Appendix A INSTRUMENTATION Shelf geometries from bottom of window: A.1 COLLECTOR IDENTIFICATION Collector designations are shown in Figure A.1. A.2. Shelf DETECTOR DATA A.2.1 End-Window Counter. Crystal dimensions and type: 14-inch diameter x 4% inch thick, Nal(T1), Harshaw Photomultiplier tube type: 6292 DuMont Scaler types: Model 162 Nuclear Instrument Cor- ards Branch). Counting chamber dimensions: 54-inch diameter Al absorber thickness: '/ inch ings were normalized to the latter value. Pwd cm 1.0 2.6 4.2 5.8 7.4 Thimble dimensions: 1°4-inch inside diameter x Ratios to Shelf 5 (most commonly used) for cen- 12 inches deep tered Cs!9” point source: 2 3.02 3 1.88 4 1.31 5 1.00 Use of pre- cision resistors (1 percent) eliminated scale correction factors. ) Gas type and pressure: A ~ 600 psi Shield dimensions: Pb ~ 19-inch outside diameter x 22 inches high x 4 inches thick; additional 1-foot thickness of sandbags in Site Elmer laboratory Counting chamber dimensions: 11-inch diameter x 14 inches high Distance 5.87 The response of these to 100 ug of Ra 700 x 10~* ma at 600 psi; therefore, all read- Shelf distances from bottom of absorber: 1 0.2628 0.1559 0.0958 0.0363 0.0177 (Two newer chambers of modified de- sign were also used. x 4 inches high Ratio 0.85 1.50 2.15 3.75 5.35 Correction A.2.3 4=mn Ionization Chamber (Analytical and Stand. thickness in Site Elmer laboratory Shelf 1 2 3 4 5 Physical Geometry . rection: 3.0 x 10° counts/min Pb shield dimensions: 8'4-inch outside diameter x 20 inches high x 114 inches thick; additional 2-inch 5 ——— Minimum count rate requiring coincidence loss cor- poration, and Model 182 Nuclear-Chicago (in tandem) Shelf Distance em — Useful range: ~ 217 x 107 '! ma (background) to 200 x 107* ma Correction factors to equivalent 10° scale: Scale Factor ~ ohms ‘ 1012 10% 0.936 0.963 108 1.000 10° Minimum count rate requiring coincidence loss correction: 1.0 x 10° counts/min 1.000 Response versus sample (Ra) position: Counting procedure: ordinarily 3- to 1-minute intervals for each sample A.2.2 Beta Counter. Gas proportions: 90 percent A, 10 percent CO, Pb shield dimensions: 8%4-inch outside diameter Distance from Bottom of Tube Relative Response in pet 0to3 x 12 inches high x 144 inches thick; additional 2-inch , 3.5 to 5.5 thickness in Site Elmer laboratory 100 99 to 92 Response to 100 ug Ra: 5.58 x 107° ma at ~ 600 psi Counting chamber dimensions: 5/4-inch diameter x 4 inches high Efficiency factors relative to Co® for various nuclides: Al window thickness: 0.92 mg/cm? 162