NUCLEAR RADIATION 



A gamma detector was used to make readings in the 

 vicinity of the hulk. When lowering such a sensor, a 

 definite rise In the background level Is observed as 

 the sensor approaches the bottom. This Is due to the 

 natural radiation level of the bottom sediments and 

 Is a handy check on the operation of the equipment. 

 Measurements were made simultaneously with photographs 

 so there can be no doubt when the sensor was In close 

 proximity to the hulk. No radiation above the normal 

 background was detected. Since water Is a pretty good 

 shield for gamma rays, this unit has very little range. 



PHOTOGRAPHY 



While the non-optical sensors were helpful, they all 

 lacked the ability to classify bottom contacts. For 

 this reason, the underwater cameras were the prime search 

 tool in this operation as they were in the THRESHER search. 

 Improved cameras and techniques made it possible to con- 

 duct a successful search in a time which would have been 

 impossible a few years ago. 



During the THRESHER search, EG&G model 20^1- cameras, 

 like the one shown in Figure ^, were used first in stereo 

 pairs and later as part of a three camera array. The 

 angular field of view of these cameras is 46 by 33 degrees. 

 In order to increase the coverage, a three camera array was 

 developed which had an angular coverage of 110 by 46 degrees. 

 This array provided better coverage and three times as many 

 photographs to look at. This latter factor was a significant 

 problem. 



In order to overcome this problem, the camera shown in 

 Figure 6 was developed. This is anEG&G model 204 modified 

 by the addition of a wide angle lens system developed at 

 NRL. This lens, which has been reported by Patterson""", has 

 a 114 degree field of view. This camera was first used in 

 the search for the H-bomb off Palomares, Spain and took over 

 half of the photographs taken in the SCORPION search. 



The amount of Improvement this camera represents is seen 

 in Table 1. The table compares the search capability of 

 three different camera systems: the single model 204, the 

 three camera array, and the wide angle camera. The search 

 widths are based on an operating height of 25 feet, which 

 could be increased to 30 feet in clear water such as that 

 in the SCORPION area. The number of photographs per minute 

 assumes a tow speed of one knot and provides reasonable 

 overlap. The number of photographs required to search a 

 square mile is the number to photograph two square miles. 



45 



