Preliminary Analysis and foreseen actions EN-ICE&EN-STI Cryo PLC failure at P4 Preliminary Analysis and foreseen actions EN-ICE&EN-STI

QURA X RM01_R X RM01_L Long-Term: QURC(A,B) QUI (-1) CRYO RF (-0.5) Cumulative radiation levels: few 1E5–1E6cm-2 (fairly low!) QURA Towards US85: Factor ~5-10 less X RM01_R X RM01_L Long-Term: QURC(A,B) QUI (-1) CRYO RF (-0.5)

RadMon 4RM01S: 18 counts (5 during the last days) RadMon 4LM01S: 5counts (1 during the last days) All RadMons are set to 3V (high-sensitivity), thus the fluence determination strongly depends on the R-factor (thermal neutron to high-energy hadron ratio): possible range ~105-106cm-2

Considerations Failure occurred during beam-on, in a period when the UX45 RadMons counted (6 counts in few days) Radiation levels very low at location of the PLC (~1 year surface equivalent) Failure signature compatible with SEU but to be confirmed Independent: evolution of radiation levels in UX45 (and US45 junction) to be studied – vacuum pressures when going to 25ns? Most exposed equipment is in UX45 and relocation requirements are to be evaluated

Strategy Schneider PLC Radiation levels and their evolution with time Analysis of failure (result next week) CNRAD/H4IRRAD radiation tests with suspected memory board (September - October) Installation of redundant test PLC system (CB) Analysis 2012 statistic decision on general deployment on critical Cryo CPU during LS1 Radiation levels and their evolution with time Analysis of residual gas-densities and dependencies on bunch spacing, length and intensity Review of requirements/options/possibilities during R2E review in November Decision on CB and LS1 requirements/actions