REPORT FOR ANALYTICAL CHEMISTS
Table IV. Analysis of Pulverized Samples Using Pneumatic Tube System and Standards Conventional A&M" Analysis Analysis % Std Wt % Element Seimple Wt % Deviation (16, 17) ±5.6 33.7 ± 1.9 34.15 Granite Mountain Granite Si ±5.8 32.8 ± 1.9 35.70 Graniteville Granite ±2.7 22.3 ± 0.6 22.81 Columbia River Basalt 7.28 ± 0.38 ±5.22 7.17 Granite Mountain Granite AI 6.65 ± 0.04 ±0.60 6.51 Graniteville Granite 6.38 ± 0.28 ±4.39 6.90 Columbia F:iver Basalt ±7.91 1.77 ± 0.14 2.02 Granite Mountain Granite Fe ±1.57 1.27 ± 0.02 1.23 Graniteville Granite ±3.30 9.71 ± 0.32 Columbia Fiver Basalt 11.25 0.10 Granite Mountain Granite Mg 0.05 Graniteville Granite 3 . 0 9 Ï 0.15 ±4.85 2.87 Columbia River Basalt 45.6 ± 1.3 ±2.9 48.24 Granite Mountain Granite 0 49.6 ± 0.5 ±1.0 49.06 Graniteville Granite 44.8 ± 0.3 ±0.7 44.40 Columbia River Basalt " These values obtained from three separate irradiations of each rock sample. The oxygen results were obtained from two analyses, each of four, separate, shorter irradiations of each sample.
sis Research Laboratory using a small automated system (15). This automatic system incorporates a Cockcroft-Walton accelerator producing 14 MeV neutrons, a pneumatic sample transfer system and two 3 in. χ 3 in. N a l crystals coupled to a 400 channel pulse height analyzer. The results ob tained are shown in Table IV where they are compared with the results of conventional chemical analyses. The validity of the conventional chemical analyses is not known since these were carried out only on typical samples of the rock type named and not on the; actual sam ples used for activation analysis. It can be seen, however, that con siderable agreement exists between the results of the two methods, indi cating the feasibility of the activa tion analysis technique. The " T u r n a r o u n d " S y s t e m
A prototype small system was constructed to demonstrate an approach to the problem of analyz ing large rock samples under remote operating conditions. The system consists essentially of a small neu tron generator and a 3 in. χ 3 in. Nal scintillation gamma ray detec tor which are mounted in the con figuration shown in Figure 1. The system is rotated about the central axis to reverse the positions of the generator and the detector, thus
allowing either one to be placed directly above, and close to, the sample. This configuration was chosen since it permitted the maxi mum practical distance between the generator and the detector, to pre vent activation of the detector crys tal, while providing good geometry for irradiation and counting. The generator is a Kaman Model A-702 sealed tube type capable of produc ing a 14 MeV neutron flux at the target of approximately 5 χ 107η cm^sec^1. A series of experiments were car ried out using the "turnaround" system to determine the magnitude of the volume activated when the system was used to irradiate and count a large "semiinfinite" rock sample. This was accomplished by irradiating a series of small, square (4 in. χ 4 in. χ 2 in.) and rectangu lar (2 in. χ 6 in. χ 2 in.) granite blocks positioned on the surface of a large granite block (4 ft. χ 4 ft. χ 2 ft.) and hence determining the contribution of the smaller blocks to the total observed activity. These investigations indicated that the majority of the observed activ ity was derived from a relatively small volume. Consequently most of the analyses carried out using the "turnaround" system were ob tained using samples of rock in blocks of sizes of the order of twelve inches square and three inches deep. This sample size
CARVER LABORATORY PRESS
Standard For Research . . . solves the pressing problem of forming KBr Pellets Many insoluble materials, mixed with Potassium Bromide, can be formed in a die under pressure into pellets or wafers for quantitative and quali tative analysis. The CLP supplies the pressure - up to 40,000 lbs., if needed. This specific use is only one of the ways this versatile laboratory assist ant meets the challenge of research and development. Some of the many uses are: v*
Dehydrating
f
Pressing out various oils, stéarines and waxes Pressure filtering of thick fluids Compression tests Fatty acid determinations Plastic molding, forming and blocking Embossing and forcing Pressing mother liquors from crystals Extracting Vaccines and Viruses
>* *> \* k* k* i«* v*
The Standard (12-ton) CARVER LABORATORY PRESS complete with Gauge $345.00 (illustrated) 20 Ton Models also available — additional Standard Accessories for other applications can be supplied. Send for latest
bulletin.
FRED S. CARVER INC. HYDRAULIC E Q U I P M E N T I 54
RIVER
ROAD,
SUMMIT.
N.
I.
Circle No. 95 on Readers' Service Card VOL 39, NO. 2, FEBRUARY 1967
·
33 A
