BCal Beam Test Plots, January 3, 2007

From suggestions from Alex and others I wrote a piece of code that runs in ROOT that plots z finds sigma and then adjusts the PMT gain correction factors until the sigma of the gaussian fit is at it's minimum. Z is defined as

$z={\frac {E_{{cal}}-E_{{beam}}}{E_{{beam}}}}$

You can find the peakfit.C code here. ( in ROOT > .x peakfit.C )

The code goes through and adjusts each gain correction factor by an amount epsilon ( set at 0.01 now) until sigma is minimal. Of course the ADC conversion factor (E_beam/E_cal) has to be calculated each time too. Doing this shows a good improvement in the "floor term" and the energy dependent term is still approximately 5%.

The fit is using $\sigma _{{z}}={\frac {a}{{\sqrt {E(GeV)}}}}+b$ in the package xmgrace.