Monte Carlo uncertainties

Many of the systematic effects in our Monte Carlo modelling were tested by running the MC calculations with the parameters in question varied in the input. In some cases we estimate the uncertainties without the Monte Carlo, relying on, for example, an analytical approximation. We treat these Monte Carlo errors separately from our measurement errors given in the previous section. In most of these tests, we ignore the difference in spectrum shape and consider only the changes in the fusion yield due to the input variations, which is usually a good approximation.

  

Table 8.18: Estimated effects of various systematic uncertainties on the TOF fusion yield. Values denoted ^* were either ignored or included in other errors.

Our estimate of the Monte Carlo uncertainties in the time-of-flight fusion yield are given in Table 8.18. By performing fits with intentionally varied Monte Carlo amplitudes, we found that 15.2% error in the fusion yield translates into a relative 8.6% uncertainty in the formation rate strength parameter $S_{\lambda }$. Also given in Table 8.18 are the statistical and the experimental uncertainties in the fusion yield which have been extensively discussed and already included in the fit.

Regarding the resonance energy measurements, our major uncertainty is expected to come from the US-DS target foil spacing, and (US) layer thickness, whose effects in energy we estimate to be about 6% each, resulting in about an 8.5% error. Note that the energy measurement is not very sensitive to small variations in the fusion yield.