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Journal Articles

Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350$$^{circ}$$C; A Monte-Carlo simulation study

Sanguanmith, S.*; Muroya, Yusa*; Tippayamontri, T.*; Meesungnoen, J.*; Lin, M.; Katsumura, Yosuke*; Jay-Gerin, J.-P.*

Physical Chemistry Chemical Physics, 13(22), p.10690 - 10698, 2011/06

 Times Cited Count:21 Percentile:60.1(Chemistry, Physical)

Monte-Carlo simulations of the radiolysis of the ferrous sulfate (Fricke) dosimeter with low-linear energy transfer (LET) radiation have been performed as a function of temperature from 25 to 350$$^{circ}$$C. The predicted yields of Fe$$^{2+}$$ oxidation are found to increase with increasing temperature up to 100-150$$^{circ}$$C, and then tend to remain essentially constant at higher temperatures, in very good agreement with experiment. Moreover, the observed dependence of G(Fe$$^{3+}$$) on temperature largely reflects the influence of temperature upon the primary free-radical product yields of the radiolysis, especially the yield of H atoms. Above 200-250$$^{circ}$$C, the more and more pronounced intervention of the reaction of H atoms with water also contributes to the variation of G(Fe$$^{3+}$$), which may decrease or increase slightly, depending on the choice made for the rate constant of this reaction.

Journal Articles

Low-linear energy transfer radiolysis of liquid water at elevated temperatures up to 350$$^{circ}$$C; Monte-Carlo simulations

Sanguanmith, S.*; Muroya, Yusa*; Meesungnoen, J.*; Lin, M.; Katsumura, Yosuke*; Mirsaleh Kohan, L.*; Guzonas, D. A.*; Stuart, C. R.*; Jay-Gerin, J.-P.*

Chemical Physics Letters, 508(4-6), p.224 - 230, 2011/05

 Times Cited Count:42 Percentile:82.34(Chemistry, Physical)

Our Monte-Carlo modeling of the high-temperature radiolysis of water by low-LET radiation was re-examined in an attempt to reconcile our computed $$g$$-values of the various radiolytic products with recently re-assessed experimental data up to 350$$^{circ}$$C. The inclusion in our simulations of the abrupt drop in the rate constant for the self-reaction of hydrated electron above 150$$^{circ}$$C led us to re-evaluate the temperature dependence of certain parameters intervening in the physicochemical stage of the radiolysis. A very good agreement was found between model and experiment. The importance of the reaction of H atoms with water in the unexplained yield of H$$_{2}$$ above 200$$^{circ}$$C was also briefly discussed.

Journal Articles

Monte-Carlo simulation of the low-LET radiolysis of liquid water over the range 25 to 350$$^{circ}$$C

Sanguanmith, S.*; Muroya, Yusa*; Meesungnoen, J.*; Lin, M.; Katsumura, Yosuke*; Mirsaleh Kohan, L.*; Guzonas, D. A.*; Stuart, C. R.*; Jay-Gerin, J.-P.*

Proceedings of 5th International Symposium on Supercritical Water-Cooled Reactors (ISSCWR-5) (CD-ROM), 13 Pages, 2011/03

A re-examination of our Monte-Carlo modeling of the high-temperature radiolysis of liquid water by low linear energy transfer (LET $$sim$$0.3 keV/$$mu$$m) radiation was undertaken in an attempt to reconcile our computed g-values of the various radiolytic products with newly measured or recently re-assessed experimental data over the range from 25 up to 350$$^{circ}$$C. Using a global-fit procedure, experimental data were found to be best reproduced when a discontinuity in the temperature dependence of certain physicochemical parameters was introduced at $$sim$$100-150$$^{circ}$$C. The presence of such a discontinuity was hypothesized to be associated with a change in the liquid structure of water around these temperatures. In addition to the physicochemical factors intervening in the radiolysis, the importance of the reaction of H atoms with water in contributing to the unexplained yield of H$$_{2}$$ above 200$$^{circ}$$C was also investigated.

