...
40 deg < theta < 50 deg
55 deg < theta < 65 deg
The visible deviations of fit from the spectrum is explained by low energy tails increasing with theta angle, as confirmed by simulation:
Using peak position for theta < 10 deg as normalization I found the deviation for linearity as a function of crystal energy (not corrected for angle):
...
I'm developping alternative method, which could be applied to all peaks, including p, He, and Li.
Method is based on energy split between adjacent crystals.
The high energy tail of GCR peak is explained by GCR energy spectrum and rather well reproduced by simulation:
So far, the effect of GCR spectrum was not properly taken into account for protons and He peaks fitting.
I plan to do it and hope it will improve data/MC agreement and will allow to use big angle protons for calibration.
GCR peak shape depends on momentum of incident ion
p = 3.5 GeV/ nuclon
p=5.6 GeV/nuclon
p=11 GeV/nuclon
p=18 GeV/nuclon
Peaks are perfectly fitted with lognormal function, but its parameters significantly depend on ion momentum.
Explaination: while for p=3.5 GeV/nucl the maximum energy of secondary electron is 12 MeV, for p=18 GeV/nucl this energy becomes 320 MeV
and high energy tail increases.
To get proper peak shape for fitting data we have to find peak shape versus momentum and then fold it with GCR spectrum.
Non-gaussian tracker PSF for GCR's
