Program - Brookhaven National Laboratory

Session JF Neutron Cross Section Measurements
Wednesday March 6, 2013
Room: Central Park East at 10:30 AM
JF 1 10:30 AM
Measurement of Neutron Induced Fission Cross Sections by Surrogate Methods
V.V. Desai, B.K. Nayak, A. Saxena and S. Kailas
Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India
The neutron induced compound nuclear fission cross section data are required for nuclear energy, national
security and nuclear astrophysics applications [1]. Unfortunately, for a large number of reactions the
relevant data cannot be directly measured in the laboratory, since the desired nuclei are often too difficult
to produce with currently available experimental techniques or too short-lived to serve as target in present
day setups. The Surrogate method provides an access to such nuclear data indirectly. In recent years,
the surrogate reaction methods in various forms such as: (i) direct surrogate method, (ii) surrogate ratio
method and (iii) hybrid surrogate ratio method, have been employed to get indirect estimate of the neutron
induced fission reaction cross sections of many compound nuclear systems in actinide region, which are
not accessible for direct measurements. In an earlier work, the 233Pa(n,f) cross sections in the equivalent
neutron energy range 11.0 MeV to 16.0 MeV have been determined employing the Hybrid Surrogate Ratio
Method (HSRM)[2]. In a recent work, we have determined the 234Pa(n,f), 239Np(n,f), and 240Np(n,f) cross
sections by HSRM in the equivalent neutron energy range 9.0 MeV to 16.0 MeV, by measuring ratios of
fission decay probabilities of the compound nuclear residues produced in [ 232Th( 7Li, α) 235Pa/ 232Th( 7Li, t) 236U], [ 238U( 6Li, α) 240Np / 238U( 6Li, d) 242Pu], and [ 238U( 7Li, α) 241Np / 238U( 7Li, t) 242Pu] transfer
reactions respectively. We have also determined 241Pu(n,f) cross sections using 238U ( 6Li, d) 242Pu and
232Th ( 6Li, d) 236U transfer reactions by employing surrogate ratio method. Details of experiments and
results for various reactions will be presented.
Corresponding author: B.K. Nayak
[1] J.E. Escher et al. Rev. of Mod. Phys. 84, 354 (2012). [2] B.K. Nayak et al. Phys. Rev. C78, 061602
(R) (2008).
JF 2 11:00 AM
Neutron-induced Capture Cross Sections of Actinides via the Surrogate-Reaction Method
Q. Ducasse, B. Jurado, M. Aiche, L. Mathieu, I. Companis, S. Czajkowski, J. Matarranz, I.
Tsekhanovich, CENBG, Chemin du Solarium B. P. 120, 33175 Gradignan, France. T.Tornyi, F.
Giacoppo, A. Goergen, M. Guttormsen, A. C. Larsen, T. Renstrom, S. Rose, S. Siem, G. M. Tveten, T.
Wiborg-Hagen, University of Oslo, Department of Physics, 0316 Oslo, Norway. F. Gunsing,
CEA/Saclay, 91191Gif-sur-Yvette, France. M. Lebois, J. N. Wilson, IPN, 91406 Orsay, France. M.
Wiedeking, iThemba LABS, 7129 Somerset West, South Africa. O. Serot, CEA/Cadarache, 13108 Saint
Paul lez Durance, France. G. Boutoux, V. Meot, O. Roig, CEA/DAM, 91297 Arpajon, France.
Neutron-induced cross sections of short-lived nuclei are crucial for reactor physics. In particular, (n, γ) cross
sections on minor actinides are one of the largest sources of uncertainty in modeling new reactors for nuclear
waste transmutation using fast neutrons. However, very often the high radioactivity of the actinide samples
makes the direct measurement of these cross sections extremely difficult. The surrogate-reaction method
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