[Rgc] ERR

[kuhn]

Dear all,

here a short summary of today’s meeting of Run Group C:

We had Patrizia join us as special guest to discuss timing for the ERR. In the end, we settled on a “late March” time frame for the RG C ERR. It seems, looking at Chris Keith’s time plan (see today’s agenda), that at that time all major items will have been designed and we (hopefully) will have first results from refrigerator cooldown and DNP measurements, putting us on a strong footing for the review. There really is no point to try to push it earlier (January would have been the earliest available for Patrizia).

In the meantime, there is a lot to do - especially on the simulation front. NOW is the time to get serious about simulating your favorite physics, as well as backgrounds (incl. Møllers and DC occupancies) with the newest versions of GEMC and COATJAVA. We will have to decide
- do we want one target cell or two? Do we want 2 cells with opposite polarization or with different target species?
- how large can the raster size be without too much background in the DCs?
- can we live without the FMT? Can we live WITH the FMT?
- can we use the “FTon” configuration of the Møller shield under ANY of these circumstances? Do we need to design a polarized target-specific beefed-up Møller shield because of the raster?
- What is the optimum trade-off between target depolarization, NMR accuracy, overall integrated luminosity -> statistics, small angle acceptance, systematical uncertainties, and physics output?

All of these points are correlated with trade-offs. In particular, if your physics requires the FT, you MUST demonstrate that it can be used with realistic raster radii. On the other hand, if you prefer 2 cells vs. one for systematic reasons, will the vertex reconstruction be sufficient to clearly identify the two targets? Etc. - all of this must be corroborated with simulations. I anticipate that we will have to produce a straw man run plan (including commissioning and auxiliary measurements) for what will be the first installment of RG C - assuming maybe 150 calendar days (75 PAC days) in the most optimistic scenario. Finally, we will have to address radiation and experimental safety, documentation, TOPs, ERGs etc. Please let me know ASAP if you are willing to work on any of the above in the next 6 months. Please look at https://clasweb.jlab.org/wiki/index.php/Run_Group_C for more information, as well as the attached summary for ERR preparations.

Greetings - Sebastian

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