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H4iirrad test results - fgc 25 th August 2011

H4iirrad test results - fgc 25 th August 2011. Q. King, D. Calcoen. Outline. Component description Goal of the test Radiation conditions and dosimetry Results Conclusions. Components under test. FGC2 (60A COD)

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H4iirrad test results - fgc 25 th August 2011

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  1. H4iirrad test results - fgc25th August 2011 Q. King, D. Calcoen

  2. Outline • Component description • Goal of the test • Radiation conditions and dosimetry • Results • Conclusions

  3. Components under test • FGC2 (60A COD) • Used only with 60A closed orbit dipole converters under the magnets in the LHC tunnel – 750 installed • Analogue interface uses SAR ADC that doesnot require a filter, so no SRAM based FPGAs are used • FGG2 (Generic) • Used for all other converters – 1000 installed, ~300 exposed to radiation in non-tunnel areas • Analogue interface uses delta-sigma ADCs and Spartan 20 FPGAs for the FIR filters • Both FGCs ran the radiation test function under their boot software • This function was previously used in CNRAD (2008/9) and Prospero (2009) • Both FGCs were installed in the internal H4IIRAD zone during the June and July slots

  4. Motivation • FGCs were already tested in CNRAD and are known to have an SEL cross-section due to Xilinx 95000 series CPLDs (and perhaps other components) • CNRAD spectrum is not equivalent to LHC so tests in H4IIRAD were of particular interest to see if the higher energy spectrum in the tunnel will significantly affect the rate of SELs K. Roeed (2011)

  5. Radiation dosimetry

  6. SEU Results • SEU rate in SRAM is affected by rate of access – makes calibration essentially impossible • External SRAM has a clear and significant cross section to thermal neutrons • Ratio of SEUs in internal SRAM is inconsistent – hard to draw conclusions D. Calcoen

  7. SEL Results • For 750 FGCs in the tunnel with ~1 Gy per year, this would predict about 300 crashes in total or about 0.8 days MTBF • The CNRAD results suggested 2.4 days MTBF • Perhaps there is an effect due to the higher energy spectrum? D. Calcoen

  8. LHC results this year • Several FGCs have proven corruptions of the Spartan 20 FPGA memories that contain the FIR filter for the ADCs. This is expected and mitigation measures are being introduced (scrubbing) • Only one SEL candidate has been observed (as far as I know) • Overall the FGCs seem quite robust (fortunately)

  9. Conclusions • The H4IIRAD test facility worked very well and was very useful to have a more realistic model of the LHC • Both FGCs survived 30Gy as expected based on previous CNRAD test results • SEU memory results are hard to interpret but the presence of a thermal neutron cross section seems very likely and coherent with LHC results • H4IIRAD results might indicate an elevated SEL cross section in the tunnel with higher energy hadrons • So far, FGCs are proving quite robust in the LHC but at 5% of the potential radiation levels so statistics are still not very good • The H4IIRAD results definitely support the need for the development of a new FGClite controller to replace the FGC2s exposed to radiation

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