1. Studies of SiPM @ Padova
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

2. Flavio Dal Corso INFN-Padova
Plans & Objectives
Characterization of Silicon Photo Multipliers of different manufacturers and geometries:
Currents
Gain & Efficiency
Dark Rate
Time resolution
Long term stability …
Search for the best working point.
Comparison of performances.
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

3. Flavio Dal Corso INFN-Padova
SiPM are very sensitive to temperature  Measurements must be performed in a thermostatic chamber.
Range: 10 – 40 °C
Precision: 1/16 °C
Cooling element (peltier)
improvement
heating resistor
SiPM box
Control unit
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

4. Flavio Dal Corso INFN-Padova
Devices Available
Green: measurement done
Yellow: not completed
Red: tried unsuccessfully
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

5. Devices Characterization Current vs Vbias & Temperature
SiPM (FBK)
I(V) curves very regular
Low and linear T dependence
Quite high I (≈ few μA) at working point
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

6. Devices Characterization Current vs Vbias & Temperature
MPPC (Hmamatsu):
I(V) curves quite “irregular”
Higher and non-linear T dependence
Lower current (≤ 1 μA)
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

7. Devices Characterization Gain
SiPM (FBK)
Characteristics very linear, both G(V) and G(T).
G(V-Vo) doesn't depend on T (Vo = G=0)  absolute definition of “Working Point”
(no gain measurement performed on MPPC up to now)
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

8. Flavio Dal Corso INFN-Padova
Dark Rates
SiPM (FBK)
Almost flat vs temperature
Dark rate decrease very quickly with threshold,
Un solo dispositivo testato “estensivamente”
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

9. Dark Rates Comparisons
Moderate dependence on geometry (SiPM50 ≈ SiPM100)
MPPC less noisy than SiPM at 1 γ, more noisy at ≥ 2 γ (but a better comparison will require some normalization wrt gain, efficiency etc…)
Un solo dispositivo testato “estensivamente”
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

10. Devices Characterization Reverse Current Stability
FBK devices show jumps, fluctuations, slow drifts.
Impacts on dark rate, gain, device life?
Hamamatsu devices seem more stable.
Very preliminary results (few devices measured, influence from environment?)
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

11. Flavio Dal Corso INFN-Padova
CPTA
I(V) characteristic very regular: stronger T dependence w.r.t. SiPM
Quite low reverse current and Dark Rate (comparable to 1mm2 devices)
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

12. Flavio Dal Corso INFN-Padova
CPTA
Very good gain
Less linear vs T at high T  G(V-Vo) not completely independent from T
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova

13. Flavio Dal Corso INFN-Padova
Plans…
Radiation hardness studies: next week a single SIPM will be irradiated with ≈ 1 MeV neutron at LNL
Works in progress :
Characterization of all devices
Absolute efficiency measurements
Time resolution measurements
Electronics optimization : - higher amplification - s/n improvements (studies of charge integrating ADC vs peak sensing ADC)
Procurement of FBK devices ≈ 15x15 mm2 (array of 8x8 SiPM, 1.5x1.5 mm2 each, on a single chip)
Perugia 16 June 2009
Flavio Dal Corso INFN-Padova