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Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*
RSC Advances (Internet), 13(46), p.32371 - 32380, 2023/11
Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)Although scientific knowledge of photolysis and radiolysis of water is widely used in the life sciences and other fields, the formation mechanism of the spatial distribution of hydrated electrons (spur) resulting from energy deposition to water is still not well understood. The chemical reaction times of hydrated electrons, OH radicals, and H
O
in the spur strongly depend on the spur radius. In our previous study, we elucidated the mechanism at a specific given energy (12.4 eV) by first-principles calculations. In the present study, we performed first-principles calculations of the spur radius at the deposition energies of 11-19 eV. The calculated spur radius is 3-10 nm, which is consistent with the experimental prediction (~4 nm) for the energy range of 8-12.4 eV, and the spur radius gradually increases with increasing energy. The spur radius is a new scientific knowledge and is expected to be widely used for estimating radiation DNA damage.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*
RSC Advances (Internet), 13(11), p.7076 - 7086, 2023/03
Times Cited Count：3 Percentile：81.33(Chemistry, Multidisciplinary)Scientific insights of water radiolysis are widely used in the life sciences and so on, however, the formation mechanism of radicals, a product of water radiolysis, is still not well understood. We are challenging to develop a simulation code to solve this formation mechanism from the viewpoint of radiation physics. Our first-principles calculations have revealed that the behavior of secondary electrons in water is governed not only by collisional effects but also by polarization effects. Furthermore, from the predicted ratio of ionization to electronic excitation, based on the spatial distribution of secondary electrons, we successfully reproduce the initial yield of hydrated electrons predicted in terms of radiation chemistry. The code provides us a reasonable spatiotemporal connection from radiation physics to radiation chemistry. Our findings are expected to provide newly scientific insights for understanding the earliest stages of water radiolysis.
Tsuchida, Hidetsugu*; Majima, Takuya*; Kai, Takeshi
Oyo Butsuri, 91(9), p.553 - 557, 2022/09
In recent years, basic research has been conducted to understand the biological effects of radiation at the atomic level toward advancing particle beam cancer treatment. Here we show some recent results on the basic process of biomolecular damage caused by ion beams in liquid water. A biomolecular solution target was introduced to the vacuum by a liquid molecular beam or microdroplet method. Secondary ion mass spectrometry was applied to measure the fragments of biomolecules emitted from a target irradiated with an ion beam. For the simulation study using a PHITS code, physical nature of secondary electrons produced by ion beam in water was analyzed. The experimental and simulation research determined the energy range of secondary electrons involved in damaging biomolecules in liquid water caused by ion beams. The damage process by secondary electrons near the ion track is described.
Tsuchida, Hidetsugu*; Kai, Takeshi; Kitajima, Kensei*; Matsuya, Yusuke; Majima, Takuya*; Saito, Manabu*
European Physical Journal D, 74(10), p.212_1 - 212_7, 2020/10
Times Cited Count：3 Percentile：17.64(Optics)Fundamental study of interaction between biomolecules and heavy ions in water is very important to predict an initial stage of radiation biological effects. A heavy ion irradiation experiment into droplet target assumed as a biological system in a vacuum was performed to measure production yields of cations and anions for glycine, which was ejected from the droplet target to the vacuum. However, the production mechanisms have been unknown. The PHITS code adapting ion track structure mode was used to analyze the production mechanisms from the dose evaluation at the surface between the vacuum and the water. It is found that induction yields of ionization and excitation, and dissociative electron attachment involved in the secondary electrons were correlated with the production yields of cations and anions of the glycine. The results provide us newly scientific insights to predict an initial stage of radiation biological effects.
ions through micro- and nano-capillariesTsuchida, Hidetsugu*; Majima, Takuya*; Tomita, Shigeo*; Sasa, Kimikazu*; Narumi, Kazumasa; Saito, Yuichi; Chiba, Atsuya; Yamada, Keisuke; Hirata, Koichi*; Shibata, Hiromi*; et al.
Nuclear Instruments and Methods in Physics Research B, 315, p.336 - 340, 2013/11
Times Cited Count：3 Percentile：26.71(Instruments & Instrumentation)Iwase, Akihiro*; Chimi, Yasuhiro; Ishikawa, Norito; Nakatani, Rikizo*; Kato, Yuzaburo*; Fukuzumi, Masafumi*; Tsuchida, Hidetsugu*; Baba, Yuji
Nuclear Instruments and Methods in Physics Research B, 245(1), p.141 - 144, 2006/04
Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)Diffusion of Si atoms in Pd under energetic ion irradiation is studied in Pd-Si thin layer system using synchrotron radiation photoemission spectroscopy. Specimens are prepared by depositing Pd on Si single crystals. The Pd layer thicknesses are 10-300 nm. Before irradiation, we observe photoemission spectra only for Pd, but do not find any trace of Si. After irradiation with 3-MeV Si ions, 1-MeV O ions or 200-MeV Xe ions, we observe an additional photoemission component at the binding energy about 3 eV higher than that of Si 1s bulk component. The experimental result implies that the energetic ion-irradiation induces the diffusion of Si atoms from the Si-Pd interface to the Pd layer surface. The shift of the binding energy from the value for the Si bulk can be interpreted as arising from electron charge transfer from Si to Pd. The dependences of photoemission spectra and ion-irradiation induced diffusion on ion-species and ion-fluence are discussed.
