Duane and Judge, 1969), and towed behind the LARC XV amphibious vehicle 

 which also carries the onboard data collection system. Sensitivity 

 of the detector system, comprised of four 2- by 2-inch cesium iodide 

 crystals, is 1 microcurie per square foot. The detector array can 

 examine a zone about 2 feet wide along the length of the track. 



The data acquisition system was modified slightly and now includes 

 electronic circuitry for collecting two channels of radiation data and 

 water depth (Figure 6) . A high-speed, paper-tape punch was added to 

 permit accumulation and punching of data on a 1-second basis. However, 

 normal operational mode was at 2-second intervals, i.e., every 2 seconds 

 the operating data channels are interrogated and read into the real-time 

 data display and punch paper tape storage for later data handling and 

 analysis. The system development and modifications were accomplished by 

 the participating ORNL personnel and are detailed in reports by Acree, 

 et al. (1969) and Case, et al. (in preparation). 



The mix of gold 198-199 provides three gamma photon maxima: 80 kilo 

 electron volts and 0.4 million electron volts for gold 198, and 0.2 million 

 electron volts for gold 199. Discriminator settings are selected so that 

 radiation Channel 1 sees the photon energy range from 80 kilo electron 

 volts to 0.6 million electron volts, and Channel 2 is focused on the 80 

 kilo electron volts peak. 



4. Computer Program 



Radiation measurements are made continuously as the mobile 

 detector is towed along a beach, through the surf zone, or along the 

 offshore bottom. Interpretation of the detected radioactivity, in terms 

 of speed and direction, and ultimately in volume of sand movement, depends 

 in large measure on making maps based on the collation and manipulation 

 of data pertaining to position, observed radiation, and time. 



Individual surveys generally last from 1,000 to 6,000 seconds (about 

 16 to 100 minutes) . As data from seven channels are accumulated every 

 2 seconds during the course of field surveys, as many as 21,000 bits of 

 information may be collected. The only means of handling the data is 

 by a computer. The basic CERC program, RAPLOT, which is written for a 

 UNIVAC 1108, 64,000 memory computer, has undergone several modifications 

 to refine the data processing procedures and to provide more complete 

 and useful printed and graphic output. Details of the RAPLOT II program 

 and information of continued direction of program modification (RADCON) 

 are presented by Turner (1970) . An example of printed output is shown in 

 Figure 7. Graphic output consists of maps drawn on an incremental plotter 

 (Benson- Lehner Model 305) driven by RAPLOT II-generated data. These 

 working maps are the basis for those in Section III of this report. Work 

 to improve data handling and analysis continues at CERC, and at ORNL. 



