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Journal Articles

Utilization status at TIARA facility

Haruyama, Yasuyuki; Takizawa, Haruki; Hosono, Masakazu; Mizuhashi, Kiyoshi*; Nakamura, Yoshiteru*; Kaneya, Satoshi*; Asai, Takahiro*; Kawabata, Michiko*; Imai, Koji*

JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 177, 2014/03

https://doi.org/10.11484/jaea-review-2013-059

Cyclotron use in FY 2012, was 2243.5 hours beam time. Among them, the use time of Bio technology and Medical application relationship most, I occupy the time spent for the Quarter of the total. Use offer to the outside utilization was 17%. Use the number of days in Electrostatic Accelerators was 490 days. Among them, Basic technology is accounted for using the percentage of 46%, but the use of irradiation Reactor materials and irradiation of Material for space even more, I accounted for 18 percent utilization rate, respectively, of 15%. Use offer to the outside utilization was 8%.

Journal Articles

Feature in FY2011, utilization status and beam time proportion at TIARA facility

Mizuhashi, Kiyoshi; Takizawa, Haruki; Hosono, Masakazu; Nakamura, Yoshiteru*; Kaneya, Satoshi*; Mochizuki, Seigo*; Asai, Takahiro*; Kawabata, Michiko*; Daikubara, Kazuko*

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 171, 2013/01

https://doi.org/10.11484/jaea-review-2012-046

Fiscal year 2011 was significantly influenced by the East Japan Great Earthquake (March 11, 2011). The operation of the TIARA facility which was being planned from April started from the middle of May. Lost beam-time of the experiment due to the great earthquake was compensated with operations on Saturday biweekly. And it was obliged to re-examine the operation plan during the period of electric power reduction in July, August, and September. The demanded reduction rate of electric power in daytime for summer season was 15% as compared with 2010. The limited value in daytime was 3,600 kW. Therefore, the experiment in daytime was conducted with light ions (H, D with 20 MeV) only by the AVF Cyclotron. As mentioned above, the electric power in the daytime of summer did not exceed 3,200 kW. Moreover, the beam time as an ordinary year was secured.

Journal Articles

Identification of a Frenkel-pair defect in electron-irradiated 3 SiC

Son, N. T.*; Janzn, E.*; Isoya, Junichi*; Morishita, Norio; Hanaya, Hiroaki; Takizawa, Haruki; Oshima, Takeshi; Gali, A.*

Physical Review B, 80(12), p.125201_1 - 125201_8, 2009/09

https://doi.org/10.1103/PhysRevB.80.125201

Times Cited Count：10 Percentile：41.44(Materials Science, Multidisciplinary)

Defects in electron irradiated 3-SiC were studied by electron paramagnetic resonance EPR. The spectrum labeled LE1 was observed in -type 3 SiC after electron irradiation at low temperatures (80-100 K). Supercell calculations of different configurations of silicon vacancy-interstitial Frenkel-pairs, V $_{rm Si}$ -Si $_{rm i}$ , were carried out. Comparing the data obtained from experiments using EPR and supercell calculations, the LE1 center is assigned to the Frenkel-pair between V $_{rm Si}$ and a second neighbor Si $_{rm i}$ interstitial along the [100] direction in the 3+ charge state. In addition, a path for the migration of Si $_{rm i}$ $^{4+}$ was found in 3 SiC. In samples electron-irradiated at low temperatures, the LE1 Frenkel-pair was found to be the dominating defect whereas EPR signals of single vacancies were not detected. The center disappears after warming up the samples to room temperature.

Journal Articles

Spin multiplicity and charge state of a silicon vacancy ( $_{V2a}$ ) in 4-SiC determined by pulsed ENDOR

Mizuochi, Norikazu*; Yamasaki, Satoshi*; Takizawa, Haruki; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Umeda, Takahide*; Isoya, Junichi*

Physical Review B, 72(23), p.235208_1 - 235208_6, 2005/12

https://doi.org/10.1103/PhysRevB.72.235208

Times Cited Count：51 Percentile：83.11(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Absorbed dose rate distribution in 300 keV electron beam irradiation field for waste-gas purification

Hakoda, Teruyuki; Sunaga, Hiromi; Takizawa, Haruki; Hirota, Koichi; Kojima, Takuji

Radioisotopes, 53(2), p.59 - 69, 2004/02

https://doi.org/10.3769/radioisotopes.53.59

no abstracts in English

Journal Articles

3-45MeV/u ion beam dosimetry using thin film dosimeters

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki*; Hanaya, Hiroaki; Tachibana, Hiroyuki*

Radiation Physics and Chemistry, 68(6), p.975 - 980, 2003/12

https://doi.org/10.1016/j.radphyschem.2003.02.001

Times Cited Count：2 Percentile：18.63(Chemistry, Physical)

Four kinds of film dosimeters well-characterized for low LET radiations were applied to 3-45 MeV/u ions. The dose responses relative to those for low LET radiations are almost one up to about 10 MeV/(mg/cm $^{2}$ ) and gradually become smaller with increase of the stopping power. Overall uncertainty in ion beam dosimetry using these characterized dosimeters is better than 5%(1) including uncertainty in fluence measurement(2%). Lateral and depth dose profile measurements were achievable using characterized Gafchromic dosimeters with the spatial resolution of better than 1 and 10 m, respectively.

