ORTEC RADEAGLET, Руководство пользователя

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B Technological Background, Limitations
B.1 Stabilization
The primary spectroscopic detector of RADEAGLET is the NaI scintillation crystal. This crystal produces
light pulses whenever gamma photons interact with the crystal material. The light pulses are very weak
so they must be amplified. Therefore, the NaI crystal requires a photo-multiplier tube (PMT) which is
coupled to the crystal. This assembly allows the incident gamma photons to be digitized by the internal
electronics and the pulses (which are proportionate to the energy of the incident gamma rays) form a
histogram or gamma spectrum. This spectrum is stored in the embedded multi-channel analyzer.
The response of both the NaI detector and the PMT may vary based on measurement conditions such as
temperature or magnetic field. The peaks in the gamma radiation spectrum may shift due to these tem-
perature variations. As temperature changes are encountered, modern scintillation based instruments
must apply some means of stabilization. Shown below is the procedure the RADEAGLET uses to correct
for peak shifts and to adjust the peaks in the spectrum to their scientifically correct positions.
B.1.1 Initial stabilization
Each time the system is turned on, during the start-up the RADEAGLET performs an initial stabilization.
This process takes about 80 seconds. It runs temperature checks and searches for known peaks in the
spectrum. It is strongly advised not to have check sources in the immediate area during this initial phase,
because this can confuse the process.
B.1.2 Continuous temperature monitoring
During the manufacturing process, each RADEAGLET is tested in a climate chamber to learn the individ-
ual temperature dependencies of crystal and PMT. Both the absolute value of the temperature as well as
the temperature gradients are used in this process. In the field, the instrument continuously monitors
and adjust the gain by measuring the temperature. It also distinguishes between slow temperature drifts
and quick temperature shocks.
B.1.3 Continuous spectroscopic adjustments
Although there is not always an actual source present, the natural background spectrum often contains
valuable information. The RADEAGLET uses the natural background peaks for an advanced stage of self-
stabilization. When turned on, the RADEAGLET is automatically taking background spectra and analyzing
them. All this happens automatically in the instrument, and is completely transparent to the user. Once
the RADEAGLET finds known radiation patterns and is sufficiently confident about the analysis result, it
© innoRIID GmbH RADEAGLET User Manual• Software 2.1.16 • Document 1.32o • 2017-12-15 Page 49 of 60