実験報告書様式（プロジェクト利用）

MLF Experimental Report

提出日 Date of report2016.1.4

実験課題番号 Project No.

装置責任者 Name of responsible person

2012P0701

Hideo Harada

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Research on nuclear astrophysics, nuclear data, and trace-element analysis

BL-04

using pulsed neutrons

利用期間 Dates of experiments

実験責任者名 Name of principal investigator
Hideo Harada
所属 Affiliation
Japan Atomic Energy Agency
１．研究成果概要（試料の名称、組成、物理的・化学的性状を明記するとともに、実験方法、利用の結果得られた主なデータ、考察、結論、図表等を記述してください。
Outline of experimental results (experimental method and results should be reported including sample
information such as composition, physical and/or chemical characteristics.
On nuclear data, systematic capture cross section measurements have been started of Cm-244、Cm-246、Am-241、Np-237, Pd-107, Zr-93, I-129, Tc-99, and their stable isotopes by utilizing techniques developed
previous years.

We have also analyzed data obtained up to now of Tc-99 and stable isotopes of Sn, Se, Pd,Cs.
On Tc-99, primary gamma rays from theneutron capture resonances were measured
at the J-PARC/ANNRI. The analysis
showed that the transition pattern from thefirst resonance is similar to that from thecapture reaction of thermal neutrons. On theother hand, transition patterns from thehigher energy resonances are completely
different, and there is no clear dependence on the spin-parities of the resonances. Figure shows fitting of
the prompt gamma-ray spectrum from the 5.58 eV resonance state as an example. (published in Nuclear DataSheets)
On tin isotopes, the neutron-capture cross sections of Sn-112 and Sn-118 were measured by thetime-of-flight method in the energy range from 10 meV to 2 keV with an array of germanium detectors ofANNRI at J-PARC. Twelve new resonances for Sn-112 were identified, whereas the 21.02-, 40.38- and
166-eV resonances for Sn-112 and the 289-eV resonance for Sn-118 which are listed on JENDL-4.0 and/or
ENDF/B VII.1 were not observed.

This gave a strong evidence of miss assignment of these resonances innuclear data libraries JENDL-4.0 and/or ENDF/B VII.1.
1１．研究成果概要（つづき） Outline of experimental results (continued).
On Pd isotopes, the measurements of the neutron-capture cross sections were performed for the radioactive
Pd-107 and stable Pd-105, 108 nuclei by the time-of flight method in the low energy region from the thermal
to a few hundreds eV. From the measurements, new assignments were also obtained for some resonances ofthese Pd nuclei.

Right figure shows an example

showing resonance miss assignment. These
results together with tin isotopes resonanceassignments showed the needs of systematic
study of neutron resonance assignments not only
for radioactive nucleus but also stable isotopes.
(published in Nuclear Data Sheets)
On astrophysics study, neutron-capture crosssection of Ni-61 and Nb isotopes were measured
using the Ge spectrometer of ANNRI. The
preliminary data are slightly discrepant compared to
the JENDL-4.0 library in the energy range from 10eV to 1000 eV. It might due to underestimation of
the background subtraction. Figure shows γ-ray
pulse-height spectra for Ni-61 sample (black curve)
and Blank (red curve). Multi-scattering neutron
corrections are needed in future analyses.
Mono-element samples and standard samples are prepared for development of prompt gamma ray analysis(PGA) by using a pulsed neutron beam by taking into account neutron capture cross sections, resonanceenergies, etc. in the selection procedure. The background spectrum in time-of-flight PGA measurement withGe spectrometer at ANNRI has evaluated. The sources of a particular gamma-ray in the background spectrum
are Al-28 (1779keV) and B-10 (478keV) in B-10 (n,α)Li-7 reaction. A LiF neutron shield, which insert into theAl alloy beam duct, could reduce the gamma rays from the beam duct. The gamma rays of B-10 are mainly
emitted from neutron shield that are used for Ge detectors. Therefore, the replacement of the B neutron
shield with a Li neutron shield can suppress these gamma rays. Accurate elemental analysis is important inany scientific research. The effects of a neutron attenuation and scattering have to be determined to achieve
accurate and precise quantitation. The correction factors were calculated by simulation code PHITS andprovided accurate and reliable results. Thus, we conclude that the neutron attenuation and scattering can beaccurately corrected with simulation. Data analysis software which is a beta version has developed. Some ofmono-element and standard samples were measured at ANNRI, and analyzed with the developed software.
必要に応じて、A4 サイズの用紙に続きを記入して下さい。
Please use A4-size papers for further reporting, if necessary.

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