Software Manual Section 23

Previous Section

Home

Next Section

Trace Analysis Running
	Introduction Once a measurement is started, the trace analysis running window shows up. The options in this window change depending on which phase of the analysis is currently executed. Some initial steps require operator interaction to tune up the beam or the magnetic field.
	Analysis Record Window Together with the 'Analysis Running' window, the 'Analysis Record' windows appears. The function of this window has been described in section 14. It gives detailed information about the current status of the measurement.
	Mass Array Display Also along with the 'Analysis Running' window this extended mass array display appears on the bottom of the screen. The displayed mass range corresponds to the one of the current measurement and the red triangle-pointer always shows the current mass. This display does not have any active functions or buttons.
	Step/Cycle Number This part of the display changes at various times throughout a measurement. All of those measurement steps are described in detail below. The number on the right can be changed in two situations: (a) when 'Hysteresis Cycle #' is shown and (b) when the actual measurement 'Cycle #' is displayed. In these situations it is possible to increase or decrease the total number of cycles, even while the measurement is running.
	Run Number Here the number of the current run is shown together with the total number of runs chosen. The total number can be changed at any time during the execution, but (of course) cannot be any lower than the current run number.
	Current Peak During the initial startup steps, the current mass is displayed here.
	Option: Allow Printing Simple Printing on-off switch. Independent of the selection in Trace Setup 2 it is here possible to turn off the printing on the ThinkJet Printer. Once turned off, it cannot be turned on again from here. This option is 'on' by default.
	Option: Show Peak Centering By default the peak centering and the energy edge determination windows pop up whenever necessary during the run. To prevent these windows from showing up, deselect this option. This option can be changed back and forth as desired.
	View Data Files Up to three different data files can be created during a measurement. It is possible to watch what is written into those files in real time by clicking on these buttons. Buttons for file types that have not been selected during the setup will show up dimmed out and disabled. For a description of the data file viewing see Section 18. Note: These buttons do not show up until the startup routines are over and the actual measurement has started.
	View Graphs It is possible to watch graphical displays of various parameters in real time during the measurement by clicking on these buttons: This option is not yet working for trace measurements (as of 9-20-2000). Coming soon. Note: These buttons do not show up until the startup routines are over and the actual measurement has started.
	Show Results of Last... During a measurement the windows for the automatic mass centering and the determination of the energy edge briefly pop up and disappear again. To view the results of one of these previous routines, click on one of these buttons. Please note that these windows are completely static and do not automatically update with the execution of a new centering routine. Click on "Update" to manually update the display in these two windows. Note: These buttons do not show up until the startup routines are over and the actual measurement has started.
	Measurement Time The total running time depends on the number of masses to be measured and on their count rates. This can be up to several hours for one run of a trace element measurement. If the option "Get Preliminary Counts" (in Trace Setup 2) is selected there cannot be a good estimate of the measurement time before the preliminary counts are actually measured. Therefore, this display will be blank until that point in the analysis. Once the measurement of the preliminary counts begins you will be able to see the run time estimate being continually updated until the count times for all masses have been determined. In the beginnig, the run time estimate is based on the assumption that all masses are to be measured for 1 second each. Since this is only a lower estimate of the actual count times, the displayed "Time/Run" will increase during the preliminary counts cycle. In addition to the time per run the estimated finishing time for the run is also displayed along with the day of the week (for really long measurements). Note that the time display is in the 24 hour format. Of course, these measurement times are only estimates and the actual completion time of the run may be off by a few minutes. Since the completion time estimate depends on the accuracy of the system time, make sure that the current time is displayed correctly in the lower right hand side of the Windows monitor. The measurement time per run also depends on the number of cycles chosen. If -at any time during the analysis- you change the number of cycles, the measurement time estimate will be updated accordingly.
	Steps of the Trace Element Measurement Routine One important principle of the trace element measurements is that the list of masses will always be cycled through in the right order. There are no situations where the magnet jump back to a lower mass before reaching the highest mass to be measured. Example: Assume that there are 60 masses (#1 through #60, sorted in ascending order) to be measured and that the program has just finished a mass calibration at mass #14. If the next step is a determination of the energy edge at mass #13, the program will not just jump to this mass, but will instead cycle through all the masses from #14 to #60, then jump to #1, cycle through all masses from #1 to #13 and only then perform the steps that are necessary at mass #13. This way of doing the measurement may seem slower, but it is the only way to avoid problems with the magnet's hysteresis effect.
	Local Calibration Loop (Startup Step 1 of 3) In the first step of the measurement, the program goes (through a hysteresis loop as described above) to the mass that has been designated in the setup as the 'local calibration mass' (in the case shown on the left, this mass is 24). It then turns on the beam and selects the 'slit' mode for the channel plate detector. This window pops up on the screen: Adjust the magnetic field manually until the crossover image is centered in the channel plate image. Then click on 'Valid' or hit the 'Enter' key to continue the measurement. Note that the instrument will wait for operator interaction at this point with the beam turned on! Make sure to be there for this local calibration and have the channel plate gain turned down to avoid damage to the detector. In other words, be prepared for this step when you start a measurement.
	Energy Offset Loop (Startup Step 2 of 3) Now the program goes to the mass that has been designated as 'energy edge' mass (in this case: mass 12). Here it performs an automatic determination of the energy edge by changing the secondary acceleration voltage and then sets the HV to the desired offset value. All steps after this one will be at the offset voltage. No operator interaction is required for this step.
	Tune Up Loop (Startup Step 3 of 3) In this step, we go to the local calibration mass again. The program turns on the beam and then selects the 'image' mode for the channel plate detector. This window pops up on the screen: Now optimize the beam shape at the HV offset. Then click on 'Valid' or hit the 'Enter' key to continue the measurement. Note that the instrument will again wait for operator interaction at this point with the beam turned on! Make sure to be there for this beam tune up and have the channel plate gain turned down to avoid damage to the detector.
	Hysteresis Loop Next the program goes through all the masses several times. The number of these hysteresis loops can be changed by entering a different value in the display shown here. The default value is three.
	End of the Startup Routines Up to this point the Analysis Record window shows 'Startup Routines' as the current step as shown above. This indicates that there was some limited operator interaction required/possible. After the hysteresis loops, the startup routines are over and the actual measurement without any further operator interaction begins. From now on, the 'Current Step' display in the Analysis Record window will always show the actual step. Note: Even after the end of the startup routines, it is possible to modify the measurement by changing the number of analysis cycles.
	Mass Calibration Loop Here the program goes to pre-selected masses for mass calibration and determines the peak shift for each of these masses. The average mass correction will then be applied to all masses at the end of this mass calibration loop. The energy offset will also be determined again during this cycle.
	Getting Preliminary Counts If this option was selected in the setup, the program now goes through all the masses to get preliminary count rates. It then determines a counting time for each mass based on its count rate.
	Measurement Cycles Finally the program goes through the actual measurement cycles and measures each mass for up to 20 seconds. The total number of cycles can be changed at this point if necessary.
	Measurement Completed After the end of the last run of a measurement, the Analysis Runnig window, the Analysis Record window and the mass array display disappear and this window shows up instead. It gives information about the time of the completion of the measurement and about how much time has passed since then. Click on Done with Trace to completely exit the trace element measurement routines. To go back to Trace Setup 2 (for more measurements) click on this button or hit Enter on the keyboard.
	Abort Measurement It is possible to abort any running measurement by clicking on this button. If a measurement is aborted, the data files may not contain much useful information. Note that the response to this button may take a few seconds; especially in the middle of a 20 second measurement.

FJ Stadermann	Back to Top	Next Section