1. STS Radiation Environment 11 th CBM Collaboration Meeting GSI, February 2008 Radoslaw Karabowicz GSI

2. Outline 1.Cave geometry and STS layout 2.Fluka results on cave radiation environment 3.Fluka results on STS radiation environment 4.Geant3 results on STS radiation environment 5.Conclusion 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

3. STS detector layout STS geometry: 8 double-sided micro-strip silicon stations composed of sectors with thickness of 300  m Support structure made of carbon boxes Cables are represented as capton boxes with thickness of 200  m Readout: thick layers of silicon and aluminium 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

4. STS Radiation Environment (Geant3) Particle energy loss in central Au+Au collisions at 25 AGeV on different STS stations. 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

5. STS Radiation Environment (Geant3) Particle energy loss in mbias Au+Au collisions at 25 AGeV on different STS stations. 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

6. STS Radiation Environment (Geant3) Comparison between energy loss in mbias collisions and central collisions 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

7. STS Radiation Environment (Geant3) Comparison between energy loss WITH and WITHOUT Much system 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

8. STS Radiation Environment (Geant3 vs Fluka) Comparison between energy loss produced in Geant and that produced in Fluka. 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

9. Occupancy Sensors’ occupancy in one Au+Au central 25 AGeV collision 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008 Station 1, z =30cm

10. Work in progress – realistic response Sector view: Front strips in blue Back strips in green MC points in circles Reconstructed hits: stars Size of plot [cm] Position in STS: X Y Z Front strips’ ADC distribution Back strips’ ADC distribution Simple Event Display 11 th CBM Collaboration Meeting, GSI R.Karabowicz Feb 27 th, 2008 Hit sharing multiply factor: ~3 (guestimated) In other experiment: 1.4

11. Radiation levels Radiation doses in megarads on the STS silicon stations as calculated by Geant during 6 years* of CBM running. *1 year = 2 months at full intensity (10 7 interactions/s) 11 th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008 Station 8, z =100cm Station 4, z =50cm Station 1, z =30cm

12. Conclusions -Difference between minimum bias and central collisions or with/without the MUCH system is rather straight forward -Comparison between Fluka and Geant is not easily to be understood, but was not a surprise for Fluka/Geant experts -Radiation dose on STS is tough, but still tolerable (up to 20MRads in 6 years) -Occupancy reaches 5.7%, but assuming hit sharing of ~1.4 it would rise to almost 10%