Theoretical Adjustment Of The High Voltage And The Thresholds; Figure 4-1. Theoretical Adjustment Of The High Voltage And The Thresholds - Thermo Scientific 5030 Instruction Manual

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Theoretical Adjustment of
The following images provide some technical information on the operation
of the detector, and its theory of operation.
the High Voltage and the
Thresholds
a) Detector - Plateau b) Height of Pulse

Figure 4-1. Theoretical Adjustment of the High Voltage and the Thresholds

During the factory setup, the High Voltage of the detector, the thresholds
and the plateau are determined and documented within the final test
protocol. Only in case of a detector error or instrument status condition
should this readjustment be done.
The Model 5030 SHARP - detector is a proportional counter, which
depends on the operating High Voltage (HV). Figure 4-1a shows the
relation of count rate versus HV. The detector is operational within the
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range of the plateau and all pulses caused by the C betas can be counted.
Figure 4-1b shows the height of pulse as a relation of count rate versus the
threshold in mV. This system is designed to be able to separate the beta (β)
radiation from natural alpha radioactivity (Radon). The natural alpha
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particles have higher energies than the C betas. Therefore the alpha
particles give a higher signal.
If the HV is too low the count rate of the detector is not in the plateau. If
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the HV is too high the system measures more C beta counts as alpha
activity.
Thermo Fisher Scientific Model 5030 SHARP Monitor Instruction Manual 4-5