The CMS HF Frontend Status Report

1
The CMS HF Front-endStatus Report

• Gueorgui Antchev, Eric Hazen, Jim Rohlf,
  Shouxiang Wu
• Boston University
• Tom Zimmerman and others, Fermilab

2
HF Readout Status

• PMT/Base/HV/QIE system is quitecomplex and is
  under study
• Readout packaging agreed (3U std crate)
• QIE Noise performance looks good with 3m cable
• May or may not need custom bonding of QIE
• Tests with PMT to start soon at B.U.

3
PMT / Base / HV Issues

• HV questions
• Separate 100v, 200v for last dynodes?
• Voltage control per how many PMTS?(gain
  matching, turn down hot tubes)
• Interconnect Topology
• Grounding (single-point ground for each PMT
  board, but isolated from box and HV ground)
• Coax vs twisted pair to QIE (tentatively, 2 x
  coax)
• PMT box ground ?? PMT base ground ?

4
HF PMT / QIE Interface
1000V
Resistive Divider Chain
for Dynodes 1-6
Dy1
PMT Box
12 PMTs Per PC board
Dy6
Two coax cables per PMT 3-5m long
Dy7
200V
QIE GND
Dy8
100V
(Die Attach Pad)
QIE Signal In
An
QIE Ref In
HV GND
"10K"
Safety GND
5
HF Readout Card
How to get optical fibers out? (No front panel
space.)
(6) QIE
(3) CCA
(2) GOL
(2) VCSEL
Backplane same As RBX (exceptslot spacing)
1/8 coax From PMTs
18 slots 108 ch
(12) SMB or similar coax connector Possibly in
multi-pin housing
120 x 83mm HCAL readout card size
160 x 100mm Eurocard 3U size
6
HF Readout Packaging

• Produce Readout Cards in 3U Format
• Connectors and Cables t.b.d.
• Use Commercial 3U Card Cage
• Need to engineer power distribution and cooling
  (BU)
• Produce Custom Backplane (FNAL?) (similar to HB,
  HE and HO)
• Crate Layout
• 18 slots for Readout Cards (108 channels)
• 3 slots for Clock and Control Modules
• (3) 3U crates per quadrant per end
• Lots of space in racks for patch panels, etc

7
QIE PMT Input Testing

• Latest results (from Tom Z)
• Noise is quite good (1fc) with 3m coax
• Lemo connectors on PCB
• Two coax per QIE input (signal, reference)
• Coax shields connected together at both ends
• RG-174 and RG-58 are similar in performance
• Next steps
• Try 93 ? cable
• Connect a PMT!
• Make new PCB layout dedicated to HF (FNAL or BU?)

8
HF FE Summary

• Lots of work to be done
• Update cost estimate and plan
• Finalize PMT / Base / HV configuration
• Pick cable and connectors for PMT inputs
• Output fiber solution
• Design (air-cooled) 3U readout board
• Design 3U crate (power, cooling)