Appendix A
INSTRUMENTATION
Shelf geometries from bottom of window:
A.1 COLLECTOR IDENTIFICATION
Collector designations are shown in Figure A.1.
A.2.
Physical Geometry
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-
Shelf
Distance
Correction
1
2
3
4
5
0.85
1.50
2.15
3.75
5.35
0.2628
0.1559
0.0958
0.0363
0.0177
cm
Minimum count rate requiring coincidence loss correction: 3.0 x 10° counts/min
poration, and Model 182 Nuclear-Chicago (in tandem)
Pb shield dimensions: 84-inch outside diameter
x 20 inches high x 114 inches thick; additional 2-inch
A.2.3 4-m lonization Chamber (Analytical and Stand.
ards Branch). (Two newer chambers of modified design were also used. The response of these to 100 ug
thickness in Site Elmer laboratory
Counting chamber dimensions: 5'4-inch diameter
x 4 inches high
Al absorber thickness: 44 inch
of Ra= 700 x 107° maat 600 psi; therefore, all read-
Shelf
cision resistors (1 percent) eliminated scale correction
factors. )
ings were normalized to the latter value.
Shelf distances from bottom of absorber:
Distance
moon
cm
5
Gas type and pressure: A ~ 600 psi
Shield dimensions: Pb ~ 19-inch outside diameter
22 inches high x 4 inches thick; additional 1-foot
thickness of sandbags in Site Elmer laboratory
Counting chamber dimensions: 1l-inch diameter
x 14 inches high
1.0
2.6
4.2
5.8
7.4
Thimble dimensions: 14-inch inside diameter x
Ratios to Shelf 5 (most commonly used) for cen-
12 inches deep
Useful range: ~ 217 x 1071! ma (background) to
tered Ca**" point source:
Oo
f& WN eH
Shelf
200 x 107* ma
Ratio
Correction factors to equivalent 10° scale:
5.87
3.02
Scale
Factor
~ ohms
1.88
1.31
1.00
Use of pre-
10%#
.
0.936
1028
0.963
10°
1.000
10°
Minimum count rate requiring coincidence loss
correction: 1.0 x 10° counts/min
Counting procedure: ordinarily 3- to l-minute
intervals for each sample
1.000
Response versus sample (Ra) position:
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
0 to 3
, 3.5 to 5.5
x 12 inches high x 114 inches thick; additional 2-inch
thickness in Site Elmer laboratory
Counting chamber dimensions: 5/4-inch diameter
x 4 inches high
Al window thickness: 0.92 mg/cm?
100
99 to 92
Response to 100 yg Ra: 5.88 x 107* ma at ~ 600 psi
Efficiency factors relative to Cofor various nuclides:
162