Program - Brookhaven National Laboratory

differential yield data at requested energy and angular range, the MCNPX calculations need to be validated
against the independent experiments. Recently, the dosimetry-foils method was successfully used to the
validation of the MCNPX prediction of spectral flux characteristics for the p+D2O (thick) source. In the
present work, this method was employed to determine the spectrum of the Be(p,xn) source reaction at
the position of irradiated samples. The wide set of dosimetry foils (Al, Sc, Mn, Fe, Co, Ni, Ti, Y, In, Lu,
Ta, Au, Nb, and Bi) was selected to cover the energy range under interest. In the experiment, the thick
beryllium target was bombarded by the 35 MeV protons at beam current of 9 µA. Activated foils were
investigated by the nuclear gamma-spectrometry technique (the HPGe detector). To unfold the neutron
spectrum from resulting reaction rates, a modified version of the SAND-II code was used. Results and
uncertainty of the validation are discussed in details.
PR 33
A CVD Diamond Detector for (n, α) Cross-section Measurements
C. Weiss, E. Griesmayer,C. Guerrero, The n TOF collaboration, Vienna University of Technology,
Vienna, Austria, CERN, Geneva, Switzerland, https://ntof-exp.web.cern.ch/ntof-exp/.
In the last years, the experimental program at the n TOF facility at CERN has been extended to (n,
cp) cross section measurements of astrophysical and medical interest. These measurements require using
thin samples and often feature small cross sections, which results in small yields and thus call for a highresolution
and low-background detector. In this context, we have developed a dedicated device, based on
the chemical vapor deposition (CVD) diamond technology. The high performance of the detector, an array
of 9 sCVD diamonds, tested in 2011 and used in 2012 for a 59 Ni(n, α) 56 Fe measurement, is presented here.
CIVIDEC Instrumentation GmbH, Vienna, Austria, sponsored this work.
PR 34
Gas-filled Parallel-Plate Avalanche Counters for Fission Studies
C.Y. Wu, A. Chyzh, E. Kwan, R.A. Henderson, J.M. Gostic, D. Carter, Lawrence Livermore National
Laboratory. T.A. Bredeweg, A. Couture, M. Devlin, R.C. Haight, M. Jandel, H.Y. Lee, B. A. Perdue, T.
N. Taddeucci, J.L. Ullmann, Los Alamos National Laboratory.
To study the prompt gamma and neutron emission in either spontaneous or neutron-induced fission using
the DANCE [1] or Chi-Nu [2] arrays respectively requires a starter detector to identify uniquely the fission
event by detecting the fission fragments. A gas-filled parallel-plate avalanche counter (PPAC) has many
advantages for this application such as fast timing ( 1 ns), resistance to radiation damage, and tolerance of
high counting rate. Therefore, a new generation of PPAC was developed at Lawrence Livermore National
Laboratory specifically for those arrays, located at Los Alamos Neutron Science Center (LANSCE), to
make the needed measurements possible. For DANCE, a compact PPAC was fabricated with two anodes
placed at 3 cm away on either side of the cathode [3]. The anodes are made of the 1.4 µm thick aluminized
mylar. The cathode holds a 3 µm titanium foil with the electrodeposited target material that is sandwiched
between two mylar foils of the same thickness. The target is double-sided using the electrodeposition cell
described in Ref. [4]. For the Chi-Nu array, a low-mass multi-foil fission chamber was fabricated to
accommodate 10 sets of PPAC [5]. Each one has the same geometrical arrangement of the anodes and
cathode as the PPAC for DANCE. The targets were fabricated in a similar way except for the active areas:
4 cm in diameter for Chi-Nu and 0.7 cm diameter for DANCE. The design details and performances of these
PPACs will be presented. This work performed under the auspices of the U.S. Department of Energy by
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