Program - Brookhaven National Laboratory

data via experiments and/or theory. Although 238 U is one of the most extensively studied nuclide in terms
of neutron data, the recent demands require accuracy in the energy region between 10 keV to 1 MeV, lower
than 4%. A set of neutron capture experiments based on the time-of-flight technique were performed,
in order to determine the 238 U capture cross section in the unresolved resonance region. The GELINA
facility of the Institute for Reference Materials and Measurements (IRMM) served as the neutron source.
A pair of C6D6 liquid scintillators was used to register the prompt gamma rays emerging from the uranium
sample. The analysis of the experimental data is based on the total energy principle applied in combination
with the pulse height weighting technique. The experimental details along with the analysis process are
described and results are presented in comparison to the existing data. The present measurements are part
of the European FP7 program ANDES.
DB 2 4:00 PM
Measurements of Neutron Capture Cross Section for 74 Se, 76 Se and 77 Se at KURRI-LINAC
H. Yashima, J. Hori, Y. Takahashi
Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka, 590-0494, Japan
S. Nakamura
Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai-mura, Naka-gun,
Ibaraki, 319-1195, Japan
Selenium-79 is one of the most important long-lived fission products in the transmutation study. However,
there is no experimental data of neutron-capture cross sections for 79 Se because it is difficult to prepare
its sample. Therefore, we have started a systematic measurement of neutron capture cross sections and
gamma-ray spectra of stable Se isotopes in order to improve the evaluated neutron capture cross sections
of 79 Se. In this work, we measured the neutron capture cross sections 74 Se, 76 Se and 77 Se in the neutron
energy range from 0.01 eV to 10 keV. The measurements have been performed by the neutron time-offlight
(TOF) method using the 46 MeV electron linear accelerator at the Research Reactor Institute, Kyoto
University(KURRI-LINAC). The neutron capture gamma-rays emitted from sample were detected by a
total absorption spectrometer consisting of twelve Bi4Ge3O12(BGO) scintillators, which was placed at a
distance of 12.7 m from the photo-neutron source of the KURRI-LINAC. Since base line fluctuations of
signals from the BGO spectrometer were caused by the strong bremsstrahlung (gamma flush) synchronized
with the accelerator pulse, a data taking system based on digital signal processing (DSP) technique was
employed to correct them. A data set of TOF and pulse height (PH) was obtained by analyzing of waveform
of the signals. A relative cross sections for 74 Se, 76 Se and 77 Se was obtained from the TOF spectra
discriminated by the PH spectra and the incident neutron flux on the capture sample determined by the
10 B(n, alpha) standard cross section, and then normalized by the evaluated value of capture cross section
at the thermal neutron energy in JENDL-4.0. These results will be compared with other experimental and
evaluated values. This work was supported by JSPS KAKENHI Grant Number 22226016.
DB 3 4:20 PM
Cross Sections and Excitation Functions for the Production of Long-Lived Radionuclides
D. Schumann, J. Neuhausen, R. Weinreich, PSI Villigen, Switzerland. V. Alfimov, H.-A. Synal, P. Kubik,
ETH Zürich, Switzerland. T. Wallner, ANU Canberra, Australia. J.-Ch. David, CEA Saclay, France. R.
Michel, IRS Hannover, Germany.
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