Journal Articles

Temperature and density effects on the absorption maximum of solvated electrons in sub- and super-critical methanol

Yan, Y.*; Lin, M.; Katsumura, Yosuke*; Muroya, Yusa*; Yamashita, Shinichi; Hata, Kuniki; Meesungnoen, J.*; Jay-Gerin, J.-P.*

Canadian Journal of Chemistry, 88(10), p.1026 - 1033, 2010/10

 Times Cited Count:1 Percentile:7.14(Chemistry, Multidisciplinary)

The optical absorption spectra of the solvated electron (e$$_{rm sol}^-$$) in sub- and super-critical methanol are measured by both electron pulse radiolysis and laser photolysis techniques, at temperatures in the range 220-270 $$^{circ}$$C. Over the density range studied ($$sim$$0.45-0.59 g/cm$$^{3}$$), the position of the absorption maximum ($$E$$$$_{rm Amax}$$) of e$$_{rm sol}^-$$ is found to shift only slightly to the red with decreasing density. In agreement with our previous work in water, at a fixed pressure, $$E$$$$_{rm Amax}$$ decreases monotonically with increasing temperature in passing through the phase transition at $$T$$$$_{rm c}$$ (239.5 $$^{circ}$$C). By contrast, at a fixed density, $$E$$$$_{rm Amax}$$ exhibits a minimum as the solvent passes above the critical point into the supercritical state. These behaviors are discussed in terms of microscopic arguments based on the changes that occur in the methanol properties and methanol structure in the sub- and supercritical regimes.

Journal Articles

Water radiolysis with heavy ions of energies up to 28 GeV, 3; Measurement of ${it G}$(MV$$^{.+}$$) in deaerated methyl viologen solutions containing various concentrations of sodium formate and Monte Carlo simulation

Yamashita, Shinichi; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

Radiation Research, 170(4), p.521 - 533, 2008/10

 Times Cited Count:7 Percentile:27.27(Biology)

Formation yields of methyl viologen cation radicals ${it G}$(MV$$^{.+}$$) (100 eV)$$^{-1}$$ have been measured in deaerated aqueous solutions of methyl viologen, MV$$^{2+}$$, containing various concentrations of formate anion after irradiation with six different ion beams (from $$^{4}$$He$$^{2+}$$ to $$^{56}$$Fe$$^{26+}$$ with incident energies varying from 0.6 to 28 GeV) provided by HIMAC at NIRS in Japan. In parallel to the above measurements, Monte Carlo simulations of the radiolysis of the MV$$^{2+}$$-formate solutions have been performed to investigate complementarily mechanism from which distinctive irradiation effects of heavy ions are derived from the microscopic viewpoints experimentally non-feasible.

Journal Articles

Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 $$^{circ}$$C

Jay-Gerin, J.-P.*; Lin, M.; Katsumura, Yosuke; He, H.*; Muroya, Yusa*; Meesungnoen, J.*

Journal of Chemical Physics, 129(11), p.114511_1 - 114511_7, 2008/09

 Times Cited Count:22 Percentile:61.41(Chemistry, Physical)

In this work, we measure the density dependent absorption spectra of hydrated electron in D$$_{2}$$O at 380, 390, and 400$$^{circ}$$C, and then compare with the literature data for subcritical water. The results show that at a fixed pressure (25 MPa), ${it E$_{A-max}$}$ decreases monotonically with increasing temperature in passing through the liquid-supercritical water (SCW) phase transition at t$$_{c}$$. By contrast, at a fixed density (0.2 and 0.65g/cm$$^{3}$$), ${it E$_{A-max}$}$ exhibits a minimum near ${it t$_{c}$}$. These behaviors are explained in terms of local density and configurational fluctuations of water structure in SCW.

Oral presentation

Water radiolysis with heavy ions, 2; Monte-Carlo simulation for discussion of intra-track reactions

Yamashita, Shinichi*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

no abstracts in English

Oral presentation

Investigation on initial structure of heavy-ion track in water radiolysis; Simulation based on diffusion kinetic model and comparison of proposed track structures

Yamashita, Shinichi*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Simulation based on diffusion kinetic model has been carried out to investigate on "initial" track structure at 10$$^{-12}$$ s formed by heavy-ion irradiation and to compare with reported values such as primary yields in pure water and ${it G}$(Fe$$^{3+}$$) in the Fricke solution. Several dose distributions proposed in literatures were taken into the simulation. Spatial distributions of "initial" products at 10$$^{-12}$$ s calculated with Monte-Carlo simulation were compared with the dose distributions reported in the literature.

