Calibration of the VA2

B Pal,R Mountain,

M Artuso6/29/2010

Goal: get an absolute calibration of a VA2 channel to measure diamond charge collection

Calibration fixture is replaced by single channel fixture

Single channel fixture schematic

1.0 pF

Channel Gain Channel 141 previously used in diamond measurements

Input Bias

Nominal gain from specs is 30 mV/fC, which is ½ of the gain we measured in ch 141.

Nominal value value Used

Vfp -0.2 to 0.5 V -0.4 V

Vfs 700 mV 700 mV

Pre_Bias 100 mV 99.8 mV

Sha_Bias 22 mV 22.3 mV

i_buf 14 mV 13.8 mV

Gain vs. I_buf

To do

• Calibrate the ADC (have adc/fC now), • Check the gain after ADC calibration ,• Fix the diamond holder,• Start studies of “unusual” diamond behavior.