Appendix C–8
SOURCE DECAY
The strength of radioactive material is measured by its activity, or
rate of decay. This activity decreases with time. The length of time
it takes a given amount of radioactive material to decay to half of its
original strength is referred to as the
half-life
. The half-life of the
Am-241:Be source is 432 years. The half-life of the Cs-137 source
is 30 years.
The
Source Decay
feature allows the operator to view how the
decrease in the radiation intensity of the source affects gauge
measurements. It displays the actual standard count, the predicted
standard count, and the error between the two sets of counts. The
gauge calculates the predicted standard count by correcting the
calibration standard count for source decay.
To access the
Source Decay
feature, press the
〈
SPECIAL
〉
key. At
the
Special
functions menu, access the
Gauge Status/Test
menu by
pressing
〈
2
〉
. At the
Gauge Status/Test
menu, press
〈
6
〉
Source
Decay.
To scroll through the displays, press the
〈
ENTER
〉
key. After
displaying all the displays, the gauge returns to the
Ready
screen.
Current D1 Std:xxxx
Predict D1 Std:xxxx
% Difference: xx.x%
Press ENTER
Summary of Contents for RoadReader Plus 3450
Page 7: ...Model 3450 vii NOTES...
Page 13: ...xii NOTES...
Page 17: ...1 4 GAUGE PARTS AND ACCESSORIES Figure 1 1 Model 3450 Parts and Accessories...
Page 23: ...2 4 Figure 2 1 Effect of Moisture on Depth of Measurement...
Page 53: ...3 28 NOTES...
Page 169: ...Appendix E 2 STANDARD COUNT LOG Gauge Serial Number Date Moisture MS Density DS1 Density DS2...
Page 171: ...Appendix E 4 STANDARD COUNT LOG Gauge Serial Number Date Moisture MS Density DS1 Density DS2...
Page 173: ...Appendix E 6 STANDARD COUNT LOG Gauge Serial Number Date Moisture MS Density DS1 Density DS2...
Page 175: ...Appendix E 8 STANDARD COUNT LOG Gauge Serial Number Date Moisture MS Density DS1 Density DS2...
Page 181: ...Appendix G 4 NOTES...
Page 187: ...Appendix H 6 NOTES...
Page 199: ...Index 12 NOTES...
