Sec. 5-2] RADIATION TRANSDUCERS 303 



the current pulse is proportional to the X-ray dose to which the 

 crystal was exposed. 



The method has been investigated with potassium bromide crys- 

 tals by Lichtenstein. 1 The magnitude of the output pulse is pro- 

 portional to the X-ray dosage in the range between 2.5 to about 

 5,000 mr. The lowest value of radiation dose to be measured is 

 imposed by the residual (dark) photoconductivity of the crystal and 

 is about I mr. A dosage of 1 roentgen given to a crystal of 1 cm 3 

 results in an output pulse of about 5 volts. The sensitivity varies 

 for different crystals of the same type by about 1 to 3; the variation 

 is probably due to differences in impurities. 



1 R. M. Lichtenstein, AIEE-IRE Conference on Electronic Instrumentation 

 in Nucleonics and Medicine, New York, Oct. 31-Nov. 2, 1949. 



