Refurbishment for Run15 Stephen Trentalange August 16 2013 STAR Management Meeting StatusProblems with the FMS Run11 New management Run11Run13 Physics addressed Run 11 500 GeV A N for ID: 556773
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Slide1
FMS UpdateRefurbishment for Run15
Stephen
Trentalange
August 16, 2013
STAR Management MeetingSlide2
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
Run 13 500
GeV
A
LL
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 damageSlide3
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 neededSlide4
FMS Problems: PMT Gain Drift
We
Gain jumps
Gain Drifts
PMT Base Circuit Diagram
LED Amplitude
vs
Time
10K Seconds
We can follow gain
vs
time with LEDs, but trigger becomes extremely unreliable.Slide5
Radiation Damage to Lead Glass
Damage inversely proportional to distance from
beamline
Radiation hardened lead glass positioned closest to
beamline
Problem much less for large cells
Run 12
Run 13
Day
Day
LED pulse
amplitudeSlide6
PMT Health
No Signal
Gain Jumps
Gain Varies
Multiple
Small cells :
Radiation damage
Large cells :
Gain problems
~41% (323) basesSlide7
Radiation Damage/Exposure to Sunlight
0 hours 15 hours 40 hours
300 500 700 900
Wavelength (nm)
300 500 700 900
Wavelength (nm)
Relative Absorption
Relative Absorption
Large Cell
Small CellSlide8
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, heatSlide9
PMT Repair: Suggest new PMTs
(
Elke
Aschenauer
’’s contacts at
Fermilab
)
CDF D
ecommisioning Manager Jonathan Lewis offers 750 EMI 9954 (51mm) PMTs100 EMC 9814 (51 mm) availableSuggests D0/INFN may have moreAdditional request to George Ginther, D0 Decommisioning
Manager Additional ~900 Hamamatsu R580 (34 mm) These might be useful for the preshower detector.Slide10
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?Slide11
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?