Program - Brookhaven National Laboratory

comparison of results C/E of fission rates indicates that the n TOF data overestimate the fission cross
section which turns out to be between those data and previous ones.
Session FF Neutron Cross Section Measurements
Tuesday March 5, 2013
Room: Central Park East at 10:30 AM
FF 1 10:30 AM
Target Mass Dependency of Light Mass Fragment Energy Spectra for Intermediate Energy
Proton Induced Reaction
Toshiya Sanami, Masayuki Hagiwara
High energy accelerator research organization
Estimation on detail distribution of energy deposition due to single nucleon incidence with intermediate energy
is required to evaluate irradiation effects depending on linear energy transfer. To estimate the energy
deposition, several kinds of fragment production models have been used as a part of multi particle transport
codes. The model itself, their combination and parameters should be examined through the comparison
with experimental data. Systematic experimental data covering variety of incident energies, targets and
production fragments have been desired to establish a theoretical model describing their production, properly.
We have been developed a Bragg Curve Counter (BCC) that has capability of particle identification
with large solid angle to provide the systematic data. The BCC has a data taking electronics to achieve
lower particle identification threshold than a conventional BCC has, by measuring fragment range [1]. The
data taken by the BCC are analyzed with compensation of missing energy due to penetration, to enhance
it’s measurable energy range [2]. Experimental data of double differential cross section (DDX) for Li, Be,
B and C production at 30, 45, 60, 90 and 135 degree emission angles for 40, 50, 70, 80, 140, 200 and 300
MeV proton on C, N, O, Al, Ti and Cu targets have been measured using four BCCs at same time using
cyclotron facility in National Institute of Radiological Science (NIRS) and Ring Cyclotron of Research
Center of Nuclear Physics at Osaka University (RCNP), Japan. For 200 MeV, the data with combining
one taken by another group [3,4] provides fragment emission DDXs for C to Au target that enable us to
obtain target dependency. Suppression of fragment emission was observed for energy spectrum of fragment
with increasing target mass due to varying coulomb barrier of residual nuclei.
[1] T.Sanami et al., Nucl. Instrm. Meth. A Vol 589 193 (2008) [2] M. Hagiwara et al., Nucl. Instrm. Meth.
A Vol 592 73 (2008) [3] H.Machner et al., Phys.Rev.C73, 044606(2006) [4] R.Green et al., Phys.Rev.C22
1594(1980)
FF 2 11:00 AM
Spin Measurements of Neutron Resonances of 87 Sr for Level Density Studies
F. Gunsing, et al. (the n TOF Collaboration)
CEA Saclay, Irfu, F-91191 Gif-sur-Yvette, France
Neutron resonances reveal nuclear levels in the highly excited region of the nucleus around the neutron
binding energy. Nuclear level density models are therefore usually calibrated to the number of observed
levels in neutron-induced reactions. The energy position of nuclear levels above the neutron binding energy
can be accurately determined for resolved resonances using neutron time-of-flight experiments. To a certain
extent, spin and parity distributions are in general much less straightforward to obtain. The gamma-ray
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