We will now go step by step to understand how the values in the table relate to the diagram.
Below you see the result of a gamma measurement presented in a table. The left column contains energy values, and the right column shows the measured counts. A row in the table indicates how many counts were measured at the respective energy. For example, consider the energy of 73.83 keV. If you go to the right in this row, you will see the value 955, meaning that 955 counts were measured with an energy of 73.83 keV.
Next to the table, the same values are represented in a diagram. The energy values are shown on the horizontal axis, while the measured counts are on the vertical axis. To determine the number of counts at a specific energy, you locate the energy on the energy axis and go straight up until you touch the curve. At this point, you move horizontally to the left to the counts axis. The value where the counts axis is touched corresponds to the number of counts measured at the selected energy.
Exercise:
Scroll in the table above to the value for the energy at 661.78 keV. In the column next to it, you will find the number of measured counts at this energy, here the value 58016.
Did you find the value 58016? It corresponds to the "peak" in the diagram, which is marked by the red dashed line. For the two other peaks to the right of it, look for the corresponding values in the diagram. If you did everything correctly, you should have found the values 1846 and 1696.
Now you should be able to explain the relationship between the values in the table and the corresponding diagram.
