1. The Tunnel Background Source Study Vasily Dzhordzhadze University of Tennessee Trigger Upgrade Meeting BNL, April 12, 2004 V.Dzhordzhadze

2. The Run3 background study V.Dzhordzhadze

3. South arm, gap 4 o  + MuID GUI and MuID hit area E W V.Dzhordzhadze

4. The Run 4 “Typical” MARS simulated interaction Green - neutrons Neutrons can scatter from the tunnel walls and go around the shielding blocks V.Dzhordzhadze

5. The MARS Run4 simulation Result E W 3034 3337 3748 W 0.42 0.46 0.52 E • 3475 7223 0.63 0.48 1.00 • 3632 0.38 0.50 -------------------- -------------------- • 3010 0.28 0.42 • 1057 1026 0.16 0.15 0.14 197 125 123 0.03 0.02 0.02 Simulation contradicts with experimental observation On left-right particle fluxes V.Dzhordzhadze

6. MARS simulation models • Run 4 Shielding and Geometry • Geometry with magnet cryogenic vessels • Extended geometry with QM04 • Beam-scrape at QM01 • Beam-scrape at D0 (1) • Beam-scrape at D0 (2) V.Dzhordzhadze

7. The Run4 with cryogenic vessels V.Dzhordzhadze

8. The Run4, beam-scrape at QM04 V.Dzhordzhadze

9. The Run4, possible beam-scrape points FCAL D0 QM01 V.Dzhordzhadze

10. The Run4, beam-scrape at QM01 V.Dzhordzhadze

11. The Run4, beam-scrape at D0 (1) V.Dzhordzhadze

12. The Run4, beam-scrape at D0 (2) V.Dzhordzhadze

13. The MARS Run4 simulation Results Vessels QM04 W E W E 0.38 0.47 0.56 0.09 0.10 0.07 0.65 0.62 1.00 0.17 0.29 0.21 0.42 0.79 0.11 0.22 ----------------------- ---------------------- 0.39 0.43 0.20 0.21 0.26 0.18 0.18 0.11 1.00 0.10 0.03 0.03 0.03 0.01 0.03 0.02 V.Dzhordzhadze

14. The MARS Run4 simulation Results Beam-scrape at QM01 W E 0.28 1.00 0.51 0.30 0.49 0.36 0.23 0.25 -------------------------- 0.13 0.24 0.07 0.23 0.09 0.01 0.01 0.01 V.Dzhordzhadze

15. The MARS Run4 simulation Results (1-MuID close) scrape at D0 (2-MuID away) W E W E 0.26 0.20 0.12 0.24 0.21 0.12 0.76 0.54 0.30 0.70 0.74 0.35 1.00 0.36 1.00 0.47 ----------------------- ---------------------- 0.94 0.31 0.98 0.42 0.37 0.31 0.08 0.39 0.61 0.12 0.04 0.02 0.01 0.05 0.03 0.01 V.Dzhordzhadze

16. Conclusions • MARS simulation correctly describes experimental picture under the assumption of the beam scrape at D0, not at QM01, QM03 or QM04 • Observed in simulation picture is also in agreement with the relative count rates of S5 and S6 counters • To check the validity of this observation it will be good to put two additional scintillators close to the beam pipe after the D0 • If the beam-scrape at the D0 is correctly predicted by simulation, the shielding strategy arises naturally: Put a shielding material around the beam pipe just after the D0 or put shielding symmetric to FCAL V.Dzhordzhadze

17. V.Dzhordzhadze

18. MuID Shielding Configuration for Run 4 IRON WALLS South Wall ValveBox ValveBox S5,S6 123” S4 S1 S2 S3 MUID FCAL 69.5” 155.5” 16” 52” 288” 198” 158” 28.5” East Side Side View from West 105” S5 105” ValveBox Wall FCAL S4 MUID D0 Q1 Q2 Q3 24” 54” 50” 82” S3 S2 79” S1 33” 52” S6 48” Anchor Buoy Stacks LxWxH = 40x40x80” Top View Not to Scale or Proportion! Measurements good to ~1” VD 12/20/03 West Side V.Dzhordzhadze

19. South Tunnel New Cranes Shielding MuID Wall Beam FCAL East Side West Side V.Dzhordzhadze