Program - Brookhaven National Laboratory

National Laboratory funded by the Department of Energy under contract W-7405-ENG-36.
[1] M. Heil et al, Nucl. Instr Meth. A 459, 229 (2001)
LA 7 5:30 PM
Precision Measurement of Neutron Capture in 238 Pu at DANCE
A. Chyzh, C.Y. Wu, E. Kwan, R.A. Henderson, J.M. Gostic
Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
T.A. Bredeweg, A. Couture, R.C. Haight, M. Jandel, H.Y. Lee, J.L. Ullmann
Los Alamos National Laboratory, Los Alamos, NM 87545 USA
Cross sections of neutron capture and neutron induced fission in actinides are important to many applications
in nuclear physics, nuclear power generating industry, and Stockpile Stewardship program. Most
common challenges in these measurements are inherited radioactivity of a target, and difficulty in distinguishing
(n,g) from other reaction channels, such as fission, that may contribute to background. We have
successfully performed the first cross section measurement in a laboratory environment of the neutron capture
in Pu-238 using DANCE [1] and PPAC [2]. DANCE is a 4π γ-ray calorimeter designed at LANL. It
consists of 160 BaF2 crystals capable of measuring total and individual energies of γ-ray cascades from neutron
capture. PPAC is a gas filled parallel plate avalanche counter designed to tag fission events and thus
distinguish γ-rays between capture and fission. It fits inside the DANCE beam pipe, has fast timing ( 1.7
ns), capable of high counting rate, and very resistant to radiation damage. Because of its low mass, PPAC
attenuates only