CDC transfer func attempt

Setup

Setup (GS 4001)

Circuit

Charge injection circuit from Fernando's GlueX-doc-1364

Actual component values used were... 51.1 Ohms, 908 Ohms and 2pF.

This is to measure the impulse response of the electronics chain.

Early results

100mV leading edge of sq wave step up (yellow) and trigger from pulser (purple) - average

output of shaper - average	output of shaper - expanded time scale
output of fadc - average	output of fadc - expanded time scale

Final results

Borrowed Phillips 5771 (no attenuators needed)

pulser output - single

pulser output - average

pulser output - average

output of shaper - single

output of shaper - average

output of shaper - average

fADC data

upsampled fADC data

Fitted function

mean of upsampled fADC data

fitted function

blue=refit with powers fixed, pink= pars 137, 118, 8, 91.4, 9

Beware typos in filenames, this was run #31941!

Input charge: 2 pF x 103 mV = 206 fC

Input current: divide by 12ns peaking time of preamp: 206 fC / 12 ns = 17.2 uA

Peak value of output data is 635 adc_units ~ 635 * 495 mV / 4096 = 76.7 mV

Electronics gain is 76.7 mV / 206 fC = 0.37 mV/fC

(Gain of preamp alone measured by FJB as 0.57 mV/fC)

Convert to current using 50 Ohm resistance: 76.7 mV / 50 Ohm = 1.53 mA

Current gain is 1.53 mA / 17.2 uA = 89.0

Integrated value of output data is 19.03 adc_units.us ~ 19.03 * 495 mV / 4096 = 2.30 mV.us

Convert to charge using 50 Ohm resistance: 2.3 mV.us / 50 Ohm = 0.046 mA.us = 0.046 nC = 46 pC

Charge gain is 46 pC / 206 fC = 223

To convert histograms of summed ADC data (with 8ns sample time) to charge, multiply by 8 ns * 46 pC / 19.03 us = 19.3 fC

Garfield needs the transfer function expressed as current gain, but I want to see the results in adc units, so I need to scale the transfer function x 89 (current gain) x 635/1530 (adc units/uA). The remaining gain factor needed to match garfield adc data to real life data is the gas gain.