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59 results on '"Rikito Murakami"'

51. Multiple shaped-crystal growth of oxide scintillators using Mo crucible and die by the edge defined film fed growth method

Author

Fumiya Horikoshi, Akihiro Yamaji, Yasuhiro Shoji, Hiroki Sato, Vladimir V. Kochurikhin, Kyoung Jin Kim, Hironori Saito, Yuui Yokota, Toshiro Kotaki, Martin Nikl, Shunsuke Kurosawa, Akira Yoshikawa, Kei Kamada, Masao Yoshino, Satoshi Toyoda, Yuji Ohashi, Rikito Murakami, and Masayuki Miyazaki

Subjects
010302 applied physics, Materials science, Dopant, Analytical chemistry, Oxide, chemistry.chemical_element, Crystal growth, 02 engineering and technology, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Inorganic Chemistry, Metal, chemistry.chemical_compound, chemistry, Molybdenum, Aluminium, visual_art, 0103 physical sciences, Materials Chemistry, visual_art.visual_art_medium, 0210 nano-technology, Luminescence, Single crystal
Abstract

Edge defined Film Fed Growth (EFG) method with molybdenum (Mo) crucible and die was studied for the growth of several oxide-based single crystals. At first, reactivity between the molybdenum (Mo) metal and oxide melts of Ce:(Lu,Y)2SiO5 (LYSO) Ce:Y2SiO5 (YSO), Ce:Gd3(Al,Ga)5O12 (GAGG), Ce:Lu3Al5O12 (LuAG), Ce:Y3Al5O12 (YAG) was investigated. The experimental and calculation results on the reactivity with Mo show that the aluminum garnets (LuAG, YAG) had the smallest reactivity with Mo metal. On the contrary, GAGG showed the strongest reaction with Mo. Then, the multiple-die grown shaped single crystal growth of Ce:LuAG was demonstrated by EFG method. Single crystal plates up to 320 mm in length were grown successfully. The homogeneity of dopant distribution, Mo contamination, luminescence and scintillation responses of the grown crystals were evaluated.

Published
2020

52. Luminescence study on Eu or Tb doped lanthanum–gadolinium pyrosilicate crystal

Author

Kei Kamada, Takamasa Sugawara, Yuji Ohashi, Kunio Yubuta, Yasuhiro Shoji, Shunsuke Kurosawa, Yuui Yokota, Akira Yoshikawa, Jan Pejchal, Toetsu Shishido, Rikito Murakami, and Akiko Nomura

Subjects
Scintillation, Materials science, Gadolinium, Organic Chemistry, Doping, Analytical chemistry, chemistry.chemical_element, Scintillator, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Inorganic Chemistry, Crystal, chemistry, Lanthanum, Emission spectrum, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Luminescence, Spectroscopy
Abstract

(Eu 0.01 , Gd 0.90 , La 0.09 ) 2 Si 2 O 7 (Eu:La–GPS) and (Tb 0.01 , Gd 0.9 0 , La 0.09 ) 2 Si 2 O 7 (Tb:La–GPS) crystals were grown by the floating zone method, and their optical and scintillation properties were investigated. Gd 3+ -to-Tb 3+ or –Eu 3+ energy transfer processes were found, and photo-luminescence and radio-luminescence emission spectra showed 5 D 0 – 7 F i ( i = 1–4) Eu 3+ transitions in Eu:La–GPS, and 5 D 3 – 7 F i ( i = 3–6) and 5 D 4 – 7 F i ( i = 3–6) transitions in Tb:La–GPS. Using these scintillators, alpha-ray imaging was possible with a CMOS camera. These materials can be used for X-ray detection as well.

Published
2015

53. Temperature Dependence of Luminescence Properties for Zr Codoped Ce:(Gd, La)2Si2O7 Scintillator

Author

Yuji Ohashi, Martin Nikl, J. Pejchal, Shunsuke Kurosawa, Akihiro Yamaji, Takahiko Horiai, Kei Kamada, Yuui Yokota, Akira Yoshikawa, Vitezslav Jary, Rikito Murakami, and Yasuhiro Shoji

Subjects
Materials science, 010308 nuclear & particles physics, 0103 physical sciences, Analytical chemistry, 02 engineering and technology, Scintillator, 021001 nanoscience & nanotechnology, 0210 nano-technology, Luminescence, 01 natural sciences
Published
2016

54. Radiation Hardness of Ce:(Gd, La)2Si2O7 Scintillator Using 80-MeV Alpha Rays

Author

J. Pejchal, Shunsuke Kurosawa, Yuui Yokota, Kei Kamada, Yuji Ohashi, Yasuhiro Shoji, Akira Yoshikawa, Rikito Murakami, and Akihiro Yamaji

Subjects
010302 applied physics, Materials science, 0103 physical sciences, Radiochemistry, 02 engineering and technology, Alpha particle, Scintillator, 021001 nanoscience & nanotechnology, 0210 nano-technology, 01 natural sciences, Radiation hardening
Published
2016

