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SIS100 simulation (Geometry optimization)

SIS100 simulation (Geometry optimization). Partha Bhaduri (VECC) Arun Prakash(BHU). Motivation Physics performance analysis for SIS-100. Determine a “standard” version of Much for SIS-100 . Look for an optimized version of Much for SIS-100.

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SIS100 simulation (Geometry optimization)

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  1. SIS100 simulation (Geometry optimization) Partha Bhaduri (VECC) Arun Prakash(BHU)

  2. Motivation Physics performance analysis for SIS-100. Determine a “standard” version of Much for SIS-100. Look for an optimized version of Much for SIS-100. This optimized version will be used for subsequent physics analysis.

  3. Optimization should be done with low mass vector mesons (lmvms) and J/ψ at SIS100 energy. • We have chosen central Au+Au events at 8 AGeV and pAu collisions @ 30 GeV . • Use the same set-up for in simulation for J/ψ & LMVM. For LMVM use information from stations just before the last thick absorber. • Run full simulation & obtain signal reconstruction efficiency & S/B ratio.

  4. We have to decide upon : • Total number of stations(layers) • Total absorber thickness, total no. of absorbers & the absorber material • Number of stations (2/3) in between two absorbers • Distance between stations & absorber to station distance • Present constraints : • Absorber material (Fe, Pb, W ) • Layer to layer distance >= 10 cm. • Layer to absorber distance >= 5cm.

  5. Plan • Segmentation optimization based on hit loss & cell multiplicity criteria (Arun, YPV : presented in BHU collab meet, Dec 2009) 2. Reduced setup for SIS100 • 32cm x 32 cm GEM • Absorber thickness (LMVM + J/Psi) • Segmentation (start from above, do some fine tuning) • Detector inefficiency (5% hit loss) • Input: AA: 8AGeV (Partha), pA (30GeV): Arun LMVM, J/Psi : Pluto (valid??), started work with HSD as input (Partha) pA: Only J/Psi Optimize for both

  6. Geometry (Dec 2009), LMVM setup) Transport:1000 UrQMD mbias @8A.GeV+1000 Omega Geometry: Compact +Modular+32cmX32cm GEM sts_same_z.geo pipe_much.geo shied_standard.geo cave.geo target_au_250mu.geo magnet_standard.geo

  7. Station radii Station-1 Station-1 R=70cm Decided to remain within nominal outer radius at each station (no extra radii), adds pad multiplicity artificially R_max+20cm R_max+0.6cm

  8. Particle density The kink ???

  9. Item Pads No of regions 2 2 2 1 1 No of Channels 256 256 256 256 256 ~636k V1 R int 32 50 70 - - Lx 0.5 0.5 1.0 - - Ly 0.5 0.5 1.0 - - Rout 70 96 120 150 182.5 Lx 1.0 1.0 2.0 2.0 2.0 Ly 1.0 1.0 2.0 2.0 2.0 Segmentation : First attempt, guided by particle density Av. Hit loss ~ 1.5%

  10. Item Pads No of regions 1 1 1 1 1 No of Channels 256 256 256 256 256 ~430k V2 R int - - - - - Lx - - - - - Ly - - - - - Rout 70 96 120 150 182.5 Lx 1.0 1.0 2.0 2.0 2.0 Ly 1.0 1.0 2.0 2.0 2.0 How bad can it be ? Av hit loss ~4.8%

  11. Item Pads No of regions 1 1 1 1 1 No of Channels 256 256 256 256 256 ~120k V3 R int - - - - - Lx - - - - - Ly - - - - - Rout 70 96 120 150 182.5 Lx 2.0 2.0 4.0 4.0 4.0 Ly 2.0 2.0 4.0 4.0 4.0 Can we worsen it further ? Av hit loss ~ 14.8%

  12. Item Pads No of regions 2 2 1 1 1 No of Channels 256 256 256 256 256 ~528k V4 R int 25 40 - - - Lx 0.5 0.5 - - - Ly 0.5 0.5 - - - Rout 70 96 120 150 182.5 Lx 1.0 1.0 2.0 2.0 2.0 Ly 1.0 1.0 2.0 2.0 2.0 Next stage : fine tuning Av. Hit loss ~2.20%

