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Journal Articles

Impact of the temperature on the non-destructive nuclide assay in the transmission NRF method

Omer, M.; Shizuma, Toshiyuki*; Koizumi, Mitsuo; Taira, Yoshitaka*; Zen, H.*; Ogaki, Hideaki*; Hajima, Ryoichi

UVSOR-50, P. 37, 2023/08

no abstracts in English

Journal Articles

Measurement of the spatial polarization distribution of circularly polarized gamma rays produced by inverse Compton scattering

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

Journal Articles

Crystallinity in periodic nanostructure surface on Si substrates induced by near- and mid-infrared femtosecond laser irradiation

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 $$mu$$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 $$mu$$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.

Journal Articles

Evaluation of analyzing power of gamma-ray polarimeter

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

Journal Articles

Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

Fujimori, 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:4 Percentile:27.19(Physics, Applied)

To clarify the existence of cation vacancies in Ce-doped Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ (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:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$, 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$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Journal Articles

Reaction-yield dependence of the ($$gamma$$, $$gamma$$') reaction of $$^{238}$$U on the target thickness

Negm, 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:33.51(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 $$^{238}$$U using a laser Compton back-scattering (LCS) $$gamma$$-ray beam at the High Intensity $$gamma$$-ray Source facility at Duke University.

Journal Articles

Analysis of nuclear resonance fluorescence excitation measured with LaBr$$_{3}$$(Ce) detectors near 2 MeV

Omer, 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:44.21(Instruments & Instrumentation)

The performance of LaBr$$_{3}$$ (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 $$gamma$$-rays, of 2.12 MeV energy, hit a B$$_{4}$$C target to excite the $$^{11}$$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$$_{3}$$ (Ce). Both detection and determination limits were deduced from the experimental data.

Journal Articles

Nuclear resonance fluorescence of $$^{235}$$U measured with high-resolution LaBr$$_3$$(Ce) scintillation detectors

Omer, 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:30.83(Physics, Applied)

A nuclear resonance fluorescence (NRF) experiment was performed on a $$^{235}$$U target with quasi-monochromatic $$gamma$$-rays at the High Intensity Gamma-ray Source (HIGS) facility of Duke University using a 1733 keV resonant energy. A LaBr$$_3$$ (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$$_3$$ (Ce) detector array. The integrated cross section of the NRF level, measured with LaBr$$_3$$ (Ce) detectors, showed good agreement with the available data.

Journal Articles

Recent progress in the energy recovery linac project in Japan

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.

Oral presentation

Nuclear resonance fluorescence in U-238 using LaBr detectors for nuclear security

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 $$^{235}$$U or $$^{239}$$Pu has been proposed for the nuclear security. These isotopes are measured by using nuclear resonance fluorescence (NRF) with monochromatic energy $$gamma$$-ray beams generated by laser Compton-scattering (LCS). We have proposed that one measure scattered $$gamma$$-rays from NRF with LCS $$gamma$$-ray beams using the LaBr$$_{3}$$(Ce) detectors. The LaBr$$_{3}$$(Ce) crystals include internal radioisotopes of a meta-stable isotope $$^{138}$$La and alpha decay chains from some actinides as $$^{227}$$Ac. There is a broad pump at about 2 MeV. This pump is considered to be an overlap of $$alpha$$-rays from decay chains of some actinides but its detailed structure has not been established. Here we have measured NRF spectra of $$^{238}$$U using the LCS $$gamma$$-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 $$gamma$$-rays plus the Compton scattered $$gamma$$-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$$_{3}$$(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$$_{3}$$(Ce).

Oral presentation

Development of gamma-ray induced positron annihilation lifetime spectroscopy

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 $$^{22}$$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$$^{circ}$$ collision laser Compton scattering at UVSOR.

Oral presentation

Development of gamma-ray induced positron annihilation lifetime spectroscopy at UVSOR

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 $$^{22}$$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$$^{circ}$$ collision laser Compton scattering at UVSOR.

Oral presentation

Vacancy-type defects in garnet crystals revealed by gamma-ray-induced positron annihilation spectroscopy

Kitaura, Mamoru*; Fujimori, Kosuke*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

Positron annihilation spectroscopy is the only way to investigate the properties of cation vacancies because they are negatively charged. We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg$$^{2+}$$ ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.

Oral presentation

Origin of phosphorescence in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ crystals revealed by gamma-ray induced positron annihilation lifetime spectroscopy

Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Hirade, Tetsuya; Kamada, Kei*; Watanabe, Shinta*; Onishi, Akimasa*

no journal, , 

We generated high-energy pulsed gamma rays by the vertical collision of an ultrashort pulse laser and electron beam. In this study, we investigated the vacancy-type defects present in the crystals of GAGG(Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$), GAGG: Ce and GAGG: Ce, Mg by positron annihilation lifetime spectroscopy using the high-energy gamma rays. The lifetime of the defect-related component was significantly changed by Mg co-doping. This indicates that the Al/Ga vacancies disappear. This fact corresponds well with the suppression of the phosphorescence component and is an important result showing that the Mg co-doping is effective in suppressing the shallow electron capture center.

Oral presentation

Development of polarimeter for circular polarization measurement of gamma-rays emitted from neutron capture reactions

Endo, Shunsuke; Abe, Ryota*; Ishizaki, Kohei*; Ito, Yuki*; Oku, Takayuki; Okudaira, Takuya*; Omer, M.; Kameda, Kento*; Kitaguchi, Masaaki*; Kimura, Atsushi; et al.

no journal, , 

no abstracts in English

Oral presentation

Development of gamma ray sources and their application studies in UVSOR-III

Taira, Yoshitaka*; Sugita, Kento*; Okano, Yasuaki*; Hirade, Tetsuya; Endo, Shunsuke; Zen, H.*; Shizuma, Toshiyuki*

no journal, , 

At UVSOR, a synchrotron radiation facility at the Institute for Molecular Science, gamma rays are generated by inverse Thomson scattering. Compared to gamma rays generated from radioisotopes and bremsstrahlung gamma rays, it has excellent features such as variable energy, quasi-monochromatic, low background, and high directivity. It is also possible to generate polarized gamma rays by using a polarized laser. Using this gamma ray, nuclear physics experiments such as isotope imaging by nuclear resonance fluorescence scattering, evaluation of gamma ray detectors, and research on material analysis by gamma ray-induced positron annihilation spectroscopy are being carried out. Positron annihilation spectroscopy is a powerful method that can analyze defects of sub-nm to several nm such as monatomic vacancies. Positrons can also be generated from gamma rays by pair production. By irradiating the sample with gamma rays, positrons are generated inside the sample, and it is possible to analyze defects in a bulk sample with a thickness of several cm. At this year's meeting, we will present the development of gamma ray sources in UVSOR, the magnetic Compton scattering experiment of circularly polarized gamma rays, the development of gamma ray-induced positron annihilation spectroscopy, and the development of measurement technology for spin-polarized positrons using circularly polarized gamma rays.

Oral presentation

Investigating effects of coaxial HPGe detector structure on the measurement of LCS $$gamma$$-ray beam

Omer, M.; Shizuma, Toshiyuki*; Koizumi, Mitsuo; Hajima, Ryoichi*; Zen, H.*; Taira, Yoshitaka*

no journal, , 

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