Simulation conditions for He (Air) Box

1. Simulation conditions for He (Air) Box 1 -> B+C @ 20 and 158 AGeV/c were generated with GEANT4 (10000 events) 2 -> p @ 20 and 158 GeV/c were generated with GEANT4(100000 events) Geometry scheme: Pipe thickness is fixed Box thickness ( PSD position) depend on the ion energy Carbon Target Pipe material –He Box materials – Air or He Pipe Box B ions PSD -5.8 m 0 9 m Beam direction M.Golubeva, A.Ivashkin, INR RAS

2. Etot distributions on PSD surface B+C@158 AGeV/c Distance from target 32 m PSD shift 28 cm PIPE – 14.8 m, BOX – 17.2 m Etot from secondaries produced in target Etot from secondaries produced in “PIPE” 6.56% in AIR 1.51% B ions interact in target 1.94% in HE Etot from secondaries produced in “BOX” There are no events with low energies, probably the GEANT4 problem with ions. For central events the proton interactions are the most important. So we go to protons… 7.45% in AIR 1.63% in HE

3. Etot distributions on PSD surface p@20 GeV/c, BOX – 2.2 m p@158 GeV/c, BOX – 17.2 m 1.5σ HE + AIR HE + HE 1.5σ HE + AIR HE + HE σ = 60%/√E σ20GeV = 13.4% (2.7 GeV) σ158GeV = 4.8% (7.5 GeV) 20 GeV 158 GeV He+Air He+He He+Air He+He Interactions (%) 0.73 0.47 3.00 1.04 0.5σ ( 0 – 18.6 GeV) ( 0 – 154.3 GeV) Degradation (%) 0.65 0.42 2.39 1.68 1.5σ (0 – 16.0 GeV) (0 – 146.8 GeV) Degradation (%) 0.33 0.32 0.84 0.60

4. Conclusions • We've tried to estimate the number of non target interactions in HE and AIR BOX • for ions with GEANT 4 simulations. • Unfortunately the energy spectra do not contain central events and presumably • are not correct • The proton interactions in BOX are crucial for central events. • Therefore the proton interactions in HE and AIR BOX were simulated with GEANT4 • The difference in the degradation of energy resolution between AIR and HE • is ~ 1.5 and the absolute values are at the level of 1- 2%.