Papers by Michihiro Shibata
Applied Radiation and Isotopes, 2015
In order to determine the γ-ray emission intensities of nuclei far from the β-stability line with... more In order to determine the γ-ray emission intensities of nuclei far from the β-stability line with HPGe detectors under large solid-angle geometry, coincidence summing corrections should be performed, even if full energy peak efficiencies of detectors are accurately measured with standard sources. Because the summing effects depend on decay schemes and emission intensities, the correction needs to be iterated several times starting from the initial values of intensities obtained directly from the measured peak counts of γ-rays. Considering (134)Cs, (154)Eu and (56)Co as typical examples, we discuss the number of iterations of summing correction required for self-consistency with respect to the total efficiencies of the detectors.
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We examined the reliability of prompt γ-ray intensities by measuring ratios of thermal neutron ca... more We examined the reliability of prompt γ-ray intensities by measuring ratios of thermal neutron capture cross sections on 23Na, 27Al, 51V, 55Mn, 64Ni, 65Cu, 141Pr, 186W, and 197Au at the Kyoto University Research Reactor Institute. The cross sections were obtained by two methods: the first is detecting prompt γ-rays (which we call the prompt-γ method), and the other is detecting γ-rays following β-decay (the activation method). Intensities of prompt γ-rays and decay γ-rays have been reported to have an uncertainty of about 5% and 1%, respectively. It is found that values of 65Cu and 186W have large discrepancies in the results of the two methods, by about 30%. The disagreement would be caused by inaccuracy of the absolute intensities of prompt γ-rays. The inaccuracy is estimated to be due to the incompleteness of level schemes and the detector efficiency of prompt γ-rays. We need to examine absolute intensities of prompt γ-rays when we use the prompt-γ method.
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Journal of Nuclear Science and Technology, 2002
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Journal of the Physical Society of Japan, 2015
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Journal of Nuclear Science and Technology, 2002
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ND2007, 2007
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Nuclear Data Sheets
A spectrometer to measure nuclear level half-lives has been installed at the on-line isotope sepa... more A spectrometer to measure nuclear level half-lives has been installed at the on-line isotope separator of the Kyoto University Reactor. This spectrometer consists of a LaBr3 scintillator, a thin plastic scintillator and an HPGe detector. Half-lives are deduced using the β-γ-γ delayed coincidence method. The prompt-time distribution curves measured with the spectrometer give a time resolution (FWHM) of 600 ps for 100-keV γ rays. This resolution means that half-lives down to the subnanosecond range or shorter can be measured. We reported recent measurements of the half-life of 149Pr and 149Nd. Some of the more interesting results include the first determination of the half-lives of 149Pr levels at 86.5 and 125.6 keV, which are 4.2(5) ns and 1.0(2) ns, respectively. In addition, the data indicate that the half-life of the 270.8-keV level in 149Nd is not 5.1(3) ns as reported previously, but 0.42(3) ns.
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Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, 2014
Full-energy peak efficiency at the center position of a through-hole-type clover detector was det... more Full-energy peak efficiency at the center position of a through-hole-type clover detector was determined by the measurement of standard sources and by Monte Carlo simulation. The coincidence summing under the large-solid-angle condition was corrected using Monte Carlo calculation based on the specific decay scheme for (133)Ba, (152,154)Eu, and (56)Co. This allowed the peak efficiency to be extended from 0.05 MeV to 3.2 MeV with an approximate uncertainty of 3%.
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2010
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Journal of the Physical Society of Japan, 1993
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Journal of the Physical Society of Japan, 2002
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Journal of the Physical Society of Japan, 1994
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Journal of the Physical Society of Japan, 1996
A new neutron-rich isotope 166Tb produced in 16 MeV proton-inducedfission of 238U has been identi... more A new neutron-rich isotope 166Tb produced in 16 MeV proton-inducedfission of 238U has been identified using the JAERI on-lineisotope separator (JAERI-ISOL) coupled to a gas-jet transport system.Dy KX-rays and gamma rays originating from the decay of 166Tb werefound in both mass-166 and 182 fractions,where the 166Tb nuclides were mass-separated as elemental ions166Tb+ and monoxide ions 166TbO+, respectively.The half-life of 166Tb
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Journal of the Physical Society of Japan, 1991
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Journal of the Physical Society of Japan, 1990
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Journal of the Physical Society of Japan, 1998
For neutron-deficient 124,125,127-130La, Q EC measurement has been performed by determining beta+... more For neutron-deficient 124,125,127-130La, Q EC measurement has been performed by determining beta+-ray maximum energies. The radioactive sources were prepared by on-line mass-separation following the fusion-evaporation reactions 92, natMo(36Ar, 3pxn). The beta+-rays were measured with an HPGe detector in beta-gamma coincidence mode in which gamma-rays were detected with another HPGe detector for specifying an excited state in daughter nucleus. By unfolding
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Journal of Nuclear Science and Technology, 2008
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Applied Radiation and Isotopes, 2013
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Papers by Michihiro Shibata