MINOS

Gaussian fit to 'last plane hit' of 0.8 GeV muons in GEANT simulation

Gaussian fit to 'last plane hit' of 1 GeV muons in GEANT simulation

Gaussian fit to 'last plane hit' of 1.4 GeV muons in GEANT simulation

Gaussian fit to 'last plane hit' of 1.6 GeV muons in GEANT simulation

Gaussian fit to 'last plane hit' of 2 GeV muons in GEANT simulation

Same as above - for comparison

The distribution of last plane hit (lph) at 2 GeV across planes and strips in GEANT

LEFT: Lph against energy from GEANT for +ve and -ve muons. Errors are shown.
RIGHT: Lph against energy from real data for +ve muons. One point at 1.4 GeV for -ve muons. This is significantly outside the error of the +ve muons.

LEFT: Lph against energy for positive and negative muons with errors shown
RIGHT: The differences in lph. The effect is always positive, as expected from theory i.e. Positive muons stop quicker than negative ones. The effect seen is about 0.75% - we expect about 0.25% from theory.

Lph gamma fit of pions (left) and gaussian fit to muons (right) in GEANT at 2 GeV.

Zoom in of the region where the two fits overlap

LEFT: Mean of pion lph increases linearly with energy
RIGHT: Maximum number of entries at gamma mean of pion lph is non-linear with energy ( useless! )

Now I'm going to look at real data. Attenuation and PMT response has to be taken into account.

The gamma and gaussian fit parameters can be used find the numbers of pions and muons in real data samples.

The level of contamination of 'pions that look exactly like muons' can be found.

Then dE/dX can be investigated for the pions that are contaminating the muon sample to see if it helps to remove them.