NMRs

The programs for both the S800 analysis line and spectrograph can be started by clicking on the icons labeled S800A_NMR and S800S_NMR, located on the desktop of uxpc2. The picture shows the spectrograph GUI as an example. The top (yellow) panel shows the data relevant to the NMR module, the middle (pink) the digitized signal from the oscilloscope and the bottom (blue) the status and measurements for the dipoles.

The NMR program constantly checks the status of the various dipoles from the EPICS system and updates the status column. In addition, the program checks the log file at startup for the closest previously measured value. In case no previous measurement can be used the program searches for a signal around the guessed value of the field. This search can take some time if the calibration is off or the hysteresis of the dipole is large.

If a dipole is turned off or its field is being changed, the status shows either “Off” or “Unstable” and the program issues a beep. If this happens under running condition in data-taking mode, stop the beam and ask the operator to assist you in investigating the situation of the magnet giving the problem. The operators have the possibility to check on all magnet power supplies and helium fill levels in the control room. A magnet current below the set value, for example, is indicated in Barney as a blue circle on the respective optics element. The S800 Barney page with all magnets operational looks like that:

The magnet currents, measured fields, and deviation from the set value are logged in a file that is soft-linked from the "current run " directory. An example of the log file (analysis.log) for the four dipoles of the analysis line is shown below.

For technical details of the NMR GUIs please read this.