1. β-Source Setup for the charge collection efficiency measurements of radiation damaged sensors
Kröhnke,
14 November 2012
FCAL Collaboration Meeting
Sergej Schuwalow
Universität Hamburg/ DESY Zeuthen
Sr-90 Setup
14 November 2012

2. Why we need a new design?
New setup has to have the following abilities:
Measuring of very low signals (highly radiation damaged sensors, study of charge collection at low electric field, study of sensors with small CCE).
- Low noise, good shielding, reliable trigger system
- Separate measurements of signal and pedestal, perfect beam collimation
Study of charge collection in the wide range of sensor temperatures
- temperature control
- good thermal contact between the sensor and thermal sink
Ability to acquire signals of different polarity (polarization studies, testing of semiconductor structures)
- specially designed readout electronics
No need of sensor bonding (sensors production tests)
“probe station like” design, cold chuck + test needle contact
Sr-90 Setup
14 November 2012

3. Operation principle e- Trigger counter Readout Sensor HV Collimator e-
Cooling
Collimator e- e-
b-source
Trigger:
Gate for signal digitization
MIP selection
Sr-90 Setup
14 November 2012

4. Mechanical design 90Sr, 37MBq β-Source 90Sr 37 MBq Sr-90 Setup
14 November 2012

5. Mechanical design
Source holder
Sr-90 Setup
14 November 2012

6. Mechanical design
Positioning mechanism
Sr-90 Setup
14 November 2012

7. Mechanical design Cooling head Cooling liquid inlet Sr-90 Setup
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8. Mechanical design Positioning system Peltier Element Sr-90 Setup
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9. Mechanical design Gold plated cold chuck Collimator Vacuum pump inlet
Sr-90 Setup
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10. Mechanical design Dry air or nitrogen nozzle Sr-90 Setup
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11. Mechanical design
Needle
Preamplifier
Sr-90 Setup
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12. Mechanical design
5cm
Sensor
under test
Sr-90 Setup
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13. Trigger counter Scintillator Lightguide Multianode PMT HV base
Sr-90 Setup
14 November 2012

14. Trigger and Readout
Sr-90 Setup
14 November 2012

15. Uni-Hamburg setup
First version of the setup had been built for Si sensors studies
Some results: see next slides
DESY-Zeuthen version:
- improved shielding
- usage of DC-coupled ADC (CAEN v965)
instead of AC-coupled (CAEN v265)
- safe temperature control
- new fast shaper?
Sr-90 Setup
14 November 2012

16. Physical calibration: 60 keV g 241Am line, Si detector 280 mm
Noise ~ 600 e
Compton scattering
Sr-90 Setup
14 November 2012

17. ADC gate width optimization
Use test pulse ~20000 e
For each gate width perform
delay scan to define max response t
Delay scan
Sr-90 Setup
14 November 2012

18. Example: 200 mm Si diodes
Sr-90 Setup
14 November 2012

19. Conclusion and outlook
New 90Sr-setup optimized for small signal measurements had been designed and produced (Uni-Hamburg for Si sensors, DESY-Zeuthen optimized for diamond, GaAs and sapphire sensors)
First results available from Uni-Hamburg setup
DESY-Zeuthen setup construction is finished, first tests started (Oliver)
Looking forward to see results
Next steps:
Readout adjustment (baseline, SNR optimization)
Calibration
Measurements at room temperature
Chiller and Peltier element connection, temperature control
Thank you
Sr-90 Setup
14 November 2012