5.5.1.2. Report Generator. ORTEC A66-BW GammaVision

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5.5.1.2. Report Generator

If the customizable GammaVision Report

Writer (A44-BW) is installed, the Report

Generator Settings dialog (Fig. 145) will open. There are several report options to choose from.

See the Report Writer user manual for more details on these options. The standard

Fig. 145. Report Generator.

GammaVision analysis report is described in Chapter 7.

5.5.1.3. Attenuation Coefficients

This command opens the submenu shown in Fig. 146. These commands allow you to create, modify, or view the absorption correction files or database.

Fig. 146. Attenuation

Coefficients Submenu.

Coefficient Table

This command lets you add to, modify, and view the absorption correction database. The attenuation database supplied with GammaVision 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.

GammaVision 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. 147.

To select an absorber from the Attenuation Worksheet, click the down-arrow button in the

Absorber section to display the list of materials in the database, and click 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

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Fig. 147. Attenuation Worksheet Table for Absorber Coefficient Table.

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

GammaVision 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 either the Mass or Linear radio button.

2) Click Add. This will open the Absorber Definition dialog (Fig. 148).

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3) Enter the Name of the new material. As an example, we will use NaI.

4) Next, decide whether to describe the ratio of components in the material as a percentage or a mass ratio; this will determine which radio button should be marked in the Units section of the Absorber Definition dialog.

! If you know the relative number of atoms (or molecules) of each constituent in the absorber — for example, NaI — click on %. Amounts entered are multiplied by the atomic weight of the constituent and normalized to 100%.

! Click Mass Ratio if you know the relative amounts of constituents by weight — for example, 90% sand, 10% lead.

5) NaI contains sodium and iodine in a 1-to-1 ratio. Therefore, it should be entered in the

Absorber Definition dialog as two separate Constituents, Na and I, each in the relative

Amount of 1. (Similarly, Al

2

0

3

would be entered as aluminum in the amount of 2, and oxygen in the amount of 3.)

! In the Constituent section, enter Na and an amount of 1, then click Add. The Constit-

uent droplist in the upper part of the dialog will now list Na as a component of NaI

(Fig. 148).

Fig. 148. Defining a New Absorber.

! Return to the Constituent section, enter I and an amount of 1, then click Add. The droplist at the top of the dialog will now show both components.

! Click OK to close the Absorber Definition dialog.

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The new material’s name will now be displayed in gray on the sidebar Absorber droplist.

NOTE

If you choose Mass Ratio instead of %, the ratios of the masses must be entered and must total 1.00. For example, the atomic mass of NaI is 149.89, so the Na mass ratio is 0.153 ( = 22.989/149.89) and the I mass ratio is 0.847 ( = 126.90/ 149.89).

If an absorber has only one constituent, the mass ratio is 1.00.

6) If you clicked on Mass in step (2), the Absorber section of the sidebar will contain a field labeled Mass; enter the atomic mass units for the total compound or element. (The atomic mass for NaI is 149.89 [ = 22.9897+126.904].) If you clicked on Linear in step (2), this field will instead be labeled Density; density values can be found in various reference books. (For example, the density of NaI is 3.67 g/cm

3

.). Enter the Mass or Density.

7) Click Calculate. If the database contains attenuation data for all of the components in the new material, the Attenuation Table of coefficients will be displayed. Otherwise, a “Check

the mass attenuation data list for missing elements” message will be displayed.

8) Click the Constituents droplist and check spelling and spacing against the Worksheet’s droplist. To correct an entry, click it to load it into the bottom section of the Absorber

Definition dialog, make the corrections, click Enter, then click OK to close the dialog.

Return to the Attenuation Worksheet and click again on Calculate.

9) Once the new absorber’s attenuation coefficients have been calculated, the final step is to either save the new absorber to the database (click Save... at the bottom of the sidebar) or delete the new entry (Delete Absorber). If you save it, the absorber list at the top of the

Worksheet will become active, and will now list your new material.

10) To close the Attenuation Coefficient feature, including Worksheet, table, and graph, click the Worksheet’s × box.

NOTE

The Linear and Mass attenuations are stored separately in the database. If you wish to use both, each must be added, calculated, and saved.

Editing or Deleting the Constituents in an Absorber

Suppose that in our example we used an incorrect chemical formula for sodium iodide, Na

2

I instead of NaI, and now wish to correct the error. To do this:

1) On the Attenuation Worksheet sidebar, select NaI(Tl) from the Absorber drop list, then click Edit. This will open the Absorber Definition dialog.

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2) Click the Constituents drop list at the top of the dialog, and select Na. The fields at the bottom of the dialog will now display Na as the Constituent, in the Amount of 2. Change the amount to 1 and click Enter.

3) To delete a component from an absorber, select it from the Constituent drop list and click

Delete. (This Delete button does not remove an absorber from the database, just changes the absorber’s composition. To completely remove an absorber, close this dialog, go to the bottom of the sidebar, and click Delete Absorber.)

4) Click OK to close the Absorber Definition dialog.

5) Next, enter the mass or density as shown in the Absorber section at the top of the sidebar and click Calculate.

6) Click Save to store the complete record in the database.

Adding a New Element or Single-Constituent Material to the Database

Adding a new material involves (1) defining the absorber name, then (2) using the Attenuation

Worksheet sidebar to create the corresponding table of attenuation coefficients. To do this you will need enough energy/attenuation pairs to generate a good attenuation function. These values can be found in reference books.

1) If the attenuation values are in g/cm

2

, click the Mass radio button in the Attenuation section of the sidebar. If the attenuation values are in units of 1/cm, click Linear. Either method can be used in simple cases, however, if you expect to use the materials entered here in creating absorber files for compounds, Mass must be used.

2) On the sidebar, click Add to open the Absorber Definition dialog.

3) In the Name field, enter the chemical symbol for the element (or substance name) — for example, Co.

4) In the Constituent section, enter Co and an Amount of 1.0, then click OK to close the dialog and return to the sidebar.

5) Now, in the Attenuation section of the sidebar (Fig. 149), enter the energy/attenuation pairs for as many energies as necessary to obtain a good attenuation function. When entering the

X-ray edge, use energy values that are close but not equal, e.g., 13.420 and 13.421 keV.

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