1. BLM internal beam abort request 03.05.2015 13:24:50 Bernd Dehning CERN BE-BI 08.05.2015 MPP, B. Dehning

2. Event Date 03.05.2015 beam dumped by monitor BLMQI.21R6.B1E10.MQ, 13.24.50 higher signal already observed in the whole octant, 13.24.30 change in HV current observed at 13.23.52 08.05.2015 MPP, B. Dehning

3. 08.05.2015 MPP, B. Dehning 13.24.31 13.24.32 13.24.3313.24.34 Loss = 4E-7 Loss = 6E-4

4. IP 6 beam loss signal - sum of 8 channels vs time 08.05.2015 MPP, B. Dehning Crate left site Crate centre site Crate right site Same signal structure seen at all groups of monitors

5. D4R6 B4R6 F4R6 H4R6 J4R6 A5R6 A4R6 B4R6 C4R6 D4R6 E4R6 F4R6 G4R6 H4R6 I4R6J4R6K4R6 A5R6 B5R6C5R6 A8R6 A9R6 A10R6 A11R6 UD68 Direct Dump A13R6 A12R6 A15R6 A14R6A17R6 A16R6 A19R6 A18R6 A21R6 A20R6 A23R6 A22R6 A25R6 A24R6 A27R6 A26R6 A29R6 A28R6 A31R6 A30R6 A32R6 A33R6 Point 6R 08.05.2015 SR6 BY02 A34R6 UD6 8 Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction HT SEM Analog A4R6B4R6C4R6D4R6E4R6F4R6G4R6H4R6 I4R6 J4R6 K4R6 A5R6 B5R6 C5R6 A8R6 A9R6 A10R6 A11R6 TD68-1 TD68-2 UD68 1619172161917316056531605654161917416056551605651161314316056521613144161314516056561605657161314616056581605659 16056601605661161528116176441615281 UJ67 BY 03 Crate 1 Slot1Crate 1 Slot2Crate 1 Slot3Crate 1 Slot4Crate 1 Slot5Crate 1 Slot6Crate 1 Slot7Crate 1 Slot8Crate 1 Slot9 Crate 1 Slot10 Crate 2 Slot1Crate 2 Slot2Crate 2 Slot3Crate 2 Slot4Crate 2 Slot5Crate 2 Slot6Crate 2 Slot7Crate 2 Slot8 Crate 3 Slot1 Crate 2 Slot9 Crate 2 Slot10 175 212 252 269 377497 617 750 1 channel 3 channels 1 channel 3 channels 1 channel 19 channels 16 BLECF to repair 1 Filter capacitors exchanged 1 input filter capacitors broken 1 channel Test in the labo: Track burns with a 35 Ampere pulse With the input RC network a pulse of 16.5kV needed Surface Tunnel MPP, B. Dehning

6. B4L6D4L6F4L6 A4L6 C4L6 B4L6 E4L6 D4L6 G4L6 F4L6 I4L6 H4L6 K4L6 J4L6 B5L6A5L6A8L6C5L6 A10L6 A9L6 A11L6 UD62 A13L6 A12L6 A15L6A14L6 A17L6 A16L6 A19L6 A18L6 A21L6 A20L6 A23L6 A22L6 A25L6 A24L6 A27L6 A26L6 A29L6A28L6 A31L6 A30L6 A33L6 A32L6 Point 6L 08.05.2015 SR6 BY02 H4L6 UD62 A5L6 J4L6 Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction Boite Jonction Direct Dump UD62 TD62-2TD62-1 A11L6A10L6A9L6A8L6C5L6B5L6A5L6K4L6J4L6I4L6 H4L6G4L6F4L6E4L6D4L6C4L6B4L6A4L6 1615272 1617643160565016056491605648160564716056461605645161261716056441605643161261416056401612616160564116056421619171161261516191701619169 Crate1 Slot1Crate1 Slot2Crate1 Slot3 Crate1 Slot4 Crate1 Slot5Crate1 Slot6Crate1 Slot7Crate1 Slot8Crate1 Slot9 Crate1 Slot10 Crate2 Slot1 Crate2 Slot2 Crate2 Slot3Crate2 Slot4Crate2 Slot5Crate2 Slot6Crate2 Slot7Crate2 Slot8Crate3 Slot1 Crate2 Slot9 Crate2 Slot10 175212252269 377497617750 HTSEMAnalog UJ63 BY03 8 input filter capacitors broken 1 channel 3 channels 2 channels 1 channel 2 channels 1 channel 2 channels 1 channel 17 channels 12 BLECF to repair 1 HV Filter box replaced 8 Filter capacitors exchanged 1M HV resistor burned As consequence of the broken the capacitors MPP, B. Dehning

7. Summary and foreseen actions Observations Damage of several tunnel digitizer cards input circuits Damage of filter components Damage could not come from BLM equipment, because of the power needed for the damages, several tenth of ampere in 100 us Comparison with October event It is assumed that causes for the ionisation chamber high voltage increase are identical Investigation Try of determination of entry location of high voltage pulse by data analysis From the Sunday event postmortem data are stored Action Installation of a overvoltage protection on the tunnel cables May preventive exchange of HV in IP6 cables during TS1 08.05.2015 MPP, B. Dehning