Nino ro chip qualification with the laser test system
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NINO RO chip qualification with the laser test system. Sakari and Fadmar. Diode specifications - reminder. Pixelized diode from the IRST wafer 200 um thickness 300 um x 300 um pixel dimension (nominal) 3 x 20 pixel matrix 1 pixel under study  neighboring pixels grounded

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NINO RO chip qualification with the laser test system

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Nino ro chip qualification with the laser test system

NINO RO chip qualification with the laser test system

Sakari and Fadmar


Diode specifications reminder

Diode specifications - reminder

  • Pixelized diode from the IRST wafer

    • 200 um thickness

    • 300 um x 300 um pixel dimension (nominal)

    • 3 x 20 pixel matrix

    • 1 pixel under study  neighboring pixels grounded

    • An opening in the Al-layer covering the p+-pad etched to allow laser illumination

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -2-


Opening in the al layer

Opening in the Al-layer

  • From the previous measurements it was seen that there’s a big uncertainty on focusing the laser beam into the diode

  •  A better mechanical stability was achieved

  •  An opening in the Al-layer of the diode to provide better photon injection was etched

  • The opening was made by Serge Ferry (chemical lab)

    • The hole was done with chemical etching. A photo-resist was placed to protect the rest of the Al-layer. The diameter of the opening is ~100 um

  • With the opening the laser may be manually scanned to the center providing a maximum photon injection

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -3-


Opening in the al layer1

Opening in the Al-layer

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -4-


Irst diode pixelized and wire bonded

IRST diode pixelized and wire-bonded

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -5-


Connection to the nino chip

Connection to the NINO chip

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -6-


Laser position scan

Laser position scan

To make sure all the photons are injected in to the diode, the laser beam is

manually focused by measuring the output pulse width at different positions.

The dark red color shows the ‘hot spot’,

meaning the center of the hole. The red

circle shows the assumed ~100um

diameter hole.

The higher the pulse width, the more

photons enter the diode, meaning the

laser is better focused to the hole

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -7-


Height scan

Height scan

SATURATION

Complete illumination with the laser light

 calibration possible using an ALICE SPD assembly (same sensor specifications)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -8-


Measurements

Measurements

Laser Calibration


Calibration of the laser light

Calibration of the laser light

  • Reminder: W/O calibration between the laser and input charge the measurements with a calibration capacitance and the diode are incomparable

  • BUT!!! Cross calibration possible with an Alice SPD assembly

  • Assumptions:

    • The complete laser beam illuminates the detector  demonstrated (plateau reached in the fiber height scan)

    • Sensors of the ALICE SPD assemblies have the same specifications as the detector under study  they come from Si-wafers with same specifications

  • Response of the ALICE SPD assembly to two different radioactive sources (109Cd and 55Fe) calibrates the laser beam at different settings

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -10-


Pulse area vs laser bias

Pulse Area vs Laser Bias

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -11-


Laser calibration

Laser Calibration

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -12-


Measurements1

Measurements

Laser Bias Scan


Jitter

Jitter

300ps

300ps

Laser bias (V)

Laser bias (V)

2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Jitter vs. laser bias

(w/ detector,

no time-walk correction)

Jitter vs. input charge

(w/ openeddetector,

no time-walk correction)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -14-


Jitter1

Jitter

300ps

50ps

Laser bias (V)

2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Jitter vs. laser bias

(w/ 100fF calibration capacitance

no time-walk correction)

Jitter vs. input charge

(w/ opened detector,

no time-walk correction)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -15-


Pulse width

Pulse Width

Laser bias (V)

Laser bias (V)

1.5 2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

1.5 2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Pulse width vs. laser bias

(w/ opened detector)

Pulse width vs. laser bias

(w/ detector)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -16-


Pulse width1

Pulse Width

Laser bias (V)

1.5 2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Pulse width vs. laser bias

(w/ 100fF calibration capacitance)

Pulse width vs. laser bias

(w/ opened detector)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -17-


Time walk vs pulse width

Time-walk vs. Pulse width

Time-walk vs. Pulse width

(w/ opened detector)

Time-walk vs. Pulse width

(w/ detector)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -18-


Time walk vs pulse width1

Time-walk vs. Pulse width

Time-walk vs. Pulse width

(w/ opened detector)

Time-walk vs. Pulse width

(w/ 100fF calibration capacitance)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -19-


Measurements2

Measurements

Detector Bias Scan


Pulse width and jitter

Pulse width and Jitter

=~3 MIPs

=~3 MIPs

Pulse width vs. detector bias

(w/ opened detector)

Jitter vs. detector bias

(w/ opened detector)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -21-


Measurements3

Measurements

NINO Threshold Scan


Jitter as function of the nino threshold for 3 different laser bias settings

Jitter as function of the NINO threshold for 3 different laser bias settings

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -23-


Conclusions

Conclusions

  • Mechanical stability achieved

    • New precision mechanics installed

    • NINO board fixed to a reference plane

    • repeatability tested and improved

    •  system mechanically stable

  • Opening in the Al-layer allows the complete illumination with the laser light

    • Procedure established with TS/DEM group

    • Verified on 5 samples  openings range from 100 um – 3 mm

    • laser calibration finally! possible

  • Measurements on the NINO chip show improved results: jitter <200 ps for high det-bias and >1.8 V laser bias (~3 MIPs)

    • With the current RO-setup (detector wire-bonded to the NINO chip, no pre-amp) NO further improvement possible!

    • Next step: demonstrator

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -24-


Spare slides

SPARE SLIDES

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -25-


Jitter comparison 1pf

Jitter Comparison 1pF

300ps

300ps

Laser bias (V)

2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Jitter vs. laser bias

(w/ 1pF calibration capacitance

no time-walk correction)

Jitter vs. input charge

(w/ opened detector,

no time-walk correction)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -26-


Pulse width comparison 1pf

Pulse Width Comparison 1pF

Laser bias (V)

1.5 2.6 3.6 4.7 6.3 7.3 8.3 9.2 10 10.7

Generated charge (fC)

Pulse width vs. laser bias

(w/ 1pF calibration capacitance)

Pulse width vs. laser bias

(w/ opened detector)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -27-


Time walk vs pulse width comparison 1pf

Time-walk vs. Pulse widthComparison 1pF

Time-walk vs. Pulse width

(w/ opened detector)

Time-walk vs. Pulse width

(w/ 1pF calibration capacitance)

Fadmar Osmić – P326 GTK Meeting, December 11, 2007 -28-


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