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Omer, M.; Shizuma, Toshiyuki*; Koizumi, Mitsuo; Taira, Yoshitaka*; Zen, H.*; Ogaki, Hideaki*; Hajima, Ryoichi
UVSOR-50, P. 37, 2023/08
no abstracts in English
Taira, Yoshitaka*; Endo, Shunsuke; Kawamura, Shiori*; Nambu, Taro*; Okuizumi, Mao*; Shizuma, Toshiyuki*; Omer, M.; Zen, H.*; Okano, Yasuaki*; Kitaguchi, Masaaki*
Physical Review A, 107(6), p.063503_1 - 063503_10, 2023/06
Times Cited Count：0 Percentile：0.01(Optics)no abstracts in English
Miyagawa, Reina*; Kamibayashi, Daisuke*; Nakamura, Hirotaka*; Hashida, Masaki*; Zen, H.*; Somekawa, Toshihiro*; Matsuoka, Takeshi*; Ogura, Hiroyuki*; Sagae, Daisuke*; Seto, Yusuke*; et al.
Scientific Reports (Internet), 12, p.20955_1 - 20955_8, 2022/12
Times Cited Count：0 Percentile：0(Multidisciplinary Sciences)We evaluated Laser-Induced Periodic Surface Structure (LIPSS) crystal structures using the stress imaging station at BL22XU of JAEA-BL on SPring-8. Crystallization of LIPPS was used different two types laser these are Ti:Sapphire laser (wavelength: 800 nm) and MIR-FEL (mid-infrared free electron laser, wavelength 11.4 
m). These lasers are different in the laser pulse structure and the wavelength. We investigated on the effects of formed LIPSS crystallization using different kind of laser. Measured synchrotron X-ray energy is 30 keV and beam size is 20 m. Detector of diffracted X-ray is two-dimensional detector (PILATUS300K, DECTRIS). LIPSS formed using Ti:Sapphire laser has deformed structure with good crystallinity. LIPSS formed using MIR-FEL has dislocation or fault without structural stress. These results show depending on select of laser forming LIPPS structure. These information becomes important a point of the functional application of LIPSS.
Endo, Shunsuke; Shizuma, Toshiyuki*; Zen, H.*; Taira, Yoshitaka*; Omer, M.; Kawamura, Shiori*; Abe, Ryota*; Okudaira, Takuya*; Kitaguchi, Masaaki*; Shimizu, Hirohiko*
UVSOR-49, P. 38, 2022/08
Al
GaO
scintillators by gamma-ray-induced positron annihilation lifetime spectroscopyFujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.
Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08
Times Cited Count：5 Percentile：33.01(Physics, Applied)To clarify the existence of cation vacancies in Ce-doped GdAlGaO (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:YAl
O, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg
ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.
Amamoto, Ippei; Kobayashi, Hidekazu; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Fukayama, Daigen*; Nagano, Yuichi*; Jantzen, T.*; Hack, K.*
Journal of Nuclear Science and Technology, 53(10), p.1467 - 1475, 2016/10
Times Cited Count：3 Percentile：28.28(Nuclear Science & Technology)The iron phosphate glass (IPG) medium is known to be a high-efficiency glass medium, therefore we try to evaluate its applicability to immobilize sludge bearing radioactive nuclides arising from treatment of contaminated water at the stricken Fukushima Daiichi Nuclear Power Plant. For this study, many physical and chemical properties of target materials are necessary to evaluate the behaviours of IPG medium and its waste forms. Inevitably, it will entail the need for many and varied types of experiments to be carried out under high temperature. It is therefore rational to apply appropriate theoretical analysis first so as to reduce the number of experimental run. For this reason, some necessary thermodynamic values for theoretical analysis were estimated by CALPHAD approach followed by making up the calculated phase diagrams. By comparison with experimental results, they were found to be reliable for evaluating the behaviours of IPG medium and its waste forms.
, ') reaction of 
U on the target thicknessNegm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Zen, H.*; Kii, Toshiteru*; Masuda, Kai*; Hori, Toshitada*; Hajima, Ryoichi; Shizuma, Toshiyuki; et al.
Journal of Nuclear Science and Technology, 52(6), p.811 - 820, 2015/06
Times Cited Count：4 Percentile：33.25(Nuclear Science & Technology)The dependence of the nuclear resonance fluorescence (NRF) yield on the target thickness was studied. To this end, an NRF experiment was performed on U using a laser Compton back-scattering (LCS) -ray beam at the High Intensity -ray Source facility at Duke University.
Hoheisel, R.*; Gonz
lez, M.*; Lumb, M.*; Scheiman, D.*; Messenger, S. R.*; Bailey, C. G.*; Lorentzen, J.*; Tibbits, T. N. D.*; Imaizumi, Mitsuru*; Oshima, Takeshi; et al.
