Calibration of the Neutron Activation System on the Frascati Tokamak Upgrade: Comparison Between Measured and Calculated Activation Response Coefficients

The Frascati Tokamak Upgrade (FTU) neutron activation system has been calibrated using indium foils and a ²⁵²Cf spontaneous fission neutron source located at several positions within the tokamak. The same experimental arrangements have been simulated with the MCNP Monte Carlo neutron and photon transport code in order to numerically reproduce the activation response coefficients measured experimentally. The main purpose of the comparison is to assess the accuracy of the numerical simulation and of the modeling of the FTU device. This analysis has a more general relevance in view of the use of the activation system as an independent method for the absolute measurement of the neutron yield in next-step fusion devices. An overall agreement at the 22% level between experiment and calculation has been demonstrated.