Last Updated on Wednesday, December 15, 2004 at 10:54:48. by Author: Kris Gulbrandsen

Radiation Monitor, General Information/Help

(Expert)

Contents

• Description of Radiation Monitoring System
• Explanation of BLM readout display
• Explanation of Chipmunk readout display
• Alarm Instructions
• Checklist Instructions
• How to contact author

Description of Radiation Monitoring System

   Short Description (longer one will exist later):

    We have 10 argon filled bottles sitting around our detector. They are installed to detect large losses of beam that could damage our detector. When a loss occurs, the bottles produce a signal proprtional to the loss which is sent to some amplifiers and then to an ADC. This data is then collected by processes in the Rhic system. After going through a couple of levels of processing in the Rhic system where the data is converted to a dose, it is made available to us via a Cdev Portal Server. The computer in the phobos counting house queries this server for data. It then displays it (in a rather primitive way currently) and also logs the data in the database. Once in the database, web dispalys can be made to view the data.

    In addition to the BLMs we have 2 chipmunks in Phobos that detect radiation in basically the same way as the BLMs except that they integrate the charge accumulated by radiation and give out logic pulses, the number of which is proportional to the amount of radiation traversing the gas tube. This allows for a better determination of actual dose taken by a detector. The values of this detector are also written to the database and displayed on the web.

Explanation of BLM readout display

The radiation monitoring display:

Points to note about the display:

• In the upper left is the date and time when the program started. This is simply there to tell the developer how long the program has been able to run without needing to be restarted.
• Backup File Name is where the file that possesses failed sql queries sits so that they may be corrected or executed later (the file would be filled if a poorly constructed sql query was made or if the database was down).
• time diff, cdev time, and LV time are simply debugging type info which will probably be removed later. cdev time is the time that data we get from cdev is stamped with. LV time is the time Labview has. time diff is the difference between these times. If this time is too large (> than 20) then a problem is occurring. If the time diff is large for an extended period of time, then a persistent problem is occurring.
• 10a-blm1 temp and 10a-blm2 temp are the temperatures in the electronics racks where the adcs sit for the blm signals. There seems to be a large dependence of the pedestals of the blms on these temperatures.
• The middle left part of the screen contains the main BLM display. There is one graph for each dot around the beamline (represented by the blue and yellow arrows). The red dots tell you where the loss monitors are and each graph gives a 10 minute history of the dose in each blm.
• The instantaneous data for each of these displays is in the lower right where the blm list,status,instant dose, integrated dose, and missed data columns exist. It is not clear if this should be on the display because there (currently) is no way for the viewer to tell which of these data is for which graph (unless they look at the graphs   closely). This should probably be changed. The only reason for it not to be changed is that it tells the viewer that data is being fetched if the instant dose keeps changing and also tells if there is a lot of missed data due to network traffic or other things.
• The graphs on the right are of the yellow and blue beam current. They indicate how much beam is in the machine and if injection or dumping has occurred. Note: you can right click on these graphs to turn on or off autoscaling and you can click on the axis values to set them (but make sure you have turned off autoscaling first or your axis adjustment will go away in the next data read when the y axis is autoscaled again).
• The error reports box lists the last 100 errors that have occurred which can range from almost negligible errors to severe error. The viewer (who is not an expert) should only be alarmed if this error box kept scrolling out errors continuously.
• Sector [X] HV where X=9A,9B,10C, or 10D is the high voltage on the BLMs. This should be around 1400V if the BLMs are on.
• Timestamp is the time that the BLM data is currently arriving with. This should count up 1 second every second (except for missing a second every once in a while). If this is not counting up or it reads some stupid time (stupid being far from the current time) then there is a problem.
• DB Write Time is the time at which the program will try to write the integrated doses to the database.
• DB Write interval[s] is the amount of time over which the program integrates the dose and then attempts to write this value to the database (this can be changed at any time during running although you shouldn't change it unless you know what you are doing).
• STOP terminates execution of the program (but not of Labview). It is there so that network connections can be closed by the program properly before execution terminates.

Dose Levels:

    The BLMs are normally very quiet (only showing pedestal). It takes a very high dose to make a signal in the blms. 3.6 rad/hr = 1 mrad/s. If you see a dose of 1 mrad/s above the pedestal (the value that most previous counts sit at), then you should call MCR and ask what they are doing to have this occur (if anything) and note the incident in the logbook.

Explanation of Chipmunk readout display

The radiation monitoring display:

Points to note about the display:

• The graph on the left shows the current microrads/second accumulated by the chipmunks. The graph should update every number of seconds determined by the control 'Sample Time (Sec)'.
• The 4 numbers in the upper left tell the most recent number of microrads/second given out by the chipmunks in its last interval and the raw number of counts of the most recent reading (uncalibrated info).
• Every amount of time determined by 'DB Write Interval (Sec)'  the total amount of counts in the DB write interval is written to the database. Note: if 'DB Write Interval (Sec)' is not a multiple of 'Sample Time (Sec)' then the smallest amount of time greater than or equal to the 'DB Write Interval (Sec)' that is a multiple of 'Sample Time (Sec)' will be used.
• Use the Stop button in the lower right of the display to stop the Chipmunk monitor.

Dose Levels:

    The chipmunks are very sensitive but also have low noise. A dose above 1000 microrad/s is currently considered high (although this number needs to be studied more). If this occurs on the chipmunk monitor, then there is fairly high activity with the beam. If it happens call MCR and ask what they are doing to have this occur (if anything) and note the incident in the logbook.

