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Project Scope

Development of an SiPM based multichannel array photon detector for the SciFi Tracker upgrade. The detector part includes also a flexible PCB and connectors together with a detector mounting structure that allows for a mechanical unit of typically 4 detector arrays.

Link the SciFi Tracker upgrade TDR:


Automated measurement of the detectors for the most important characteristics:

  • Breakdown voltage, gain and gain uniformity (multichannel) measurement
  • DCR at room temperature and at -40C for irradiated detectors (multichannel)
  • X-talk measurement (multichannel)
  • PDE (single channel)
  • LED light spectrum recording for super-module
  • Functional test (I-V) for series production acceptance test without soldering to flex
Possibility of measurement:
  • Temeprature coefficient (T vs Gain) (single channel)
  • After-pulse (single channel)


Optimization of the detectors for the requirements in the SciFi Tracker application includes:

1. Silicon optimization:

a) PDE optimization - maximal PDE is the most important requirement, further developments of the two providers Hamamatsu and KETEK need to be driven into this direction, higher fill-factor (FF) (Hamamatsu), green shifted or flat spectral response (KETEK), pixel size optimisation

b) X-talk optimization - trenches between pixels can redue x-talk but decrease the FF, larger pixels have higher x-talk

2. Silicon Packaging:

a) Low dead area between detectors is required to keep an overall high hit detection efficiency, tolerances regarding thermal expansion have to be defined. Thermal cycling of package to qualify resistivity against thermal stress

3. Flex and mounting:

a) Flex PCB needs to be optimized for low thermal conductivity and highest possible imunity for environmental electrical noise (RF) and good signal transmission between detector and FE ASIC.

b) Detector alignment and mounting to the Flex.

4. Detector characterisation:

a) Automated tests for production testing

b) Irradiation studies on latest generation of prototypes and final devices

c) Characterisation of devices in the lab for in depth understaning of certain parameters and characteristics

Lab Facilities:


  • Automated test stand for non-soldered SiPM arrays for acceptance test
  • Warm and cold (-60C) characterisation box for arrays and single channel detectors (VATA64, FEMTO single channel amplifier), Gain, PDE (rel.), I-V, X-talk, after-pulse
  • Fiber module test stand with x-y table for laser, LED or e-gun injection tests
  • Neutron irradiation facility for irradiation of 2*10^10 neq/cm^2
  • Mulitchannel bias voltage power supply CAEN (32channels, 10mA, 10mV adj, current monitoring)

Presentation given in LHCb meetings

-- GuidoHaefeli - 15 Jul 2014

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Topic revision: r7 - 2014-07-15 - GuidoHaefeli
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