Thermo Scientific SAM12 Manual page 103

Issue: 1.0
Notes regarding Low
Background
Thermo Fisher Scientific
Amplifier "dead-time", a High Background fault condition will
also be enforced. Monitoring of articles cannot be performed
unless one or more of the following occurs:
1. The background activity drops sufficiently for the
current alarm level to be detected, or,
2. The Health Physicist modifies one or more of the
following parameters:
• Increases the maximum monitoring time - see
Params 2 (page
• Relaxes the Probability of Detection - see
(page 5-10).
• Relaxes the Probability of False Alarm - see
2 (page 5-10).
• Raises the Normal Alarm level - see
5-12).
Minimum Detectable Activity (MDA) and High Background
Criterion (page 6-7) describes how the SAM12 decides if a
high background condition exists.
The "Out Of Service –
Temporary Error has Occurred"
if Low Background conditions
exist.
"Out of Service – Low Background Counts Top Detector"
message is displayed when the count rate in the gross counts
window over the 10 second background check period on any
single detector falls below the threshold. It will remain in this
state until the background count rate once again exceeds the
threshold on all detectors.
Operating Instructions
5-10).
Alarms (page
SAM12 User Manual
Params 2
Params
5-63