■SOURCE PEDESTAL 

 PREAMP^ ^SHUTTER 



Fig. 6. Cut-away of rotary shutter transducer. 



Fig. 7- Photograph of rotary shutter transducer. 



Fig. 8. Experimental transducer with counter readout. 



Fig. 8 shows a photograph of the rotary shut- 

 ter transducer connected to a digital counter 

 readout. This counter is modified so as to 

 include an infinitely variable time base gen- 

 erator so that direct transducer readings may 

 be obtained in terms of any units desired. For 

 example, the sliding shutter transducer can be 

 made to read the micrometer screw setting 

 directly in thousandths of an inch. 



EXPERIMENTAL RESULTS 



Shutter plots obtained with the sliding shut- 

 ter and rotary shutter transducers are shown in 

 Figs. 9 and 10, respectively. The straight 

 lines obtained in these plots demonstrate the 

 highly linear characteristics of nuclear digital 

 transducers. It is also possible, by shaping 

 the shutter and aperture, to produce a nonlinear 

 characteristic. For example, it might be 

 desirable to compensate an otherwise nonlinear 

 system in this manner . 



The slight scatter of the experimental points 

 in Figs . 9 an d 10 is a result of nuclear counting 

 statistics. 2 Use of stronger sources or longer 

 counting times would greatly reduce the scatter. 

 If each accumulated count had been 100 times as 

 large, for example, so that all numbers shown on 

 the ordinate scale were multiplied by 100, then 

 the percentage standard deviation of the trans- 

 ducer readout would be only 1/10 as great and the 

 points would lie still more closely on the line. 

 It should be mentioned that the data shown were 

 taken with very weak Radium D-E-F sources con- 

 taining only 1 to 5 microcuries of activity. 

 Weak sources were used in these experiments inas- 

 much as a high data rate was not required . In 

 transducers designed for practical use, con- 

 siderably stronger sources would be desirable. 



In order to test the immunity of nuclear 

 transducers to temperature changes, the sliding 

 shutter transducer shown in Figs, h and 5 was 

 placed in the refrigerator at ^0 o F. After 

 thorough cooling a plot similar to Fig. 9 wa s 



177 