55. Growth and scintillation properties of Ce doped Gd2Si2O7/SiO2eutectics

Author

Yuui Yokota, Rikito Murakami, Shunsuke Kurosawa, Jan Pejchal, Kei Kamada, Yuji Ohashi, and Akira Yoshikawa

Subjects
History, Scintillation, Yield (engineering), Materials science, Photon, Doping, Analytical chemistry, Computer Science Applications, Education, Matrix (chemical analysis), Crystallography, Phase (matter), Orthorhombic crystal system, Eutectic system
Abstract

Ce:Gd2Si2O7/SiO2 eutectic was grown by the μ-PD method. The square-shape sample with a side of 5 mm and a length of 15 mm was obtained. Two phases of orthorhombic Gd2Si2O7 and SiO2 was observed. Rod-phase was SiO2 and matrix phase was Gd2Si2O7. Ce3+ 4f5d emission have been observed at 400nm. The sample showed light yield of around 16,000 photons/MeV. Scintillation decay time was 46.3ns(21%) 249ns(79%).

Published
2015

56. Single Crystal Growth and Co-doping Effects of Lanthanum Substituted Gadolinium Pyrosilicate Scintillator

Author

Kei Kamada, Rikito Murakami, Yuui Yokota, Shunsuke Kurosawa, Yuji Ohashi, Jan Pejchal, and Akira Yoshikawa

Subjects
History, Scintillation, Gadolinium, Doping, Analytical chemistry, chemistry.chemical_element, Radioluminescence, Scintillator, Computer Science Applications, Education, chemistry, Yield (chemistry), Lanthanum, Luminescence, Nuclear chemistry
Abstract

Ca 100, 200, 500, 1000 and 3000 at. ppm co-doped (Ce0.01,La0.3Gd0.69)2Si2O7 single crystals were grown by the μ-PD method. Luminescence and scintillation properties such as radioluminescence spectra, light yield and decay time were evaluated. Expected Ce3+ 4f5d emission have been observed in 350-430nm peaking at 360nm. Emission intensity took maximum at the Ca 100at.ppm co-doped sample and decreased by increasing the Ca concentration. The Ca 100at.ppm co-doped sample showed the highest light yield of around 20,000 photons/MeV. Scintillation decay time was accelerated with increasing Ca concentration. Scintillation decay time of the Ca 0, 100, 200, 1000 and 3000 at. ppm co-doped samples were 66.5ns(21%) 468ns(79%) and 44.0ns(22%) 430ns(78%), respectively.

Published
2015

57. Scintillation properties of Ce:(La,Gd)2Si2O7 at high temperatures

Author

Takamasa Sugawara, Shunsuke Kurosawa, Jan Pejchal, Kunio Yubuta, Akira Suzuki, Akira Yoshikawa, Kei Kamada, Rikito Murakami, Akiko Nomura, Yuui Yokota, and Toetsu Shishido

Subjects
010302 applied physics, Physics, Nuclear and High Energy Physics, Scintillation, Photon, 010308 nuclear & particles physics, Resolution (electron density), Analytical chemistry, Atmospheric temperature range, 01 natural sciences, 7. Clean energy, Particle detector, Crystal, Full width at half maximum, Nuclear magnetic resonance, 0103 physical sciences, Constant (mathematics), Instrumentation
Abstract

Temperature dependence of scintillation properties was investigated for (Ce0.01, Gd0.90, La0.09)2Si2O7 grown by floating zone method. The light output over 35,000 photons/MeV was found constant in the temperature range from 0 °C to 150 °C. In addition, FWHM energy resolution of Ce:La-GPS (roughly 7–8%) at 662 keV remained constant up to 100 °C. Thus, this crystal can be applied to oil well logging or other radiation detection application at high temperature conditions.

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59. Luminescence properties of Pr-doped (La,Gd)2Si2O7 grown by the floating zone method.

Author

Rikito Murakami, Shunsuke Kurosawa, Toetsu Shishido, Takamasa Sugawara, Akiko Nomura, Kunio Yubuta, Akira Suzuki, Yasuhiro Shoji, Yuji Ohashi, Jan Pejchal, Kei Kamada, Yuui Yokota, and Akira Yoshikawa

Abstract

Scintillation properties of a Pr-doped gadolinium lanthanum pyrosilicate (Pr:La-GPS) crystal grown by the floating zone (FZ) method were investigated, because the Pr3+ 5d–4f transition is expected to show a shorter decay time than the Ce3+ 5d–4f transition. In both α-ray radioluminescence and photoluminescence spectra, the emission peak related to the Pr3+ 5d–4f transition was observed at around 350 nm. The photoluminescence decay time of Pr:La-GPS was found to be as short as ∼23 ns, whereas Ce:La-GPS had a decay time of ∼31 ns. [ABSTRACT FROM AUTHOR]

Published
2015
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