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
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
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
Mechanical design 90Sr, 37MBq β-Source 90Sr 37 MBq Sr-90 Setup 14 November 2012
Mechanical design Source holder Sr-90 Setup 14 November 2012
Mechanical design Positioning mechanism Sr-90 Setup 14 November 2012
Mechanical design Cooling head Cooling liquid inlet Sr-90 Setup 14 November 2012
Mechanical design Positioning system Peltier Element Sr-90 Setup 14 November 2012
Mechanical design Gold plated cold chuck Collimator Vacuum pump inlet Sr-90 Setup 14 November 2012
Mechanical design Dry air or nitrogen nozzle Sr-90 Setup 14 November 2012
Mechanical design Needle Preamplifier Sr-90 Setup 14 November 2012
Mechanical design 5cm Sensor under test Sr-90 Setup 14 November 2012
Trigger counter Scintillator Lightguide Multianode PMT HV base Sr-90 Setup 14 November 2012
Trigger and Readout Sr-90 Setup 14 November 2012
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
Physical calibration: 60 keV g 241Am line, Si detector 280 mm Noise ~ 600 e Compton scattering Sr-90 Setup 14 November 2012
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
Example: 200 mm Si diodes Sr-90 Setup 14 November 2012
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