Triplet string test campaign preparation Triplet string test

Triplet string test – campaign preparation Triplet string test campaign preparation – 06/02/2019

Intro The purpose of this presentation is to : • describe the tests foreseen on the triplet string test • consider new test proposals in view of the previous presentations • share the tentative test planning and resource request

Past test No vacuum – limited instrumentation • Longitudinal friction in the Q 1 jacks (nut removed) – see EDMS 2033117 An average longitudinal force of ~550 kg is required to displace a “free” Q 1 magnet • Longitudinal jack body deflection (with jack nut on) • Q 2 cold mass longitudinal position range Given its supporting scheme, a longitudinal position uncertainty exists on the Q 2 cold mass. It was measured to be ~6. 5 mm longitudinal – radial/vertical dispersion are being investigated (EN/SMM)

Proposed test – without vacuum Magnet in the nominal longitudinal position • Tie-rod ears deflection when in operational conditions (Interconnection closed – in nominal and non-conformant situations) • Calibration of the relation between the Q 1 longitudinal position and the force on each tie-rods (forced by using the nut of Q 1 D – limited load) • Realignment tentative without vacuum – vacuum vessel misalignment vs. tie-rod loading

Proposed test – with vacuum Magnet in the nominal longitudinal position • Tie-rod ear deflection when under vacuum (using dial gauges) with the tie -rod instrumentation on (strain gauges) • Realignment trial on each jack to see the jack load evolution, tie-rod load evolution and triplet realignment kinematic in a nominal situation • Successive realignment to see potential magnet longitudinal position drift Is there a progressive backward drift of the magnet ?

Proposed test – with vacuum Magnet in the extreme longitudinal position (jack loaded) The jack loading will be controlled by progressive unloading of the tie-rods (a safety stop will be implemented on the Q 1). • Realignment test on each jack to see the jack load evolution, tie-rod load evolution and triplet realignment kinematic Depending on the results of this test and the result of past tests, a consolidation solution will be devised and proposed for implementation.

Test recap Test proposal Instrumentation required Acquisition system Planned test start date Resource required Longitudinal friction in Q 1 None No Done None Longitudinal jack body deflection None No Done None Q 2 cold mass position range Laser tracker EN/SMM No Finished yesterday EN/SMM (thank you Vivien !) Tie-rod ears deflection No (Dial gauges) No Next week (+1) None Q 1 position vs. force on tie-rods Tie-rod strain gauges (DOMS preferable) Preferable Week 8 or 9 (+2/3) EN/MME (strain gauge installation + output) Realignment tentative without vacuum Tie-rod strain gauges (WPS preferable or laser tracker) Preferable Week 9 -10 (+3/4) EN/SMM (WPS or laser tracker) Tie-rod ear deflection under vacuum Tie-rod strain gauges DOMS Yes Week 11 -15 (+5 +10) EN/SMM (DOMS installation + output, Acquisition set up) Realignment trial on each jack Tie-rod, DOMS, WPS, Load cells Yes Week 11 -15 (+5 +10) EN/SMM (Load cell installation, motorized jack) Successive realignment to assess the position drift Tie-rod, DOMS, WPS, Load cells Yes Week 11 -15 (+5 +10) EN/SMM (motorized jack) Blocked jack – realignment trial Tie-rod, DOMS, WPS, Load cells Yes Week 15 -19 (+10 +15) EN/SMM (motorized jack)

Conclusion • This test program should clarify the working conditions of the triplet string in the current installation. • From there we will have hopefully a clear direction to : • • design a consolidation solution implement it in b 181 review its adequacy propose it to the management