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Fast Beam Losses during Beam Dump Process due to ( missing ) LR Beam-Beam kick. LBOC Tobias Baer July, 31 st 2012 . Acknowledgements : S. Bart Pedersen, E. Effinger, B. Dehning, M Hempel, M. Schaumann, R. Schmidt, D. Valuch, J. Wenninger. Beam Dump on 8.7.2012 20:46.
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Fast Beam LossesduringBeam DumpProcessdue to (missing) LR Beam-Beam kick • LBOC Tobias Baer July, 31st 2012 Acknowledgements: S. Bart Pedersen, E. Effinger, B. Dehning, M Hempel, M. Schaumann, R. Schmidt, D. Valuch, J. Wenninger.
Beam Dump on 8.7.2012 20:46 • Beam dump due totriggerby B2 LL-RF (cryoproblem) Strange: Single-turn losses on B1 in before beam dump. Losses in IR7 forB1andB2. 1 turn 28.07.2012 10:06. Losses B1 Dump B1(cut off) 250mV · 1380b≈ 0.7 Gy/s atBLMEI.06L7.B1E10_TCHSH.6L7.B1 RS1 Dump B2(cut off) Signal fromdiamond BLMs in IR7.
Event Sequence • Dumptriggerby RF for B2 only. B2 AG Fire MKD.B2 B1 AG IR5 IR4 IR6 0 8/8 turns IR3 IR7 IR2 IR8 IR1
Event Sequence • Perturbation of Horizontal B1 trajectorydownstreamof IR5 due tomissing LR beam-beam kick in IP5. Fire MKD.B2 No IR5 bb kick IR5 IR4 IR6 0 1/8 8/8 turns IR3 IR7 IR2 IR8 IR1 200µm B1 H Turn-by-Turn BPM postmortemdata IR5 IR8 IR1 IR5 IR2 200µm B1 V
Event Sequence • Start of B1 losses in IR7. Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 8/8 turns IR3 IR7 IR2 IR8 IR1 Pacmanstructureof beam losses.
Event Sequence No IR2, IR1, IR8 bb kick • No beam-beam kick in IR2, IR1 and IR8 anymore(somebunches). Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 6/8 8/8 IR3 IR7 IR2 IR8 IR1 200µm B1 H Measurement is a convolutionof all bunches! IR5 IR8 IR1 IR5 IR2 200µm B1 V
Event Sequence No IR2, IR1, IR8 bb kick • Losses due touncaptured beam in abortgapduringMKD rise time observable in IR7. Dumplosses Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 6/8 8/8 IR3 IR7 IR2 IR8 IR1
Event Sequence No IR2, IR1, IR8 bb kick • B2 completelydumped.B1 H trajectoryperturbation observable byADT pickup. B2 dumped Dumplosses Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 6/8 8/8 IR3 IR7 IR2 IR8 IR1 15µm ADT postmortemdata
Event Sequence No IR2, IR1, IR8 bb kick • Fire B1 MKD 1.25 turns (=111µs) after B2 MKD. Fire MKD.B1 B2 dumped Dumplosses Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 6/8 8/8 10/8 IR3 IR7 IR2 IR8 IR1
Event Sequence No IR2, IR1, IR8 bb kick • Losses due touncaptured beam in abortgapduringMKD.B1 rise time observable in IR7. Fire MKD.B1 Dumplosses B2 dumped Dumplosses Fire MKD.B2 Losses in IR7 No IR5 bb kick IR5 IR4 IR6 0 1/8 3/8 6/8 8/8 10/8 IR3 IR7 IR2 IR8 IR1
Summary & Outlook • A single-turn beam lossduringthe beam dumpprocess was observed. The effectcanbeexplainedbythemissing LR beam-beam kickafter a dumpof B2, whichleadsto a B1 trajectoryperturbationofseveral 10µm. • Outlook: • Calculatedtheexpectedmissing kick andcompareittothe BPM reading. • End-of-filltestwithbunch-by-bunch ring BPM acquisition?