ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 1 Information on Alignment Issues for ATF2 magnets: for discussion Cherrill Spencer, SLAC Member of ATF2 Magnet Team

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 2 Main issues to be brought up today- not expecting to find resolution today Are 3 sets of ATF2 magnets that are being “made from” old SLAC magnets: –Final doublet quads: QF1 and QD0 –Final doublet sextupoles: SF1 and SD0 –Final focus sextupoles: SD4,SF5 and SF6 These 3 sets cannot be modified to fit in with the KEK way of aligning magnets (problem will be described in detail in this presentation)

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 3 Main issues continued The magnet roll tolerances given in figure 3.6 on page 16 of chapter 3 of the ATF2 proposal are extremely tight and probably not achievable: –Approx 40 μrads for the FF quads & sexts –Approx 5 μrads for QF1 and QD0 –Between 0.5 and 2 μrads for FF bends :B5,B2,B1 Magnets must be aligned with smaller rolls than this else the spot size will increase by 2% I have been consulting with Glen White who is running detailed simulations of the ATF2 beamline and tracking 1000s of particles passing through the magnets which have a variety of alignment errors and then he sees if he can tune the beamline to get the desired spot size- will show his alignment errors/tolerances later

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 4 Conventional Alignment Optical tooling balls are secured on the magnet: at SLAC we “fiducialize” all the tooling balls: work out how far from each tooling ball center to the magnetic center or mechanical center. Robert Ruland, SLAC

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 5 SLAC’s process of aligning a magnet- more info This sphere has a specially shaped reflector – center of reflector is at center of the sphere. Beam of laser light is bounced off reflector and can work out where ball is to a few microns. Spheres are placed without any precision on the outside of all magnets. Using pulsed stretched wire to find magnetic center and a coordinate measuring machine (CMM) to make mechanical measurements, can relate the spheres’ positions to the magnetic center. This process is called FIDUCIALIZATION. Every magnet has to be fiducialized BEFORE it is put in the beamline- each magnet has a unique identity. The fiducialization data is kept in a DATABASE “for ever”; alignment crew refer to it whenever they align a magnet.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 6 KEK’s method of aligning magnets uses a reference alignment base- is placed VERY PRECISELY on top of magnet so a target inserted in central hole lines up with the magnetic center to within the alignment tolerance Drawings of alignment base made for the ATF2 QEA quads and DEA dipoles (are brand new magnets). Units are inches – so quite large item

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 7 ATF2 QEA quad with alignment plate and target.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 8 Measurement system at KEK Ceramic coil for rigidity, smaller thermal expansion Bobbin is made of Macor. Air bearing, for smoother rotation Reference plate （基準面） for alignment Room & water temperature are controlled. Electronics (Integrator etc) are kept on all the time.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 9 Big problems with magnet & alignment base machining : 3 cases –from Masuzawa talk on QEA measurements Correct case Alignment base center Split line between the cores Bore center Must be aligned. (1) Magnet bore is not aligned. How could this happen?? EDM process??? (2) Alignment base is not aligned. (3) (1)&(2) mixed.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 10 2 mrad, we think this is not fake (coming from the System) but real difference from each magnet. Quadruple phase (median plane) for 2nd batch 50 A magnets 水平 Alignment base is not parallel to the magnet plane. Variation too large

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 11 The magnet core has to be designed from the start to use these plates in the way KEK tends to use them BUT :cannot add such a plate in the necessarily precise way after the magnet has been designed and made. The core pieces have to be toleranced to accommodate the base. How these alignment bases might fit on the FD quads.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 12 How were these FD quads aligned in FFTB: with special apparatus Invar tooling plates, so do not change size with temperature variation. Aiming for < 30 micron errors.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 13 An FFTB quad in FFTB with its alignment apparatus Invar tooling plate

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 14 Problem because of the difference between KEK’s and SLAC’s alignment techniques 2 sets of SLAC magnets will be fiducialized using SLAC style tooling ball and alignment process, then will be magnetically measured at SLAC– I think KEK does not have the equipment to measure them at KEK. HOW to align them in the ATF2 beamline?

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 15 Brand new ATF2 FF dipole- just completed at IHEP, with 2 alignment bases

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 16 From Glen White: Static Error Parameters Assume movers on all FF and FD quadrupoles and sextupoles. Cavity BPMs fixed to all FF Quads + Sexts. Also assume IP BPM with 5nm RMS resolution. Model for SM measurement: mean spot size from 90 consecutive pulses +/- RMS error. Quad, Sext x/y transverse alignment 200 um Quad, Sext roll alignment (including QF1 & QD0) 300 urad Initial BPM-magnet field center alignment 30 um dB/B for Quad, Sexts1e-3 syst. + 1e-4 random Mover resolution (x & y)50 nm BPM resolutions100 nm Power supply resolution14 - bit Shintake Monitor Resolution 2nm

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 17 Tuning Results- from Glen White CaseMedian Spot Size / nm Initial EXT Tuned Lattice36.2 FFS Errors + GM ‘A’37.6 GM ‘A’ (Turn off EXT Sexts)38.6 ATF GM (EXT Sexts on) (no BEND errors)38.2 As Above but: 600 urad magnet roll errors40.9 As Above but: 150 urad magnet roll errors37.8 As Above but: add 1mr RMS BEND roll errors 37.9 ‘Nominal case’

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 18 Conclusion from Glen’s simulations Can ignore the tolerances in fig 3.6 in proposal and use his much looser tolerances – still tight but do-able with SLAC’s alignment techniques. But what about when they have to be put into ATF2 beamline at KEK? How/can will KEK use our fiducialization data.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 19 FF sextupoles have SLAC tooling balls – how to align them at ATF2? Sockets to hold SLAC tooling balls. This sextupole has 6 sockets.

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 20 Same problem with the small sextupoles to be used in FD. Sockets to hold SLAC tooling balls

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 21 Another problem– fitting in the MONALISA apparatus on top of QD0! Place a very flat and precise thickness shim in each split plane to “explode” the quad and enlarge the bore diameter. Shim will be low carbon steel, ground to ” flatness

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 22 Info from David Urner re putting MONALISA on top of QD0 We will have to stabilize QD0. The stabilization will connect QD0 to the Shintake monitor table. Indeed we will not be ready by next January. More likely by January We can of course bring a dummy system earlier if that would help. We would indeed need the LCWS hoses moved so that we can extend our platform. Alignment transfer: I agree that this needs some thought. I could imagine two different approaches: 1. Assuming you would use two alignment plates. They look fairly sturdy, so we could mount our base-plate on it and transfer the alignment using external theodolites. (Although I'm not sure that they have those available at KEK, we would have to inquire.) 2. What about putting a rectangular tube on top of the magnet. When we are ready we would slide our interferometer setup inside that tube. And you could mount the ATF2 alignment base-plates on top of it?

ATF2 Magnets ATF2 Magnets 2 Oct 2007Cherrill Spencer Info for ATF2 magnet alignment discussion 23 Space on poletip end is limited by the G10 clamps which exist on BOTH ends of the final doublet quads Urner et al want to mount a retro-reflector on a QD0 poletip end, I suppose on the upstream end? BUT HOW TO FIT IN WITH BPM and its adapter which cover up the poletips ? At the “terminal end” the maximum space between the G10 piece and the tip of the pole is 0.6” At the non-terminal end this space is 1”. BUT THIS SPACE WILL HAVE SMALL STEEL BUTTONS TO REDUCE 12-pole component. THESE INTERFERENCES HAVE TO BE RESOLVED!