IEEE Journal of Photovoltaics, 4(1), p.253 - 259, 2014/01
Times Cited Count：19 Percentile：60.33(Energy & Fuels)Analysis on the radiation response of solar cells with multi quantum wells (MQW) included in the quasi-intrinsic region between the emitter and the base layer is presented. We found that in the case of MQW devices, carrier removal (CR) effects are also observed. Experimental measurements and numerical simulations reveal that with increasing radiation dose, CR can cause the initially quasi-intrinsic background doping of the MQW region to become specifically n- or p-type. This can result in a significant narrowing and even the collapse of the electric field between the emitter and the base where the MQWs are located. The implications of the CR-induced modification of the electric field on the current-voltage characteristics and on the collection efficiency of carriers generated within the emitter, the MQW region, and the base are discussed for different radiation dose conditions. This paper concludes with a discussion of improved radiation hard MQW device designs.
(Ce) detectors near 2 MeVOmer, M.*; Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Bakr, M.*; Zen, H.*; Hori, Toshitada*; Kii, Toshiteru*; Masuda, Kai*; et al.
Nuclear Instruments and Methods in Physics Research A, 729, p.102 - 107, 2013/11
Times Cited Count：6 Percentile：44.02(Instruments & Instrumentation)The performance of LaBr (Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussedin terms of limits of detection and in comparison with high-purity germanium (HPGe)detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity Gamma-ray Source (HIGS) facility of Duke University. The incident -rays, of 2.12 MeV energy, hit a B
C target to excite the 
B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate theback ground and enhance the limits of detection for the spectra measured with LaBr (Ce). Both detection and determination limits were deduced from the experimental data.
U measured with high-resolution LaBr
(Ce) scintillation detectorsOmer, M.*; Negm, H.*; Zen, H.*; Daito, Izuru*; Kii, Toshiteru*; Masuda, Kai*; Ogaki, Hideaki*; Hajima, Ryoichi; Shizuma, Toshiyuki; Hayakawa, Takehito; et al.
Japanese Journal of Applied Physics, 52(10), p.106401_1 - 106401_4, 2013/10
Times Cited Count：7 Percentile：30.71(Physics, Applied)A nuclear resonance fluorescence (NRF) experiment was performed on a U target with quasi-monochromatic -rays at the High Intensity Gamma-ray Source (HIGS) facility of Duke University using a 1733 keV resonant energy. A LaBr (Ce) detector array consisting of eight cylindrical detectors, each with a length of 7.62 cm and a diameter of 3.81 cm, was implemented in this measurement. Moreover, a high-purity germanium (HPGe) detector array consisting of four detectors, each of which has a relative efficiency of 60%, was used as the benchmark for the measurement taken using the LaBr (Ce) detector array. The integrated cross section of the NRF level, measured with LaBr (Ce) detectors, showed good agreement with the available data.
Gonzlez, M.*; Hoheisel, R.*; Lumb, M.*; Scheiman, D.*; Bailey, C. G.*; Lorentzen, J.*; Maximenko, S.*; Messenger, S. R.*; Jenkins, P. P.*; Tibbits, T. N. D.*; et al.
Proceedings of 39th IEEE Photovoltaic Specialists Conference (PVSC-39) (CD-ROM), p.3233 - 3236, 2013/06
The radiation response of multi quantum wall (MQW) triple junction and component cells was analyzed. Initial results show that for 1MeV electron irradiation the middle MQW cell governs the degradation of the triple junction. This is attributed the specific middle cell design, in particular the thick 0.98 m depletion region, and alternative, more radiation hard, designs are presented. Additionally, characterization studies, including dark IV, external quantum efficiency, electroluminescence, as well as defect characterization were investigated.
Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05
Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.
Harris, R. D.*; Imaizumi, Mitsuru*; Walters, R. J.*; Lorentzen, J. R.*; Messenger, S. R.*; Tischler, J. G.*; Oshima, Takeshi; Sato, Shinichiro; Sharps, R. P.*; Fatemi, N. S.*
IEEE Transactions on Nuclear Science, 55(6), p.3502 - 3507, 2008/12
Times Cited Count：8 Percentile：49.01(Engineering, Electrical & Electronic)The performance of triple junction InGaP/GaAs/Ge solar cells have been studied following low temperature irradiation while using low intensity illumination. High energy electron and proton irradiations have been performed with cell characterization carried out in situ at the irradiation temperature with no intermediate temperature changes. As such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements which permitted the extraction of the four principle solar cell parameters: short circuit current, open circuit voltage, maximum power, and fill factor. In addition, quantum efficiency measurements were made prior to and following the irradiations. The low temperature irradiations were followed by a room temperature anneal to determine if any subsequent recovery was present.
Walters, R. J.*; Harris, R. D.*; Imaizumi, Mitsuru*; Lorentzen, J. R.*; Messenger, S. R.*; Tischler, J. G.*; Oshima, Takeshi; Sato, Shinichiro; Sharps, R. P.*; Fatemi, N. S.*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.105 - 108, 2008/12
The performance of triple junction InGaP/GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out 
at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation.
