1. Invariant mass plot for different geometry schemes using HSD generator Hemen Kalita*,B Bhattacharjee*, P Bhaduri and S Chattopadhyay * Dept of Physics, Gauhati University, Guwahati-14 VECC, Kolkata - 64 1

2.  The MuchCave length was approximately kept same. Criteria taken into consideration for changing the geometry :  The layer to absorber and absorber to layer dists. was kept same  The layer to layer distance was kept on changing  The original geometry was much_standard.geo HSD Event Generator Signal : J/Psi decayed muons from HSD for p+Au system for 30 GeV p beam Background : central UrQMD events for p+ Au at 30 GeV/n Total no. of events:-2k 2

3. Analysis criteria:-  70% hit criterion (reconstructable track)‏ eg: no. of MuchHits = 10 (for much_standard geometry)  70% true hit criterion Fraction of true hits (No. of true Hits/ no. of much Hits) = 0.7 ) 3

4. MuchCave Zin position [cm] : 105 Acceptance tangent min : 0.1 Acceptance tangent max : 0.5 Number of absorbers : 6 Number of stations : 6 # Absorber specification Absorber Zin position [cm] : 0 40 80 120 170 225 Absorber thickness [cm] : 20 20 20 30 35 100 Absorber material : I I I I I I # Station specification Station Zceneter [cm] : 30 70 110 160 215 340 Number of layers : 2 2 2 2 2 3 Detector type : 1 1 1 1 1 1 Distance between layers [cm]: 10 10 10 10 10 10 Support thickness [cm] : 1.5 1.5 1.5 1.5 1.5 1.5 Use module design (0/1) : 1 1 1 1 1 1 original geometry(much_standard.geo)‏ 4

5. Original Geo (signal)‏ Original Geo (embeded)‏ 5

6. MuchCave Zin position [cm] : 105 Acceptance tangent min : 0.1 Acceptance tangent max : 0.5 Number of absorbers : 5 Number of stations : 5 # Absorber specification Absorber Zin position [cm] : 0 45 90 145 205 Absorber thickness [cm] : 20 20 30 35 100 Absorber material : I I I I I # Station specification Station Zceneter [cm] : 32.5 77.5 132.5 192.5 325 Number of layers : 2 2 2 2 3 Detector type : 1 1 1 1 1 Distance between layers [cm]: 15 15 15 15 15 Support thickness [cm] : 1.5 1.5 1.5 1.5 1.5 Use module design (0/1) : 1 1 1 1 1 Geo1 6

7. Geo1(signal)‏ Geo1(embeded)‏ 7

8. MuchCave Zin position [cm] : 105 Acceptance tangent min : 0.1 Acceptance tangent max : 0.5 Number of absorbers : 4 Number of stations : 4 # Absorber specification Absorber Zin position [cm] : 0 56 112 183 Absorber thickness [cm] : 20 20 35 100 Absorber material : I I I I # Station specification Station Zceneter [cm] : 38 94 165 314 Number of layers : 2 2 2 3 Detector type : 1 1 1 1 Distance between layers [cm]: 26 26 26 26 Support thickness [cm] : 1.5 1.5 1.5 1.5 Use module design (0/1) : 1 1 1 1 Geo2 8

9. Geo2(signal)‏ Geo2(embedded)‏ 9

10. MuchCave Zin position [cm] : 105 Acceptance tangent min : 0.1 Acceptance tangent max : 0.5 Number of absorbers : 3 Number of stations : 3 # Absorber specification Absorber Zin position [cm] : 0 70 155 Absorber thickness [cm] : 20 35 100 Absorber material : I I I # Station specification Station Zceneter [cm] : 45 130 300 Number of layers : 2 2 3 Detector type : 1 1 1 Distance between layers [cm]: 40 40 40 Support thickness [cm] : 1.5 1.5 1.5 Use module design (0/1) : 1 1 1 Geo3 10

11. Geo3(signal)‏ Geo3(embedded)‏ 11

12. red-> for signal Blue-> for embedded 1. Plots for the no. of entries within the inv. mass peak for different station nos.(layer nos.) 2. Plots for the total no. of entries for different station nos.(layer nos.) 12

13. Conclusion:- -> For the different station nos. the integral no. in the inv. mass plot was approximately found to be same. ~ 506 -> The reconstruction efficiency ~ 25 % Next step:- -> Can try for the other geometry configuration and see how the reconstruction efficiency and background changes. 13

14. Thank you & A happy new year 2010