1 ME4/2 Studies Ingo Bloch, Rick Wilkinson

2 ME 4/2 Studies Focus on the trigger Try to prevent: – Low energy muons mismeasured high Dominates trigger rates Highest priority – High energy muons mismeasured low Efficiency for very interesting events Requires verilog coding!

3 Keeping Down Trigger Rates Require three stations – Low-energy muons can scatter to low  – Trackfinder has logic to catch this, with a third station Require ME1 or MB1 – Magnetic field too small otherwise

4 L1 Efficiency (Darin’s old plots) ME4/2 fixes the hole at  = 1.7

5 L1 Efficiency (Us) Fixes the hole at  = 1.6!

6 Eta gaps ME 4/2 should fix both holes! Navigation problem in the Trackfinder? – ME2/1 - ME4/2 Florida people looking into it.

7 Trigger Rates Start from single muon samples – 3 < pT < 100 GeV, 1.25 < || < 1.9 Weight by the muon rate in min bias – CMS Note 1997/096, by G. Wrochna – dN/(d dp T ), in GeV -1 s -1, L = – Prompt muons, from b & c – Decays, p & K Weight each event by the curve – Based on its true muon p T Divide by number of events Multiply by number of  and p T bins –  = 1.25 – 1.9, p T = GeV, so multiply by 2*97*0.65 Work around the trackfinder problem at ||=1.7 – Double-weight events around 1.6 – Zero-weight events around 1.7 Integrate and smooth

8 Behavior in Cracks

9 Trigger Rates

10 Conclusions Low energy muons in cracks can be easily mismeasured. ME4/2 covers two big gaps in three- station efficiency. Requiring three stations helps a lot to reduce the rate.