Journal Articles

EPR studies of the isolated negatively charged silicon vacancies in -type 4- and 6-SiC; Identification of $_{3v}$ symmetry and silicon sites

Mizuochi, Norikazu*; Yamasaki, Satoshi*; Takizawa, Haruki; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Isoya, Junichi*

Physical Review B, 68(16), p.165206_1 - 165206_11, 2003/10

https://doi.org/10.1103/PhysRevB.68.165206

Times Cited Count：43 Percentile：83.27(Materials Science, Multidisciplinary)

Isolated silicon vacancies with negative charge (V $_{Si}$ $^{-}$ ) in 4H- and 6H-SiC were studied using EPR. The samples used in this study were irradiated with electron at 3 MeV at RT. After irradiation, the samples were annealed at 300 $^{circ}$ C in Ar to eliminate C-related isolated vacancies. As the result of $^{13}$ C hyperfine spectra, two kinds of V $_{Si}$ $^{-}$ (I) and V $_{Si}$ $^{-}$ (II) were distinguished and they are assigned to be arising from hexagonal and cubic sites of Si. In addition, both V $_{Si}$ $^{-}$ (I) and V $_{Si}$ $^{-}$ (II) signals have C $_{3v}$ symmetry, which means nearest-neighbor carbon atoms silightly distorted from a regular tetrahedron.

Journal Articles

Dosimetry for a few hundred keV electron beams

Kojima, Takuji; Hakoda, Teruyuki; Sunaga, Hiromi; Takizawa, Haruki; Hanaya, Hiroaki

Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00

Dosimetry study for 300 keV electron beams was performed using Gafchromic film dosimeters having 8-m thick radiation-sensitive layer for dose rate measurement, a prototype total-absorption aluminum calorimeter for energy fluence measurement and semi-empirical calculation using EDMULT code for depth-dose distribution estimation. The three preliminary results are compared concerning to dose rate distribution and energy fluence as a function of depth in air. Influences in dosimetry for 300 keV electrons are discussed based on these results.

Journal Articles

Continuous-wave and pulsed EPR study of the negatively charged silicon vacancy with S=3/2 and C $_{3nu}$ symmetry in -type 4H-SiC

Mizuochi, Norikazu*; Yamasaki, Satoshi*; Takizawa, Haruki; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi; Isoya, Junichi*

Physical Review B, 66(23), p.235202_1 - 235202_12, 2002/12

https://doi.org/10.1103/PhysRevB.66.235202

Times Cited Count：115 Percentile：95.22(Materials Science, Multidisciplinary)

EPR study was performed to understand vacancy-type defects in electron-irradiated 4H-SiC. In this study, the T $_{V2a}$ center which was reported to be S=1 was charactrized. As a result of untation method of EPR technique, it was revealed that the multipicity of the center is not triplet (S=1) but quartet (S=3/2). From the analysis of $^{13}$ C hyperfine interactions of nearest-neighbors, the canter was determined to be single silicon vacancy. In addition, it was found that the center is negativly charged silicon vacancy with C $_{3nu}$ symmetry.

Journal Articles

Dosimetry for 3-45 MeV/u ion beams using thin film dosimeters

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki; Hanaya, Hiroaki; Tachibana, Hiroyuki*

JAERI-Review 2002-035, TIARA Annual Report 2001, p.123 - 124, 2002/11

Thin film dosimeters of about 10-200 mm in thickness, which were well -characterized for $^{60}$ Co -rays or 2-MeV electrons, have been applied to dosimetry for ion beams. For development of dosimetry covering the dose range of 0.005 to 200 kGy with high precision within 5%, the linear energy transfer (LET) characteristics of thin films were studied involving development of precise fluence measurement. Dose mapping technique was also developed achieving high spatial resolution values of about 1m and 10m for lateral and depth directions respectively. The outline of the recent development is summarized in this paper.

Journal Articles

EPR study of single silicon vacancy-related defects in 4H- and 6H-SiC

Mizuochi, Norikazu*; Isoya, Junichi*; Yamasaki, Satoshi*; Takizawa, Haruki; Morishita, Norio; Oshima, Takeshi; Ito, Hisayoshi

Materials Science Forum, 389-393, p.497 - 500, 2002/00

https://doi.org/10.4028/www.scientific.net/MSF.389-393.497

Times Cited Count：3 Percentile：15.90(Materials Science, Multidisciplinary)

The spin triplet (S=1) single silicon vacancy relared defects in electron irradiated (3MeV 410 $^{18}$ e/cm $^{2}$ , room temperature) n-type 4H- and p-type 6H-SiC were studied by electron paramagnetic resonance (EPR) spectroscopy. By laser irradiation, the hyperfine couplings (HFC) with nearest-neighbor (NN) atoms of T $_{V2a}$ were observed. As a result of detailed analysis, T $_{V2a}$ was unambiguously assigned to be the single silicon vacancy.

Journal Articles

Application of thin film dosimeters to measurement of ion beam dose distribution, 2

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki; Hanaya, Hiroaki; Tachibana, Hiroyuki

JAERI-Review 2001-039, TIARA Annual Report 2000, p.120 - 121, 2001/11

https://doi.org/10.11484/jaeri-review-2001-039

Gafchromic film (MD-1260) characterized for MeV/u ion beams was tested for measurement of the lateral distribution profiles in the plastic phantom. Gafchromic film was irradiated to 120 Gy using 450 MeV $^{129}$ Xe $^{23+}$ ions through the 10 thick mesh mask having 6 m line-width and 19 inner latice distance to make artificial dose distribution on the film. Analysis of radiation-induced color change of the film was tried using a microscopic spectrophotpmeter having 1 dia. analyzing light. The film has a potencial to know exact lateral irradiation area with sufficient sharpness and dose distribution by converting absorbance to dose on he basis of dose response characteristics, with spatial resolution of 1.