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nmr_probes [2013/12/14 16:26] pereira [Operation] |
nmr_probes [2013/12/14 16:28] pereira [Matching] |
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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 maximum number of attempts is limited to 200. After that the status is marked as “Failed” and the program gives up on this dipole. | + | 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" |
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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- | If a dipole is turned off or its field is being changed, the status shows either | + | If a dipole is turned off or its field is being changed, the status shows either |
{{: | {{: | ||
- | The magnet currents, measured fields, and deviation from the set value are logged in a file that is soft-linked from the " | + | The magnet currents, measured fields, and deviation from the set value are logged in a file that is soft-linked from the " |
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===== Matching ===== | ===== Matching ===== | ||
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+ | The button labeled “Match” opens a new window for matching the dipoles by pairs (see picture below). 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. | ||
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- | 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. | ||
===== Troubleshooting ===== | ===== Troubleshooting ===== |