nmr_probes
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nmr_probes [2019/10/17 10:32] pereira [Manually setting Dipole Fields] |
nmr_probes [2023/06/09 14:27] swartzj |
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| ====== NMR Control ===== | ====== NMR Control ===== | ||
| - | Two digital oscilloscopes are dedicated to NMR readout – one for the analysis line NMRs and one for the spectrograph NMRs. The scopes are located in data-U6, in upper two shelves on the right electronics rack. They are isolated from clean ground because this signals from the NMR probes are on a dirty ground. | + | Two digital oscilloscopes are dedicated to NMR readout – one for the analysis line NMRs and one for the spectrograph NMRs. The scopes are located in the S3 mezzanine. They are isolated from clean ground because this signals from the NMR probes are on a dirty ground. |
| ===== Motivation ===== | ===== Motivation ===== | ||
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| ===== Description ===== | ===== Description ===== | ||
| - | The NMR running programs for both the S800 analysis line and spectrograph dipoles can be started | + | The NMR running programs for both the S800 analysis line and spectrograph dipoles can be started |
| - | Sometimes the initialization of these applications fail. In that case check section [[nmr probes# | + | $ ssh [your-user-name-on-EXP]@exp-s3-nmr -Y |
| + | |||
| + | and typing, for the analysis line dipoles | ||
| + | |||
| + | $ / | ||
| + | |||
| + | and for the spectrograph dipoles | ||
| + | |||
| + | $ / | ||
| + | |||
| + | Now press start on the GUI and you should see a field reading. | ||
| {{: | {{: | ||
| + | ===== Terminating processes run by another user ===== | ||
| + | |||
| + | A solution has been implemented for the case where one user needs to run the NMR software via the ' | ||
| + | |||
| + | If a user is running ' | ||
| + | |||
| + | * Log on to exp-s3-nmr virtual machine (as described above) | ||
| + | * Type 'ps aux | grep wish' to find out the name of the user that is running wish | ||
| + | * Let's suppose user ' | ||
| + | * This will stop both wish processes that are running as user ' | ||
| + | * Now user ' | ||
| + | |||
| + | In short, | ||
| + | $ ps aux | grep wish | ||
| + | $ sudo -u usernameRunningWish pkill wish | ||
| + | | ||
| + | and you should be able to run the NMR software. | ||
| ===== Operation ===== | ===== Operation ===== | ||
| 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. The maximum number of attempts is limited to 200. After that the status is marked as " | 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. The maximum number of attempts is limited to 200. After that the status is marked as " | ||
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| ===== Troubleshooting ===== | ===== Troubleshooting ===== | ||
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| + | |||
| + | ==== NMR GUI does not start ==== | ||
| The NMR program is connected to the following devices and systems: | The NMR program is connected to the following devices and systems: | ||
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| + | ==== NMR GUI does not communicate with NMR controllers ==== | ||
| + | * This can be seen, for instance, when the NMR controller finds a resonance, but the NMR GUI keeps trying forever. | ||
| + | * Most likely, you need to reboot the terminal server located in S3 | ||
| + | * Go to the mezzanine level, where the NMR controllers are located | ||
| + | * The terminal server is behind the NMR controllers | ||
| + | * Simply turn it off, wait few seconds, and turn it back on | ||
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| + | ==== Spectrograph NMR GUI " | ||
| + | * This is typically the case when the thresholds in the NMR GUI are not set properly. If they are too low, the program may lock in noise. Conversely, if the thresholds are too high, it may miss a weak resonance. | ||
| + | * Threshold for the Spectrograph resonance can be adjusted by hand in the Spectrograph NMR GUI. In general, a threshold 0.15 mV is good for normal NMR signals, whereas 0.10 mV may be necessary if the signal are too weak. | ||
| ==== Manually setting Dipole Fields | ==== Manually setting Dipole Fields | ||
| (Based on notes from Mathias Steiner with some extra info included) | (Based on notes from Mathias Steiner with some extra info included) | ||
| + | |||
| + | You will need to get access to the NMR controllers in the mezzanine level of S3 (see picture below). You will also have to connect an oscilloscope to one of the NMR controllers, | ||
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| Let’s assume that you want to set the dipole I265DS (first dipole (D1) of S800 Spectrograph) to the rigidity (Brho) 3.7965 Tm (this works for any dipole in the S800) | Let’s assume that you want to set the dipole I265DS (first dipole (D1) of S800 Spectrograph) to the rigidity (Brho) 3.7965 Tm (this works for any dipole in the S800) | ||
nmr_probes.txt · Last modified: 2024/06/01 16:35 by swartzj
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