NMR water cell calibration
From Hall A Wiki
NMR signal to He3 polarization relation is calibrated by water cell test.
Water Resonance Position
Target Motion Restriction
- In normal operation, target should not move up pass the reference cell in beam position. This will be the upper-limit.
- The only time, it is needed to go beyond the upper-limit is to install/remove target cells. To go beyond the upper-limit, one will need to detach the target ladder from oven by removing two ceremaic screws and two pins.
- Inform Ed Folts that a water calibration is planned (usually over a weekend). Inform other people who might be working in the hall at the time of water calibration.
- Coordinate with Ed Folts to have possible noise sources be turned off, such as AC, pumps, LCW water, if they can be turned off without too much interruption to other works in the hall.
- Remove polarized 3He cell (authorized personal only) if it is in the system. To be able to dismount polarized 3He cell, you will need to remove target collimators and pick-up coils (keep the base fixed if there were previous water calibrations). Face-mask and hearing protections required when removing the high-pressure 3He cell. Move target ladder to the up-most position (which is only allowed when the target collimators and pick-up coils (not include bases) are removed. Then remove the 3He cell following the procedure in OSP.
- The target ladder can be removed, left out and be re-installed after water calibration is completed (optional).
- Install a water cell.
- Mount pick-up coil base if it is not already there. Mount pick-up coils.
- Connect NMR instrumentation.
- Turn on holding magnetic field power (following OSP).
- Turn on RF power (following OSP).
- Adjust coils to minimize noise.
- Measure inter-coil distances. Measure distances from the water cell to pick-up coils.
- Perform NMR water sweep program. Data recorded to disk. Check data quality.
- When water calibration is completed, stop the program.
- Do a Q-curve measurement.
- Turn off holding magnet field and RF powers if they are not going to be used.
- Remove water cell. You will need to remove the pick-up coils (not the bases) first.
- The pick-up coil bases should NOT be moved after water calibration. Note: Moving the bases will make the water calibration not useful for calibrating future 3He NMR signals.
- Re-install 3He cell, pick-up coils and target collimators.
Sep. 28, 2008 measurement
Coil Position Survey
All error below is 65% CL static error Up Stream: Cell Diameter = 19.27 +/- 0.05 mm Distance between 2 pick up coil inner surface : 21.31 +/- 0.14 mm Cell to left Coil Inner Surface = 0.34 mm (Preliminary, could come with high Error) Cell to right Coil Inner Surface = 1.70 mm (Preliminary, could come with high Error) Down Stream: Cell Diameter = 18.62 +/- 0.03 mm Distance between 2 pick up coil inner surface : 20.87 +/- 0.07 mm