1 J.DiMarco 16Nov2010 LQS01b Magnetic Measurements Results ( preliminary ) J. DiMarco 16Nov2010

2 J.DiMarco 16Nov2010 Measurements: 25Aug – cold measurements at VMTF at 5328A (100T/m) 14Oct – warm measurements in IB3 at 10A Probes: 25cm long, R=23mm radial probe (VMTF) 10cm long, R=23mm radial probe (VMTF) 10cm long, R=21.7mm tangential probe (VMTF) 49cm long circuit board, R=29.4mm (ferret) (warm meas.) on single circuit board displaced longitudinally

3 J.DiMarco 16Nov2010 ‘Ferret_MFM’ system: 59mm diameter probe, rotating inside ~63.5mm outer tube 3 signals: UnBucked (UB), Dipole Bucked (DB), and Dipole+Quad Bucked (DQB) Labview data acquisition application Matlab analysis code Measurements: LQS01b measurements 10/14 4Hz rotation rate with external flex shaft, sampling at 40kHz with NI- 4472b (DSA) (ADC) card. 10A magnet current (  gradient ~ T/m  5mT at UB radius  1 unit of harmonics is ~0.5  T) 6 channels of input (Index, Encoder, UB/DB/DQB probe signals, current) (gravity sensor not recorded) Measurements every 0.25m (probe length ~0.5m) On board amplifier has gains 10/1000/1000 for UB/DB/DQB respectively.

4 J.DiMarco 16Nov2010 Ferret probe for warm measurements

5 J.DiMarco 16Nov2010 Ferret system has only recently (Fall 2010) been assembled… measurement of LQS01b was the ferret system ‘commissioning’ ! …presentation reflects state of the system as well as magnet

6 J.DiMarco 16Nov2010 LQS01b data at z=0 position warm measurement (weak field  ~5mT quad) UB Signal DQB Signal Raw ferret data at 10A

7 J.DiMarco 16Nov2010 Probes used for cold (VMTF) measurements 10 and 25cm circuit board (radial) probes 10cm Tan Probe

8 J.DiMarco 16Nov2010 Some caveats in comparing warm/cold data: 1) The lengths of the probe used in VMTF and in warm meas. are different – 25/10cm and ~50cm respectively 2) Probe diameters are different - 46mm VMTF and 59mm IB3 - this accounts for the larger error bars in high harmonics of the cold data (taken at low gain). 3) The dipole-bucked (DB) winding of the probe in the warm measurements (ferret) was saturating the datacq, and could not be used for the absolute quad strength of the warm data (the strength is given from the un-bucked (UB) signal at the nominal radius (which should be reasonably close however)) 4) Z-positioning in warm data was very approximate (the probe had a very tight fit in the pipe and moving it disturbed the position of the pipe, etc.) - warm positions may be off by 2cm+. Z-positions in the cold data were not well matched between probes. 5) The leads position was different as configured vertically in the dewar compared to IB3. Data near end may have some effects from this.

9 J.DiMarco 16Nov2010 Error bars are statistics (sd) only Probe centering offsets are large, 4-6mm in both warm and cold data (first order correction only has been applied) Harmonics reported at reference radius of 30mm Also note….

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30 J.DiMarco 16Nov2010 Conclusions: Reasonable agreement was obtained among the cold measurements with the various probes Warm scan also agrees fairly well, but there are some significant differences in quadrupole strength and longitudinal features of sextupole component More work needed to understand/gain confidence in probe measurements: continued development, bench testing, inter-calibrations are planned LQS01b has large b4/a4 and b6 harmonics. Some other harmonics also seem to show significant variation as a function of z-position (b3, a3, a5).