1. Effect of flat cable to MPPC signal S. Uozumi (Kobe) Jun-6 2008 ScECAL meeting

2. Readout cable Idea 1: Idea 2: Idea 3: Just adopt long flat cable with MPPC (as done in DESY BT).

3. Objective How the MPPC signal skewed by passing through industrial-standard FPC cables and connectors? Any reflection clearly seen? This will determine (or give a feeling) specs of our readout flat cable (inpedance, length…). Electrocal cross-talk between adjacent lines on the flat cables?

4. Setup 20-lines FPC cables with 15cm length 1.25mm pitch and FPC connectors are used. FPC (15 cm) Relay board MPPC Readout circuit Signal connected to Oscilloscope Through x63 amp FPC cableFPC connector

5. Dark noise signal with different cable length With two cables And relay board (30 cm) With one cable (15 cm)

6. Electrical cross-talk Signal channel Adjacent channel Amount of electrocal cross-talk on the flat cable is at least below noise level.

7. Conclusion Of course those checks are not perfect, but we can somehow learn : – Better to set the cable inpedance to 50ohm, even if it makes production cost ~20% higher. (it was NOT considered at the DESY BT.) – Electrical cross-talk on flat cable is not significant level. – I suppose to go ahead with idea-I, but with 50ohm flat cable, not industrial standard FPC cable. – But, if the cable length can be short enough, taking idea-3 is also possible(but with 50ohm cable).