Download A35 - Ortec

5. MENU COMMANDS
be the Internal (working) file or a File on disk. If the Internal box is not checked, a filename
must be entered. The working file is the one loaded with Analyze/Settings/Peak Background
Correction/Select PBC... (which is discussed beginning on page 130). The correction is
explained in detail in Chapter 6.
5.5.1.2. Attenuation Coefficients
This command lets you add to, modify, and view the absorption correction database. The
attenuation database supplied with ScintiVision has many common materials already defined.
There are two ways to add new materials to this database:
! Define a new material that is composed of two or more materials already in the database.
ScintiVision will then calculate the new attenuation curve from the existing attenuation data.
! Define a completely new material, that is, one not composed of materials in the database. In
this case, you will enter the attenuation data in the Attenuation Worksheet sidebar, and save
the new material and its attenuation data it to the database.
Selecting Coefficient Table opens the Attenuation Worksheet Sidebar, Attenuation Table, and
Attenuation graph window, as illustrated in Fig. 127.
To select an absorber from the Attenuation Worksheet, click on the down-arrow button in the
Absorber section to display the list of materials in the database, and click on the desired entry.
Selecting a material loads the attenuation values and redisplays the Attenuation Table and graph.
Clicking the mouse on a the table values moves the marker to that energy in both the
Attenuation graph window and spectrum windows. Clicking the mouse in either
spectrum window or the Attenuation graph window moves the marker to that energy in the other
plots. The attenuation value is displayed on the Marker Information Line.
Adding a Material Composed of Substances Already in the Database
ScintiVision makes it easy to add a new absorber made of substances already in the absorber
database. The new absorber can be a chemical compound such as sodium iodide (NaI), or a more
complex mixture, such as sand and lead.
1. In the Attenuation section of the sidebar, click on either the Mass or Linear radio button.
2. Click on Add. This will open the Absorber Definition dialog (Fig. 128).
3. Enter the Name of the new material. As an example, we will use NaI.
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