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NSW background modeling: overlay. Max Bellomo, Niels van Eldik, Andrew Haas, Peter Kluit Muon NSW 18 April, Simulation PP 22 April. NSW modeling. Study the overlay of Zero Bias events produced by Andrew Haas. Zero bias run: data12_8TeV.00202740.physics_ZeroBias.merge.ESD.r4065_p1278/
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NSW backgroundmodeling: overlay Max Bellomo, Niels van Eldik, Andrew Haas, Peter Kluit Muon NSW 18 April, Simulation PP 22 April
NSW modeling Study the overlay of Zero Bias events produced by Andrew Haas. Zero bias run: data12_8TeV.00202740.physics_ZeroBias.merge.ESD.r4065_p1278/ The trigger is zero_bias. Technically it is the event one turn of the accelerator after L1_EM14 fires (to record events proportional to instantanuous lumi in each bunch). Overlayed events with fix for MDT cabling and CSC zeroing: https://dl.dropboxusercontent.com/u/9398450/OUT.ESDoverlay_mdtfix.pool.root The data used is standard pp 8 TeV zerobias from run 202740. For this run and lbn, 202740 107, the inst. Lumi. was 2.6e33/cm^2/s. The avg. int. per xs was 20.8 (and <Nvtx> was 11). So overlaying 10 events on top of 1 data event is like 11x the luminosity, or ~2.9e34/cm^2/s, and avg. int. per xs of ~230.
MDT Overlay What happens to the EI?
MDT EI occupancy: what happens to the EI? The zero bias data reaches the highest occupancy in the EI eta 1(-1) for low tube nrs of < 10%. The overlay data shows occupancies that go up to 50-80%. This will have a significant impact on the multiplicity distribution.
MDT EI occupancy: saturation and non-linearity Occupancy is the number of times a tube fires per event The black curve is the Zero bias occupancy scaled up by a factor of 10. The red curve the result of the overlay with 10 zero bias events. One can observe that the red curve does not scale to the black curve at high occupancies (low |tube nrs.|) At occupancies below 20% it does scale.
MDT EM/EO occupancy Same as on previous slide: no evidence for saturation EM EO Note that with occupancies below 20% this is also not expected!
CSC overlay problem? Here the black curve is scale up by a factor 10. The overlay for CSCs is about a factor 1.5 too high… why? Maybe CscStripPrepData should be used in stead of CscPrepData?
Conclusions • Distributions for the Overlay are understood in terms of the Zero bias sample for: • TGC and RPC multiplicities. • MDT: EM,EO,BI,BM,BO multiplicities • For the EI chambers many 4 hit entries are observed. • Andrew fixed a bug and the distribution has still the same characteristics. This is due to the high occupancy in the EI that goes from maximally 10% (Zero Bias) to 50-80%. There is clear evidence for saturation for occupancies above 20%. • Segments look reasonably OK; we might need more statistics to see possible issues. • CSC overlay seems to overdo by about a factor 1.5