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L2Cal Upgrade

L2Cal Upgrade. L2cal team 041807. Refresher on existing L2 clustering. Hardware based Pacman: looks for seeds then clusters all contiguous towers that satisfy a shoulder threshold

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L2Cal Upgrade

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  1. L2Cal Upgrade L2cal team 041807

  2. Refresher on existing L2 clustering • Hardware based • Pacman: looks for seeds then clusters all contiguous towers that satisfy a shoulder threshold • Problems-Jets: high rate due to jets being artificially energetic at high lumi, position of seed is used as position of jet • -Photons/electrons- 2 high Et passes

  3. Current clustering algorithms • Pass0-Look for seed tower: Em >= 2 GeV and Had/Em < 0.125-One tower per “cluster” • Pass1-Seed has Em >= 8GeV-Shoulder Em >=7.5 GeV ( no limit on number of towers , marked towers as used and don’t use again ) • Pass2 jets • Pass4 (alpha clustering )-Use Pass1 seed position then cluster using pass0 tower info (towers have Had/Em cut )-In central ( clusters do not open in phi; eta+-1 wrt to seed)-Plug ( 3x3 box )-No crossing eta = zero boundary etc

  4. Current isolation • Calculated for Pass1, Pass4 • Start with seed position-find iso for 3X3 and (4) 3x4 tower configurations-Use smallest of the 5 sums

  5. Status of algorithms ( upgrade ) • Pass0 is unchanged • Pass 1 is no more… • Pass4 ( alpha ) is unchanged • Isolation is unchanged (Pass 4) • Jets will be new (pacman→cones) • Missing Et will be new • If there are other improvements now is a good time to let us know…

  6. Offline tools • Have L2Cal simulation ( TrigSim ) which includes Pass0,Jets,Pass4, Iso, MET • Also have Stntuple version of code which will be available within HTTF tools-can also make available independent of Higgs tools-If your ntuples have DCAS info you can run new clustering • Tools already available for testing/optimizing new triggers

  7. What is the status of the upgrade • Have all hardware in hand • About half of the hardware is already installed • Software (as described) is written- beginning to run it parasitically • So things are starting to come together

  8. What happens when pass 1 is used in L2 code • Rewritten level-2 code to use alpha clustering if passed 1 or 4, 4 is used in the code.

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