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[videbaek <videbaek AT bnl.gov>]

Hi Gene,

I think it is a sensible suite of measurements to perform. My guess is 
though due to sPHENIX initial limitation it could well
take 4-6 weeks before we get to such luminosity. As you saw at JH's 
presentation at today's trigger meeting the sPHENIX plan is a very slow 
ramp up.


I this spirit of special runs we need for the  TPC I would like to get 
input with specifics for cosmic's data taking
before the runs. I believe this are scheduled to start on or about 4/11 
with FF field. What should the goals be. Do we need zero-field? Should 
we change to RFF before beam operations? Do we need some beam with FF 
too.
Let us discuss this on Thursday.

best Flemming




On 2023-03-13 14:37, Van Buren, Gene via Star-tpc-l wrote:
> Hi, TPC-ers
>
> I propose some calibration runs for the upcoming Run 23, in order to
> ensure that we're not seeing any difference in distortions (or
> anything else anyone wants to look at?) between running the gating
> grid at ~2 kHz vs. 4 or 5 kHz (e.g. we aren't expecting ion backflow
> through the gating grid). We've raised the gating grid rate before,
> but I think it's well worth doing a test under the conditions we'll
> have for Run 23.
>
> The proposed test set would consist of runs of only 50k minimum bias
> events each, enough to measure distortions, which really only takes a
> few seconds to acquire.
>
> For a given beam condition, I would take either 3 or 5 runs in
> immediate succession, all with the same mibias trigger modulo the GG
> rate limitation:
> 0 ) 5 kHz GG, if it's available
> 1) 4 kHz GG
> 2) 2 kHz GG
> 3) 4 kHz GG
> 4) 5 kHz GG, if it's available
>
> My understanding from what Tonko has told us is that we may not have 5
> kHz readout available at the very start of Run 23, so I'd like to at
> least do the 4-2-4 as early as possible though and get that measured
> quickly.
>
> Further, I want to see these at different luminosities, and I expect
> the luminosity may not be maximum at the beginning of Run 23 either.
> So here's a more concrete proposal:
>
> - Calibration Set A, taken in the first week with Run 23 beam:
>   i) a 4-2-4 set at whatever the maximum available luminosity is
> (perhaps 40-50 kHz ZDC rate?)
>   ii) a 4-2-4 set at about 75% of the maximum available luminosity
>   iii) a 4-2-4 set at about 50% of the maximum available luminosity
>
> - Calibration Set B, taken a few weeks into Run 23:
>   i) a 5-4-2-4-5 set at whatever the maximum available luminosity is
> (perhaps 40-50 kHz ZDC rate?)
>   ii) a 5-4-2-4-5 set at about 75% of the maximum available luminosity
>   iii) a 5-4-2-4-5 set at about 50% of the maximum available luminosity
>
> ....and then at some point the luminosities will be raised to allow
> for rare (e.g. high pT) triggers, which should then allow a repeat
> with even higher luminosities
>
> - Calibration Set C, taken a couple months into Run 23:
>   i) a 5-4-2-4-5 set at whatever the maximum available luminosity is
> (perhaps 100 kHz ZDC rate?)
>   ii) a 5-4-2-4-5 set at about 75% of the maximum available luminosity
>   iii) a 5-4-2-4-5 set at about 50% of the maximum available luminosity
>
> I would attempt to rapidly get results on each of these calibration
> sets to inform our operations during Run 23.
>
> Comments/feedback welcome,
> -Gene
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--
Flemming Videbaek
senior scientist, emeritus
videbaek @ bnl.gov
Brookhaven National Lab
Physics Department
Bldg 510D
Upton, NY 11973

phone: 631-344-4106
cell     :  631-681-1596