MiniPrototype CAEN V792 Calibration

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I injected a signal into the Drift chamber preamps and read it out using the CAEN V792 ADC.

12/11/07

50 dB attenutation signal

The preamp input signal of XX mV was attenutated 50 dB. The preamp output from both drift chambers was sampled with the ADC. Both Drift chambers HV's were unplugged and the preamp was powered to 5.8 V.

Run 192

200 px


Run 193. Preamp HV off

Run 194 Preamp Off, trigg rate changed from 10 Hz to 60 Hz

Run 195 Preamp Off, trigg rate changed from 10 Hz to 550 Hz

Run 196 Preamp Off, trigg rate changed from 10 Hz to 250 Hz

Run 197 Preamp Off, trigg rate changed from 10 Hz to 300 Hz

7 mV Signal

Here is a scope picture of the signal coming out of the preamp and going into the ADC (Blue) as well as the integration gate used. The signal is about 7 mv as shown below. There is a 2 mv peak to peak noise level which has structure.

ADC V792 Calib a 12-11-07.jpg [math]Q=I \Delta t = \frac{V}{R} \Delta t = \frac{\mbox{Area of trace}}{R} = \frac{2 \times \frac{1}{2} (20 ns) (7 mV) + (36 ns) (7 mV)}{50 \Omega} = (7.84 \pm 2) \times 10^{-12} coul[/math] Error estimate of 25 % is just a guess ADC V792 Calib a noise 12-11-07.jpg ADC V792 Calib a noise 2 12-11-07.jpg

The data was then collected using coda and recorded as run #189. A histogram of channel #1 is shown below.


ADC V792 Calib 7mV Output 12-11-07 Histo.gif ADC V792 Calib 7mV Ped 12-11-07 Histo.gif ADC V792 Calib 7mV S 12-11-07 Histo.gif

Signal - Ped =[math] (343.5 \pm 0.9 ) - (56.18 \pm\lt 0.3) = 287.3 \pm \sqrt{0.9^2 + 0.3^2} = 287.3 \pm 0.9[/math] Channels
ADC conversion [math]= \frac{7.84 \pm 2 \times 10^{-12} \mbox{Coul}}{287.3 \pm 0.9 \mbox{Chan}} = 27 \pm 7 \; \frac{f\mbox{Coul}}{\mbox{Chan}}[/math]

I was expecting [math] 100 \frac{f\mbox{Coul}}{\mbox{Chan}}[/math]. The signal was split between the ADC and the Scope so there is a factor of 2 but this stil comes up short.

20 mV signal

Reducing the attenuation, a 20 mV signal was sent into the ADC.

ADC V792 Calib S20mV 12-11-07.jpg [math]Q=I \Delta t = \frac{V}{R} \Delta t = \frac{\mbox{Area of trace}}{R} = \frac{2 \times \frac{1}{2} (20 ns) (26 mV) + (36 ns) (26 mV)}{50 \Omega} = (29.12 \pm 7) \times 10^{-12} coul[/math] Error estimate of 25 % is just a guess

The data was then collected using coda and recorded as run #190. A histogram of channel #1 is shown below.

ADC V792 Calib 20mV Output 12-11-07 Histo.gif ADC V792 Calib 20mV Ped 12-11-07 Histo.gif ADC V792 Calib 20mV S 12-11-07 Histo.gif

Signal - Ped =[math] (542.2 \pm 1.1 ) - (101.8 \pm\lt 2.5) = 440.4 \pm \sqrt{1.1^2 + 2.5^2} = 440.4 \pm 2.7[/math] Channels
ADC conversion [math]= \frac{(29.12 \pm 7) \times 10^{-12} \mbox{Coul}}{440.4 \pm 2.7 \mbox{Chan}} = 66 \pm 16 \; \frac{f\mbox{Coul}}{\mbox{Chan}}[/math]

I was expecting [math] 100 \frac{f\mbox{Coul}}{\mbox{Chan}}[/math]. The signal was split between the ADC and the Scope so there is a factor of 2. This would put the conversion to [math](132 \pm 33\frac{f\mbox{Coul}}{\mbox{Chan}})[/math] in agreement with manual.

100 mV signal

Reducing the attenuation, a 100 mV signal was sent into the ADC.

ADC V792 Calib S100mV 12-11-07.jpg [math]Q=I \Delta t = \frac{V}{R} \Delta t = \frac{\mbox{Area of trace}}{R} = \frac{2 \times \frac{1}{2} (20 ns) (110 mV) + (36 ns) (110 mV)}{50 \Omega} = (123.2 \pm 30) \times 10^{-12} coul[/math] Error estimate of 25 % is just a guess

The data was then collected using coda and recorded as run #191. A histogram of channel #1 is shown below.

ADC V792 Calib 100mV Output 12-11-07 Histo.gif ADC V792 Calib 100mV Ped 12-11-07 Histo.gif ADC V792 Calib 100mV S 12-11-07 Histo.gif

Calibration

Plastik's output is going into channels 1-7 and Metalicas output into 10-16. Drift Chamber High Voltage is off and preamp is powered to 5.8 volts. The post amp is not being used.

Input (mV) Chan 1 Chan 2 Chan 3 Chan 4 Chan 5 Chan 6 Chan 7 Chan 8 Chan 9 Chan 10 Chan 11 Chan 12 Chan 13 Chan 14 Chan 15 Chan 16
0
7
20
100 1538 1625 1666 510 1640 1661 648 648 605 1640 1685 1672 1684 1611 1084 587