# Field Mapping¶

## Status¶

- We have data at different currents
- For upstream SS we have survey that maps field mapper to fiducials
- For both FCs we have survey that relates the mapper to the flanges; and we can relate the flanges to the fiducials

Aim to relate the axis to the fiducials

Aim to improve knowledge of coil dimensions

## Magnetic Axis¶

Two algorithms exist to find the axis; quick one and slow one; both should converge on the same answer- Fit Bx vs x, By vs y, look for y-intercept
- Bulk field calculation vs assumed position/dimensions of the coil
- Calibration: misalignment of hall probes; python function in the code
- Calibration: mispositioning of the mapper; python function in the code
- Calibration: cross-check field integral on a loop (Maxwell law)

Follow the calibration procedure done by Atlas

All proved on fake data

## Coil Dimensions¶

Two algorithms exist; assume the axis- Brute force approach; fit to position, dimensions of the coil; go coil by coil
- Not brute force approach; take short thin field map, long thick field map, add together linear sum of the two field maps

All proved on fake data

Other issues (spoilers)- MDIC paper
- This
- Step I papers

Risk: non-linearity in the iron in SS

Risk: misalignment of coils on the bobbin

Risk: force dependent alignment

Let's meet again: Friday 14th November