NLC - The Next Linear Collider Project NLC January Video conference Status of Permanent Quadrupoles James T Volk January 18, 2001

NLC - The Next Linear Collider Project NLC Quad Specifications

NLC - The Next Linear Collider Project Corner tuner Rods rotate to adjust field Rotating tuning rods Permanent magnets Pole

NLC - The Next Linear Collider Project Wedge Quad Rods rotate to adjust field Rotating magnetsWedge Magnets Pole

NLC - The Next Linear Collider Project SSW and Wedge Quad Wire stages

NLC - The Next Linear Collider Project Gradient ((measured-average)/average)*10000 FWHM 3 units

NLC - The Next Linear Collider Project Center Stability Difference between 5 successive measurements FWHM 2 microns

NLC - The Next Linear Collider Project Calculated vs.Measured Field PANDIRA predicts 0.62 Tesla at m for m This is Tesla SSW measures Tesla 16% lower than predicted Br and Hci in calculation needs to be adjusted

NLC - The Next Linear Collider Project FWSQ001 Close to desired field 16 % low Have 20% tunable range Need to measure Center stability during adjustment The FNAL test stand is capable of these measurements New wedge tuner design in drafting magnet material on order Increase the amount of magnet material by 15% increased predicted field by 25%

NLC - The Next Linear Collider Project Status of permanent “wedge” magnet measurements at SLAC, Jan 2001,pg 1/2 Tuner rods much harder to rotate than expected –Chain drive mechanism was modified but still one rod rotated by degrees more than other 3, so resorted to no chains, rotate each rod by hand and clamp in place with special plate. If we have the rod starting positions correct, then we have the rotated the 4 tuners through the same angle to 0.37 degrees – corresponds to  1  m –Concern- does rotating one at a time introduce some magnetic hysteresis effects? Only measuring X co-ord with a stretched wire system –not the highest resolution linear stages –measuring set-up is not thermally stablilized –thermal noise is significant (signals are very small) –precision of each measurement is 3-4 microns Nevertheless we’ve measured the X center – at various tuner rod angles, corresponding to different  G.dl

NLC - The Next Linear Collider Project Status of permanent “wedge” magnet measurements at SLAC, Jan 2001,pg 2/2 X magnetic center observed to shift by up to 37  m when strength is changed by rotating tuner rods. The larger the rotation the larger the  x, 114   20% strength change  37um Several things could be causing these shifts, so not a final measurement, e.g. whole magnet moves as exert much force to rotate rods; stretched wire set-up maybe temp sensitive; rod starting angle wrong. Improvements being made to improve precision: –highest res linear stages about to be refurbished by Newport Corp –thermal noise being reduced; thermal stability to be improved –modify fitting routine From electromagnet measurements we know rotating coil’s precision in x/y is  m and is very stable so rotating coil’s length being extended so it can measure the permanent magnet prototypes Second wedge magnet being assembled with less stiff tuner rods

NLC - The Next Linear Collider Project Sliding Shunt

NLC - The Next Linear Collider Project Shunt Quad on SSW stand

NLC - The Next Linear Collider Project Shunt Quad Test Gradient Tesla\meter Maximum field Tesla Minimum Field Tesla 13.5% change Center Shift ~ 15 microns From Max field to Min field New design in works improve sliding bearings

NLC - The Next Linear Collider Project Rotational quad Permanent magnets

NLC - The Next Linear Collider Project Rotating Quad Parts are in the shop Expect to have a magnet by March

NLC - The Next Linear Collider Project Issues to test Center Stability Strength Repeatability in Tuning Speed of Gradient Change Radiation Hardness

NLC - The Next Linear Collider Project Conclusions There are three prototype permanent magnet quads Two more on their way Two test stands SLAC and FNAL capable of doing measurements Both SLAC and Fermilab agree to better than 1 part in 10,000 on strength Will start rigorous test of stability Will chose “best” model this year