The ideal gain for each tower satisfies the following relation, where E_T = 60 GeV when ADC is max scale (~4095 - ped):

(1)

We want to calculate the total energy deposited in a tower, which is the following in the ideal case:

(2)

In reality, we calculate the calibration according to the following formula:

(3)

where there is an electron correction for each eta ring, and the MIP location is determined for all towers.

Thus, to have ideal gains, we want the following relation to hold

(4)

To make this relation true, we need to adjust the high voltage for each tower according to the following relation:

(5)

We can check the changes using slopes.