nmr_probes
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nmr_probes [2013/12/14 16:23] pereira [Description] |
nmr_probes [2013/12/14 16:26] pereira [Operation] |
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| ===== 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 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 “Failed” and the program gives up on this dipole. |
| In order to reduce the searching time, the program tries to guess the field from the following sources, in priority order: | In order to reduce the searching time, the program tries to guess the field from the following sources, in priority order: | ||
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| * Calibration if no previous measurement is available | * Calibration if no previous measurement is available | ||
| - | 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 “Failed” and the program gives up on this dipole. | ||
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| Once a signal is found, the measuring sequence tries to find two resonance positions on either side of 0. Each resonance is calculated as the average between the negative and positive modulation minima (blue and green curves, and corresponding arrows). The final field is interpolated from those measurements, | Once a signal is found, the measuring sequence tries to find two resonance positions on either side of 0. Each resonance is calculated as the average between the negative and positive modulation minima (blue and green curves, and corresponding arrows). The final field is interpolated from those measurements, | ||
nmr_probes.txt · Last modified: 2024/06/01 16:35 by swartzj
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