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Radiation Doses in CBM - A first estimate and an assessment of consequences

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. Gray – Mrad – Particle Fluence. 1 Gy = 100 rad = 1 J/kg 1 J = 1 VAs = 1 CV → 1 eV = 1.6·10 -19 J

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Radiation Doses in CBM - A first estimate and an assessment of consequences

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  1. Radiation Doses in CBM - A first estimate and an assessment of consequences Walter F.J. Müller, GSI, Darmstadt 11th CBM Collaboration Meeting26 February 2008

  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/cm2) [PDG] • 1 mip/cm2↔ 1.67 MeV/g = 2.67·10-9 J/kg • This leads to the often used relations: 1 Gy ↔ 3.75·109 mip/cm2 10 krad ↔ 3.75·1011 mip/cm21 Mrad ↔ 3.75·1013 mip/cm2 • Note: For lower energy protons (typ. Cyclotron energies) the relation is changed due to higher dE/dx, e.g. 160 MeV p: 1 Mrad ↔ 1.47·1013 mip/cm2 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 ↔ 5·106 sec at 100% duty cycle • Note: 1 yr = 3.156·107 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 ↔ 3·107 sec at 100% & full intensity full intensity ↔ 107 Au+Au interactions/sec CBM-Life ↔ 3·1014 Au-Au min. bias interactions 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/cm2 per central Au-Au • 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/cm2(cent)→ 0.25 hit/cm2(min.bias)→ 7.5·1013 part/cm2 over CBM-Life→ 2 Mrad over CBM-Life • For rough lower limit estimates: 1 hit/cm2↔ 2 Mrad in CBM-Life 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

  5. Some Values • Use hit densities form CBM Technical Status Report2006 Update, Section 13.1 "Hit densities and Rates" • Detector edge hit/cm2 part/cm2 TIDSTS @ 30cm inner 10 7.5·1014 20 Mrad outer 0.25 1.8·1013 0.5 MradSTS @ 1m inner 1 7.5·1013 2 Mrad outer 0.03 2.3·1012 60 kradTRD @ 4m inner 0.04 3.0·1012 80 krad outer 0.002 1.5·1011 4 kradTOF @ 10m inner 0.01 7.5·1011 20 krad outer 0.0006 5.0·1010 1.2 krad • STS @ 30 cm is now 1st 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 1st MUCH plane are similar to STS plane @ 1m 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

  6. Consequences 1 • STS sensor • inner part 1st plane (20 Mrad) beyond LHC-style designs(CMS Si-tracker designed for 1.6·1014 part/cm2 or 6.7 Mrad; NP B78(1999)322) • → inner part of 1st plane may need replacement • CBM-XYTER • > 50 Mrad demonstrated many times for rad-hard designs • STS perimeter (1 MRad) and MUCH 1st plane center (2 Mrad) → some 'rad-hard lite' design might be ok. 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

  7. Consequences 2 • 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 • 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 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

  8. Cave Layout - Old Cave – Side View Beamdump MUCH Magnet Step in Floor, dividing cave in CBM and HADES sector No shielded area closeto STS and MUCH 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

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

  10. Cave Layout - New New space foelectronics andother services Drawing: W. Niebur Shielding 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

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

  12. Cave Layout – First FLUKA Calculation preliminary !!!! FLUKA by D. Bertinidone for 50 cm shielding Cave – Side View If correct, more than 50 cm shielding needed 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/cm2(cent)↔ 2.5·104 part/(cm2·s) [ @107 int/s ] • Typical SEU (Single Event Upset) cross section for SRAM cells: 3·10-14 cm2/bit [refs see next slide] • 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) Note: Neutronsare likely to dominate !!! This is a lower limit !!n contribution mightbe 10 times higher 20 krad ↔ 2.5·104 part/(cm2·s)20 krad ↔ 2.7 SBU/(Mbit·hour) 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 cm2 for embedded SRAMs • 0.3-8 ·10-14 cm2 for LE Flip-Flops 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

  15. SDRAM SEU Cross Sections • SRRAM SEU Cross Sections vary much more • 64 MBit ISSI IS42S16400 3·10-17 cm2/bitBunkowski et al, NIM A532(2005)708 • 512 Mbit 'Manufacturer C' 4·10-19 cm2/bit512 Mbit 'Samsung' 4·10-17 cm2/bitLangley et al., Proc. of IEEE Rad.Eff.Data Workshop 2003 • 128 Mbit Micron MT48LCM32B2 2.8·10-16 cm2/bitHiemstra et al., Proc. of IEEE Rad.Eff.Data Workshop 2007 • Again, assume '20 krad' places: Note: Neutronsare likely to dominate !!! This is a lower limit !!n contribution mightbe 10 times higher 20 krad ↔ 0.036 SBU/(Gbit·hour) for 4·10-19 cm2/bit↔ 3.6 SBU/(Gbit·hour) for 4·10-17 cm2/bit 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI

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

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