nmr_probes
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nmr_probes [2013/12/14 11:18] pereira [Matching] |
nmr_probes [2013/12/14 16:26] pereira [Operation] |
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| ===== Description ===== | ===== Description ===== | ||
| - | The NMR running programs for both the S800 analysis line and spectrograph dipoles can be started by clicking on the icons labeled S800A_NMR and S800S_NMR, located on the desktop | + | The NMR running programs for both the S800 analysis line and spectrograph dipoles can be started by selecting |
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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, | ||
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| ===== Matching ===== | ===== Matching ===== | ||
| - | {{: | + | {{: |
| - | {{: | + | |
| The button labeled “Match” opens a new window for matching the dipoles by pairs (see picture). The user has the possibility to match the dipoles to either Barney or to the average calculated from the present measurements. This last function is useful when the dipoles have been tweaked to adjust the position of the beam, leading to an unmatched pair of dipoles. Since matching the dipoles involves changing their fields, it is necessary to wait for the measuring loop to go over each dipole before the effect of matching can be observed. | The button labeled “Match” opens a new window for matching the dipoles by pairs (see picture). The user has the possibility to match the dipoles to either Barney or to the average calculated from the present measurements. This last function is useful when the dipoles have been tweaked to adjust the position of the beam, leading to an unmatched pair of dipoles. Since matching the dipoles involves changing their fields, it is necessary to wait for the measuring loop to go over each dipole before the effect of matching can be observed. | ||
nmr_probes.txt · Last modified: 2024/06/01 16:35 by swartzj
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