STS Radiation Environment

11th CBM Collaboration MeetingGSI, February 2008

Radoslaw KarabowiczGSI

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

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS detector layoutSTS geometry:

8 double-sided micro-strip silicon stations composedof sectors with thickness of 300m

Support structure made of carbon boxes

Cables are represented as capton boxes with thickness of 200m

Readout: thick layers of silicon and aluminium

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS Radiation

Environment(Geant3)

Particle energy loss in central Au+Au collisions at 25 AGeV on different STS stations.

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS Radiation

Environment(Geant3)

Particle energy loss in mbias Au+Au collisions at 25 AGeV on different STS stations.

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS Radiation

Environment(Geant3)

Comparison between energy loss in mbias collisions and central collisions

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS Radiation

Environment(Geant3)

Comparison between energy loss WITH and WITHOUT Much system

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

STS Radiation

Environment(Geant3 vs

Fluka)

Comparison between energy loss produced in Geant and that produced in Fluka.

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

OccupancySensors’ occupancy in one Au+Au central 25 AGeV collision

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

Station 1, z =30cm

Work in progress – realistic response

Sector view:Front strips in blueBack strips in greenMC points in circlesReconstructed hits: stars

Size of plot [cm]Position in STS:XYZ

Front strips’ ADC distributionBack strips’ ADC distribution

Simple Event Display

11th CBM Collaboration Meeting, GSI R.Karabowicz Feb 27 th, 2008

Hit sharing multiply factor: ~3 (guestimated)In other experiment: 1.4

Radiation levelsRadiation 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 (107 interactions/s)

11th CBM Collaboration Meeting, GSI D. Bertini, R.Karabowicz Feb 27 th, 2008

Station 8, z =100cm

Station 4, z =50cmStation 1, z =30cm

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%