3. Description of the QABrowser
Real-time Display and Waveforms
Barracuda & QABrowser Reference Manual
2012-10/4.3A
66
selected under Settings | Conditions in the same way as the AMX-4 waveform type.
Conditions - TP-factor
If an ion chamber is used, temperature and pressure
can be specified to get correct dose measurements.
The MPD and other semiconductor detectors
are virtually not affected by temperature and pressure.
Tapping Reset will set the T and P back to its default
values (101.3 kPa and 20 °C) resulting in a TP Factor
of 1.000.
The TP Factor is calculated as follows:
TP = P
0
/P × T/T
0
where: P
0
and T
0
are the reference air pressure and absolute air temperature
(normally P
0
=101.3 kPa and T
0
=293 K [20 °C])
T and P are the actual absolute air temperature and pressure in the same
units (kPa and K)
This value is used to calculate the TP-factor when ion chambers
are used. Temperature can be specified in Kelvin, degrees
Celsius, or degrees Fahrenheit. Unit is chosen in the QABrowser
Setup, under Units.
This value is used to calculate the TP-factor when ion chambers
are used. Air pressure can be specified in several different units.
Unit is chosen in the QABrowser Setup, under Units.
Please note that the pressure easily changes by 10 %. For the same effect from
temperature, it must change 30 °C (or 54 °F).
If you have an EMM-BiasW module, the atmospheric
pressure is automatically measured when changing
Type of Measurement or starting a Favourite.
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