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Semilog, Background Subtraction Page

NEW FEATURE. We added semilog plots and background subtraction to Aw-graph. These are useful for plotting decay curves, which will generate a straight line curve when the data is displayed in log format. Many things in nature assume a log format.

Note: To view an animated decay graph see: Aware's high flux monitors
Below is a plot of Pb-212 decay. It was deposited on a piece of paper by way of the radioactive gas decay from Thorium in a lantern mantle. The paper was placed next to an RM-60's alpha-beta window. Notice how the real data is matched by the Makdecay pseudo plot. Also notice how the appearance of the plot assumes a straight line since Aw-graph was directed to remove background radiation from the plot and scale the Y-axis in log format.

Semilog decay plot

Below is the same data plotted in semilog format, but without background subtraction.

Semilog with background

Next, the data without semilog scale.

Normal decay plot

Aw-graph makes it very easy to subtract background from loaded plot(s). A menu selection prompts you for a background value. The prompt defaults to a value derived from the plot's autoscale Y-axis minimum value. Another menu selection restores background to the plot(s).

While displaying a plot, Aw-graph can flip between normal plot and semilog plot with the hit of a key. If activated, Aw-graph's regression and interpolation functions act on the normal data or the semilog data as it flips between the two.

Other useful features: You can use Aw-graph's Zoom feature to zoom in on any part of a plot then flip between semilog or normal scaling.

After subtracting background and applying semilog scaling, you can enter auto-refresh mode wherein Aw-graph will update the plot(s) as more data is added to the radiation file (or any file holding the data) and will automatically subtract the background and apply the semilog function to the new data.

Semilog mode is excellent for displaying plots that contain both higher values and lower values. One can see the higher values change near the top of the graph, yet see small changes near the bottom.

Several data streams can plot real time (For example, five RM-60s plugged into one PC)
Multi semilog graph

Same data without semilog plot.
Multi normal graph

Multi semilog small graph

As indicated above, small variations of the plot near the 10 CPM area are visible, as well as larger variations near the 30,000 CPM area. Good for easy instant viewing of radiation with the potential for large swings.

The background subtraction and semilog features act upon data in memory and do not change the data on disk, so one can experiment with the data freely. You can export the data in memory (with semilog and background subtraction applied) to an ASCII file.

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