STUDY OF GAMMA-SPECTRUM DISCREPANCY IN  ^natCd(N,Xγ) REACTION

 

B.M. Bondar^1,2, O.M. Gorbachenko³, B.Yu. Leshchenko¹,

 I.M. Kadenko³, V.A. Plujko³, K.M. Solodovnik³

 

¹Nuclear Power Plants and Engineering Thermal Physics Department, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine

²All-Ukrainian Center for Radiosurgery, Clinical Hospital “Feofania”, Kyiv, Ukraine

³Nuclear Physics Department, Taras Shevchenko National University, Kyiv, Ukraine

 

The cross sections of (n,xγ) reactions are required for radiation damage and shielding calculations of the nuclear facilities, and the 14-MeV (DT) neutrons are of special importance for these tasks because of many number of open reaction channels at this energy. Despite large number of experiments performed with DT neutrons, there are still disagreements between nuclear data from different authors or between experimental results and theoretical calculations. In particular, the last one was obtained in our experiments for Cd element [1], which is commonly used in the nuclear technologies. The experimental data on gamma-ray spectrum were obtained using the 14-MeV pulse neutron generator PNG-200 and applying TOF-technique for n-γ discrimination with pulse repetition period (PRP) of 140 ns and with γ-detection time window of 20 ns.

Here we study possible reasons of the disagreement of the experimental data and calculations in the energy range 5.5-:-10 MeV (see Fig.). The MCNP simulations of experiment were performed for this study. The experimental hall, PNG-200, detector facility and all the surroundings were built for simulations, and the neutron flux was determined on the sample surface within the high (0.1-:-14 MeV) and low (0-:-0.5 eV) energy ranges. It was shown that the main reason of the discrepancy is the contribution of the gamma-ray spectra from (n,γ) reactions that can be resulted from rescattered neutrons. New experimental geometry is finalized with clear separation of primary 14-MeV and low energy rescattered neutrons.

This work is partially supported by the IAEA through a CRP on Updating the Photonuclear Data Library and generating a Reference Database for Photon Strength Functions (F41032).

 

[1] B.M.Bondar, V.M.Bondar, O.M. Gorbachenko, et al., Proc. of the 4-th Int. Conf. "Current Problems in Nucl. Phys. and At. Energy", Kyiv, Ukraine, September 3-7, 2012 (Kyiv, 2013) 270-274.