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Tel Aviv University HEP Experimental Group. C ollaboration. FCAL. High precision design. Precision Luminosity Measurement. Ronen Ingbir. Krakow 2006. Events. Events. Tel Aviv University HEP Experimental Group. Energy (GeV). (rad). C ollaboration. FCAL.
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Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Precision Luminosity Measurement Ronen Ingbir Krakow2006
Events Events Tel Aviv University HEP Experimental Group Energy (GeV) (rad) Collaboration FCAL High precision design Bhabha Scattering Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Bhabha Scattering Head-on Y (cm) Events (rad) X (cm) Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Bhabha Scattering 20mrad X-angle Detector axis Y (cm) Events (rad) X (cm) Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Bhabha Scattering 20mrad X-angle Outgoing beam Y (cm) Events (rad) X (cm) Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Outgoing beam flat azimuthal distribution Y (cm) Y (cm) X (cm) X (cm) Events Events (rad) (rad) Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Luminosity precision determination N1 : Reconstructed and generated in acceptance region. N2 : Generated in acceptance region but reconstructed outside. N3 : Generated outside acceptance region but reconstructed inside. Krakow2006
No Yes Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Counting Bhabha events Krakow2006
Headon, 14,20 mrad X-angle outgoing beam 14 mrad X-angle detector axis 20 mrad X-angle detector axis Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Krakow2006
Headon, 14,20 mrad X-angle outgoing beam 14 mrad X-angle detector axis 20 mrad X-angle detector axis Δz Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Krakow2006
Δr Δz Δr Tel Aviv University HEP Experimental Group Δz Collaboration FCAL High precision design Bhabha Scattering Outgoing beam ΔL/L=10-4 Krakow2006
Headon, 14,20 mrad X-angle outgoing beam 14 mrad X-angle detector axis 20 mrad X-angle detector axis Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Krakow2006
Headon, 14,20 mrad X-angle outgoing beam 14 mrad X-angle detector axis 20 mrad X-angle detector axis Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Are these numbers realistic ? • Bhabha events sample will not be pure (background). • Magnetic field changes the distribution (could be a dramatic effect if not aligned with the outgoing beam). • Event position and energy reconstruction is not perfect. • To evaluate the real error on luminosity one should apply MC – DATA corrections. Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design X- angle background Beamstrahlung pair background 20 mrad, DID 250 GeV 20 mrad, anti DID Christian Grah, DESY-Zuethen Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Magnetic field along the outgoing beam Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Fast detector simulation – bias Changing the bias with a fixed resolution. Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Fast detector simulation – resolution Changing the detector resolution with no bias Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design How does the LumiCal performance contribute to the detector displacements ? Krakow2006
without Including Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Adding detector performance Using bias and resolution of Pad design LumiCal Krakow2006
without Including Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Adding detector performance Using bias and resolution of Pad design LumiCal Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Data and MC In real life we can include the detector performance (which is measured in test beam) into MC. The only question is: How well should we know the detector performance ? Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Exercise Test case: 20 mrad X-angle, LumiCal sits on detector axis Unknown beam offset (amount, angle) Simulation includes detector radius resolution and bias (Pad LumiCal) Other parameters known What will be the error on luminosity after using MC to correct DATA ? Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design 20mrad X-angleDetector axis Y (cm) N3 N1 N4 N2 X (cm) Krakow2006
1 mm beam shift 0.5 mm beam shift 0.3 mm beam shift Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design “Beam position” Events (up – down) Events (right – left) Krakow2006
Before correction after correction Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design 20mrad X-angleDetector axis ΔL/L~10-3 But !!!!!! This is assuming knowing in perfect precision many parameters ΔL/L~10-2 Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Summary Our recommendation at ECFA2005 still holds Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design Head-on design Overlap region LumiCal rmin=8 cm rmax=28 cm BeamCal rmin=1.5 cm rmax=10 cm Beam hole Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design X- angle design (step 1) LumiCal rmin=13 cm rmax=28 cm (Reasonable Statistics) BeamCal rmin=2 cm rmax=16 cm Beam hole Krakow2006
Detectors are centered around the outgoing beam Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design X- angle design (step-2) BeamCal + 30o blind area (incoming beam) Krakow2006
Tel Aviv University HEP Experimental Group Collaboration FCAL High precision design http://alzt.tau.ac.il/~ronen/ Username: ronen Password : msc Krakow2006