22
User in the measurement mode of β- radiation flux density can save the measurement results into
Spectroscopic Radiation Monitor РМ1403 memory, switch off sound alarm, change set threshold value,
reset accumulated statistics and go to the first step of β- radiation flux density measurement, Figure 6.7
(6). To do it: press MENU key on Spectroscopic Radiation Monitor РМ1403and follow instructions on
the LCD
6.2.3 Search mode of
- β- radiation sources
To search
- β- radiation sources: connect BDAB to Spectroscopic Radiation Monitor РМ1403
according to 5.4 and enter the indication mode of BDAB operation modes. To do it: select "αβ
Detector [BDAB]" line and press SELECT or ENTER key on Spectroscopic Radiation Monitor
РМ1403.
When the "α Search Mode" line is selected, or "β Search Mode" line is selected BDAB enters the
test mode, Figure 6.4.
Upon testing BDAB automatically enters the gamma background calibration mode. At that
LCD will display "Calibration" message, the analogue scale in progress and "Remove alpha and beta
filters" message, Figure 6.8 (1). When the scale is completely filled, the calibration is finished.
Remove the gamma-filter upon the calibration.
When the calibration is finished, BDAB enters the search mode of
- radiation sources,
Figure 6.8 (1), or β- radiation, Figure 6.8 (2).
BDAB with Spectroscopic Radiation Monitor РМ1403 can as well be used to search for
- β-
radiation sources. But this mode is recommended when the count rate exceeds 3 cps.
If impulses count rate exceeds upper measurement range when BDAB is working in the
search mode, the Spectroscopic Radiation Monitor РМ1403’s LCD will display “OVL”.
To measure
- or β- radiation flux density: connect BDAB to Spectroscopic Radiation
Monitor РМ1403 according to 5.4 and select search mode of
- or β- radiation sources ("α Search
Mode" or "β Search Mode").
1)
2)
3)
4)
Figure 6.8
In the search mode the current value of average count rate of impulses coming from BDAB is
calculated. Then the calculated value is displayed on Spectroscopic Radiation Monitor РМ1403’s
LCD in cps in the upper line, Figure 6.8 (2, 3).
Statistical error is displayed in percents with 0.95 probability under indicated measurement
units on Spectroscopic Radiation Monitor РМ1403’s LCD (to the right). User can read the measured
value when the statistical error is 10 % or less.
Current value of count rate is compared to the operation threshold calculated in the calibration
mode. If current value of count rate exceeds the threshold value, then light, sound (audio), and vibro
alarms are activated. Alarm signals repetition rate increases when the instrument gets closer to the
radiation source, i.e. when the threshold is exceeded more and more.