SLIDE 39 Whole-body counter. was a 28 cm diameter, The detector chosen for field use by Brookhaven personnel 10 cm thick, sodium iodide thallium activated scintillation crystal NaI(T1). It is optically coupled to three low background magnetically shielded photomultiplier 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 6520, 137¢, | 60, 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