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Lab Meeting -1/12/2004

Update on the Photon + Dijet Analysis. Lab Meeting -1/12/2004. Outline: Old Photon + Dijet trigger Photon Trigger Efficiency Jets Trigger Efficiency Monte Carlo events News from the new trigger. Lab Meeting -1/12/2004. Introduction. Goal: Search for the W/Z Peak on Events with an

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Lab Meeting -1/12/2004

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  1. Update on the Photon + Dijet Analysis Lab Meeting -1/12/2004 • Outline: • Old Photon + Dijet trigger • Photon Trigger Efficiency • Jets Trigger Efficiency • Monte Carlo events • News from the new trigger

  2. Lab Meeting -1/12/2004 Introduction Goal: Search for the W/Z Peak on Events with an Associated Photon Need 200-250 pb-1 with the new trigger (unprescaled) Problem: NO TIME !! Strategy 1: Sifting all the useful events we have now (taken with Photon Triggers) Strategy 2: Make an attempt to ask for a little more Rate, just to get rid of the horrible DPS

  3. Lab Meeting -1/12/2004 The Old +jets Trigger Like 25_ISO PHOTON_DIJET: L1 - EM8 L2 - EM18_ISO L3 - 2 Jets with Et>18 GeV 1 Jet with Et>10 GeV One is the photon Found a bug on April 02 (Et>100) and Good data only from May First Run: 143938 (May 02) Last Run : 167059 (Jul 03) Total ~ 180 pb-1 Before GoodRun: ~3.5M After GoodRun: ~1.7M

  4. Lab Meeting -1/12/2004 Event Selection Step 1: Reproduce the Run I analysis 3 Sets of Cuts PHOTON_DIJET: L1 - EM8 L2 - EM18_ISO L3 - 2 Jets with Et>18 GeV 1 Jet with Et>10 GeV • Vertex and Met cuts • (only one good vtx, good z, and Met<0.8) B) Photon Cuts ( Run I ~standard. Run II official cuts Different. No Run II tight cut for serious Photon analysis ) • # Jets (0.7) > 2 • 3rd Jet Et_corr < 10 GeV • 2nd Jet Et_corr > 10 GeV • 1st Jet Et_corr > 15 GeV • #trk > 1 on 1st and 2nd jet • Delta R(jet1,jet2) > 2 C) Jets Cuts ( Run I used harder data, 25_ISO trigger With no jets requirement at trigger level) ( Offline cuts very close to trigger cuts, Efficiency will suffer… )

  5. Lab Meeting -1/12/2004 Event Selection 1615 K Only one vtx 900 K Photon Central 116 K Photon Isolation 25 K A B C

  6. Lab Meeting -1/12/2004 Trigger Efficiency L1 : EM8 considered 100% efficient for Photon >18 GeV L2 : 18_ISO feeds other triggers (25_ISO and DIPHOTON) Other people already did this study (but for higher pt gamma) Method I: Use an unbiased lower trigger (in this case a L3_EM8) and check how Often L2 is on for a good photon and make The ratio. For L3 they use a similar method (25_ISO / L3_18ISO ) Method II: Several discussions on photon Group about pi0 contamination in method I. More sophisticated approach using electron From Z and check when they fire the photon Triggers. L2

  7. Lab Meeting -1/12/2004 L3 Trigger Efficiency L3 requires some additional quality to the photon Same of the 25_ISO but I have lower pt photon… … and also I have the jets to disentangle. I need the efficiency for the photon part (ph) and for The jets (jets).(not sure about that) Trigger and analysis cuts too Close. Not only Et threshold But also eta is a problem. Jet1 Eta Jet2 Eta Eta distribution after final selection

  8. Lab Meeting -1/12/2004 Trigger Efficiency: Photon To calculate phwith method I I need a sample With only the L3 photon selection (jet unbiased) and Then make the ratio, but I don’t have such a sample. I need to reproduce offline the L3 cuts. Unfortunately I can only apply the same cuts but it is different. Events with L3_off Tested on 25_ISO , a Trigger with ONLY Photon selection 18_ISO I assume the events with L3_off Are good enough to be used in ratio. 18_ISO + L3_25ISO

  9. Lab Meeting -1/12/2004 Trigger Efficiency: Jets The L3_off events are also the unbiased sample To study the jets efficiency (jets). Et AND eta bias make the efficiency study very Complicated ( 2d plot or several sets of 1d) My approach is don’t care about them and go Directly to what I want: the dijetmass distribution The idea is have jets as a function of the dijet mass

  10. Lab Meeting -1/12/2004 Trigger Efficiency: Jets Dijet Mass Distribution I compared the unbiased dijet mass distribution with that one from the PHOTON_DIJET trigger Unbiased (L3_off) Why so inefficient ?? Trigger (Jet1 Et>18 and Jet2 Et>10) Jet1 Et Raw Jet2 Et Raw Look at the unbiased events that didn’t pass the trigger (Blue – Red)

  11. Lab Meeting -1/12/2004 Trigger Efficiency: Jets Actually that distribution was real, the unbiased sample is reasonable and really low Et jets make high Dijet distribution Unbiased but not trigger (Maybe useful for S/B separation)

  12. Lab Meeting -1/12/2004 Use the 25_ISO ?? A possible approach is to use the unbiased (for jets) 25_ISO Trigger for photon ET>26 and the DIJET trigger for 18< ET <26 DIJET All Dijet All : 25.193 No 25_ISO: 14.075 DIJET And NO 25_ISO (25 * 50% = 12.5) (15 * 50%+10=17.5)

  13. Lab Meeting -1/12/2004 Monte Carlo MC under control now and started to produce Wg events MC essential for acceptance study, almost done… There is some room from improvement on the event Selection and S/B separation, but the idea was to Reproduce the run I results first. I’m not so sure anymore… Example: FSR effect can be reduced With some merging or bigger cone. We have some experience on that… FSR MC Some tools already developed and Ready to be exploited

  14. Lab Meeting -1/12/2004 EVD

  15. Lab Meeting -1/12/2004 EVD

  16. Lab Meeting -1/12/2004 EVD Data

  17. Lab Meeting -1/12/2004 EVD Data

  18. Lab Meeting -1/12/2004 News from the new trigger New trigger replacing the PHO_DIJET in since Aug 03 Trigger rate higher than proposed (80 nb) because they Didn’t implement all our cuts and for cosmic contamination We didn’t take into account properly Final number was around 230 nb and they put a DPS of 5:1:1, the first number for HiLum (L2>300Hz) Several other problems with L2 ISO hardware, very High rate (but not clear at the beginning…)

  19. Lab Meeting -1/12/2004 New Trigger Rate L2 rate L3 rate Problem not really fixed till last week (see table) … … but now the HiLum (with L2 busy and L3 farm Problems) made things even worse.

  20. Lab Meeting -1/12/2004 Trigger Efficiency: Photon

  21. Lab Meeting -1/12/2004 Conclusion/Plan/Future In a real analysis attention to details are more Important than I expected On several of them I’m not an expert (L2, L3, photon Isolation algo,etc..) Several open issues and work in progress, probably too Much. Maybe useful some middle term tasks/ deadlines To focus on exclusively. Or a “road map” to graduation to follow point by point…

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