Changes to IR6 dump protection elements B.Goddard, W.Weterings, C.Maglioni, R.Versaci, T.Antonakakis, R.Schmidt, J.Borburgh, J.Blanco, plus many other colleagues

Contents TCDQ upgrade – Absorber material and length – Movement bellows – Controls Additional TCLA Buttons in TCSG

TCDQ upgrade Issue with robustness of present TCDQ design – Dynamic stresses exceed limit for damage at block corners – Graphite jaws, 1.8g/cc – Replace with graded Carbon Composite (1.4g/cc and 1.65 g/cc)

Absorber composition Lower density and higher yield stress material – should be below damage limit for beyond ultimate beams – FLUKA and stress analyses ongoing to derive limits Total amount of material seen by beam increases from 10.8 kg/cm2 to 13.9 kg/cm2 – Should be better for asynch dump protection Beam

Absorber length 6m -> 9m

Location of extra module More difficult upstream, due to dump line interference, but would like to maintain location of TCSG and drift to Q4, so will extend upstream.

Layout Relocation of interlock BPMs by about 3m No impact on functionality TCDQ BPMSA TCSG

Schedule Install during LS1

Another benefit? Will have 9m of CC next to beam at location with largest H beta function – Could help reduce damage elsewhere in case of major failure – Being investigated by J.Blanco & R.Schmidt

Improve present bellows (±20 mm) Presently large mechanical stress to displace Distortion of RF fingers (away from beam!) Will make double bellows system -> TE/VSC?

Controls Don’t expect any change in movement precision with 9m long absorber (10.4m) Are investigating an upgrade of controls to use collimation stepping motor system and low- level (although some other issues have been solved with existing DC motors) – Needs mechanical changes, and there is concern about precision attainable in open-loop.

Additional TCLA? Space reserved in layout for TCLA, just before TCDQM

Reduction of heat load on Q4 with MQY Factor 2 improvement

FLUKA studies of asynch dump R.Versaci

Justification for TCLA “Not needed for beam cleaning” – Ralph Two remaining justifications – Reduce scale of quench if asynch dump FLUKA studies in progress – Help contain damage if “beyond design” failure Energy tracking, retrigger failure Decision still to take – when is deadline for Coll project? – Would be good to do all IR6 work together in LS1 (TCSG with buttons, new TCDQ plus motorisation, TCLA)

Buttons in TCSGs Requested by Ralph Can only support this – Will need to investigate ‘servo’ of TCDQ position with TCSG, beyond certain offset, if TCSGs are automatically adjusted

Conclusions Some non-negligible upgrades for IR6 dump protection – TCDQ upgrade for robustness (also adds more material close to beam) – TCDQ controls – to be decided formally – New improved TCDQ bellows – TCSG with buttons – Additional TCLA – to be decided after FLUKA studies