Energy distribution of the neutron flux measurements at the Chilean Reactor RECH-1 using multi-foil neutron activation and the Expectation Maximization unfolding algorithm

We present a methodology to obtain the energy distribution of the neutron flux of an experimental nuclear reactor, using multi-foil activation measurements and the Expectation Maximization unfolding algorithm, which is presented as an alternative to well known unfolding methods such as GRAVEL. Self-shielding flux corrections for energy bin groups were obtained using MCNP6 Monte Carlo simulations. We have made studies at the at the Dry Tube of RECH-1 obtaining fluxes of 1.5(4)×10¹³ cm⁻² s⁻¹ for the thermal neutron energy region, 1.9(5)×10¹² cm⁻² s⁻¹ for the epithermal neutron energy region, and 4.3(11)×10¹¹ cm⁻² s⁻¹ for the fast neutron energy region.