Fig. 6 shows direct component of the bare 252Cf field, after a CONE from a NO-CONE measurements were subtracted. The subtraction of individual Bonner sphere count rates was performed before the unfolding was applied. This figure shows data at 103 cm height. The unfolding results for 200 cm height are not presented graphically, because these spectral shapes are almost identical to the 103 cm height results.
As evident from Fig. 6 (a)–(d), both STAY'SL and MAXED unfolded spectra are presented, together with the theoretical ISO- 8529 252Cf normalized spectrum (from Fig. 5 (a)), multiplied with the expected neutron fluence rate (calculated at the measured distances). The calculation of direct neutron fluence rates were performed using the following equation (Roberts et al., 2011):