Star-tpc-l mailing list

[Richard Witt <witt AT usna.edu>]

Present: Alexei, Daniel, Flemming, Jim, Yuri, Frank, Shinlchi, Gene, and myself == Hardware — TPC standing by for O+O — lasers everyday — drift velocity settling, approaching 5. 55 cm/us == Electronics — sector 24 RDO 4 was misbehaving with high

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

== Hardware

— TPC standing by for O+O

— lasers everyday

— drift velocity settling, approaching 5.55 cm/us

== Electronics

— sector 24 RDO 4 was misbehaving with high deadtime

— was removed from runs

— Tonko mentioned that that RDO has been associated with PS problems

— Flemming recommends masking that RDO (24,4) for all of the FXT run

— Gene will handle masking (24,4) out for entire FXT run

— Jim mentioned RDO (21,4) was also just masked out

== Software

— Gene began looking at SC for upcoming HL O+O

— may be a higher priority on FXT data we just took than on Au+Au

— plan is to calibrate SC in FXT (runs with higher voyages) first

— Daniel suggests timeline of a few months for first physics from this FXT run 

— Yuri mentioned that material from FST is currently not accounted 

— Flemming knows the geometry very well, says it is mostly cables and lines

— Daniel suggests using analysis teams to look for cables and lines using data and then cross-check with Flemming

— Yuri trying to get dE/dx calibration with what we have now (currently without SC correction) 

— expects to need SC calibration in the end

— Gene mentioned there is a non-zero (very rough) SC calibration in the dB 

 

== AOB

— Gene also brought up the topic of rates in the upcoming O+O running (more of a hardware topic, but occurred here)

— Run 21 O+O with no cuts, ZDC coincidence reached high 10’s kHz

— Flemming compared rates with Au+Au, finds mean N_part should scale by ~factor 14

— would lead to expecting 1 MHz rate (maybe factor 2 more)

— we might not be able to take 1.8 MHz rate (due to currents)

— Daniel mentioned there is indication from RHIC they won’t reach the max (1.8 MHz) in first days

— Flemming suggests requesting leveling well below 1.8 MHz or introducing crossing angle 

— 0.5 mrad of crossing angle will bring luminosity down to ~1MHz and bring vertex closer to 0

— Gene suggests a cap at 800 kHz might be better (restriction on DAQ rate to ~1 kHz)

— monitor TPC anode currents to evaluate (was about 15-18 uA in Au+Au, about 0.2 uA per section)

— CONCLUSION: start with a cap on DAQ rate of ~1kHz  and request ~=800 kHz rate (via 0.5 mrad crossing angle and beam steering)

— low-lumi cap will depend on physics goals for that running

— interest from hard probes and UPC, still some ongoing discussion 

— Flemming will pass on recommendations to JH (and they will go on to the collider from there)

— Daniel mentioned maintaining the lower (1150 V) anode voltages

— there were zero anode trips with this setting

— Jim reminds us that during pp500, trips every half hour was unacceptable and more than 5 trips on any channel was unacceptable

— recommends starting at 1150 V since we finished there

— if trips start occurring we should drop to 1120 V immediately

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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