[Rgc] RGC weekly meetings back on Tuesdays (this time focused on FTon extension)

[Sebastian Kuhn]

Dear all (especially all RG-C spokespersons),

Silvia’s proposal would leave 107 calendar days for FTout and 60 days at 40% luminosity in the FTon configuration - in other words, about 131/2 = 66 PAC days of data for DIS/SIDIS, or 33 each for NH3 and ND3. IF instead we stay with the present schedule, with a switchover beginning next weekend, we would get 43 days each, close to the amount originally planned for FTout. So any Physics arguments to STAY with the present run plan should be based on a comparison between these 2 scenarios.

Meanwhile, any Physics argument in favor of Silvia’s proposal should assume that, out of the 60 days, about 30% or 18 days would go to the various background targets necessary for DIS/SIDIS analysis, and the remaining 42 days would be split between NH3 and ND3 (21 each). Assuming a 50% efficiency (which we haven’t reached yet), the argument should then show that WITH those extra 10.5 PAC days (4 mC = roughly what we have so far if things go REALLY well) for each target, the data collected with FTon would go from “marginal” or “useless” to “enough for a publication” for the two DVCS channels, in spite of having maybe 18% fewer statistics overall (outside of FT) and most likely still less and less well-known target polarization.

- Sebastian


On Aug 21, 2022, at 1:23 PM, silvia at jlab.org<mailto:silvia at jlab.org> wrote:

Dear Sebastian,
both your points are fair, and well taken.
Here are my replies, which can of course be discussed and modified
according to the opinion of all other spokespersons.

1) if we agree on an extension of FTon, we will of course agree also on a
run plan suiting all experiments. We (DVCS people) have put a veto on
changing solenoid polarity during FTon assuming it was our only shot to
take data, but if we extend we can agree to compromises. Same holds for
the background targets runs (by the way, we took 10% of our data with
carbon so far, so we did not skip background targets altogether).

2) How about October 31?

Best regards,
Silvia

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