ORTEC
®
Fission Meter
®
(FM-P3) Portable Neutron Source Identification System
931026D / 060118
12
—
Blue = 0
–
40 cps
—
Yellow = 40
–
100 cps
—
Red = >100 cps.
•
Sigma Y2F
(Feynman variance)
strip chart and barometer
—
The strip chart tracks the value of Y2F,
which is zero for cosmic neutrons and non-zero for correlated (non-cosmic) neutrons. The barometer
indicates the σY2F factor. Blue = 0–0.02 σY2F; yellow = 0.02–0.1 σY2F; and red = 0.1–0.3 σY2F.
Figure 10. Mobile Search Mode
—
Searching.
On each trace, if an alarm is generated during a data acquisition cycle, the corresponding point on the strip
chart is a red circle instead of black (Figure 11).
Figure 11. The Red Dot Indicates an Alarm.
The Settings button opens the screen shown in Figure 12.
The default settings are as follows:
•
Alarm Thres
hold σN
, the net neutron alarm, is 3 standard deviations.
•
Alarm Threshold σ Counts
, net neutron count-rate alarm, is 5 times the change in count rate, in cps.
•
Alarm Threshold σY2F
, the Feynman variance, is 3.5 times the change in Y2F.
•
Background (cps)
can either be automatically calculated (the default) or can be set by tapping the
Calc
button.
