BTeV Silicon Pixel Detector

1
BTeV Silicon Pixel Detector
BTeV Collaboration Meeting Sept. 10 99

• Test Bench Calibration of FPIX0 chip
• bump bonded to
• p_spray and p_stop detectors

2
Introduction

• The FPIX0 chip bump bonded to a Silicon Pixel
  Detector are right now under study at the test
  beam.
• One of the main goal of the FPIX0 is to study the
  spatial resolution of the pixel detector as a
  function of the number of bits of the measured
  pulseheight.

3
Topics of Discussion

• Measurement of the basic properties of each
  Analog Cells injecting charge by the Input
  Calibration Capacitance.
• Absolute Calibration of the Input Calibration
  Capacitance by an X-Ray source.
• Comparison of the performances between the
  p_spray and p_stop sensor.
• Next Steps and Conclusions

4
Test Bench Measurements

• Sweeping on the charge Injection value
• Efficiency discriminator curve
• Adc Analog response of each cells
• Extraction of basic quantity of each cell
• Threshold, Eq.Inp. Noise
• Pedestal, Gain and AdcNoise

5
Test Bench Input calibration circuit and
8-Bits external ADC
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Test Bench Charge Injection and ADC
response
Each peak gives

1. Discriminator Efficiency
2. Mean ADC response
3. Rms ADC response

Three different region

1. Threshold region
2. ADC Linear region
3. ADC Saturation region

7
Test Bench Threshold and Inp. Eq. Noise
8
Test Bench Non Linear ADC response
10 Most Probable Charge ADC response spread
regular gain cells

• Linear Fit 0MPC for each cells
• (Pedestal)i,j
• (Gain)i,j

• Non Linear Polynomial Fit for each cells
• (an , n0,,5)i,j

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Absolute Calibration

• Observed spectrum of a Xray source by FPIX0 bump
  bonded to a pixel silicon sensor
• Determination of the Calibration Capacitance
  values for each cells

10
Absolute Calibration Xray Source Tests
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Absolute Calibration Calibration Capacitance
spread in a single FPIX0chip
Ccal 5.85 /- 0.3 fF
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Comparison p_spray and p_stop sensors
Cell type and Sensor type Threshold (e-) Eq. Inp. Noise (e-) Qslope (e-/adc) Adc Noise (e-) Noisy cells
Regular gain cells odd p_spray p_stop 2139/-294 2739/-330 81/-9 106/-13 156/-4 165/-4 186/-22 406/-96 No 1 0 1
Regular gain cells even p_spray P_stop 2075/-282 2845/-400 80/-10 105/-9 149/-2 158/-3 179/-21 410/-133 No No
High gain cells p_spray p_stop 1254/-160 1483/-228 67/-8 83/-11 91/-1 88/-5 100/-20 205/-94 No 2 4 6
13
Conclusions

• FPIX0 Analog Cell has a Threshold spread and Inp.
  Eq. Noise good enough for the BTeV experiment
• The pedestal and gain maps of the FPIX0 bump
  bonded to a p_stop and p_spray sensors are
  available for improving the position resolution
  of the pixel detector

14
Next Steps

• Increase the statistic of the Threshold spread
  testing the several FPIX1 chips bump bonded to a
  sensor
• The improving of the reconstructed track position
  in the telescope as measured by the pixel
  detector using the calibration maps must be
  proved with the beam data