0.20 0.30 0.50 0.70 1.00 1.50 2.00 3.00 4.00 61.5 54.0 43.3 37.5 33.4 29.5 27.1 25.3 24.4 A.2.8 Single-Channel Analyzer (Nuclear Radiation Branch) (Reference 57) inches thick, Nal(T1) Photomultiplier tube type: 6364 DuMont Pulse-height analyzer type: Model 510-SC Atomi, Instruments Pb shield thickness: 2'4 inches long Sample container type and size: glass vial, think correction: 1.0 x 10° counts/min diameter x 2% inches long Counting procedure: ordinarily 3- to 1-minute intervals for each sample; trays decontaminated and Distance from bottom of sample to collimator opey. ing: 2 inches _ Calibration standards: Na”, and Hg?03 counted with \4-inch aluminum cover in place A.2.7 Dip Counter. A.2.9 Gamma Time-Intensity Recorder. Crystal dimensions and type: 14-inch diameter Scaler type: Same as doghouse counter Shield thickness and counting chamber dimensions: Same as doghouse counter Sample volume: 2,000 ml (constant geometry) Counting efficiency for several nuclides: (Private communication from J. O’Connor, NRDL) Hes Au) " Cg! Nb Scfé Co® Na The en- ergy and directional response characteristice of the standard TIR detector, consisting of four ion cham-~ bers (A, Am, Bm, and Cm) with a protective dome, X 1 inch thick, Nal(T1) Photomultiplier tube type: 6292 DuMont Cel! ‘ Collimator dimensions: 14-inch diameter x 6 ince Minimum count rate requiring coincidence loss Nuclide oo Crystal dimensions and type: 4-inch diameter x 4 counts /dis x 107? 1.20 1.72 1.28 0.916 0.870 1.76 1.56 1.29 were determined at NRDL. (Measurements and cal- Culations were carried out by G. Hitchcock, T. Shirasawa, and R. Caputi.) A special jig permitted both horizontal and verticaj Totation about the center of the chamber under study. Directional response was measured and recorded continuously for 360 degrees in planes at 30~degree increments through the longitudinal axis of the Cm chamber. Relative response data was obtained by effectively exposing the chamber to a constant ioniza-~ tion rate at six different energies—four X-ray energies: 35 kev, 70 key, 120 kev and 180 kev; and two source energies: Cs’*' (0.663 Mev) and Co® (1.2 Mev). The results for three mutually perpendicular planar responses have been illustrated graphically to show: (1) shadowing interference by other chambersin the horizontal plane (Figure A.2), (2) maximum shadowing Minimum count rate requiring coincidence loss correction: 2 x 10° counts/min interference by other chambers in the vertical plane (Figure A.3), and (3) minimum shadowing interference by other chambers in the vertical plane (Figure A.4). Counting procedure: 2,000-ml sampies at constant geometry; counting intervals selected to maintain a statistical error <1.0 percent 164