Oral presentation

Water radiolysis with heavy ions of energies up to 28 GeV; Investigation of track structure and intra-track reactions

Yamashita, Shinichi*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Miyazaki, Toyoaki*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Oral presentation

Radiolysis of water with heavy ions of energies up to 28 GeV at HIMAC

Katsumura, Yosuke; Yamashita, Shinichi; Lin, M.; Muroya, Yusa*; Meesungnoen, J.*; Jay-Gerin, J.-P.*; Murakami, Takeshi*

no journal, , 

Oral presentation

Water radiolysis with heavy ions of wide range of energies; Investigation of initial track structure with deterministic simulations

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Water radiolysis with heavy ions, from helium to iron ions, of very high energies up to 28 GeV (namely several hundred MeV per nucleon) has been studied in this work. Simulations based on diffusion kinetic model were performed to examine correlation between initial track structures at the beginning of the chemical stage, 10-12 s, and primary yields as well as to estimate the validity of classical track structure model for highly energetic heavy ions.

Oral presentation

Water radiolysis with heavy ions; Correlation between heavy-ion track structure and primary yields

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Primary yields in water radiolysis with relativistic heavy ions from Heavy Ion Medical Accelerator in Chiba (HIMAC) of National Institute of Radiological Sciences (NIRS) have been measured covering wide range of beam conditions. Experimental results were summarized and compared with results obtained not only in a deterministic simulation but also in a stochastic one. Heavy-ion track structure was discussed from microscopic viewpoints based on the experimental and simulation results.

Oral presentation

Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 $$^{circ}$$C

Lin, M.; Jay-Gerin, J.-P.*; Katsumura, Yosuke; Muroya, Yusa*; Meesungnoen, J.*; Yamashita, Shinichi

no journal, , 

In this work, we measure the density dependent absorption spectra of hydrated electron in D$$_{2}$$O at 380, 390, and 400 $$^{circ}$$C, and then compare with the literature data for subcritical water. The results show that at a fixed pressure (25 MPa), ${it E$_{A}$}$-$$_{max}$$ decreases monotonically with increasing temperature in passing through the liquid-supercritical water (SCW) phase transition at ${it t$_{c}$}$. By contrast, at a fixed density (0.2 and 0.65 g/cm$$^{3}$$), ${it E$_{A}$}$-$$_{max}$$ exhibits a minimum near ${it t$_{c}$}$. These behaviours are explained in terms of local density and configurational fluctuations of water structure in SCW.

Oral presentation

Investigation on heavy-ion track structure in water using diffusion kinetic model simulation

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Jay-Gerin, J.-P.*; Meesungnoen, J.*

no journal, , 

Although water is a main component of human cells and its interaction with ionizing radiations are of crucial importance, understanding of water radiolysis with heavy ions of energies comparable to those used in actual cancer treatments is not sufficient. Recently, such highly energetic heavy ions are available at the Heavy Ion Medical Accelerator in Chiba (HIMAC) of the National Institute of Radiological Sciences (NIRS), Chiba, Japan. We have carried out measurements of primary yields of main water decomposition products, hydrated electron (e$$^{-}$$$$_{aq}$$), hydroxyl radical ($$^{.}$$OH) and hydrogen peroxide (H$$_{2}$$O$$_{2}$$) with heavy ions from $$^{4}$$He$$^{2+}$$ to $$^{56}$$Fe$$^{26+}$$ of energies up to 28 GeV (corresponding LET varies from 2 to 700 keV/$$mu$$m) provided from the HIMAC. Note that primary yields are defined as the yields at 100 ns after irradiation, which can be regarded as a time scale when diffusions and intra-track reactions of initial products are almost terminated. Then, such yields are important because they inherently involve information of initial track structure and dynamics of water decomposition products during track expansion. In the present study, not only such measurements but also discussions based on the measured data were conducted by simulations.

