Figure 7-5. Auditcheck Sensitivity - Thermo Scientific Apex Service Manual

AuditCheck™
Figure 7–5. AuditCheck Sensitivity
The AuditCheck system uses the fact that there is a fixed relationship
between the sensitivity at each point in a metal detector field. For
example, define the sensitivity at the center "C" as "S" and the
corresponding sensitivity at another point "A" as "T". If the
sensitivity at point "C" decreases by a factor "Y" to be "S/Y", then the
corresponding sensitivity at "A" will be "T/Y". If the sensitivity at
one point in the field is measured, it may be used as a reference for the
sensitivity at all other points within the aperture. This fact is the
foundation of the AuditCheck design.
Assume that the peak signal at point "C" for a given sphere = 200 (S)
and the peak signal at point "A" for a possibly different sphere = 5000
(T). If the sensitivity decreases by Y, S = 200/Y and T = 5000/Y.
If the overall metal detector sensitivity decreases by 25%, Y = 1/(1-
.25) = 1.33. Therefore, the sensitivity at point "C" would be
(200/1.33) = 150 and the sensitivity at point "A" would be (5000/1.33)
= 3750.
7-12
AuditCheck™ Thermo Fisher Scientific
REC 4258 Rev C