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[Richard Witt <witt AT usna.edu>]

Present: Alexei, Daniel, Flemming, Jim, Yuri, Gene, and myself == Hardware — physics running began around 1200 yesterday — within a couple hours a problem was noticed with methane content — somewhat low, 5. 53 cm/us rather than 5. 55 cm/us — tuned

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Present: Alexei, Daniel, Flemming, Jim, Yuri, Gene, and myself

== Hardware

— physics running began around 1200 yesterday

— within a couple hours a problem was noticed with methane content

— somewhat low, 5.53 cm/us rather than 5.55 cm/us

— tuned flow and should see the canonical drift velocity reached soon

— having some trouble keeping PT-8 above atmospheric 

— have tried changing several presets

— TPC has been sitting at ~1.8 mbar for ~past year 

— extra cooling unit were brought to compensate for cooling tower

— not yet connected

— no magnet trips since water was rerouted on tower

— expectation is that new chiller will not be needed due to incoming cold weather

== Electronics

— after start of run have already lost two RDOs

— Tonko will look at repairing during upcoming break

== Software

— Gene will be working on SC for Run25 Au+Au

— zeroed out SC for current running since not expecting as high a luminosity

— Daniel mentioned we may actually need to reconsider the changes made after DAQ upgrade

— so luminosity will be higher than previous 3.5

— A reduction in dE/dx gain was noticed in FXT vs AuAu

— Level 4 trigger is using wrong drift velocity (likely due to methane content, see above)

— may be origin of track breaking at central membrane noticed by FXT group

— expectation is there will be improvement in breaking tracks as methane content rises and drift velocity returns to expected value

— Will begin express production once some calibration is finished

— Daniel mentioned that the eToF data will likely not be usable 

 

== AOB

— Daniel presented a summary of issues noticed so far 

— some noted change in dE/dx (factor 2 lower in gain now compared to 2020)

— not specific to FXT (was in 2025 as well)

— due to an intentional reduction in gain on the inner sectors anodes (1100 —> 1070)?

— Yuri says some MIP are cut (below threshold)

— Also, rapidity distribution shows a drop for tracks crossing the central membrane

— expected to resolve with methane content increase (see above)

— asymmetry in DCA-Z peak may see a related improvement 

Best Regards,

  Richard

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"Education is the most powerful weapon which you can use to change
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 Richard Witt, Professor of Physics     Phone (USNA): 410-293-6675
    United States Naval Academy         Email: witt AT usna.edu
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