Yoshimi Kasugai

Measurement of activation cross-sections for (n,2n) reactions producing short-lived nuclei in the energy range between 13.4 and 14.9 MeV

Abstract Activation cross-sections for 18 (n,2n) reactions producing short-lived nuclei with half-lives between 20 s and 38 min were measured in the energy range between 13.4 and 14.9 MeV by an activation method. The measured target isotopes were 14N, 31P, 54Fe, 63Cu, 79Br, 87Rb, 92Mo, 108Pd, 113In, 132Ba, 138Ba, 140Ce, 141Pr, 144Sm and 165Ho. Four cross-sections for 108Pd, 132Ba, 144Sm and 165Ho were obtained at six-point energies for the first time. The intense 14 MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. All cross-section values were relatively obtained on the basis of the standard cross-section of 27Al(n, α) 24Na reaction (ENDF/B-VI). To obtain reliable neutron activation cross-sections, careful attention was paid to neutron irradiation and induced activities measurement. The present results were compared with previous data and the evaluated data in JENDL-3.2, JENDL-Activation File and ENDF/B-VI. The previous data measured at multi-point energies show reasonable agreement with the present results in comparison with those at one-point energy. There are overestimations of the cross-section for 31P in JENDL-3.2 and ENDF/B-VI, and for 132Ba and 165Ho in JENDL-Activation File.

Measurement of (n, p) cross-sections for shortlived products by 13.4–14.9 MeV neutrons

Abstract The 28 (n, p) activation cross-sections that lead to short-lived nuclei with half-lives of between 20s and 18 min were measured in the energy range 13.4–14.9 MeV using an activation method. The measured isotopes were 19 F, 28,29 Si, 37 Cl, 50 Ti, 52,53,54 Cr, 60,62 Ni, 66,68 Zn, 86,88 Sr, 97 Mo, 101,102,104 Ru, 104,105, 108 Pd, 107 Ag, 116 Cd and 119,120 Sn. The intense 14 MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. The γ-rays emitted from the irradiated samples were measured with high-purity germanium (HPGe) detectors. All cross-section values were obtained relative to the standard reaction cross-section of 27 Al (n, α) 24 Na. The present results were compared with previous data and the evaluated data of JENDL-3 and ENDF/B-VI. Ten reactions were obtained at multi-point-energies for the first time. By using intense neutron sources and making careful corrections, reliable results could be obtained. Most of the data obtained previously at multi-point-energies have shown reasonable agreement within 25%. In comparing 10 experimental reactions with the evaluated data, significant discrepancies of more than 25% were seen for three reactions.

Measurement of activation cross-sections of (n, np+d) reactions producing short-lived nuclei in the energy range between 13.4 and 14.9 MeV using an intense neutron source OKTAVIAN

Abstract Activation cross-sections for 17 (n, np+d) reactions producing short-lived nuclei with half-lives between 42 s and 23 min, were measured in the energy range between 13.4 and 14.9 MeV by an activation method. The measured target isotopes were 26 Mg, 29, 30 Si, 53, 54 Cr, 67 Zn, 87 Sr, 98, 100 Mo, 102 Ru, 105, 106, 108 Pd, 123 Te, 163 Dy, 179 Hf and 189 Os. Eleven cross-sections for 26 Mg, 30 Si, 87 Sr, 100 Mo, 102 Ru, 105, 106 Pd, 123 Te, 163 Dy, 179 Hf and 189 Os were obtained for the first time, and four cross-sections for 53, 54 Cr, 67 Zn and 108 Pd were obtained at six-point energies for the first time. An intense 14 MeV neutron source, OKTAVIAN at Osaka University was used for irradiation. All cross-section values were relatively obtained on the basis of the standard cross-section of 27 Al(n, α) 24 Na reaction (ENDF/B-VI). To obtain reliable neutron activation cross-sections, careful attention was paid to neutron irradiation and induced activity measurement. The present results were compared with the evaluated data in JENDL-3.2, JENDL-Activation File and ENDF/B-VI. The cross-sections are underestimated for 102 Ru and 108 Pd in JENDL-3.2.

Precise measurement of γ-ray emission probabilities for 66Cu

Abstract A new system was developed for measurement of γ-ray emission probabilities for nuclides with short half-lives of a few minutes or more. This system is composed of 4πβ proportional counter operated at atmospheric pressure with CF 4 gas, a high purity germanium γ-ray detector and a coincidence counting apparatus using a live-timed bi-dimensional data acquisition system. The γ-ray emission probabilities for 66 Cu, with a half-life of 5.1 min, were measured by using this system and the probability of the 1039 keV γ-rays was determined to be 0.0923±0.0009. This value is larger than the previous evaluated values by 15 to 20%, and the certainty is improved by one order of magnitude. The result shows that the present system is very powerful for measuring the γ-ray emission probabilities for short-lived nuclides.

Measurement of Formation Cross Sections of Short-Lived Nuclei by 14 MeV Neutrons

Activation cross sections for the reactions leading to short-lived nuclei with half-lives between 0.5 and 20 min were measured systematically at neutron energies of 13.4 to 14.9 MeV for various structural materials of fusion reactor by the activation method. Up to now, 53 cross sections have been obtained by using the intense 14 MeV neutron source facility of Osaka University (OKTAVIAN).

Measurement of activation cross sections on tantalum and tungsten with 14 MeV neutrons

The cross sections of 181Ta(n, p)181Hf, 181Ta(n, n′p)180mHf, 184W(n, α)181Hf, 186W(n, n′p)185Ta and 186W(n, α)183Hf reactions have been measured in the energy range between 13.4 and 14.9 MeV by the activation method. The intense 14 MeV neutron source facility (OKTAVIAN) at Osaka University was used for irradiation. The γ-rays emitted from the irradiated samples were measured with high-purity germanium (HPGe) detectors. All cross section values were obtained relative to the standard reaction cross section of 93Nb(n, 2n)92mNb obtained by Netha way. The cross sections of 181Ta(n, n′p)180mHf reaction were measured for the first time. The present results were compared with previous data and the evaluated data of JENDL-3 and ENDF/B-VI, and the comparison showed that some significant discrepancies exist.