2013-03-21

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  • Alexander: eRHIC detector simulation
  • All: discussion of eRHIC luminosity and energy requirements
  • AOB

Statistical estimate for TMDs with low luminosity

PYTHIA simulation for 5 x 250 with Q2 > 1 GeV2. I took this to be the most "efficient" configuration from a $ perspective, having the lowest electron energy coupled with the highest proton luminosity. π+ counts are binned in a couple of bins each of (Q2, x) and pT (w.r.t. virtual photon) and plotted as a function of z. Events are required to have 0.01 < y < 0.95 and pions are required to have abs(η) < 3. Statistical uncertainties are calculated by sqrt(2 / N) in each bin, with N scaled to represent 1 fb-1 integrated luminosity. PYTHIA reported a total sampled cross section of 0.48 microbarn, so 1 fb-1 would take approximately 30 weeks assuming 50% running efficiency and 1032 cm-2s-1 mean luminosity. I didn't scale for beam polarisation, but it's only intended as a rough estimate anyway.

Statistical uncertainties on TMD asymmetries.

Uncertainties still seems small enough to produce useful measurements. Uncertainties for kaons would be larger (potentially several percent for large pT and z). Measurements with D mesons (to access gluon Sivers) would be entirely unfeasible at this luminosity (they were already challenging at 1034).