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Beamline

Beamline 1. Beamline Target/Misalignment problem 2. Magnet measurements 3. Everything that’ critical and outstanding – eg d/str beamline monitors final use cases - complete commissioning plan - apologies if this section is incomplete. 4. Beamline review – 16 th .

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Beamline

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  1. Beamline 1. Beamline Target/Misalignment problem2. Magnet measurements3. Everything that’ critical and outstanding – eg d/str beamline monitors final use cases - complete commissioning plan - apologies if this section is incomplete.4. Beamline review – 16th. Kevin Tilley MICE VC. 1st November

  2. 1. Beamline / MICE-Target Misalignment Seeds of a problem:- At cm19:Observation that MICE target & beamline axis may not “necessarily” coincide. MICE target quoted as intercepting beam at ~+40mm above beam centre. Subsequent to cm19: Beamline assumes target is & points back at +65mm above beam centre. MICE target at ~+40mm above beam centre. -> beam starts at y=-25mm, y’=+9.7mrad. -> beam will misteer. -> beam will pass through ISIS vacuum vessel.

  3. 1. Beamline / MICE-Target Misalignment • What effect would the misalignment have, if true:- • Optical misalignment:- - Before decay solenoid – central ray has y=0 y’=+20mrad. - pion flux is 20% down due to steering & scraping - After TOF1:- - change in alignment of muon beam into MICE(hence effect on max cooling performance) • ii) Beam passage through vacuum vessel:- Scenario Flux at MICE (arb units of muons. Nmll +/-10% momentum cut) Basic beam optics design:- 65mm source, no steel: 5196 Current situation:- 40mm source, 10mm sidewall (at 25deg->23mm in direction of beam) 840 What we should have:- 65mm source, 2mm window parallel to ISIS (at 25deg->4.7mm in direction of beam) 2840 From 65mm point From 40mm point

  4. 1. Beamline / MICE-Target Misalignment Corroborating the numbers:- 1) Axis of beamline:- 65mm from engineering (apologies for the diagram)

  5. 1. Beamline / MICE-Target Misalignment Corroborating the numbers:- 2) Target dip: 40mm?? - 3 approaches to corroborate:Approach 1/3:- Sheffield are checking their numbers which gave position at which target intercepted beam: eg. 40mm? = physical offset in unpowered + (internal measure @ clip – internal @ unpowered)…. Underway. - From diagrams.- Else whole thing from Laras computations Internal measure @ clip Internal measure @ unpowered 40mm? physical offset in unpowered.

  6. 1. Beamline / MICE-Target Misalignment • Corroborating the numbers:- • Target dip: 40mm? 3 Approaches to corroborateApproach 2/3:- • Measurements: target dipped at least 20mm from edge of beam when at 2ms. Beam within beampipe -> Thus dips from somewhere below 67mm -> somewhere below 47mm.cf MICE 40mm measurement.

  7. 1. Beamline / MICE-Target Misalignment • Corroborating the numbers:- • Target dip: 40mm? 3 Approaches to corroborateApproach 3/3:- From the Old HEP target: Target nominal centre position: 63.5mm. Target size to tip ~ 6.25mm Target oscillation amplitude ~ 5mm ISIS Beam bumps ~ 15mm. -> 63.5-6.25-5-15 = 40mm to centre of (bumped) beam. = cf 40mm MICE tgt measurement This doesn’t take account different positions of HEP target &MICE target (MICE target is ~760mm upstream. Difft beamsizes – assume (bigger,less dense) -> same overall movement.

  8. 1. Beamline / MICE-Target Misalignment Proposal / solution. Plan to realign beamline axis & vacuum vessel around 38mm datum. - Reason: -MICE target measurement actually 40-37mm. - We may wish to dip further in to increase rates. - Thus choose 38mm. New vacuum vessel New upstream frame with largertilt to aim at +38mm.

  9. 2. Magnet measurements. Plan to measure Q4-Q9 from next week hopefully onwards. ~ 1 x Q35 per week? B2 from early December hopefully. Recheck above polarities when hooked up (Dec/Jan) Return to B1 when hooked up – late Jan (polarities) Return to Q1-Q3 when hooked up – late Jan (polarities)

  10. 3. Everything that’ critical and outstanding – eg d/str monitors final use cases (TOF0/1 good enough?) - complete commissioning plan - apologies if this section is incomplete.

  11. 4. Beamline Review 16th November. Finish Agenda/charge & forward – discussion after VC? – OR TOMORROW PREFERABLY?

  12. Extra Slides:- Effect of passing through thick vacuum vessel. Calculation of beam fraction traversing thick steel:-Assuming source at 40mm point above vacuum pipe centre:-centre relative to edge of window:- (40/2)-(65-40)+214 tan (9.7mr)~-3mm.Then beam overlap is: 3.75mm (beam half-height) -3mm -> overlap of ~ 0.75mm. Rest of beam height, 6.75mm tranverses thick steel. Note if beam drops to 38mm puts more in steel (comp a little by angle).Vessel same, quads aligned – removes angle – puts centre to -5mm. Hence all beam in steel.Thus at present, from source at 40mm, most of beam passes through the thick steel.Impact on beam at MICE:-Scenario Flux at MICE (arbitrary units of muons. Normal +/-10% momentum cut)Beam optics design:-65mm source, no steel: 5196Current situation:-40mm source, 10mm sidewall(at 25deg->23mm in direction of beam) 840Possible changes:-40mm source, 2mm window prl to to ISIS (at 25deg->4.7mm in direction of beam) 2840 40mm source, 2mm wdw perp to MICE beam(perpendicular->2mm in direction of beam) 3773

  13. From 65mm point From 40mm point

  14. Original design optic – no upstream steel.

  15. Current situation. Original design optic (red) & rms-profiles with 23mm stainless steel (below beam window & thru 10mm @ 25deg = 23mm).

  16. Possible change. 2mm window parallel to ISIS beam (as currently, but lowered).Original design optic (red) & rms-profiles with 4.7mm stainless steel (thru 2mm beam window @ 25deg = 4.7mm).

  17. Possible change. (2mm Beam window perpendicular to MICE beam: presenting 2mm only)

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