Radiation Doses in CBM - A first estimate and an assessment of consequences
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Radiation Doses in CBM -Radiation Doses in CBM -A first estimate and anA first estimate and anassessment of assessment of
consequences consequences Walter F.J. Müller, GSI, Darmstadt
11th CBM Collaboration Meeting26 February 2008
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 2
Gray – Mrad – Particle FluenceGray – 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/cm2 1 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
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 3
CBM-Year and CBM-Lifetime 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-LifeCBM-Life ↔ ↔ 33··10101414 Au-Au min. bias interactions Au-Au min. bias interactions
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 4
TTotal otal IIntegrated ntegrated DDose in CBM-ose in CBM-LifetimeLifetime 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 limitlower 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 estimatesrough lower limit estimates:1 hit/cm1 hit/cm22 ↔↔ 2 Mrad in CBM-Life 2 Mrad in CBM-Life
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 5
Some ValuesSome 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
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 6
Consequences 1Consequences 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.
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 7
Consequences 2Consequences 2
COTS (CCustom-00f-TThe-SShelf) 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 very preliminary COTS usage policy:
TID < 1 krad: selected COTS equipment can be usede.g. crates, power supplies ect.qualification done on the equipment level
TID < 20 krad: qualified COTS components can be usedqualification 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
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 8
Cave Layout - OldCave Layout - Old
Cave – Side View
Magnet MUCHBeamdump
Step in Floor, dividing cave in CBM and HADES sector No shielded area close
to STS and MUCH
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 9
Cave Layout - NewCave Layout - New
Cave – Side View
No 'Step' anymore Shielded area forelectronics ect.
Extra Shielding
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 10
Cave Layout - NewCave Layout - New
New space foelectronics andother services
Shielding Drawing: W. Niebur
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 11
Cave Layout – Cable path lengthCave Layout – Cable path length
Cable path length from STS/MUCHabout 10 m
5.7 m
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 12
Cave Layout – First FLUKA Cave Layout – First FLUKA CalculationCalculation
Cave – Side View
FLUKA by D. Bertinidone for 50 cm shielding
If correct, more than 50 cm shielding
needed
preliminary !!!!
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 13
TID and COTS TID and COTS SEU 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 (SSingle EEvent UUpset) cross section for
SRAM cells: 3·10-14 cm2/bit [refs see next slide]
Typical SEU is a SBU (SSingle BBit UUpset): 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 20 krad ↔↔ 2.5·10 2.5·1044 part/(cm part/(cm22··s)s)20 krad 20 krad ↔↔ 2.7 SBU/(Mbit 2.7 SBU/(Mbit··hour)hour)
Note: Neutronsare likely to dominate !
!! This is a lower limit !!!! This is a lower limit !!n contribution mightn contribution mightbe 10 times higherbe 10 times higher
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 14
SRAM SEU Cross SectionsSRAM 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
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 15
SDRAM SEU Cross SectionsSDRAM SEU Cross Sections
SRRAM SEU Cross Sections vary much more 64 MBit ISSI IS42S16400 3·10-17 cm2/bit
Bunkowski et al, NIM A532(2005)708 512 Mbit 'Manufacturer C' 4·10-19 cm2/bit
512 Mbit 'Samsung' 4·10-17 cm2/bit Langley et al., Proc. of IEEE Rad.Eff.Data Workshop 2003
128 Mbit Micron MT48LCM32B2 2.8·10-16 cm2/bit Hiemstra et al., Proc. of IEEE Rad.Eff.Data Workshop 2007
Again, assume '20 krad' places:
20 krad20 krad ↔↔ 0.036 SBU/(Gbit 0.036 SBU/(Gbit··hour) for 4hour) for 4··1010-19 -19 cmcm22/bit/bit↔↔ 3.6 SBU/(Gbit 3.6 SBU/(Gbit··hour) for 4hour) for 4··1010-17 -17 cmcm22/bit/bit
Note: Neutronsare likely to dominate !
!! This is a lower limit !!!! This is a lower limit !!n contribution mightn contribution mightbe 10 times higherbe 10 times higher
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26 February 2008 11th CBM Collaboration Meeting -- Walter F.J. Müller, GSI 16
The EndThe End
Thanks for Thanks for your attentionyour attention