the ball, contains photomultiplier tubes, preamplifiers, and attendant 

 circuitry. Coaxial cable for the detector circuitry exits from one end 

 of the axle, and is then attached to the wire tow cable. As presently 

 designed and constructed, the detector vehicle has a depth limit of 

 200 feet. 



Limited tests of the rolling characteristics of the ball conducted 

 at ORNL indicated the design was suitable. Turbidity of the Atlantic 

 Ocean off Cape Kennedy during the 1967 test precluded observation of 

 the deep water by project scientists using self-contained underwater 

 breathing apparatus, but its ability to track and operate in the shallow- 

 water surf was observed to be satisfactory. General operation of the 

 vehicle in 30 feet of water during the 1967 test at Surf, California, 

 was observed to be satisfactory by the project scientist, using scuba. 

 Nevertheless, it was desired to obtain specific engineering data on the 

 hydrodynamic performance of the vehicle to learn the limit of survey 

 speeds and possible means of improving the design. Under contract to 

 the RIST study, the U. S. Naval Ship Research and Development Center 

 (NSRDC), formerly the David Taylor Model Basin, undertook a program to 

 test the vehicle under a variety of conditions, most especially under 

 a variety of towing speeds and cable lengths. 



The NSRDC tests indicated that at k knots (6.75 feet per second) 

 and the cable length usually employed (200 feet), the vehicle maintained 

 bottom contact in the water depths normally surveyed (less than 60 feet) 

 and would do so to a depth of 80 feet. All field tests so far have oper- 

 ated at a speed of approximately 2 knots (3.35 feet per second). Details 

 of the test are contained in the NSRDC report attached as Appendix B. 

 The recommendation of the test program to use oceanographic-type electro- 

 mechanical tow cable in future tests is being followed. 



h. On-board Data Collection System 



Electrical signals from the four detectors mounted in the ball are 

 carried to a signal mixer on the towing vehicle and then to a HOO-channel 

 analyzer (Figure 9)- The analyzer is capable of operating in two modes: 

 multi-sealer and pulse-height. 



Normal surveying mode is "multi-sealer" whereby the analyzer operates 

 as U00 individual counters; each counter stores signals from the detectors 

 according to a preset time interval (0.01, 0.1, 1.0, or 10.0 seconds), 

 selected by the operator. At the end of the appropriate time interval 

 the counting .sequence is terminated, and data must be cleared before the 

 sequence is restarted. Assurance that the detected radiation comes from 

 the labeling isotope is ensured by use of the pulse-height mode. This 

 mode uses all U00 channels to analyze the energy spectrum of the radiation 

 being observed. Data accumulated in either mode is printed out on a tele- 

 printer and on punched paper tape as binary coded decimal. Radiation data 

 can also be displayed on an oscilloscope in the analyzer unit. The scope 

 is of particular value in calibration procedures and when operating in 

 the pulse-height mode. 



17 



