1

Simulation conditions for He (Air) Box

Geometry scheme:

Pipe Box

CarbonTarget

PSD

9 m-5.8 m 0 Beam direction

Pipe thickness is fixed

Box thickness ( PSD position)depend on the ion energy

B ionsPipe material – HeBox materials – Air or He

2 -> p @ 20 and 158 GeV/c were generated with GEANT4(100000 events)

1 -> B+C @ 20 and 158 AGeV/c were generated with GEANT4 (10000 events)

M.Golubeva, A.Ivashkin, INR RAS

2

Etot distributions on PSD surface B+C@158 AGeV/cDistance from target 32 mPSD shift 28 cmPIPE – 14.8 m, BOX – 17.2 m

1.51% B ions interact in target

Etot from secondaries produced in target Etot from secondaries produced in “PIPE”

6.56% in AIR

1.94% in HE

7.45% in AIR

1.63% 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…

3

σ = 60%/√E

σ20GeV = 13.4% (2.7 GeV) σ158GeV = 4.8% (7.5 GeV)

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

20 GeV 158 GeV

Interactions (%) 0.73 0.47 3.00 1.04 He+Air He+He He+Air He+He

Etot distributions on PSD surface

p@20 GeV/c, BOX – 2.2 m p@158 GeV/c, BOX – 17.2 m

HE + AIRHE + HE

HE + AIRHE + HE

1.5σ 1.5σ

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%.