SLIDE 39
Whole-body counter.
was a 28 cm diameter,
The detector chosen for field use +; Brookhaven personnel
10 cm thick, sodium iodide thallium activated
scintillation crystal NaI(T1). It is optically coupled to three low
background magnetically shielded photomltiplier tubes connected in parallel
through a summing box with the combined output routed to an amplifier and then
to a microprocessor~based computer and pulse height analyzer (PHA). The PHA
data is stored on a magnetic discette, and results are analyzed in the field
and at BNL using a matrix reduction, minimization of the sum of squares
techniques.
207
The gamma emitting nuclides observed have been 6570, 137¢, 609 and
Bi,
Additionally, naturally occurring
““K is present in normal amounts.
typical counting time is 15 minutes and a typical minimum detection limit is
100 Bq (3 nCi). The whole-body counting system is currently standarized
against a human like phantom.
A