1. Magnetic Measurements of MICE Stators & PMs Ben Shepherd MICE Target Workshop RAL, 13 December 2011

2. Contents Stator – Measurements – Comparison to previous results Permanent magnet measurements – New PMs – T1 PMs

3. Initial scan Along x=y=0 – to determine peak positions and give us a zero offset B0, B1 are transverse; B2 is longitudinal Arbitrary units since not calibrated in all directions

4. Centre-finding scan At each peak in B2 Fit a quadratic function in x and y: Solve to find minimum field 89.3-2.0-1.8-1.6-1.4-1.2-0.8-0.6-0.4-0.20.00.20.40.60.81.01.21.41.61.82.0 -2.00.00000-0.00026-0.00025-0.00024-0.00023 -0.00022 -0.00023 -0.00024 -0.00025 -1.8-0.00026-0.00025-0.00024 -0.00023-0.00022 -0.00021 -0.00022 -0.00023-0.00024 -1.6-0.00026-0.00025-0.00024-0.00023-0.00022 -0.00021 -0.00020 -0.00021 -0.00022 -0.00023-0.00024 -1.4-0.00025-0.00024-0.00023-0.00022 -0.00021 -0.00020 -0.00021 -0.00022 -0.00023 -1.2-0.00025-0.00024-0.00023-0.00022-0.00021 -0.00020 -0.00019-0.00020 -0.00021 -0.00022-0.00023 -0.00024-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00020 -0.00021-0.00022 -0.8-0.00024-0.00023-0.00022-0.00021 -0.00020 -0.00019 -0.00020 -0.00021 -0.00022 -0.6-0.00024-0.00023-0.00022-0.00021-0.00020 -0.00019 -0.00020 -0.00021 -0.00022 -0.4-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00018-0.00019 -0.00020 -0.00021-0.00022 -0.2-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00018 -0.00019 -0.00020 -0.00021 0.0-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00018 -0.00019 -0.00020 -0.00021 0.2-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00018 -0.00019 -0.00020 -0.00021 0.4-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00018 -0.00019 -0.00020 -0.00021-0.00022 0.6-0.00024-0.00023-0.00022-0.00021-0.00020 -0.00019 -0.00020 -0.00021-0.00022 0.8-0.00024-0.00023-0.00022-0.00021 -0.00020 -0.00019 -0.00020 -0.00021 -0.00022 1.0-0.00024-0.00023-0.00022 -0.00021-0.00020 -0.00019 -0.00020 -0.00021 -0.00022 1.2-0.00025-0.00024-0.00023-0.00022-0.00021 -0.00020 -0.00019 -0.00020 -0.00021 -0.00022-0.00023 1.4-0.00025-0.00024-0.00023-0.00022 -0.00021 -0.00020 -0.00021 -0.00022 -0.00023 1.6-0.00025 -0.00024-0.00023-0.00022 -0.00021 -0.00020 -0.00021 -0.00022 -0.00023-0.00024 1.8-0.00026-0.00025-0.00024-0.00023 -0.00022 -0.00021 -0.00022 -0.00023 -0.00024 2.0-0.00026 -0.00025-0.00024-0.00023 -0.00022 -0.00023 -0.00024 -0.00025

5. Results Good agreement between centres measured by transverse and longitudinal fields Centres all within 200µm in x and y

6. Comparison with other stators Similar spread to T2 Both worse than T3, which had a near- constant offset all the way through My nomenclature (probably inconsistent – sorry!) First stator I measured Second Third (this one was used in ISIS)

7. Measurements of new PMs Measured eight new PM assemblies in the lab PM mounted on a rotating stage Hall probe attached to spring-loaded holder to keep it at the same distance from the PMs (about 1mm away) Looking for the smallest change in B r with  z 

8. New PMs – measurement results 12345678 troughs Mean field-0.210-0.219-0.216-0.218-0.215-0.217 Standard deviation0.010 0.0060.0150.0030.0050.008 Relative standard deviation4.8%4.4%4.5%2.5%6.9%1.2%2.1%3.8% Normalised (0 = best, 1 = worst)0.630.550.560.231.000.000.150.46 peaks Mean field-0.276-0.300-0.285-0.289-0.288-0.287-0.286-0.285 Standard deviation0.0060.0030.0040.0020.004 0.0020.007 Relative standard deviation2.0%1.1%1.4%0.8%1.5%1.4%0.7%2.4% Normalised (0 = best, 1 = worst)0.790.210.430.030.450.400.001.00 overallSum of two “normalised” rows1.410.760.990.251.450.400.151.46 In each row, the green cell is the best and the red the worst. Magnet #7 has the lowest relative standard deviation for peaks (0.7%) and the second- lowest for troughs (2.1%). So in terms of field uniformity, this is probably the best, followed by #4 and #6.

9. Measurements of old PMs Used same technique to measure PMs from T1, just removed from ISIS Variation of radial field: 2.1% for troughs, 2.6% for peaks Compared to the new ones – ‘mid-range’