from 0.31 charge unit on single surface to 0.15 charge unit in rms, which is good enough for making the precise cross section measurements and no other experiments using CR-39 PNTDs or the other passive detectors have achieved such a good sZ for the trans-iron nuclei with Z/beta

Anomalous behavior has been observed on the contact angle of water droplets on PADC, poly (allyl diglycol carbonate), nuclear track detectors which is exposed to proton beams. The angel reaches to the maximum value of 89 degree from the original value of 70 degree without the exposure at a fluence of 1.0x1013 ions/cm2.In the case of heavy ion irradiations by He, C and Xe ions, the angle decreases with increasing the fluence. Similar results have been observed for gamma irradiations, UV irradiations and the exposure to corona discharge. In order to evaluate the surface structure, XPS observations were made for PADC, in which X ray irradiation are simultaneously conducted. The polyethylene like network is more radiation tolerance than the ether and carbonate ester bonds which are in the repeat units. The observed anomalous behavior of the track angle is discussed from the point of views of track core size and spatial distribution on the PADC.

The charge resolution (dZ) for heavy ions (nuclear charge: Z < 40) of 0.1–1 GeV/n energy in CR-39 plastic nuclear track detector (PNTD) and its dependence on etching time, and on projectile Z and energy were investigated and optimized as part of an effort to make precise measurements of projectile charge-changing cross sections. Two types of CR-39 PNTD, HARZLAS TD-1 and BARYOTRAK, were exposed to heavy ion beams with seven values of Z behind thick targets to produce projectile fragments. Following chemical etching (7 N NaOH at 70 degreeC) for varying etch times, dZ of the projectiles was determined for each detector type. A strong dependence of dZ on the amount of bulk etch (B) was seen. It was also observed that dZ can be remarkably improved with longer etching time as a function of B^-{1/2}, in accordance with the trend seen in other types of track detector such as glass nuclear track detector. However, for B > 60 lm(30 h etching), saturation occurs and there is no further improvement in dZ. Analysis of the correlations between projectile Z, energy, detector response, and fluctuation of the response make it possible to develop a model to predict the dZ for projectiles of given Z and energy. The predicted and measured values of dZ show good agreement within 10%. We conclude that 4 < Z < 30 at intermediate energy can be identified with good dZ in these detectors. The predictive model will be used in designing future cross section measurement experiments.

Using standard visible light microscopy, we are able to observe particle tracks produced by