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FMS Update Refurbishment for Run15

FMS Update Refurbishment for Run15. Stephen Trentalange August 16, 2013 STAR Management Meeting. Status/Problems with the FMS. Run11 New management Run11-Run13 Physics addressed Run 11 500 GeV A N for pions : high p T Run 12 200 GeV A N for pions : topology/high p T

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FMS Update Refurbishment for Run15

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

  2. Status/Problems with the FMS • Run11 New management • Run11-Run13 Physics addressed • Run 11 500 GeV AN for pions: high pT • Run 12 200 GeV AN for pions: topology/high pT • Run 13 500 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 • 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 15 hours 40 hours Large Cell Small Cell Relative Absorption Relative Absorption 300 500 700 900 Wavelength (nm) 300 500 700 900 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 (ElkeAschenauer’’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?

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