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If the count rate is below the bottom limit of the optimum detector load,
the instrument shows the message “COUNT RATE: LOW”. In this case it is
necessary to move the instrument closer to the radioactive source to
increase the count rate value on the display.
If the count rate is above the upper limit of the optimum detector load,
the instrument shows the message “COUNT RATE: HI”. In this case it is
necessary to move the instrument away from the radioactive source to
decrease the count rate value on the display. The user must observe
safety rules and organizational instructions at all times when working
near radioactive sources.
2.5.2. Acquiring spectra
If the count rate is within the optimal interval, the instrument displays
the message “COUNT RATE: OK”. Press the MODE/SET button to start
spectra acquisition. During this process, the display shows the following
information:
-
“SPEC TIME” – accumulation time in seconds;
-
“COUNT RATE: OK/LOW/HI” message;
-
count rate analog scale.
Please try to keep such a distance from the source and the instrument
that during all time of spectra accumulation the value of the count rate
on analog scale is within the marks and the message is “COUNT RATE:
OK”.
In order to save the collected spectrum, press the
MODE/SET button and select “SAVE”. The instrument
will display the message “Saving...” and the filename
of the saved spectrum. After that it will provide an
option to exit the spectrum collection mode.
2.6. Radioisotope Identification
PM1704A identifies the exact type of radioactive source that triggered an
alarm. There are two options to do that: one is directly in Search mode,
by going to the Search mode menu and selecting “Identify”. This will
commence a procedure similar to the one described in section 2.5.2, and
the following information will be displayed on the instrument LCD:
where TIME LEFT indicates the approximate time required to finish
spectra accumulation and generate identification results.