Alarm Instructions

1. Radiation Monitor has stopped receiving data

If this occurs proceed with step 5 of the checklist instructions below, but only for the BLM display. If however, you complete step 5 succesfully (i.e. without having to go on to step 6) and the alarm is still going off then you should pause the alarm and click info (so that it shuts up) and call the expert.

Checklist Instructions

1. Check Spikes in the last 48 hours.

   Go to the web portal and click on 'beam loss monitors' on the left under 'detector status'. A pop up window should have a column listing spikes. If there is 0 in every column for the upper table, then there are no spikes.

2. Check for spuriously high doses 3.6 rad/hr in BLMs above base level and in chipmunks.

   In the same pop up window as the previous step there is a column in the top table that says 'Dose'. Click on each number and get a small pop up window that show the history for today and the previous day. A sample display (of more than 2 days) is shown below. There are no spuriously high doses in the example. The base level is the slowly moving level in certain sections of the graph. The base level drifts due to temperature (rising and falling peaks over a day usually). There are occasionally some abrupt changes due to a reset of the base pedestal by MCR as shown in the transition from the end of day 2 to the start of day 3. There are also some negative drops that occur for unknown reasons as shown on day 8. You are looking for spikes 3.6 rad/hr above a pseudoflat region of this base level in blms. The chipmunks shouldn't have any pedestal shifts like the blms. Look for doses above 3.6 rad/hr (3600 mrad/hr - scale in log10(mrad/hr) for the chipmunks).

   

3. Check the nominal status of radiation monitor system.

   Go to the web and check the nominal status of the BLM system. You can get there from the portal  or from this link. If the entry for BLM says off then you don't need to do anything else. If it says on, you must proceed to step 4.

4. Check if radiation monitoring program is open.

   This is an easy step. Just go to the monitor with a label on top saying 'Radiation Monitor'. If you don't see a display taking up the whole window which has charts on the left, some text and a stop button in the lower right corner, then atleast the BLM program isn't open. If it is open, go on to step 5; Otherwise, double click on the icon on the left side of the display labeled BLMmonitor. The program should open and take up the whole window. There should also be a smaller display for the Chipmunk monitor. If a smaller window with a graph isn't evident, look at the toolbar on the bottom of the monitor that says 'Chipmunk Monitor'. If it exists, click it and the display should show up. If it isn't there, double click on the icon on the left side of the display labeled Chipmunkmonitor. This display takes over a minute to open. Then click on the white arrow in the far upper left corner to of whichever you opened to start the program. The arrow turns black when the program is running. Now go on to step 5.

5. Check that the charts on the radiation monitor programs are scrolling and that instant doses and timestamps on the BLM display are updating.

   The program should now be open and running. This step is suppose to check that the program is running properly. If the program is collecting data properly (at once per second for the BLM display and once per every 'Sample Time (Sec)' for the Chipmunk display). A chart should be scrolling slowing along the screen and atleast some of the text in the lower left corner of the BLM display and the upper right corner of the chipmunk display should be updating. Specifically, look at the column labeled 'Instant Dose' on the BLM display. Every second or so these values should update. It is possible (if there is little radiation in the tunnel that these values will appear to remain constant for longer periods of time. There is a piece of data labeled 'timestamp' to the right of the columns of data that instant dose is in. This timestamp should be updating every second. If it is, then the program is running properly. For the chipmunk display, the +Z and -Z dose rate and counts should change every 'Sample Time (Sec)' or some small multiple of it (in case the exact same amount of radiation was accumulated in multiple successive intervals). If all of this is working, you are done. If it is not, one program is working improperly and you must go onto to step 6.

6. Restart the program.

   • BLM Display: The program is not working. If (in step 4) you did actually open the program then you can proceed to step 7. If you did not do this in step 4, then press the stop button in the lower right corner of the display (wait for it to react to this click - which can happen immediately or take up to 10 seconds) and wait for the program to stop. You know when it has stopped when the arrow in the upper left corner has turned from its black color when it is running to its white color when it is not. Then go to the file menu in the upper left and choose exit from the dropdown menu. Then proceed with step 4 again as if the display was not open.
   • Chipmunk Display: For this program simply press the  white arrow in the upper left. and it should start. If there are problems then you must call the expert.

7. See if processes from Rhic are serving out data and possibly restart the server if BLM Display isn't working.

   Before asking the expert to come in and deal with the problem (which we want to avoid!), try to see if the necessary processes are running within Rhic. Call MCR (x4662) and ask if the BLM manager and the Cdev Portal Server for Phobos are running. All control room operators should know what the BLM manager is and, if not, their shift leader should know. It is possible that some of them don't know what the Cdev Portal Server for Phobos is. If they don't, either have them ask their shift leader or tell them that it is a system server and see if they can figure it out. If they cannot, I suppose you must call the expert.

   If they did figure it out and one of the programs was not running, ask them if it can be started. If not, note this in the logbook, send an email to the expert and you are done with the check for this subsystem. If they did start the program then go on to step 8.

   If the programs were running, then ask them to restart the Cdev Portal Server for Phobos. They are suppose to honor this request but occasionally they like to have some expert of theirs do this. Then have them do this and call back when the server has been restarted. When you have been told that the server has been restarted go on to step 8.

8. Try one last time to get program running.

   Close the program as described earlier (stop it and exit -> you will have to exit the chipmunk monitor program and restart it again). Start the programs up again. If the BLM monitor still does not work (timestamp not updating and chart is not scrolling), then call the expert. If it does work, then pat yourself on the back for getting this far and proceed with the next subsystem check.