Simplified Muon Track Reconstruction in CBM Victor Baublis ( for PNPI/GSI muon team)

1. Simplified Muon Track Reconstruction in CBMVictor Baublis (for PNPI/GSI muon team)

2. Victor Baublis, CBM MUCH Workshop Goals of the study:1 To reduce the number of Coordinate Detectors2. To relax requirements for Detectors Specifications

3. Victor Baublis, CBM MUCH Workshop Simulation details: Cbmroot framework: v.OCTO4 Magnetic field: FIELD_v.04_pavel.map Events: 25 GeV Au+Au central and min.bias collisions Background: UrQMD generator Signal (J/Psi and LMVM): Pluto generator Absorber geometry: 145cm Carbon + up to 60 cm Iron

4. Victor Baublis, CBM MUCH Workshop MUCH layout It was studied:145cm Carbon + 15cm Iron145cm Carbon + 30cm Iron145cm Carbon + 45cm Iron145cm Carbon + 60cm IronLet's compare: LI X0Carbon 86.3 18.8Iron 131.9 1.76Tungsten 185 0.35Conclusion: Carbon is most appropriate material!

5. Victor Baublis, CBM MUCH Workshop How is realistic to use corridor method for muon track reconstruction in MUCH?The answer depends on correspondence between:- MS corridor width, Wc- hit density behind absorber, Wh- candidate track projection density behind absorber, WpIdeal is when: Wc < Wh and Wc < WpHere: Wh(R) is mean distance between hitsWp(R) is mean distance between candidate track projection point

6. Victor Baublis, CBM MUCH Workshop RHO muons: Wc(pz), Wh(R) and Wp(R) distributionsDesign Conclusion:Two Tracking Station required:First one - behind CarbonSecond one - behind Iron

7. Victor Baublis, CBM MUCH Workshop The ways to reject Backgound:1. STS track-candidate selection: Pt cut and Pz cut2. Cut of hits from the area around the beam pipe3. Hit selection in MS Corridor4. Hit and Track Projection density cut.5. Three corridor triggers in coincidence6. Openning angle cut.7. Two track-candidates of different charge

8. Victor Baublis, CBM MUCH Workshop Pt,Pz cuts: comparison for J/Psi and Rho mesonsMomentum componentsof tracks on the MUCH entrance were randomized to provide 1% momentum resolution

9. Victor Baublis, CBM MUCH Workshop Pz cut for Rho and Omega mesons

10. Victor Baublis, CBM MUCH Workshop Cut of hits from area around beam pipe

11. Victor Baublis, CBM MUCH Workshop Corridor width (sigma) versus absorber thickness

12. Victor Baublis, CBM MUCH Workshop Corridor Width (sigma) versus Pz

13. Victor Baublis, CBM MUCH Workshop Muon Corridor Width versus Hit Radius

14. Victor Baublis, CBM MUCH Workshop MS Corridor Cuts summary:1. dR < 2*corridor_Sigma(sts_Pz) for TS-1, TS-2 and TS-33. dR < 0.18*project_MeanDistance(Radius) for TS-14. dR < 0.09*project_MeanDistance(Radius) for TS-25. dR < 0.09*hit_MeanDistance(Radius) for TS-16. dR < 0.18*hit_MeanDistance(Radius) for TS-2Where:dR = |project_R – hit_R| project_R – radius of STS track candidate projection on coordinate detectorhit_R – radius of hit candidate

15. Victor Baublis, CBM MUCH Workshop Detector DigitizationIt was investigated two cases:1. Pad_size = Pad_size0 (= constant)2. Pad_size = Pad_size0*normalized_Corridor_Sigma_(R)Conclusions:1. Both cases give the same results within statistics errors.2. Muon reconstruction efficiency falls slowly with pad size increasing. See the table on next slide:3. Signal/Background practically does not change when pad size varies in the range from 0 mm to 20 mm

16. Victor Baublis, CBM MUCH Workshop Pad size impact on reconstruction efficiency and Signal/Background5000 mixed UrQMD and RHO PLUTO eventsGeometry: 145 Carbon + 60 cm Iron;Pad size Rho meson Background pares reconstructed reconstructed1mm*F(R) 233 42mm*F(R) 247 55mm*F(R) 237 410mm*F(R) 222 120mm*F(R) 139 2

17. Victor Baublis, CBM MUCH Workshop Signal/Background Ratio145cm Carbon + 60cm Iron1mm*F(R) pad size in 2 sigma windowOmega: S/BG = 1.2Rho: S/BG = 0.15Efficiency = 5%

18. Victor Baublis, CBM MUCH Workshop Iron Thickness impact on Signal/Background5000 mixed eventsfor each pointPad size = 1mm*F(R)

19. Victor Baublis, CBM MUCH Workshop Rho meson Pt versus Rapidity10000 mixed URQMD and Rho PLUTO events Geometry: 145 Carbon + 15cm Iron; Pad size = 1mm*F(R) left side: MUCH entrance, right side: Reconstructed Signal

20. Victor Baublis, CBM MUCH Workshop Conclusions:1. It is shown that corridor track matching method allows to reach a reasonable performance of CBM MUCH system.2. Advantages of this approach: Moderate requirements to tracking station space resolution. Small number of coordinate detectors is required. Fast operation.3. Disadvantage of this approach: about two times lower signal reconstruction efficiency than it is for track following method.

21. Victor Baublis, CBM MUCH Workshop Explanations to Hit Track Angle Cut

22. J/Psi: Hit Track Angle Cut: Victor Baublis, CBM MUCH Workshop