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Nakamura, Shoji; Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Takamiya, Koichi*; Fujii, Toshiyuki*
Journal of Nuclear Science and Technology, 56(1), p.123 - 129, 2019/01
Times Cited Count：1 Percentile：10.81(Nuclear Science & Technology)Accurate data of 
-ray emission probabilities are frequently needed when one quantitatively determines the amount of isotope by -ray measurements or obtains neutron capture cross-sections using them. Americium-243, one of the most important minor actinides, produces 
Am after neutron capture. The 744-keV -ray decaying from the ground state of Am has a relatively large -ray emission probability c.a. 66%, however, its uncertainty is as large as 29%. The uncertainty of the -ray emission probability leads to a major factor of the systematic uncertainty on determining an amount of isotope, and therefore the -ray emission probability was measured by using an activation method and an examined level structure of Cm. In this study, the emission probability of 744-keV ray was derived as 66.5
1.1%, and its uncertainty was improved from 29% to 2%.
Am, 
Am, 
Tc and 
CeNakagawa, Tsuneo; Iwamoto, Osamu; Hasegawa, Akira
JAERI-Research 2002-035, 94 Pages, 2002/12
JAERI-Research-2002-035.pdf:2.73MB
no abstracts in English
Nakagawa, Tsuneo; Takano, Hideki; Hasegawa, Akira
NEA/WPEC-8, p.1 - 116, 1999/00
no abstracts in English
*
PNC TJ9604 97-001, 108 Pages, 1997/03
A lead slowing-down spectrometer was installed coupled to the 46 MeV electron linac at Research Reactor Institute, Kyoto university (KURRI). Characteristics of the Kyoto University Lead Slowing-down Spectrometer (KULS) were measured for (1)the relation between neutron slowing-down time t(
s) and energy E (keV) (E=190/t
in Bi hole and E=156/ in Pb hole), (2)energy resolutlon (
40 % in Bi and Pb holes), and (3)neutron energy spectrum by the neutron TOF method. The results obtained by the MCNP code were in general agreement with these experimental ones. The KULS has been applied to the fission cross section measurements of Am-241, Am-243 and Am-242m relative to that of U-235 from 0.1 eV to 10 keV, making use of the back-to-back type double fission chambers. For Am-241, Dabbs and ENDF/B-VI data are in good agreement with the present measurement. The JEND L-3.2 data are smaller by a factor of 2 between 10 and 200 eV. The ENDF/B-VI data for Am-243 are lower between 15 and 60 eV, and the JENDL-3.2 are lower in general above 100 eV. It has been found that the preliminary result for the Am-242m(n,f) reaction is close to the ENDF/B-VI and the JENDL-3.2 data. Thermal neutron cross sections for Am-241 and Am-243 have also been measured in a standard Maxwellian distribution spectrum field. Finally, aiming at the measurement of capture cross section for MA nuclides, the experimental investigation for Np-237 sample (2 mg) has been performed with the KULS. Due to the comparable background counts to the foreground ones, the capture events from the sample have scarecely been detected with an Ar-gas proportional counter.
*
PNC TJ9601 97-001, 51 Pages, 1997/03
In fuel cycles with recycled actinide, core characteristics are largely influenced by minor actinide (MA:Np, Am, Cm). Accurate nuclear data of MA such as fission cross section are required to estimate the effect of MA with high accuracy.In this study fast neutron induced fission cross section of MA is measured using Dynamitron Accelerator in Tohoku University. The experimental method and the samples, which were developed or introduced during the last year, were improved in this fiscal year: (1)Development of a sealed fission chamber, (2)Intensification of Li neutron target, (3)Improvement of time-resolution of Time-of-flight (TOF) electronic circuit, (4)Introduction of Np237 samples with large sample mass and (5)Introduction of a U235 sample with high purity. Using these improved tools and samples, the fission cross section ratio of NP237 relative to U235 was measured between 5 to 100keV, and the fission cross section of Np237 was deduced. On the other hand, samples of Am241 and Am243 were obtained from Japan Atomic Energy Research Institute (JAERI) after investigating fission cross section of two americium isotopes (Am241 and Am243) which are important for core physics calculation of fast reactors.
AmNakamura, Shoji; Shibahara, Yuji*; Endo, Shunsuke; Kimura, Atsushi
no journal, ,
Research and development were made for accuracy improvement of neutron capture cross-section data on Am among minor actinides. First, the emission probabilities of decay -rays were obtained with high accuracy, and the amount of the ground state of Am produced by reactor neutron irradiation of Am was examinded by-ray measurement. Next, the total amount of isomer and ground states was examoned by 
-ray measurement. This presentation will give the details of the measurenmets and the results of the neutron capture cross-sections of Am.
