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

26 February th 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· 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

26 February th 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 full intensity  CBM-Life ↔ 3·10 7 sec at 100% & full intensity full intensity ↔ 10 7 Au+Au interactions/sec CBM-Life ↔ 3 · Au-Au min. bias interactions

26 February th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 4 Total Integrated Dose in CBM-Lifetime Reference system is 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

26 February th 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 30cminner107.5· Mrad outer · Mrad 1minner 17.5· Mrad outer · krad 4minner · krad outer · krad 10minner · krad outer · krad 30 cm is now 1 st plane in 'all strips' configuration (the hit rate for cm is scaled from the 20 cm plot of the CBM TSR) Hit rates in 1 st MUCH plane are similar to STS 1m

26 February th 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.

26 February th 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 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

26 February th 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

26 February th 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

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

26 February th 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

26 February th 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 !!!!

26 February th 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 7 int/s ] SEU Typical SEU (Single Event Upset) cross section for SRAM cells: 3· 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· 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

26 February th 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· cm 2 for embedded SRAMs · cm 2 for LE Flip-Flops

26 February th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 15 SDRAM SEU Cross Sections SRRAM SEU Cross Sections vary much more  64 MBit ISSI IS42S164003· cm 2 /bit Bunkowski et al, NIM A532(2005)708  512 Mbit 'Manufacturer C'4· cm 2 /bit 512 Mbit 'Samsung'4· cm 2 /bit Langley et al., Proc. of IEEE Rad.Eff.Data Workshop 2003  128 Mbit Micron MT48LCM32B22.8· cm 2 /bit Hiemstra et al., Proc. of IEEE Rad.Eff.Data Workshop 2007 Again, assume '20 krad' places: 20 krad ↔ SBU/(Gbit · hour) for 4 · cm 2 /bit ↔ 3.6 SBU/(Gbit · hour) for 4 · 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

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