1. FMS Update Refurbishment for Run15
Stephen Trentalange
August 16, 2013
STAR Management Meeting

2. Status/Problems with the FMS
Run11 New management
Run11-Run13 Physics addressed
Run GeV AN for pions: high pT
Run GeV AN for pions: topology/high pT
Run GeV ALL for pions; glue at low x
Problems increasing with time:
Increase in gain variations in large cells ~50->~300
Graying of lead glass due to radiation damage

3. Tasks/People Summer 2013 Fall/Winter 2013 Summer 2014
Remove FMS lead glass/unwrap cells (5mm)
Expose to sunlight (2mm)
Fall/Winter 2013
Fix large cell PMT bases (???)
Glue PMTs to lead glass (5 mm)
Re-wrap cells with aluminized mylar (3mm)
Summer 2014
Re-stack FMS (6mm)
Test electronics (3mm)
People: Trentalange/Mondal/Dilks/Heppelman/Marshall/Boone + extra UCLA/PSU/StoneyBrook/Valparaiso Students, as needed

4. FMS Problems: PMT Gain Drift
LED Amplitude vs Time
PMT Base Circuit Diagram We
Gain Drifts
Gain jumps
We can follow gain vs time with LEDs, but trigger becomes extremely unreliable.
10K Seconds

5. Radiation Damage to Lead Glass
LED pulse
amplitude
Run 12
Run 13
Day
Day
Damage inversely proportional to distance from beamline
Radiation hardened lead glass positioned closest to beamline
Problem much less for large cells

6. PMT Health No Signal Gain Jumps Gain Varies Multiple Small cells :
Radiation damage
Large cells :
Gain problems
~41% (323) bases

7. Radiation Damage/Exposure to Sunlight
0 hours hours hours
Large Cell
Small Cell
Relative Absorption
Relative Absorption
Wavelength (nm)
Wavelength (nm)

8. Repair of PMT bases
Bases potted in insoluable* rubber/ repair time is ~1+ hour/base + ~10-20 components
Risk mechanical damage to tubes, base components. Other 60% of tubes NOT repaired might fail in similar fashion.
* Checked alcohols, acetone, dimethyl chloride, gasoline, oils, acetic acid, heat

9. PMT Repair: Suggest new PMTs
(Elke Aschenauer’’s contacts at Fermilab)
CDF Decommisioning Manager Jonathan Lewis offers 750 EMI 9954 (51mm) PMTs
100 EMC 9814 (51 mm) available
Suggests D0/INFN may have more
Additional request to George Ginther, D0 Decommisioning Manager
Additional ~900 Hamamatsu R580 (34 mm) These might be useful for the preshower detector.

10. PMT Replacement Each tube/base needs testing Glue/optical coupling?
HV/signal connectors and cables? Current FMS uses “bayonet”-style HV connector. May need to find/buy 788 SHV bulkheads for patch panel, plus 788 lemo cables/lemo-bnc adapters
Additional problems?

11. Conclusions FMS Disassembly: finished
Exposure to sunlight: in progress
100% for small cells
12% of large cells
Repair of PMTs too difficult; exploring promising sources for new PMTs
Budget depends on connectors/style of new PMTs. ROUGHLY ~$20-40K?