FCAL Collaboration Meeting

1
Readout electronics for LumiCal first approach

• Wojciech Wierba
• Witold Daniluk
• Krzysztof Oliwa

2
Topics

• Mechanical design
• Space for electronics
• Pads strips designs
• Readout based on analog transmission
• Digital data transmission
• Readouts based on digital transmission

3
Mechanical design of LumiCal

• Segmented silicon sensors interspersed into the
  tungsten half disks
• Two half barrels to allow for mounting on closed
  beam pipe
• The blue bolts support the heavy part of the
  detector, tungsten half disks
• The red bolts carry only the sensors
• Holes for precision survey the sensors position

4
Space for electronics

• There is a limited space for the FE electronics
  for the 300 mm radius of LumiCal
• Bolts for tungsten sensors support takes
  additional space
• Si sensors online positioning needs place also

5
Pads Strips Design
Strips
Pads

• Both designs becomes very similar
• Different number of electronic channels Strips
  8000, Pads 25000

6
Possible readout designs

• Analog transmission simple, low heat
  dissipation, easy to maintenance a huge number
  of cables, crosstalk, noise
• Digital transmission small number of digital
  links, no crosstalk on the transmission
  complicated, high heat dissipation

7
Analog transmission

• 25000 analog cables (coaxial or TP) needs 30 mm
  round the LumiCal

8
Digital Transmission LVDS link

• Current speed 0.6 Gb/s
• Up to 10 m

9
Number of LVDS links for LumiCal

• 5000 bunches i one train 1 ms
• Break between trains 300 ms
• Number of channels 25000
• 10 bit ADC

• Amount of data per train 1.25 Gb
• Transmission during train 1.25 Tb/s - 2000
  links
• Transmission during break 3.75 Gb/s - 6 links

gtgt
10
Parallel conversion

• ADC in each channel expensive and space on chip
  consuming

11
Multiplexed ADC

• One ADC for a group of channels cheaper, needs
  S/H and MUX

12
Analog pipelined
Analog pipeline with 5000 cells and 10 (12) bits
accuracy over 300 ms is not a easy project, but
the number of ADC can be reduced by a factor of
300
13
Conclusions

• Number of channels is essential to chose the
  readout solution
• Digital data transmitted over the break between
  trains
• Analog pipeline or MUX can reduce a number of
  ADCs
• This talk seems to be a background for the
  discussion