Shibata, Hiromi*; Saito, Yuichi; Chiba, Atsuya; Narumi, Kazumasa; Tsuchida, Hidetsugu*; Ito, Akio*; Kamiya, Tomihiro; Fukuda, Mitsuhiro*
no journal, ,
no abstracts in English
Shibata, Hiromi*; Tsuchida, Hidetsugu*; Ito, Akio*; Saito, Yuichi; Chiba, Atsuya; Narumi, Kazumasa; Arakawa, Kazuo
no journal, ,
no abstracts in English
Shibata, Hiromi*; Tsuchida, Hidetsugu*; Ito, Akio*; Saito, Yuichi; Chiba, Atsuya; Kamiya, Tomihiro; Narumi, Kazumasa
no journal, ,
no abstracts in English
microbeams by single-microcapillary methodsTsuchida, Hidetsugu*; Majima, Takuya*; Tomita, Shigeo*; Sasa, Kimikazu*; Narumi, Kazumasa; Saito, Yuichi; Chiba, Atsuya; Yamada, Keisuke; Hirata, Koichi*; Shibata, Hiromi*; et al.
no journal, ,
Tsuchida, Hidetsugu*; Nakajima, Kaoru*; Yokoe, Junya*; Sugiyama, Motohiko*; Ota, Yushi*; Majima, Takuya*; Shibata, Hiromi*; Tomita, Shigeo*; Sasa, Kimikazu*; Hirata, Koichi*; et al.
no journal, ,
no abstracts in English
Tsuchida, Hidetsugu*; Majima, Takuya*; Tomita, Shigeo*; Sasa, Kimikazu*; Hirata, Koichi*; Shibata, Hiromi*; Saito, Yuichi; Narumi, Kazumasa; Chiba, Atsuya; Yamada, Keisuke; et al.
no journal, ,
no abstracts in English
Ueda, Daisuke*; Konishi, Suzuka*; Minagawa, Hideaki*; Hirade, Tetsuya; Tsuchida, Hidetsugu*
no journal, ,
Damaged conditions under irradiation such as ion beams irradiation are transient and unstable. Understanding of this transient damage state is important to clarify the process from damage generation to stabilization. We are developing Age-MOmentum Correlation (AMOC) measurement system by 
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coincident measurement to investigate the triplet positronium (o-Ps) reactions as a probe of reactive species. From the correlation between "positron annihilation time" and "momentum of electron / positron at pair annihilation" obtained by AMOC measurement, it is possible to investigate the process of o-Ps reactions. We report on AMOC measurement system newly constructed by digital method.
- based AMOC measurement systemKonishi, Suzuka*; Ueda, Daisuke*; Xu, Q.*; Hirade, Tetsuya; Tsuchida, Hidetsugu*
no journal, ,
In order to elucidate the transient damage state by ion beam etc., positron annihilation lifetime - momentum correlation (Age-MOmentum Correlation: AMOC) apparatus by - simultaneous measurement is newly constructed by the digital method. In this study, we investigated the effect of -irradiation of polystyrene using the AMOC apparatus. As a result, we obtained that the S parameter near 1 ns decreases corresponding to the increase of damage amount.
Konishi, Suzuka*; Minagawa, Hideaki*; Majima, Takuya*; Imai, Makoto*; Saito, Manabu*; Hirade, Tetsuya; Tsuchida, Hidetsugu*
no journal, ,
To clarify the damage behavior under ion irradiation in quartz glass, Age-Momentum Correlation measurement that is a coincidence measurement of positron annihilation lifetime and annihilation gamma ray Doppler broadening was performed under 2 MeV proton irradiation. From the change in momentum distribution of electrons involved in positron annihilation in voids of the quartz glass, flux dependence of damage behavior could be detected.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Ito, Yuma*; Yokoya, Akinari*
no journal, ,
Irradiation of living systems forms complex DNA damage that induces biological effects in very rare cases. This complex DNA damage is called cluster damage and is very difficult to detect experimentally. In this study, we have developed physical and chemical codes for analyzing DNA damage, and are working to elucidate the formation mechanism of cluster damage. In this study, we analyzed the results of calculations in a simple system in which energy is deposited to DNA and secondary electrons are emitted, and showed that the formation mechanism of cluster damage strongly depends on the deposition energy to DNA. This scientific insight is expected to contribute to the elucidation of the repair mechanism of DNA damage and lead to the elucidation of radiation biological effects.
