Program - Brookhaven National Laboratory

LF 5 5:00 PM
A New Signal Processing Technique for Neutron Capture Cross Section Measurement
Based on Pulse Width Analysis
T. Katabuchi, M. Mizumoto, K. Terada, T. Matsuhashi, M. Igashira
Tokyo Institute of Technology
K. Hirose, A. Kimura, S. Nakamura, Y. Toh, K. Y. Hara, F. Kitatani, K. Furutaka, M. Koizumi, M.
Oshima, H. Harada
Japan Atomic Energy Agency
J. Hori
Kyoto University
K. Kino, T. Kamiyama, Y. Kiyanagi
Hokkaido University
We have been developing an NaI(Tl) spectrometer for neutron capture cross section measurement at the
Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex
(J-PARC). The NaI(Tl) spectrometer was installed at the beam line of the Accurate Neutron Nucleus
Reaction Measurement Instrument (ANNRI) in the MLF. The purpose of the NaI(Tl) spectrometer is (1)
to provide reliable nuclear data by combining with measurement using a Ge spectrometer installed upstream
of the ANNRI beam line and (2) to extend the achievable high energy limit of measurement beyond the
Ge spectrometer measurement, using faster signal response of an NaI(Tl) detector than a Ge detector.
To achieve the second goal, electronics and data acquisition system with a small dead time are required.
Thus, we developed a new fast signal processing technique for neutron capture cross section measurement
based on pulse width analysis. In the technique, pulse width of anode negative signals from photomultiplier
tubes of the NaI(Tl) spectrometer were determined from time under a threshold level measured with a
fast time digitizer (FAST ComTech MCS6). Then, the pulse width of each signal was converted to the
pulse height from width-height calibration measurement using standard gamma-ray sources, and discrete
gamma-rays from the neutron capture reactions, 28 Si(n,γ) 29 Si and 14 N(n,γ) 15 N. To test this pulse width
method, we carried out cross section measurement of the 197 Au(n,γ) 198 Au and 99 Tc(n,γ) 100 Tc reactions.
The pulse-height weighting technique was applied to derive the neutron capture cross sections. In this
presentation, we present the whole scheme of the signal processing and data analysis, and compare the
obtained cross sections with the evaluated nuclear data.
LF 6 5:15 PM
Neutron Flux Characterization of the Cold Beam PGAA-NIPS Facility at the Budapest
Research Reactor
Tamas Belgya, Zoltan Kis, Laszlo Szentmiklosi
Centre for Energy Research IKI, HAS, Budapest, Hungary
A reliable flux characterization is essential for facilities using neutron beams. The NIPS station at the
Budapest Research Reactor (BRR) has recently been equipped with neutron-tomographic equipment. In
addition to this, the beam could be characterized using a large surface wire chamber (on loan) applying
time-of-flight method. The energy distribution was measured at 3 horizontal positions with this latter
in pinhole geometry, while the spatial inhomogeneity was measured with our new neutron-tomographic
equipment. The PGAA-NIPS facility at the BRR is heavily involved in the determination of nuclear data
for reactor and other applications [1]. The cold neutron beam makes it possible to avoid problems arising
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