A Summary of the Fermilab Magnetic Measurements Of MICE Spectrometer Solenoid 2 M. Tartaglia 18 January 2013

The Spectrometer Solenoid M1 M2 E1 C E2 40 cm diameter warm bore 2.6m long cryostat SS2 under test; SS1 under repair All coils wound on one machined Aluminum (6061-T6) Mandrel; Outer Aluminum Bands

Solenoid Power, Control & Monitoring Testing and Measurements used 3 power supplies: Configured to power M1-only, M2-only, E1+C+E2 in series

The Measurement System Hall Probe: Senis 10T probe (S/N5406) Field Readout:Keithley 2700 Mux/DMM – Student developed Labview system Probe positioning System – Probe mount with close pair of bearings shaft side – Long G10 shaft (sections) with continuous scale – Scribe line to keep probe angular orientation – Stainless Steel guide tube (2 joined sections) Tested in TC1206 at 4 T to ensure non magnetic joint – Guide Tube positioning plates at each end Tube positioning slots Machined to 0.1mm precision G10 capture rings each end fix the Z position reference

The Measurement System

3D Hall probe calibration checked against NMR probe up to 4 T at Fermilab MTF in Tevatron dipole TC1206; stainless steel guide tube and seam also verified as non- magnetic.

The Measurement System Coordinate Systems – Probe Readout: +Z is from M1 towards E2 +Y is up +X is to the left as viewed from M1 looking toward E2 – Probe Position: +Z is from M1 towards E2; measured wrt M1 end of the guide tube (fixed by capture rings wrt end plates) “X100” is really X= -100 mm in probe frame “Y100” is really Y= -100 mm in probe frame – Field: Bz points from E2 to M1 (along –Z); Opera matches Data +Bx +By +Bz

The Measurement System Magnet Current Readout – Visual front panel display on each PS – Internal shunt recorded by LINUX monitoring sys. – Digital values agreed with nominal settings (<1%) Measurement Procedure (2 people) – Start a new file for each Z-scan Encode coils, current, date into file name – Move Guide Tube to desired location, adjust ref. angle – Manually position probe in Z (moving in or out) 1 or 2 cm steps, except when centering bearings near end – Adjust probe angle to align scribe mark – Manually enter current, Z position to Labview GUI – Trigger reading of Hall probe voltages (avg ~3/min) Automatically recording 10 measurements for each Z step

The Measurement History 6/11/2012 – 0 A noise, offset levels – Checkout 10 A M1+M2, X0Y0 6/12 – 0 A noise, offset check – M2 50A scans, X0Y0; X100Y0; X0Y100 – ECE 50A scans, X0Y0; X100Y0 6/13 – Shaft jammed in tube; removed and repaired (Z shifted!) – M1 50A scan, X0Y0 – ALL 185 A started (3 points), then Quench 6/14 – ALL 150A scans, X0Y0; X100Y0; X0Y100

The Magnetic Model Opera2D is adequate (assuming cyl. symmetry) – Independently modeled in Opera3D by Marc B. As-Built Geometry and Winding Data Used – MICE note 207, table 5 for SS2 (SS1 is VERY close) – Dimensions known at room temperature to 50μm – Thermal Contraction Coefficient ? I used 3*10 -3 This gives 7.5 mm shrinkage over the magnet length! 4*10 -3 is probably a better number for Aluminum… Generate {Bz, Br} vs Z to match each data set −For Specified coils at 50A or 150A, at R=0 and R=100mm −Fine 1mm spacing in Z, to make best match to data

The Magnetic Model

The Data Analysis Use MATLAB to calculate dBz, dBr (data-model) – For each data set, determine Z offset to give best agreement to match Bz (by eye; to ~± 2mm) – For each Z data, the program: calculates averages, errors of the 10 Bx, By, Bz data measurements calculates BxCor= Bx + α ·Bz, where α=-.016 (later -.018) – Due to constant X-Z tilt of the probe (this is ~ 1 degree) Loops through array of model points, finds index of (Z model -Z offset ) that is closest to Z data then calculates dB=B data -B model for that Z data Writes a new excel spreadsheet of B’s and dB, vs Z – Run program separately to generate dBz and dBr Plot data, model, differences in Excel

Summary of Results 1)Zoffsets, from best match of Bz DateCoilsCurrentPositionZoffset, cm 6/11M1M210X0 Y0(-40.0) 6/12M250X0 Y /12M250X100 Y /12M250X0 Y /12ECE50X0 Y /12ECE50X100 Y /13M150X0 Y /13ALL185X0 Y0QUENCH! 6/14ALL150X0 Y /14ALL150X100 Y /14ALL150X0 Y Shaft stuck

Summary of Results 2)Bz vs Z M1M2 on axis

Summary of Results 2)Bz vs Z M1 on axis

Summary of Results 2)Bz vs Z M2 on axis

Summary of Results 2)Bz vs Z M2 off axis

Summary of Results 2)Bz vs Z M2 off axis

Summary of Results 2)Bz vs Z ECE on axis Why the slope?

Summary of Results 2)Bz vs Z ECE off axis Why the slope?

Summary of Results 2)Bz vs Z ALL on axis 100 G shift in measured Bz 1A change is 2.25T/150A =150 G

Summary of Results 2)Bz vs Z ALL off axis Why the slope?

