Jens Janssen Diploma Thesis - Prof. Dr. Norbert Wermes ...

More documents

Recommendations

Info

2. The tuning was changed to a gain of 30 ToT at a collected charge of10, 000 e - . This tuning is comparable to the standard tuning (60 ToT at20, 000 e - ) but for the ToT distribution a higher precision 6 can be achievedfor shorter ToT which is the case for irradiated detectors. The generatedcharge for a MIP passing through a highly irradiated sensor material isexpected to be between 15 ke - and 19 ke - (250 µm bulk silicon, 1 MeV neutronequivalent fluence of 1 ◊ 10 15 cm ≠2 ) caused by charge trapping [6].The charge seen per pixel is reduced even more due to charge sharingbetween adjacent pixels n[8]. Setting the tuning values of the ToT Calibrationclose to the expected charge is important to achieve high precisionmeasurement results (see also section 5.9.1 and 5.9.3).During the tuning process the threshold of the discriminator and the feedbackcurrent of the preamplifier of each pixel get adjusted. The threshold is controlledby the GDAC global register and the TDAC pixel register. For tuning the ToTresponse, the feedback current of the preamplifier can be adjusted by changingthe IFDAC global register, the FDAC pixel register and the TrimIF globalregister. Changing the global register has an influence on the entire FE-I3readout chip (coarse tuning), while the pixel register determines the behaviorof a single pixel (fine tuning).GDAC The GDAC is a 5-bit global DAC (global register [227:223], often referredto as GlobalTDAC) controlling the threshold of the discriminatorfor every pixel (coarse tuning of the threshold). It covers a thresholdrange of 0–5000 e - . The standard value for GDAC is 16 and targets amean threshold of 4000 e - if all TDAC pixel registers are set to 64. Toreflect the lower target threshold of 3200 e - , which is used during characterization,the GDAC was manually set to 13. This will result in a TDACmean value close to 64 (in the middle of the TDAC range, see figure 5.3).TDAC The TDAC is a 7-bit pixel register that determines the threshold ofeach pixel (fine tuning of the threshold). Within the range of 40 to 100,the TDAC DAC is linear and thus the threshold which depends on it [45].The GDAC must be set manually to a reasonable value, so that the TDACmean value (after tuning) is in the middle of its range (see figure 5.3).The TDAC tuning works as follows: for each pixel, a Threshold Scans isperformed at di erent TDAC settings. The appropriate TDAC value isderived from the measured thresholds (linear regression).IFDAC The IFDAC is an 8-bit global DAC (global register [132:125]) controllingthe feedback current of the preamplifier of every pixel (coarse tuningof the feedback current). Changing the IFDAC changes the collected ToTto-chargecalibration. The standard value is 32 and targets a charge ofapproximately 20, 000 e - that is expected for a MIP (TrimIF is set to 16).To obtain a gain of 30 ToT at a collected charge of 10, 000 e - the IFDACmust be manually set to a value equal or below 16. Setting the IFDAC toan appropriate value is of great importance for the FDAC tuning becauseof the limited range that is covered by the FDAC.6 This is due to the fact that the ToT-to-charge calibration is only linear in the first order(see section 5.9.1).54
DAC: TOT_VERIF.Module "ATLAS_7A"0 pixels with DAC=0, 0 pixels with DAC=127Map of TDAC chip 0Row140120100806040200120100806040200 2 4 6 8 10 12 14 16ColumnDAC distribution12010080604020Constant 107.7Mean 64.6Sigma 10.450 20 40 60 80 100 120DACDAC scatter plot0DAC1201008060402000 500 1000 1500 2000 2500"Channel" = row+160*column+2880*chipFigure 5.3: TDAC distribution after fine tuning.DAC: TOT_VERIF.Module "ATLAS_7A"116 pixels with DAC=0, 113 pixels with DAC=7Map of FDAC chip 0Row1401201008060402000 2 4 6 8 10 12 14 16ColumnDAC distribution500400300200100Constant 533.7Mean 3.351Sigma 2.17976543210DAC scatter plot0 1 2 3 4 5 6 7DACDAC765432100 500 1000 1500 2000 2500"Channel" = row+160*column+2880*chipFigure 5.4: FDAC distribution after fine tuning.55
Page 1:
Universität BonnPhysikalisches Ins
Page 7 and 8: Chapter 1IntroductionThe ATLAS expe
Page 9 and 10: Chapter 2The LHC Experiment2.1 The
Page 11 and 12: Figure 2.3: Cut-away view of the in
Page 13 and 14: The electromagnetic calorimeter use
Page 15 and 16: Chapter 3Silicon Pixel Detectors3.1
Page 17 and 18: Figure 3.2: Layout and interconnect
Page 19 and 20: (a) (b)Figure 3.4: On top view of t
Page 21: Figure 3.5: The analog pixel block
Page 24 and 25: Figure 3.8: The digital block of th
Page 26 and 27: the digital readout of the chip can
Page 28 and 29: Stopping power [MeV cm 2 /g]100101L
Page 30 and 31: The free charge carriers need to be
Page 32 and 33: The first point particularly concer
Page 34 and 35: Figure 3.14: A 3D n-in-p sensor (le
Page 36 and 37: few µm compared to a few 100 µm).
Page 38 and 39: Figure 4.1: The USBpix test system
Page 40 and 41: e accessed through a 20-bit wide ad
Page 42 and 43: hardware, USBpixdll library uses fu
Page 44 and 45: 100Scan overlaythreshold80604020MSC
Page 46 and 47: mand clock (CCK, 4 MHz 17 ) by mult
Page 48 and 49: aw data word bit [31:0]hit wordw/o
Page 50 and 51: Figure 4.7: Overview of interconnec
Page 52 and 53: SOURCE_SCAN.Module "test"Cluster To
Page 54 and 55: Figure 5.1: The USBpix test setup:
Page 56 and 57: Not only the wafer processing a ect
Page 60 and 61: FDAC The FDAC is a 3-bit pixel regi
Page 62 and 63: probability of 50%. Mathematically,
Page 64 and 65: that the particles first impinge th
Page 66 and 67: 2. Conversion of (clustered) Time-o
Page 68 and 69: from the expected charge of 10000 e
Page 70 and 71: 6.2 Unirradiated Planar SensorsThe
Page 72 and 73: Sensor 3631-303 “ATLAS W11 19GR-2
Page 74 and 75: (a)(b)(c)Figure 6.4: Planar devices
Page 76 and 77: 6.3.1 Results of the Bias ScanLeaka
Page 78 and 79: (a)(b)Figure 6.7: Leakage current o
Page 80 and 81: (a)(b)Figure 6.9: FBK 3D devices: m
Page 82 and 83: Appendix AFE-I3 StandardConfigurati
Page 84 and 85: Appendix BFPGA ConfigurationRegiste
Page 86 and 87: Appendix CTuning ResultsThis page i
Page 88 and 89: Figure C.1: Tuning of the 3631-303
Page 90 and 91: 8642Figure C.3: Tuning of the WR13
Page 92 and 93: 8642Figure C.5: Tuning of the 4EM9
Page 94 and 95: [13] Peric, I. et al.: The FEI3 rea
Page 96 and 97: [37] Backhaus, M. et al.: Developme
show all

Jens Janssen Diploma Thesis - Prof. Dr. Norbert Wermes ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?