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and vertical full-scale values are shown on the toolbar (see Fig. 224). This command is duplicated by Keypad<+>, the toolbar’s Zoom In button, and Zoom In on the right-mouse-button menu.
5.9.7. Zoom Out
Zoom Out adjusts the horizontal and vertical scales in the Expanded Spectrum View to view a larger portion of the spectrum. The vertical scale is doubled and the horizontal scale is increased by about 6% of the full horizontal scale. This command is duplicated by Keypad<
!>, the toolbar’s Zoom Out button, and Zoom Out on the right-mouse-button menu.
5.9.8. Center
This function forces the marker to the center of the screen by shifting the spectrum without moving the marker from its current channel. This function is only required when moving the marker with the mouse; the keyboard functions for moving the marker automatically shift the spectrum to center the marker when the marker travels past the end of the current expanded display. Center is duplicated by Keypad<5> and the Center button on the toolbar.
5.9.9. Full View
This function sets the Expanded Spectrum View to the maximum number of channels in the spectrum (the ADC conversion gain).
5.9.10. Isotope Markers
The isotope markers can be used in energy calibrated spectra to locate other gamma rays of the same nuclide (from the library) when any one of the gamma rays from that nuclide is selected. In this way, you can easily see if the selected nuclide is present by comparing the spectrum peaks with the displayed markers. The marker is a solid color rectangle placed at the energy of the gamma ray, with the nuclide name shown above the top of the rectangle (Fig. 225). The markers are shown in both the full and expanded views (Fig. 226). The base of the rectangle is positioned at the level of the background for the peak.
The amplitude of the marker for the selected peak is normally proportional to the peak area.
Fig. 225. Isotope Markers.
However, the amplitude can be changed by placing the mouse in the rectangle, where it will
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become a double-sided arrow. While the double arrow is displayed, click and hold the left mouse button and move the pointer higher or lower on the y-axis to make the rectangle larger or smaller. The amplitude of the marker for the other peaks is proportional to the amplitude of the first peak and the yield (branching ratio). As the amplitude of the peak is changed with the mouse, all the other rectangles will change proportionally.
The markers are shown in one of two colors. If the peak area, calculated in the same manner as for Peak Info, is positive (indicating the peak was found), then the rectangle is one color (normally green). If the peak area is negative or zero (indicating the peak was not found), then the rectangle is another color (normally blue).
Fig. 226. Isotope Markers, Expanded View.
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