  13. segmentation station-3 station-1 station-2 station-4 station-5 pads~528k

  14. Hits Simple Gem

  15. Hits Advanced GEM Occupancy increases in advanced GEM by factor of~3 compared to Simple GEM. CONSEQUENCES FOR DETECTOR FABRICATION

  16. SIS -100 Geometry : version 1 To start with we have used a geometry with total 9 stations with (3+3+3) configuration. Effective no. of stations for lmvm is thus 6. Total abs. thickness: lmvm : 100 cm. (30 +70) J/Psi : 225 cm. (30+70+125) Specification of distances : layer to layer : 10 cm. abs. to layer : 0 cm. layer to absorber : 10 cm. Extra Radius (change in CbmMuchGeoscheme class) : station : 0 cm. absorber : 100 cm.( to keep stations inside absorber)

  17. Simulation (AA) Transport : Central Au+Au @ 8A GeV Signal : Pluto (ω→μμ) Background : UrQMD Events : 10k Reconstruction : Segmentation scheme : Manual segmentation Station 1 (layers 1, 2, 3) : 2 regions (pad size in the central region : 0.2 – 0.6 cm.) Station 2 (layers 4, 5, 6) : one region with pad size 3.2 cm * 3.2 cm. Station 3 (layers 7, 8, 9) : one region with pad size 5 cm.*5 cm. Implementation of detector in-efficiency at hit producer level. Simple Hit producer w/o clustering

  18. Eta distribution @ station 1 Signal muons Primary Bkg. Input tracks Primary tracks hitting station 1 Midrapidity not covered??

  19. Momentum distribution @ station 1 Signal muons Primary Bkg. Input tracks Primary tracks hitting station 1

  20. Azimuth distribution @ station 1 Signal muons Primary Bkg. Input tracks Primary tracks hitting station 1

  21. Acceptance of primaries @ station 1 Signal muons Primary Bkg. Input tracks Primary tracks hitting station 1

  22. Implementation of detector in-efficiency No loss 10% hit loss

  23. Effect of hit loss on reconstructed tracks 5% hit loss No hit loss Global tracks No hit loss 5% hit loss Much tracks

  24. Distribution of chi2vertex Signal Tracks Background tracks

  25. Cuts : No. of Muchhits>=4 No. of STS Hits >=4 chi2primary < 3 Super event (SE) analysis for bkg (combine all the positive tracks with all the negative tracks over all the events excluding only tracks from same event). Gaussian fit to signal Polynomial (pol 8) fit to bkg. Invariant mass spectrum (ω→μμ ) 10k central embedded events for Au + Au @ 8 GeV/n

  26. Results for various pad size(ω→μμ )

  27. Invariant mass spectra (I/Psi) Super event (SE) analysis for bkg (combine all the positive tracks with all the negative tracks over all the events excluding only the tracks from the same event). One signal event in 10^7/BR bkg events Gaussian fit to signal Polynomial (pol 7) fit to bkg. Cuts : No. of Muchhits >= 7 No. of STS Hits >= 4 Chi2primary < 3 Reconstruction efficiency : 5.1 % S/B : 18.9

  28. pA: Acceptance of reconstructed pairs Background Signal Conditions : 70% true hits 4 STS hits + 7 MUCH layers Same geometry as AA 5mm pad size at the inner region of station 1

  29. pA: 30 GeV Reco. eff. 20.2 % S/B : 127 Polynomial of order 8 fitting to background Work in progress w/o 70% criterion Conditions : 70% true hits 4 STS hits + 7 MUCH layers

  30. SUMMARY: First step of optimization done for SIS10 MUCH Comparisons will be made with other geometry options (absorber/no of stations) Clustering will be added. (should not have large effect as GEM cluster size ~100 micron) Minimum pad size of 4 mm seems reasonable and we plan to build one test chamber with these. pA results needs to be updated.

  31. Study of J/Psi (AuAu) Run the full simulation chain for J/Psi with 4mm. pad size 10k central Au+Au embedded events @ 8 GeV/n Cuts : No. of Muchhits>=7 No. of STS Hits >=4 Chi2primary <3 Only bkg. Track (UrQMD generated) from different events for SE All tracks (uncorrelated signal muons+ bkg. Tracks) from different events for SE

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