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APD Tests : Status and APD Tests : Status and ProtocolProtocol

Giuseppe S. PappalardoGiuseppe S. Pappalardo

INFN CataniaINFN Catania

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• APD testing station in Catania

• Protocol

• Test results

• Conclusions and Perspectives

Outline

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Testing set-up / 1

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Testing set-up / 2

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Testing set-up / 3

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APD dependence on the bias voltage

M(V) = H(V) / H(plateau)

Parameterization with an exponential plus a constant:

M(V) = p0 + p1 exp(p2V)

16 APDs under test simultaneously

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Definition of the plateau /1

1) H(plateau) = p0+p1 (from fit) -> not stable

2) H(plateau) = H(50)

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Definition of the plateau /2

Fit done only in the V30 region

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Time schedule for the tests

• ~10 min to assembly APDs on the plate

• ~20 min for the temperature stabilization

• ~40 min for the measurement of the gain curve + analysis

About 1 h 10 min to test 15 APDs (1 APD left as a reference)

About 6.5 week to test 1300 APDs (from Sept 1 to Oct 15)

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APD Gain dependence on temperature /1

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APD Gain dependence on temperature/2

APD 1-8

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APD Gain dependence on temperature/3

APD 9-16

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APD Gain dependence on temperature/4

- Small fluctuations from APD to APD

- Realistic measurement of the temperature (thermal equilibrium and thermocouple position)

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Temperature coefficient

1/M dM/dT = -1.7 % (@ M =

30)

Example:

T = 1° C

M = 30 0.5

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Since now we have tested about 170 APDs

The average value of V30 is 362 Volts with an RMS of 13 Volts

10% of APDs have a V30>380 Volts

3.5% of APDs have a V30>390 Volts

V30 statistics:

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Conclusions and Perspectives

Present Status:

• A working testing station has been set up

• Procedure tested

In the future:

• Starting the testing activity for APD mass production in September

• Realization of the system for gluing APD and light guide

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