Oral presentation

Water radiolysis with high-energy ion beams

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

It is phenomenologically well known that heavy-ion beams, which are known to be typical high-LET radiations, give distinctive irradiation effects compared to more popular low-LET radiations such as electron beam and $$gamma$$-rays. Here, LET is abbreviation of linear energy transfer, defined as energy deposition from radiation to surrounding matter per unit length of its trajectory. Most of earlier studies focus lighter ions ($$^{1}$$H, etc.) of lower energies ($$<$$ 10 MeV/nucleon). Moreover, knowledge under neutral pH, which is close to human body, has not been accumulated well. In this study, it is purposed to investigate chemical change occurring in neutral aqueous solutions after irradiation of high-energy (10-500 MeV/nucleon) heavy ions ($$^{12}$$C, $$^{56}$$Fe, etc.). Especially, structure of heavy-ion track and radiation-chemical yields are discussed.

Oral presentation

Ion beam radiation chemistry relevant to radiation therapy

Katsumura, Yosuke; Yamashita, Shinichi; Lin, M.; Maeyama, Takuya*; Muroya, Yusa*; Baldacchino, G.*; Jay-Gerin, J.-P.*; Meesungnoen, J.*; Murakami, Takeshi*

no journal, , 

Oral presentation

Water radiolysis with heavy ions

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Lin, M.; Muroya, Yusa*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Water radiolysis with high-energy heavy ions has been investigated through measurement of product yield and simulation of intra-track reactions. Ions from helium to xenon of energies up to 500 MeV per nucleon were taken for irradiation at the biological irradiation port of HIMAC installed at NIRS, Japan. Taking long range of the ions, typically longer than 10 cm, as an advantage, track-segment yields of main water decomposition products, e$$^{-}$$$$_{aq}$$, $$bullet$$OH and H$$_{2}$$O$$_{2}$$, have been determined. Utilizing energy absorber made of PMMA, ion energies were decreased down to about 10 MeV per nucleon to vary beam properties in sample solutions, and then, product yields for wide ranges of ion types and energies were accumulated. Influences of scavenger concentration have also been discussed and yield of approximate sum of $$bullet$$OH, H$$bullet$$ and e$$^{-}$$$$_{aq}$$ was measured. In parallel to these measurements, Monte-Carlo simulation of intra-track reactions has been conducted not only to reproduce the experimental results but also to discuss further track structure and its dynamics from microscopic viewpoint.

Oral presentation

Water radiolysis with therapeutic ion beam; Contribution of fragmentations to $$^{.}$$ OH yields estimated by PHITS

Funtowiez, D.*; Maeyama, Takuya*; Yamashita, Shinichi; Katsumura, Yosuke; Meesungnoen, J.*; Jay-Gerin, J.-P.*; Murakami, Takeshi*

no journal, , 

no abstracts in English

Oral presentation

Water radiolysis with heavy ions of energies up to 28 GeV

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Baldacchino, G.*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*

no journal, , 

Water radiolysis with heavy ions has been investigated from the viewpoint of correlation between track structure and yields of water decomposition products. Primary yields of main products were determined for wide variety of heavy ion beams of energies up to 28 GeV provided at HIMAC (Heavy Ion Medical Accelerator in Chiba). A fluorescent probe, 7-hydroxyl-coumarin-3-carboxylic acid, was utilized in sensitive detection and quantification of hydroxyl radical. This method was extended to investigation of water radiolysis near the Bragg peak with considering fragmentation reactions. Gaseous products detection has also been started.

Oral presentation

Water radiolysis with heavy ions; Spatial distributions and dynamics of water radicals

Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Meesungnoen, J.*; Jay-Gerin, J.-P.*; Baldacchino, G.*; Murakami, Takeshi*

no journal, , 

Although water is one of the most ubiquitous molecules as well as a main component of human body, understanding of water radiolysis is not always sufficient. Among many types of ionizing radiations, heavy ions deposit their energies very densely, resulting in distinctive following processes. Comprehension of water radiolysis itself is essential to consider indirect actions of ionizing radiations. Moreover, energy deposition distributions in water is related to that in/on biomolecules including DNA, proteins, and so on, and spatial distributions and temporal behaviors of water radicals give a clue to think over the fate of DNA damage produced within several nanoseconds. In this presentation, yields of water decomposition products which have been measured at HIMAC will be introduced in comparison to one of the most advanced Monte-Carlo simulation.

23 (Records 1-20 displayed on this page)