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--- nmr_probes [2013/12/14 11:15]
pereira
+++ nmr_probes [2013/12/14 11:20]
pereira [Matching]
@@ Line 2: / Line 2: @@
 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.
-==== Motivation ====
+===== Motivation =====
 Due to the location of the NMR probes in the dipoles of both the S800 analysis line and spectrograph, the NMR signals are usually too small for the NMR module to lock on. This has been a long standing problem which required the users to manually search the resonance, a painful and lengthy process (especially at 3:00 AM!), as well as costly in beam time. The improvement made in 2001 was a remote control panel for the NMR modules that prevented the users from having to enter the vault in order to measure the fields and match the dipoles. Although it greatly shortened the amount of time and energy spent in performing those tasks, it still remained laborious compared to a fully autonomous system like the NMR program running on the A1900 for which the signals are strong enough for the module to lock on.
@@ Line 8: / Line 8: @@
-==== 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 of uxpc2. The picture below shows the spectrograph GUI as an example. The top (yellow) panel shows the data relevant to the NMR module, the middle (pink) the digitized signal from the oscilloscope and the bottom (blue) the status and measurements for the dipoles.
@@ Line 15: / Line 15: @@
-==== 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.
@@ Line 47: / Line 47: @@
 ===== Matching =====
-{{:wiki:matching.png?700|Pannel to match dipoles.}}
+{{:wiki:NMR-matching.gif?550|Pannel to match dipoles.}}
-{{:wiki:matching.png?700|Display when running log file.}}
 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.
@@ Line 66: / Line 66: @@
 In case nothing happens after clicking on the icon, the connection to the NMR module is probably locked and needs to be freed. To free it, type the following from any shell window (actual typing show in this font ):
-  - telnet 35.8.35.139
+  - **telnet 35.8.35.139**
-  - enter any username
+  - enter any **username**
-  - su
+  - **su **
-  - system
+  - **system**
-  - unattach port x where x=1 for the analysis line and x=2 for the spectrograph
+  - **unattach port x** (where x=1 for the analysis line and x=2 for the spectrograph)
-  - logout
+  - **logout**
   - Click again on the starting icon and the program should start.

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