Hoheisel, R.*; Gonzlez, M.*; Lumb, M.*; Scheiman, D.*; Messenger, S. R.*; Bailey, C. G.*; Lorentzen, J.*; Tibbits, T. N. D.*; Imaizumi, Mitsuru*; Oshima, Takeshi; et al.
no journal, ,
In this paper a detailed analysis on the radiation response of solar cells with multi quantum-wells (MQW) included in the quasi-intrinsic region between the emitter and the base layer is presented. Whilst the primary source of radiation damage of photovoltaic devices is generally associated with minority carrier lifetime reduction, we found that in the case of MQW devices another effect of radiation damage, the so called carrier removal (CR) requires additional consideration. Experimental measurements and numerical simulations reveal that with increasing radiation dose, CR can alter the initially quasi-intrinsic background doping of the MQW region to become further n or p type. This can result in a significant narrowing and even in a collapse of the electrical field between the emitter and the base where the MQWs are located. Eventually, remarks for improved radiation hard MQW device designs are provided.
Amamoto, Ippei; Kobayashi, Hidekazu; Yamashita, Teruo; Nagai, Takayuki; Kitamura, Naoto*; Takebe, Hiromichi*; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Fukayama, Daigen*; Nagano, Yuichi*; et al.
no journal, ,
no abstracts in English
Hayakawa, Takehito; Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Kii, Toshiteru*; Zen, H.*; Omer, M.*; Shizuma, Toshiyuki; Hajima, Ryoichi
no journal, ,
Recently, a nondestructive measurement method of shielded fissional isotopes such as U or 
Pu has been proposed for the nuclear security. These isotopes are measured by using nuclear resonance fluorescence (NRF) with monochromatic energy -ray beams generated by laser Compton-scattering (LCS). We have proposed that one measure scattered -rays from NRF with LCS -ray beams using the LaBr(Ce) detectors. The LaBr(Ce) crystals include internal radioisotopes of a meta-stable isotope 
La and alpha decay chains from some actinides as 
Ac. There is a broad pump at about 2 MeV. This pump is considered to be an overlap of 
-rays from decay chains of some actinides but its detailed structure has not been established. Here we have measured NRF spectra of U using the LCS -rays with energy of about 2.5 MeV at the HIgS facility of the Duke University. The background has been evaluated using a simulation code GEAT4. The 9 peaks, 8 NRF -rays plus the Compton scattered -ray of the incident beam, are finally assigned in an energy range of about 200 keV at about 2.5 MeV. The 8 integrated NRF cross-sections measured by LaBr(Ce) have been consistent with results by an HPGe detector. The three levels are newly assigned using the HPGe detector. Two of them are also measured by LaBr(Ce).
Amamoto, Ippei; Oyama, Koichi; Nagano, Yuichi*; Jantzen, T.*; Hack, K.*; Fukayama, Daigen*
no journal, ,
As the vitrified study of the high-level radioactive waste is usually carried out under the high-temperature circumstance, it spends a lot of time and effort. The actual experiments and/or measurement, therefore, should be undertaken rationally after ascertaining the behaviors of target materials by the theoretical calculation, if possible. From such point of view, the construction of phase diagrams is considered after obtaining necessary thermodynamic properties from existing phase diagrams by CALPHAD method and/or published data. In this paper, several phase diagrams are presented such as the borosilicate glass which is currently used as the vitrified medium for the HLW, the iron-phosphate glass which will be potential vitrified medium for various wastes. Some phase diagrams are also prepared for the vitrified wastes which was loaded fission products such as molybdenum, palladium, etc..
-BO-NaO-LiO systemAmamoto, Ippei; Oyama, Koichi; Fukayama, Daigen*; Nagano, Yuichi*; Hack, K.*; Jantzen, T.*
no journal, ,
The thermodynamic data of glass medium and FP, essential for estimation of the technical development of HLW as vitrified waste, is obtained by the CALPHAD method. As Ru-Rh-Pd-SiO-BO-NaO-LiO system could be constructed this time, it became possible to construct the phase diagram and/or estimation of FP loading amount under various conditions.
Taira, Yoshitaka*; Fujimoto, Masaki*; Fujimori, Kosuke*; Kitaura, Mamoru*; Zen, H.*; Okano, Yasuaki*; Hosaka, Masahito*; Yamazaki, Junichiro*; Kato, Masahiro*; Hirade, Tetsuya; et al.
no journal, ,
For general positron sources, radioisotopes such as 
Na are often used. However, there is a problem that positrons cannot probe the deep region of metal materials with a thickness of 1 mm or more. Gamma-ray induced positron annihilation lifetime measurement (GiPALS) is a method for generating positrons in bulk samples with a thickness of several centimeters and samples placed in vessels such as high temperature and/or pressure furnaces. The annihilation lifetime of positrons is about 200 ps for metal materials, so it is important to use gamma rays with a shorter pulse width for GiPALS in order to accurately measure the positron lifetime. We have succeeded in the proof-of-principle experiment for GiPALS of ultra-short pulse gamma rays with a pulse width of 2 ps, which was originally developed using 90
collision laser Compton scattering at UVSOR.
