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nmr_probes [2019/10/14 00:01] pereira [Troubleshooting] |
nmr_probes [2019/10/14 00:12] pereira [Manually setting Dipole Fields] |
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- | ====== Manually setting Dipole Fields | + | ==== Manually setting Dipole Fields ==== |
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) | ||
- | **Method 1**: | ||
+ | **Method 1** | ||
* Divide Brho by the dipole radius 2.8028m (you can see the nominal radius of each dipole in Barney) to determine the desired field (in Tesla). In this case, it will be 1.35454 T (or 13.5454 kG) | * Divide Brho by the dipole radius 2.8028m (you can see the nominal radius of each dipole in Barney) to determine the desired field (in Tesla). In this case, it will be 1.35454 T (or 13.5454 kG) | ||
- | * Get access to the NMR controller in the mezzanine level of S3 vault (see FIGURE). Push the “SEARCH LOCAL” button to take control out of REMOTE mode. | + | * Get access to the NMR controller in the mezzanine level of S3 vault (see figure below). Push the “SEARCH LOCAL” button to take control out of REMOTE mode. |
- | * Select the right probe by turning the “probe knob” (see FIGURE). Remember, each dipole has two probes: probe 4, covers fields in the range 0.34 – 1.05 T, and probe 5 covers fields in the range 0.7–2.1 T. In this case, we should set the knob of the Spectrograph controller to position B | + | * Select the right probe by turning the “probe knob” (see figure below). Remember, each dipole has two probes: probe 4, covers fields in the range 0.34 – 1.05 T, and probe 5 covers fields in the range 0.7–2.1 T. In this case, we should set the knob of the Spectrograph controller to position B |
* The list of probes that can be selected with the knobs are, for the Spectrograph: | * The list of probes that can be selected with the knobs are, for the Spectrograph: | ||
* Use the “coarse” and “fine” knobs to select the field that you want (in T): 1.35454 T. By doing this, you are asking the NMR controller to just look at that field. | * Use the “coarse” and “fine” knobs to select the field that you want (in T): 1.35454 T. By doing this, you are asking the NMR controller to just look at that field. | ||
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* As you get close to that value, the oscilloscope will show the NMR resonance. Keep moving until the resonance is well centered. At that point, your dipole is set to the desired field | * As you get close to that value, the oscilloscope will show the NMR resonance. Keep moving until the resonance is well centered. At that point, your dipole is set to the desired field | ||
- | Manually setting a dipole (method 2) | + | **Manually setting a dipole (method 2)** |
- | • Alternatively, | + | |
- | • Set EPICS channel I265DS_MAG.BSET to 13.5454 (note, the default value of this channel is always an (impossible) 9999.1111, which is ignored. Typing 13.5454 will cause the magnet to go to 257.577 A, and I265DS_MAG.BSET goes back to 9999.1111. Setting the magnet this way will get you to plus or minus half a percent of where you want to be. | + | |
- | • At that point, the quickest way may be to use the FINE knob in the NMR controller to find the actual field value. Just turn the knob until the resonance is centered in the oscilloscope, | + | |
- | • Once you know the value of the field, type it (in Tesla) into the EPICS channel I265DS_MAG.FELD. Note that is what Daniel' | + | |
- | • Having done that, you can use the BARNEY ' | + | |
- | • Repeat until satisfied. | + | |
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