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The Phi_EtMiss in data & MC a problem of 35% reduced to few %

24/02/2010. The Phi_EtMiss in data & MC a problem of 35% reduced to few %. Topics: Beamspot Corrections Focus on the FCAL. By Marcel Vreeswijk (Nikhef/UvA). Thanks: Email-info by Pieter Krieger Other talk on this subject: Dag Gillberg in LaR meeting of 15 feb. What is the problem.

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The Phi_EtMiss in data & MC a problem of 35% reduced to few %

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  1. 24/02/2010 The Phi_EtMiss in data & MCa problem of 35% reduced to few % Topics: Beamspot Corrections Focus on the FCAL By Marcel Vreeswijk (Nikhef/UvA) Thanks: Email-info by Pieter Krieger Other talk on this subject: Dag Gillberg in LaR meeting of 15 feb. Marcel Vreeswijk (Nikhef/UvA)

  2. What is the problem MET_TOPO Default 35% effect MC 900GeV (mc09_105001, Pythia minbias) data 142193, reprocessed Is it the beamspot?  Apply vertex correction Marcel Vreeswijk (Nikhef/UvA)

  3. Vertex correction Vertex Corrected • <x,y,z>data= -0.2, 1.0, -8mm • <x,y,z>MC = 1.5, 2.5, -7mm • Correct TopoCluster Position for Beamspot position • Recalculate MET_Topo  Still ~30% effect Data behaves different than MC Marcel Vreeswijk (Nikhef/UvA)

  4. E in FCAL, DATA, A-side more BP Y (mm) less Difference due to: Beamspot (Vertex) or is the FCAL shifted? X (mm) Marcel Vreeswijk (Nikhef/UvA)

  5. FCAL Energy deposit Beampipe Vertex Corrections can be tricky in FCAL Rin=90mm Rout=450mm • Gedankenexperiment: • Let’s focus on a nice symmetric energy splash around the Beampipe hole in FCAL. • Next step: displace the (true) vertex upward and correct for that Marcel Vreeswijk (Nikhef/UvA)

  6. lost After vertex correction Vertex Corrections can be tricky in FCAL Deposit shifts up (true) vertex displaced up Obviously, after a vertex displacement correction, the situation remains assymetrical: What is lost, remains lost. Solution: cut out the energy inside a fiducial circle (wrt corrected coordinates) that envelopes lost deposits.  i used R_vtx>105mm (larger values give similar results) Marcel Vreeswijk (Nikhef/UvA)

  7. Vertex Corrected + R>105mm MC relatively flat ~5% Data still has Phi Modulation ~15%  FCAL shifted in y? Marcel Vreeswijk (Nikhef/UvA)

  8. DATA – phi Etmiss- FCAL shifts Vtx correction + xx FCAL shift + R=105mm cut Vtx correction + xx FCAL shift + R=105mm cut FCAL 0mm shifted FCAL 1mm shifted Vtx correction + xx FCAL shift + R=105mm cut Vtx correction + xx FCAL shift + R=105mm cut FCAL 3mm shifted FCAL 2mm shifted Marcel Vreeswijk (Nikhef/UvA) Phi etmiss Phi etmiss

  9. Phi EtMiss evolution Default Data FCAL 2mm shifted Default: +-20% effect Corrected: +-5% effect • The data becomes flat in phi_etmiss, after: • -Vertex Correction • -FCAL fiducial cut (R>105mm) • -FCAL shifted 2mm Marcel Vreeswijk (Nikhef/UvA)

  10. DATA - METx,y Data default Data default 19 MeV -183 MeV METx METy 15 MeV Data corrected Data corrected 1 MeV METy METx • DATA corrected = Vtx correction + 2mm FCAL shift + R=105mm cut • Correction reduces METy offset from -183MeV to 1MeV (Note: an offset of METy=-183 MeV leads to default phi modulation) Marcel Vreeswijk (Nikhef/UvA)

  11. SumET evolution Data Corrected= Vtx correction + 2mm FCAL shift + R=105mm cut Marcel Vreeswijk (Nikhef/UvA)

  12. DATA FCAL projections <x>=S (E_i . x_i) / S E_j Data Corrected= Vtx correction + 2mm FCAL shift + R=105mm cut  Not understood (by me): many structures ~5 mm. A A C C Marcel Vreeswijk (Nikhef/UvA)

  13. MC FCAL projections <x>=S (E_i . x_i) / S E_j MC Corrected= Vtx correction + R=105mm cut  Not understood (by me): <x,y> ~ 1mm. Biases? A A C C Marcel Vreeswijk (Nikhef/UvA)

  14. Conclusions Also see the work presented by Dag Gillberg et al. in Lar meeting  Confirms FCAL behavior by position measurements. The data also suggests that the MC behaves too ‘smooth’ • Phi modulation appears consistent with a FCAL shift of dy=-2mm. • Position measurement by FCAL shows structures ~5mm (there is not much documentation on position measurement in testbeam – difficult to place this into context.). • With the Beamspot correction and fiducial FCAL cut, a 35% problem reduces to a 5% problem. Marcel Vreeswijk (Nikhef/UvA)

  15. Back up Marcel Vreeswijk (Nikhef/UvA)

  16. E in FCAL, MC, A-side BP Y (mm) X (mm) Marcel Vreeswijk (Nikhef/UvA) Next plots: 1Dim. profile in X and Y of this 2Dim. histo.

  17. DATA, R in slices of phi around (clusters at y<0 get –R) Signed R in phi slices (mm) this is the BP hole Marcel Vreeswijk (Nikhef/UvA) phi

  18. Vertex in Data & MC <x,y,z>data= -0.2, 1, -8) <x,y,z>MC= 1.5, 2.5, -7 Note: data Z vertex close to nominal for this run (142193) Marcel Vreeswijk (Nikhef/UvA)

  19. Vertex Corrected + FCAL 2mm Marcel Vreeswijk (Nikhef/UvA)

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