Q calc needs to extend beyond the Q range

[pkienzle]

Looking at some time of flight data with individual angles fit separately, there can be a downturn in the theory function for the section that starts in a steeply sloping region. This is because of a bad assumption in the resolution handling that R(Q) is approximately flat at the ends of the data, and so the calculated Q values were not extended beyond the Q range.

This is true enough most of the time: at low Q below the critical edge the data is flat, and at high Q the measurement is dominated by background.

However, when the data does not extend for the full Q range, or when there are gaps in the data, additional Q values are needed to cover the full resolution range.

Note also that due to the $Q^{-4}$ trend in the data we may want to extend the Q range longer toward the left than to the right.

[bmaranville]

Yes - this causes real problems in TOF data.