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Measurement Principles & Theory
2021.5B
RTI Scatter Probe User's Manual
24
Measurement Principles & Theory
The RTI Scatter Probe has a number of measurement algorithms and applications built-in. This section describes the main
measuring principles, how some values are calculated, and the basic meaning of them.
4.1 Waveforms and Triggers
Short Exposure (<2 s)
To get an understanding of how triggers, delays, and windows work, please refer to the waveform below. This illustrates a
radiation measurement shorter than 2 seconds.
1. Pre-trig buffer start point. The pre-trig buffer (500 ms) is in use to avoid loosing any radiation information just before trig.
2. Trig On - The measurement starts, when irradiation rate goes over the detector's lowest trig level (or is manually started).
The status LED starts flashing GREEN.
3. The signal reaches 50 % of its maximum. This is the starting point for the irradiation time calculation.
4. The signal reaches its maximum.
5. The signal goes below 50 % of its maximum. This is the end point for the Irradiation time calculation.
6. The irradiation rate goes under the detector's lowest trig level.
7. Post-trig buffer end point - A post-trig buffer (500 ms) is in use to avoid loosing any radiation information just after trig off.
8. If the signal has been below the trig level during Post delay (point 6-8, 3 sec), the exposure is considered finished. All
exposure readings are calculated and displayed.
9. Restart buffer end point - During the Restart buffer the display software gets ready for a new exposure. The status LED turns
RED during Restart buffer, but may not be visible due fast communication and thereby a very short Restart buffer.
Integrated signal - Air kerma and Ambient Dose Equivalent H*(10)
This is the integration of all signal which means the area below the curve above from point 1 to 7.
Irradiation time
The irradiation time is defined as the time between point 3 and 5 as described above.
Signal rate (dose rate and H*(10) rate)
When the measurement ends, point 6 above, the average for the whole measurement is displayed. The signal rate is calculated
as the integrated signal from point 1 to 7 as described above) divided by the Irradiation time (point 3 to 5).
Peak rate
The peak rate is the highest detected signal rate value during the measurement. Point 4 as described above.
HVL and Mean Energy
HVL and Mean Energy is calculated in the same window as described for Signal rate above.
Summary of Contents for Scatter Probe
Page 2: ...2021 5B RTI Scatter Probe User s Manual...
Page 3: ...RTI Scatter Probe...
Page 6: ...2021 5B RTI Scatter Probe User s Manual...
Page 8: ...2021 5B RTI Scatter Probe User s Manual...
Page 9: ...Chapter 1 Introduction...
Page 11: ...Chapter 2 Product Overview...
Page 15: ...Chapter 3 Measure...
Page 22: ...2021 5B RTI Scatter Probe User s Manual...
Page 23: ...Chapter 4 Measurement Principles Theory...
Page 27: ...Chapter 5 Hardware and Specifications...
Page 33: ...Chapter 6 Maintenance...