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nmr_probes

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nmr_probes [2013/12/14 16:26]
pereira [Operation] 		nmr_probes [2014/03/10 09:37]
pereira [Troubleshooting]
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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" 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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-If a dipole is turned off or its field is being changed, the status shows either “Off” or “Unstable” and the program issues a beep. If this happens under running condition in data-taking mode, stop the beam and ask the operator to assist you in investigating the situation of the magnet giving the problem. The operators have the possibility to check on all magnet power supplies and helium fill levels in the control room. A magnet current below the set value, for example, is indicated in Barney as a blue circle on the respective optics element. The S800 Barney page with all magnets operational looks like that:+If a dipole is turned off or its field is being changed, the status shows either "Off" or "Unstable" and the program issues a beep. If this happens under running condition in data-taking mode, stop the beam and ask the operator to assist you in investigating the situation of the magnet giving the problem. The operators have the possibility to check on all magnet power supplies and helium fill levels in the control room. A magnet current below the set value, for example, is indicated in Barney as a blue circle on the respective optics element. The S800 Barney page with all magnets operational looks like that: 
 + 
 + 
 +THIS FIGURE IS OBSOLETE. NEW A NEWER VERSION
  
 {{:wiki:barney_magnets.jpg?700|Barney display for the S800.}} {{:wiki:barney_magnets.jpg?700|Barney display for the S800.}}
  
  
-The magnet currents, measured fields, and deviation from the set value are logged in a file that is soft-linked from the "current run " directory. An example of the log file (analysis.log) for the four dipoles of the analysis line is shown below. +The magnet currents, measured fields, and deviation from the set value are logged in a file that is soft-linked from the "current run" directory. An example of the log file (analysis.log) for the four dipoles of the analysis line is shown below. 
  
  
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 ===== Matching ===== ===== Matching =====
  
-{{:wiki:NMR-matching.gif?550|Pannel to match dipoles.}}+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. 
  
- +{{:wiki:NMR-matching.gif?550|Pannel to match dipoles.}}
-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 =====
  
-  * The NMR program is connected to the following devices and systems: +The NMR program is connected to the following devices and systems: 
  
   * The NMR module through a terminal server    * The NMR module through a terminal server 
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   * The EPICS system through the caRepeater process launched by the et_wish shell running the program    * The EPICS system through the caRepeater process launched by the et_wish shell running the program 
  
-Any of these connections can eventually be broken, and the program tries to catch the failures and report them to the user. However there are cases when the program “hangs” and need to be manually aborted. The little heart displayed at the top left corner of the oscilloscope display indicates the liveliness of the EPICS loop, as well as the liveliness of the program itself. If the heart stops beating for more than 10 seconds, it probably means the program is frozen. To restart it, simply click on the program's icon again, which will kill the existing process and start a new one. +Any of these connections can eventually be broken, and the program tries to catch the failures and report them to the user. However there are cases when the program "hangs" and need to be manually aborted. The little heart displayed at the top left corner of the oscilloscope display indicates the liveliness of the EPICS loop, as well as the liveliness of the program itself. If the heart stops beating for more than 10 seconds, it probably means the program is frozen. To restart it, simply click on the program's icon again, which will kill the existing process and start a new one. 
  
 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 ):  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 35.9.56.212**  
-  - enter any **username**  +  - Enter any **username**  
-  - **su **   +  - **set priv **   
-  - **system** +  - The system will ask you the password (ask the S800 device physicist) 
   - **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.    - Click again on the starting icon and the program should start. 
  
nmr_probes.txt · Last modified: 2024/06/01 16:35 by swartzj

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