Update on tests on the INMAPS 32x32 matrix

G. Rizzo SVT –April 10- 2012 1

Update on tests on the INMAPS 32x32 matrix

G.Rizzo, S. Bettarini,F.Morsani

Universita & INFN Pisa

Tests performed and open issues

•   Noise and gain from analog output measured on several chips:

•   On pixel 31,31 in the 32x32 matrix

–  Gain 600-650 mV/fC , Noise ~ 2.5-4 mV à ENC ~ 30 e-

•   On pixels from 3x3 analog matrix

•  Gain 800-850 mV/fC (higher than in 32x32??) , ENC ~ 30 e-

–   Gain with Cinj consistent with Fe55 end point measurements

G. Rizzo SVT –April 24 - 2012 2

•   In the 32x32 matrix noise from the digital output (noise scans) not consistent with the noise measured on the scope:

–  Fitted values around 1 DAC=0.3 mV too small!

–   Noise scans not simmetric!

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,0)

h_pixel_14_0

Entries 1240 Mean 2448 RMS 1.418

occupancy for pixel (14,0)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,1)

h_pixel_14_1

Entries 4012 Mean 2474 RMS 2.934

occupancy for pixel (14,1)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,2)

h_pixel_14_2

Entries 1104 Mean 2459 RMS 1.568

occupancy for pixel (14,2)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,3)

h_pixel_14_3

Entries 2289 Mean 2456 RMS 2.014

occupancy for pixel (14,3)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,4)

h_pixel_14_4

Entries 2578 Mean 2448 RMS 1.864

occupancy for pixel (14,4)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,5)

h_pixel_14_5

Entries 7757 Mean 2497 RMS 3.024

occupancy for pixel (14,5)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,6)

h_pixel_14_6

Entries 2175 Mean 2444 RMS 1.604

occupancy for pixel (14,6)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,7)

h_pixel_14_7

Entries 3673 Mean 2471 RMS 3.199

occupancy for pixel (14,7)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,8)

h_pixel_14_8

Entries 3170 Mean 2489 RMS 2.317

occupancy for pixel (14,8)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,9)

h_pixel_14_9

Entries 2151 Mean 2484 RMS 2.295

occupancy for pixel (14,9)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,10)

h_pixel_14_10 Entries 1771 Mean 2470 RMS 1.782

occupancy for pixel (14,10)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,11)

h_pixel_14_11 Entries 2673 Mean 2483 RMS 2.165

occupancy for pixel (14,11)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,12)

h_pixel_14_12 Entries 3217 Mean 2440 RMS 1.786

occupancy for pixel (14,12)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,13)

h_pixel_14_13 Entries 3091 Mean 2464 RMS 2.956

occupancy for pixel (14,13)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,14)

h_pixel_14_14 Entries 1282 Mean 2454 RMS 1.566

occupancy for pixel (14,14)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (14,15)

h_pixel_14_15 Entries 1275 Mean 2464 RMS 1.718

occupancy for pixel (14,15)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,0) h_pixel_28_0

Entries 2749 Mean 2464 RMS 2.694 occupancy for pixel (28,0)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,1) h_pixel_28_1

Entries 4942 Mean 2454 RMS 4.178 occupancy for pixel (28,1)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,2) h_pixel_28_2

Entries 1629 Mean 2424 RMS 0.7373

occupancy for pixel (28,2)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,3) h_pixel_28_3

Entries 849 Mean 2463 RMS 1.528 occupancy for pixel (28,3)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,4) h_pixel_28_4

Entries 1246 Mean 2447 RMS 1.129 occupancy for pixel (28,4)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,5) h_pixel_28_5

Entries 2677 Mean 2428 RMS 1.563 occupancy for pixel (28,5)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,6) h_pixel_28_6

Entries 1138 Mean 2470 RMS 1.875 occupancy for pixel (28,6)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,7) h_pixel_28_7

Entries 1750 Mean 2485 RMS 2.195 occupancy for pixel (28,7)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,8) h_pixel_28_8

Entries 4514 Mean 2497 RMS 2.501 occupancy for pixel (28,8)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,9) h_pixel_28_9

Entries 1025 Mean 2445 RMS 1.16 occupancy for pixel (28,9)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,10) h_pixel_28_10 Entries 2762 Mean 2436 RMS 1.621 occupancy for pixel (28,10)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,11) h_pixel_28_11 Entries 1409 Mean 2465 RMS 1.937 occupancy for pixel (28,11)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,12) h_pixel_28_12 Entries 3097 Mean 2501 RMS 2.757 occupancy for pixel (28,12)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,13) h_pixel_28_13 Entries 1452 Mean 2443 RMS 1.184 occupancy for pixel (28,13)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,14) h_pixel_28_14 Entries 1289 Mean 2478 RMS 2.11 occupancy for pixel (28,14)

thrDAC

24000 2420 2440 2460 2480 2500 2520

0.2 0.4 0.6 0.8 1

occupancy for pixel (28,15) h_pixel_28_15 Entries 1380 Mean 2460 RMS 1.679 occupancy for pixel (28,15)

•  Response of the discriminator, studied with

injection scans, showed a very strange behavior

that need to be investigated with simulation!

