Campbell CS725, Инструкция по эксплуатации

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Appendix Title
D-4
Appendix D. FAQ
D.1 What is the calculation of height versus sampling
foot print if the sensor were to be mounted at 10 m?
This is of interest as the CS725 can easily sample a larger area than 3 – 5 m
2
of
snow pillow or snow scale.
Answer:
When the CS725 is installed with a collimator, 80% of the radiation is
eliminated outside of the 60° angle from center. Using the effective
measurement angle of 60°, the circular radius is Tan(60°)*H. Table D-3 shows
the height versus effective measurement area.
TABLE D-3. Height versus Effective Measurement in Meters
Sensor Height Circular Radius Effective Measurement Area
1 M 1.73 M 9.4 M²
2 M 3.46 M 38 M²
3 M 5.2 M 85 M²
4 M 6.93 M 151 M²
5 M 8.66 M 236 M²
6 M 10.39 M 339 M²
7 M 12.12 M 461 M²
8 M 13.86 M 603 M²
9 M 15.59 M 764 M²
10 M 17.32 M 942 M²
If a site is very open and has good uniformity, it is desirable to remove the
collimator rather than raising the sensor height to increase the measurement
angle. Removing the collimator substantially increases the counts that come
from outside the 60° measurement angle. Typically, the total radiation counts
for potassium are doubled when the collimator is removed. Theoretically,
increasing the height of the sensor does not increase the counts, but simply
increases the measurement area that is not attenuated by the collimator.