Program - Brookhaven National Laboratory

We measured the isomeric yield ratio for the photonuclear reaction of nat Sm (γ,xn) 143m,g Sm by using the
activation method with bremsstrahlung beam. The high purity natural Sm foil in disc shape was irradiated
with beam of energy range from 40 to 60 MeV. The experiment was performed at the 100-MeV electron
linac of Pohang Accelerator Laboratory. The induced activity in the irradiated Sm foil was measured by
the high-purity germanium detector (HPGe) and the experimental data was analyzed through the Gamma
Vision program. The present results are the first measurement at bremsstrahlung energies above the giant
dipole resonance region and the obtained data was compared with the corresponding values found in the
literature. The study of isomeric yield ratio is useful for understanding of nuclear reaction mechanism,
approaching of nuclear structure and testing of theoretical nuclear models.
Corresponding author: Guinyun Kim
PB 6 5:15 PM
New Measurements of the 241 Am(n,2n) 240 Am Cross Section
A. Kalamara, M. Diakaki, R. Vlastou, M. Kokkoris, N.G. Nicolis , A. Tsinganis
Department of Physics, National Technical University of Athens, 157 80 Athens, Greece
S. Ashley, M. Axiotis and A. Lagoyannis
Institute of Nuclear Physics, NCSR ”Demokritos”, 153 10 Aghia Paraskevi, Greece
The study of 241 Am(n,2n) 240 Am reaction is important as Am is one of the most abundant isotopes in the
spent fuel cycle and one of the most highly radiotoxic among the actinides. Five recent works provide data
from threshold to 20 MeV, with severe discrepancies among them in the energy region 10 to 12 MeV [1,5].
In order to resolve these discrepancies between the existing data, new measurements have been performed
at the 5 MV Tandem T11/25 accelerator laboratory of NCSR “Demokritos,” with a high purity Am target
provided by JRC-IRMM, Belgium. Due to its high radioactivity (5 GBq), the Am target was placed inside
a 3 mm lead cylindrical shielding and was irradiated with 10.4 and 10.8 MeV neutrons. Gamma-ray spectra
were taken at a distance of 10 cm from a Ge detector, before and after the irradiation, to ensure that there is
no contamination in the 987.8 keV photopeak from the decay of the 240 Am residual nucleus. The efficiency
of the detection setup, including the extended geometry of the Am sample, was extracted by using two
different techniques, an experimental and a simulated one. The cross section has thus been deduced with
respect to the 27 Al(n,α) 24 Na, 93 Nb(n,2n) 92m Nb and 197 Au(n,2n) 196 Au reference reactions, implementing
the activation technique. This research has been co-financed by the European Union (European Social Fund
– ESF) and Greek national funds through the Operational Program “Education and Lifelong Learning”
of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II.
Investing in knowledge society through the European Social Fund.
Corresponding author: R. Vlastou
[1] A. A. Filatenkov and S. V. Chuvaev, Phys. At. Nucl. 63, 1504(2000). [2] R. W. Lougheed, W.
Webster, M. N. Namboodiri, D. R. Nethaway, K. J. Moody, J. H. Landrum, R. W. Hoff, R. J. Dupzyk,
J. H. McQuaid, R. Gunnink., Radiochim. Acta90, 833 (2002). [3] G. Perdikakis, C. T. Papadopoulos,
R. Vlastou, A. Lagoyannis, A. Spyrou, M. Kokkoris, S. Galanopoulos, N. Patronis, D. Karamanis, C.
Zarkadas, Phys. Rev. C 73, 067601(2006). [4] A. P. Tonchev, C. T. Angell, M. Boswell, A. S. Crowell,
B. Fallin, S. Hammond, C. R. Howell, A. Hutcheson, H. J. Karwowski, J. H. Kelley, Phys. Rev. C 77,
054610 (2008). [5] C. Sage, V. Semkova, O. Bouland, P. Dessagne, A. Fernandez, F. Gunsing, C. Nastren,
G. Noguere, H. Ottmar, A. J. M. Plompen, P. Romain, G. Rudolf, J. Somers, and F. Wastin. Phys. Rev.C
81, 064604 (2010).
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