Injection test on pixel 31,31 (chip3)

•  Pixel 31,31 injected with a variable pulse Qinj=-0.3-0.3 fC (on Cinj=30 fF) and pulse height measured with:

1.  Analog output: V_sh_out à oscilloscope

2.  Digital output: threshold injection scan à THR @ 50% Occu

G. Rizzo SVT –April 24 - 2012 3

1.  Analog output: Good linearity for negative signal (right sign),

response to positive pulse less linear (expected)

2.  Digital output:

–  For signals smaller than ~ 40mV (scope) the discriminator response doesn’t follow the signal and

saturate at the “baseline”

measured from the noise scans –  NO positive signals seen (above

baseline)

•  Different slope in linear region due to buffer gain ~0.9

1MIP~1000e-=0.16 fC 40 mV ~ ½ MIP

•  Baseline from noise scan ~ 755 mV very different from the expected one from intercept (~ 820 mV!)

•  How do we estimate the real baseline and threshold

dispersion from noise scans?

Injection test on pixel 31,31 (chip3)

•  When we set a threshold how do we covert to electrons if we just have the noise scan available for each pixel?

•  Very low “apparent gain” for low signal (90 mV/fC) can probably explain why noise from noise scan is so small.

–  gain=90 mV/fC close to baseline instead of 750 mV/fC

•  With this very low apparent gain the voltage threshold dispersion of 20 DAC=6 mV, measured from noise scan, corresponds to a charge threshold dispersion of 6 mV/gain=6/90=0.074 fC = 0.46 MIP!!

•  Considering only points above ~40 mV the gain at the scope and the one with digital output are consistent with a buffer gain of ~0.9.

G. Rizzo 4

Injection test on pixel 31,31 (chip4)

•  Similar behavior on chip 4

–  gain=140 mV/fC close to baseline instead of 580 mV/fC

•  With this very low apparent gain the voltage threshold dispersion of 20 DAC=6 mV, measured from noise scan, corresponds to a charge

threshold dispersion of 6 mV/gain=6/140=0.05 fC = 0.3 MIP!!

•  Considering only points above ~40 mV the gain at the scope and the one with digital output are consistent with a buffer gain of ~0.9.

G. Rizzo 5

Same effect in Superpix0

G. Rizzo 6

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•  In Superpix0 the same effect was seen and, the problem started for signal pulse of

~ 40 mV as in INMAPS (Superix 1MIP=2.6 fC 200 um Si)

•  This very low apparent gain was thought to be due to the amplifier response since no comparison with analog output was available

•  This effect if not taken into account properly false the interpretation of the threshold setting on the chip in term of charge-electrons!

•  Need to revise this before publishing the Superpix0 testbeam data!

•  Mesaured baseline from plot=210 mV

•  Using gain from linear part and baseline want to calculate the THR for ¼ MIP

à baseline + 0.65 fC=210+27 mV à 237 mV THR

•  BUT this corresponds to ~ 1 fC THR

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How do we proceed?

•   Need to investigate/understand the discriminator behavior.

•   Simulation ?

•   The discriminator output in the 3x3 analog chip doesn’t work properly and cannot be used for debugging.

G. Rizzo 7

backup

G. Rizzo 8

Chip 3 noise scan

G. Rizzo 9

RUN 3001

Baseline ~ 2475 DAC

THR

Baseline -655 DC

Test con injection INMAPS

G. Rizzo 10

Shaper out - 200 mV

THR

Baseline -655 DAC=1820 DAC

Baseline = 2475 DAC

Vinj=+10 mV

RUN 3003

Test con injection INMAPS

G. Rizzo 11

Shaper out +/- 100 mV

THR

Baseline= 2475 DAC Baseline +327 DAC=2802 DAC

Baseline +327 DAC=2152 DAC

Vinj=+10 mV

RUN 3004

Injection of a negative pulse

G. Rizzo SVT –Elba Tech. Board June 2 - 2011 12

•  Blue MLE

•   PINK Injection trigger from PG to Agilent

•   GREEN Injection pulse

• Yellow shaper out with -4 mV injected

Injection of a positive pulse

G. Rizzo SVT –Elba Tech. Board June 2 - 2011 13

•  Blue MLE

•   PINK Injection trigger from PG to Agilent

•   GREEN Injection pulse

•  Blue MLE

•   PINK Injection trigger from PG to Agilent

• Yellow shaper out with

+ 5 mV injected

G. Rizzo 14