Instrumentation 
Two instruments appropriate for 
analyses like those just described are 
shown in Figs. 2 and 3. The five-win- 
dow analyzer is the faster. The step- 
ping single-channel analyzer on 
the other hand combines automatic 
printout and unattended operation. 
Five-window Analyzer. The five- 
window analyzer has a nonoverloading 
linear amplifier, a servo-regulated high- 
voltage supply, and a _ window-dis- 
criminator chassis to perform the actual 
pulse-height analysis. Five separate 
windows are provided. Each can be 
located electrically to include any de- 
sired portion of the total spectrum, 
which normally is divided into 50 sec- 
tions. Provision is made to locate 
each of the five windows on any group 
of the fifty division points (7). The 
narrowest possible window is a single 
segment, or }49 of the spectrum, while 
the widest setting includes all fifty 
channels. The windows can be ad- 
jacent, with gaps, or overlapping. 
Data are recorded completely in 
digital form to allow accurate mathe- 
matical treatment of the final data. 
Two scales-of-ten are provided for each 
window system to allow rapid accumu- 
lation of information. These are 
Ericsson glow-transfer decade counter 
tubes, the first of which has a resolving 
time of 50 usec (GC 10/D). The sec- 
ond is of the slower GC 10/B type. 
These glow tubes are followed by a four- 
digit electromechanical register, so that 
total counting capacity is 10° counts 
per window. Ata rate of 30,000 cpm 
there is 1% coincidence loss. 
A control chassis is included. It 
contains a pulse generator for testing 
and aligning the equipment and a digi- 
tal clock to provide preset time op- 
eration. A separate ‘‘patch panel” 
sets the windows (Fig. 4). 
For certain operations such as the 
continuous wear-rate study mentioned 
in the box, the pulses at the input to 
the GC 10/D are fed to independent 
ratemeters, one for each channel. 
Stepping Analyzer. The instru- 
ment of Fig. 3 was designed to permit 
accumulation of spectral data auto- 
matically (8). The discriminator sys- 
tem consists of a single window posi- 
tioned by a 50-position selector switch. 
The data-recording system is a specially 
designed scaler, accompanied by a 
solenoid-actuated electric typewriter. 
In automatic operation the window is 
placed at the first position, a preset 
18 
% of counts mn channels 
Tsotope Determination A B ¢ 
Gei44 1 91.3 5.1 3.6 
2 SVL 5.3 3.6 
3 91.5 5.1 3.4 
4 91.0 5.5 3.5 
5 91.0 5.4 3.6 
6 90.7 5.6 3.7 
Wtd. avg.: 90.9 5.5 3.6 
Cr5! i 28.3 (ARG) 0.2 
2 29.2 70.6 0.2 
3 29.4 70.4 0.2 
4 30.8 68.9 0.3 
5 28.7 70.9 0.4 
6 31.2 68.5 0.3 
Wtd. avg. 30.0 69.7 0.3 
Sc46 1 42.3 19.5 38.2 
2 42.8 19.8 37.4 
3 43.2 19.3 37.4 
4 41.6 20.0 38.4 
5 41.6 19.7 38.7 
6 41.3 20.1 38.6 
Wtd. avg.: 41.7 19.9 38.4 
time, preset count, or both are chosen, BIBLIOGRAPHY 
and the start button is depressed. 
The scaler accumulates information 
from the first position until either 
the preset count or preset time is 
reached and the information is printed 
automatically by the electric type- 
writer on an appropriate data sheet. 
Although the system is slower than 
a multichannel analyzer, operation 
without attendance makes up, to some 
extent, for additional time required. 
The analyzer can operate with a suit- 
able automatic sample changer. 
For manual operation a patch panel 
also is provided as in the five-window 
analyzer. This allows, for instance, 
measurement of the decay of any peak 
in a complex spectrum. 
An illustration of the final data of 
the instrument is shown in Fig. 5. 
The gamma ray of Ce!4! and its corre- 
sponding ‘“‘Compton lump” are clearly 
resolved from the K X-ray line of Pr14! 
due to internal conversion of the soft 
gamma ray. 
* * * 
This article is based on a talk presented at 
the Fourth International Instruments and 
Measurements Conference, Stockholm, Swe- 
den, September 18, 1956. 
1. S. D. Softky, D. H. Perkel, Private communi- 
cation to A. DeHaan Jr., July 10, 1956 
2. V. P. Guinn, Nucteonics 14, No. 5, 68 
(1956) 
3. E. Singer, D. B. Todd, V. P. Guinn, Catalyst 
mixing patterns in commercial catalytic 
cracking units. (Meeting of the American 
Chemical Society, Dallas, Texas, April 1956) 
4. D. B. Todd, W. B. Wilson, Stack loss of 
catalyst from commercial catalytic cracking 
units. (Meeting of the American Chemical 
Society, Dallas, Texas, April 1956) 
6. W. B. Wilson et al., Commercial performance 
of fluid cracking catalysts—a new technique 
of study. (Meeting of the American Chemi- 
cal Society, Dallas, Texas, April 1956) 
6. B. Crasemann, H. Easterday, NucLEonics 
14, No. 6, 63 (1956) 
. Tracerlog, No. 72, 6 (1955) 
. Tracerlog, No. 78, 2 (1956) 
L. W. Toelke, Scintillation spectrometer well 
logging . (Joint Meeting of Rocky Mountain 
Petroleum Sections, American Institute of 
Mining and Metallurgical Engineers, Denver, 
Col., May 26-27, 1955) 
10. D. B. Smith, G. R. Church, Prompt gamma 
rays from neutron capture as a means of oil 
well control AERE 1/R 1688 (Atomic 
Energy Research Establishment, Harwell, 
Eng., 1955) 
11. A. Hundere, G. C. Lawrason, L. P. O’Meara, 
Application of radioactive tracers to engine 
research. (Nuclear Engineering and Science 
Congress Cleveland, Ohio, December 12-16, 
1955) (Available from American Institute 
of Chemical Engineers N. Y. 36, N. Y., 30¢) 
12. B. D. Grozin, ‘‘International Conference on 
Peaceful Uses of Atomic Energy,” vol. 15, p. 
160 (United Nations, New York, 1956) 
13. J. L. Putman, Private communication, June 
13, 1956 
14. P. Leveque, C. Fisher, Private communica- 
tion, June 28, 1956 
15. A. DeHaan, Jr., 
January 4, 1956 
16. C. J. Atchison, W. H. Beamer, Anal. Chem, 
28, 237 (1956) 
wOoOR 
Private communication, 
