Ludlum Measurements 334A, Руководство по эксплуатации

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Model 334A Operations Manual
Ludlum Measurements, Inc 33 January 2021
determine whether the instrument is still serviceable. As with any statistical test, given a
mean and a set of limits, there is a finite probability that the test may fail, even though the
instrument is operating normally. A reading slightly out of range may indicate that the unit
should be Response Checked again and the results compared to historical records. A
reading significantly out of range is a warning that the instrument is not operational.
Tap the Close button, or just wait for the dialog to time out after a minute of inactivity, to
exit the Response Check routine. Another dialog will prompt you to remove the source, then
install a clean filter, and reinsert the filter holder into the detector head.
Normal Measurement Operation
Once the Response Check is completed, the Model 334A enters normal operation and
begins monitoring for the alpha isotope(s)-of-interest activity. The instrument will begin
measuring dose and concentration immediately and can alarm on a measurable activity.
Minimum-Detectable Levels & Window Times
The minimum-detectable levels of concentration and dose will be elevated until the Acute
and Chronic Window times have elapsed, defaulted to 120sec and 240min respectively.
Until the full window times have elapsed, the Model 334A is using incomplete spectrum
accumulations to calculate the dose and concentration and has elevated statistical
fluctuations of the results.
This means that for the first 240 seconds (using twice the default Acute Window time), the
Acute MDD will be elevated, and, for the first eight hours (again, using twice the default
Chronic Window time), the Chronic MDC and MDD will be elevated.
For the unit to alarm, it is required that the dose or concentration must exceed the
minimum-detectable level and t he alarm set point . In the beginning, the minimum-
detectable levels will likely be above the alarm set points, but will gradually decline and
plateau below the alarm set points.
Display: Meter/Spectrum/Log
The Model 334A display components, the Meter, Log and Spectrum, were described in
greater detail in Section 1. What follows is a brief summary.
The meter displays readings on a continual basis during operation. The default meter display is
the Chronic Dose reading for the first Isotope-of-Interest channel. The Dose, Concentration,
activity and net count rate for the other isotope-of-interest—as well as the radon daughters, Po-
212, Po-214, Po-218—will be displayed as well through the use of the buttons on the front panel
of the Model 334A.