1. Status of CBM muon studies I.Vassiliev, S.Gorbunov, I. Kisel and A.Kiseleva 16-Oct-06 Motivation Simulation tools cbmroot2 v06 Signal and background simulations new absorber materials, WFeC absorbers Tracking with thick absorbers J/  and , ,  reconstruction Low rapidity region coverage, momentum dependent tracking Summary

2. Motivation – NA60 experiment   Sanja Damjanovic QM2005 Budapest, GSI 2006 ~ 1m Muon Spectrometer MWPC’s Trigger Hodoscopes Toroidal Magnet Iron wall Hadron absorber ZDC Target area beam Matching in coordinate and momentum space

3. Signal and Background simulation J/    BG: 10 4 central UrQmd events Signal: J/ , ,  and    +  - Y~ 3.5 @ NA60 N ch ~190 central Y~ 2.0 @ CBM N ch ~600 central

4. V. Baublis: Signal and Background simulation MC a) 120 cm of Fe equivalent b) SF ~ 20 per track c) LMVM bg unavoidable 2 GeV 6 GeV

5. Excellent tracking in the Sts detector exist L1 ACCUMULATED STAT : 10000 EVENTS Ref. Prim.efficiency99.653840594 Ref. Sec.efficiency64.21290678 Refsetefficiency95.934131272 Allsetefficiency91.515250531 Extra Prim.efficiency89.10941690 Extra Sec.efficiency47.43177569 Extraefficiency78.201119259 Cloneprobability00.01344 Ghostprobability00.4825374 MC tracks/event found:525 CA Track Finder time:1.15 (1.05 + 0.10) s/ev MAPS: Physical hits: 1063Hybrid: 633 MCPStrips:MCP: 2518 Background hits: 1865 614 hitsMCPS:2415 Total hits created: 2928True:2408 Lost hits: 31Fake:15897 Fake hits: 87

6. Muon track finding -- ++ Fe C MC points -> hits smeared with  xy = 100  m Active Progressively Increasing Thickness Absorber  z2tr < 50 µm  zpv = 4 µm

7. Muon track finding  -hit  bg-hit estimated hit position APIT Absorber

8. Muon track finding  -hit  bg-hit estimated hit position

9. Muon track finding  -hit  bg-hit estimated hit position  

10. Muon track finding  -hit  bg-hit estimated hit position W Reconstructed track: (NSts MCT + NMuch MCT ) > 70%

11. 1 Step Hit 2 and 3 lost Thick absorber detectors n Steps All hits found 22 GEANT3 engine trajectory Tracking with thick absorber

12. Much detector C: 1.2 m W: 5 (cm) Fe: 10, 20, 30 (cm) Sts 16 active layers: (1+5*3) 7.1 nI, 43.4 X 0 7.3 nI, 54.9 X 0 µ+µ+ µ-µ- no W W

13. Transport 1k central urqmd W Fe C Hits distribution 60/event particleReco- track/ev. p0.04 ++ 0.135 K+K+ 0.09 ++ 0.003 -- 0.1 K-K- 0.005 -- 0.002 all0.38

14. Transport 1k central urqmd +  +  -   +  - Background – 29 events Eff = 15.6% Signal – 156 events

15. signal efficiencies 10k events

16. no cuts except track's χ 2 and hits # (16)! signal/background ratios S/B ~ 1/5 (  ) S/B ~ 1/25 (  ) S/B ~ 1/500 (  ) BG: 10 6 central urqmd events

17. RECO IM 13 &16 hits/track additional information min bias central

18. mid rapidity coverage

19. Variables and cuts. Cuts optimization J/  reconstruction variable Cut J/  Cut lmvm p1.0 GeV/c0.9 GeV/c ptpt 1.0 GeV/c0.23 GeV/c OA12 0 SP t [-2.4, -2.05] (GeV/c) 2 [-0.26, 0.13]

20. Variables and cuts. Cuts optimization (GeV/c) 2 SP t = p x1 * p x2 + p y1 * p y2

21. J/  reconstruction Geometry 150cm Fe equivalent BG: 10 8 central urqmd events S/B ~ 30 Eff = 13% Eff = 24%

22. Plastic scintillators wall MIP Eloss 2 MIP Eloss 3 MIP Eloss ++ --      other  p  (s) e-e-  e-e- e-e- e+e+  MIPS! MIP e-e-

23. Summary Vector mesons reconstruction with CBM muon detector looks very promising Using W as an absorber material allows significantly reduce hit density for the first Much layers; J/  and especially  needs more absorber material All helps, comments and suggestions are cordially welcome