Summary of Results 2)Bz vs Z ALL off axis Why the slope?

Summary of Results 2)Bz vs Z: Maximum dBz(data-model)/Bz DateCoilsCurrentPositionM1M2ECE 6/11M1M210X0 Y0~1%~7 % 6/12M250X0 Y02.5% 6/12M250X100 Y02.5% 6/12M250X0 Y1003.0% 6/12ECE50X0 Y00.5% 6/12ECE50X100 Y00.5% 6/13M150X0 Y00.5% 6/14ALL150X0 Y00.5%1.0%3.0% 6/14ALL150X100 Y00.5%1.0%3.0% 6/14ALL150X0 Y1000.5%1.0%3.0% Small discrepancies might be improved by a) Z scale (use CTE=4 10-3), b) slight radial offsets (next section)

Summary of Results 2)Bz vs Z: Sensitivity to radial position? For small R, not very: look at M2-only, at peak Bz: at R=0.1m for dR=10mm, dBz/Bz~5/375=1.3% (ECE: even less)

Summary of Results 3)Br vs Z: Sensitivity to radial position M1 50A Br vs Z at R=0.1m Br vs R at peak (Z=-0.3m) Br ~linear with R; dBr/dR= 9.1

Summary of Results 3)Br vs Z: Bx and By offsets Bx(0A) ~ +4 to +5 GBy(0A) ~ 0to -5 G

Summary of Results 3)Br vs Z: M1 on axis - easily affected by probe tilts Consistent with radial offsets ~ 1mm from magnetic axis

Summary of Results 3)Br vs Z: M2 on axis – peak dB/dR ~ 5 R=0:  X ~ +2 mm,  Y ~ -2.5 mm

Summary of Results 3)Br vs Z: Data vs Model M2 off axis – Bx at X=-100mm (compare to –Br(0.1m))

Summary of Results 3)Br vs Z: Data - Model M2 off axis – peak dBr/dR = 6.7 R=0.1m  X~0 (<1mm); By affected by probe rotations!

Summary of Results 3)Br vs Z: Data vs Model M2 off axis – By at Y=-100mm (compare to –Br(0.1m))

Summary of Results 3)Br vs Z: Data - Model M2 off axis – either  Y~ -4mm (or some coil ellipticity?) Bx affected by probe rotations

Summary of Results 3)Br vs Z: Data vs Model ECE on axis – peak dB/dR ~ 9.4 R=0:  X ~ +3 mm,  Y ~ -4 mm Why the slope?

Summary of Results 3)Br vs Z: Data vs Model ECE off axis – Bx at X=-100mm (compare to –Br(0.1m))

Summary of Results 3)Br vs Z: Data - Model ECE off axis –  X ~ +5 mm,  Y (probe rotation)

Summary of Results 3)Br vs Z: Data vs Model ALL on axis – dBr/dR=18.5, 29.3 G/mm at E1,E2  X~ +1.3, +2.1  Y~ -7.4, -7.3 mm Why the By slope? Shift in Bx due to 2 mrad change in probe tilt

Summary of Results 3)Br vs Z: Data vs Model ALL off axis – Bx at X=-100mm (compare to –Br(0.1m))

Summary of Results 3)Br vs Z: Data - Model ALL off axis –  B model /1mm = { 25.7, -11.0, 7.5, -4.5, 17.5, } T/mm  X ~ { 4.7, 1.6, 14.1, 4.2, 7.3, 5.5 } mm (30 G corr. for Bx shift = 1 mrad) (probe rotated in Y)

Summary of Results 3)Br vs Z: Data vs Model ALL off axis – By at Y=-100mm (compare to –Br(0.1m))

Summary of Results 3)Br vs Z: Data - Model ALL off axis –  B model /1mm = { 25.7, -11.0, 7.5, -4.5, 17.5, } T/mm  Y ~ { -5.8, ҉, -16.7, -14.7, -15.4, } mm (probe rotated in X)

Summary of Results 2)Br vs Z:  X,  Y (in mm) DateCoilsCurrentPositionM1M2E1E2 6/11M1M210X0 Y0 6/12M250X0 Y /12M250X100 Y0<1 6/12M250X0 Y /12ECE50X0 Y /12ECE50X100 Y /13M150X0 Y0~1 6/14ALL150X0 Y /14ALL150X100 Y /14ALL150X0 Y Not completely sure what conclusions we can draw from these numbers

Summary of Results 2)Br vs Z: 1)There appears to be a small slope dX/dZ and dY/dZ ~1-2 mrad wrt meas. axis 2)Did cold mass move after the quench (or at 150A due to greater ext. forces)? (or, what else might be going on?) 8 mm shift ! On axis/ Off axis difference

Lessons Learned Improvements To Make – Stiffer beam or tube; Key/slot to fix probe angle – Digital encoder for Z-position (e.g., “string pot”) – Bearings along the length, better shaft centering – Better yet, Motorize and automate the scans Piezo motor - Has to operate in high field. Short probe holder between bearings, drawn by motor Additional Data to Take – Each coil powered separately, on & off axis – Wider range of currents, better current monitors Capture current from the shunt directly, with probe V’s