1. Radiation Doses in CBM - A first estimate and an assessment of consequences Walter F.J. Müller, GSI, Darmstadt 11 th CBM Collaboration Meeting 26 February 2008

2. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 2 Gray – Mrad – Particle Fluence 1 Gy = 100 rad = 1 J/kg 1 J = 1 VAs = 1 CV → 1 eV = 1.6·10 -19 J dE/dx (mip,si) = 1.67 MeV/(g/cm 2 )[PDG] 1 mip/cm 2 ↔ 1.67 MeV/g = 2.67·10 -9 J/kg This leads to the often used relations : 1 Gy ↔ 3.75·10 9 mip/cm 2 10 krad ↔ 3.75·10 11 mip/cm 2 1 Mrad ↔ 3.75·10 13 mip/cm 2 Note: For lower energy protons (typ. Cyclotron energies) the relation is changed due to higher dE/dx, e.g. 160 MeV p: 1 Mrad ↔ 1.47·10 13 mip/cm 2

3. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 3 CBM-Year and CBM-Lifetime To estimate lifetime doses an operating scenario has to be assume. For CBM the current key numbers are: CBM-Year ↔ 5·10 6 sec at 100% duty cycle  Note: 1 yr = 3.156·10 7 sec  1 CBM-year ↔ 2 month at 100% duty cycle ↔ 4 month at 50% duty cycle CBM-Life ↔ 6 CBM-Year @ full intensity  CBM-Life ↔ 3·10 7 sec at 100% & full intensity full intensity ↔ 10 7 Au+Au interactions/sec CBM-Life ↔ 3 · 10 14 Au-Au min. bias interactions

4. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 4 Total Integrated Dose in CBM-Lifetime Reference system is Au+Au @ 25 A GeV central collisions Hit densities are given in hit/cm 2 per central Au-Au lower limit For an estimate of a lower limit of the TID  assume multiplicity (min. bias) = 0.25 · multiplicity (central)  assume particles are MIP hadrons 1 hit/cm 2 (cent) → 0.25 hit/cm 2 (min.bias) → 7.5·10 13 part/cm 2 over CBM-Life → 2 Mrad over CBM-Life rough lower limit estimates For rough lower limit estimates: 1 hit/cm 2 ↔ 2 Mrad in CBM-Life

5. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 5 Some Values Use hit densities form CBM Technical Status Report 2006 Update, Section 13.1 "Hit densities and Rates" Detectoredgehit/cm 2 part/cm 2 TID STS @ 30cminner107.5·10 14 20 Mrad outer 0.25 1.8·10 13 0.5 Mrad STS @ 1minner 17.5·10 13 2 Mrad outer 0.032.3·10 12 60 krad TRD @ 4minner 0.043.0·10 12 80 krad outer 0.002 1.5·10 11 4 krad TOF @ 10minner 0.017.5·10 11 20 krad outer 0.00065.0·10 10 1.2 krad STS @ 30 cm is now 1 st plane in 'all strips' configuration (the hit rate for STS@30 cm is scaled from the STS3 @ 20 cm plot of the CBM TSR) Hit rates in 1 st MUCH plane are similar to STS plane @ 1m

6. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 6 Consequences 1 STS sensor  inner part 1 st plane (20 Mrad) beyond LHC-style designs (CMS Si-tracker designed for 1.6·10 14 part/cm 2 or 6.7 Mrad; NP B78(1999)322 )  → inner part of 1 st plane may need replacement CBM-XYTER  > 50 Mrad demonstrated many times for rad-hard designs  STS perimeter (1 MRad) and MUCH 1 st plane center (2 Mrad) → some 'rad-hard lite' design might be ok.

7. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 7 Consequences 2 C0TS COTS (Custom-0f-The-Shelf) components  many COTS components are known to fail at 20-100 krad  some fail, e.g. bipolar transistors, can fail at 1 krad and are sensitive to displacement damage, thus neutron flux very preliminary A very preliminary COTS usage policy:  TID < 1 krad: selected COTS equipment can be used e.g. crates, power supplies ect. qualification done on the equipment level  TID < 20 krad: qualified COTS components can be used qualification done on the component level This divides the Cave in 3 Zones. Examples  TOF perimeter (1.2 krad) → COTS equipment  TOF center (20 krad) → COTS components  STS whole assembly → no COTS possible

8. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 8 Cave Layout - Old Cave – Side View Magnet MUCH Beam dump Step in Floor, dividing cave in CBM and HADES sector No shielded area close to STS and MUCH

9. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 9 Cave Layout - New Cave – Side View No 'Step' anymore Shielded area for electronics ect. Extra Shielding

10. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 10 Cave Layout - New New space fo electronics and other services Shielding Drawing: W. Niebur

11. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 11 Cave Layout – Cable path length Cable path length from STS/MUCH about 10 m 5.7 m

12. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 12 Cave Layout – First FLUKA Calculation Cave – Side View FLUKA by D. Bertini done for 50 cm shielding If correct, more than 50 cm shielding needed preliminary !!!!

13. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 13 TID and COTS  SEU Assume COTS parts are used at 20 krad 'places'  20 krad ↔ 0.01 hit/cm 2 (cent) ↔ 2.5·10 4 part/(cm 2 ·s)[ @10 7 int/s ] SEU Typical SEU (Single Event Upset) cross section for SRAM cells: 3·10 -14 cm 2 /bit [refs see next slide] SBU Typical SEU is a SBU (Single Bit Upset) : one bit toggles 0 ↔ 1 Rate of SRAM SBU's  7.5·10 -10 SBU/(bit·s)  7.5·10 -4 SBU/(Mbit·s)  2.7 SBU/(Mbit·hour) 20 krad ↔ 2.5·10 4 part/(cm 2 · s) 20 krad ↔ 2.7 SBU/(Mbit · hour) !! This is a lower limit !! n contribution might be 10 times higher Note: Neutrons are likely to dominate ! !! This is a lower limit !! n contribution might be 10 times higher

14. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 14 SRAM SEU Cross Sections SRAM cells in FPGA configuration memories: Denes et al, Proc of LECC-2006  ALTERA & ACTEL devices: 3-11·10 -14 cm 2 for embedded SRAMs 0.3-8 ·10 -14 cm 2 for LE Flip-Flops

15. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 15 SDRAM SEU Cross Sections SRRAM SEU Cross Sections vary much more  64 MBit ISSI IS42S164003·10 -17 cm 2 /bit Bunkowski et al, NIM A532(2005)708  512 Mbit 'Manufacturer C'4·10 -19 cm 2 /bit 512 Mbit 'Samsung'4·10 -17 cm 2 /bit Langley et al., Proc. of IEEE Rad.Eff.Data Workshop 2003  128 Mbit Micron MT48LCM32B22.8·10 -16 cm 2 /bit Hiemstra et al., Proc. of IEEE Rad.Eff.Data Workshop 2007 Again, assume '20 krad' places: 20 krad ↔ 0.036 SBU/(Gbit · hour) for 4 · 10 -19 cm 2 /bit ↔ 3.6 SBU/(Gbit · hour) for 4 · 10 -17 cm 2 /bit !! This is a lower limit !! n contribution might be 10 times higher Note: Neutrons are likely to dominate ! !! This is a lower limit !! n contribution might be 10 times higher

16. 26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 16 The End Thanks for your attention