MINOS

Key:

1.5_percent_spread_crate_0/1
3_percent_spread_crate_0/1
5_percent_spread_crate_0/1

Monte Carlo last plane hit with different momentum spreads
Click graph for root file
You can see that the mean stays about the same but the rms increases with momentum spread.

Chris' plot of the real data

Gaussians are fitted to the Monte Carlo last plane hit graphs for different momentum spreads.
The sigmas are extracted, plotted and fitted with a straight line.
About 4.6% momentum spread fits the real data best
Gradient=0.2674, Intercept at 1.03573

2nd Order polynomial fit with better errors says:
4.555%

I set the momentum spread to 4.6% then adjusted the energy to find the one that matched the data best.
A straight line fit gives 1.454 GeV (MC) as the best approximation to 1.4 GeV (Real)
This is a discrepancy of 3.86%
I previously measured a discrepancy of 2.5% at 2 GeV, but these new measurements are better and probably lie within the previous measurements' errors anyway.

Voila!