The objectives in producing neutron sources are to produce uniform products of as high efficiencies as possible from the neutron yielding elements and to do this in the safest manner. The purpose of the present work was to improve the methods of preparing sources and at the same time increase the types of sources available. Lithium, sodium, and their compounds were chosen because the neutron fluxes and energies are low, thus making the experimental work less hazardous to the operator. Also, the elements are quite reactive, so that techniques which are successful with them can be easily adapted to other materials. Solvents for polonium, ways of mixing polonium and target, neutron yields, reproducibility, decay of the sources, means of recovering polonium, and materials for containers, were investigated.

The constant temperature bath is in operation. A ballistic type instability was detected in the calorimeter circuits and corrected by grounding the bath. Calorimeters 37, 39, 40, and 43 have been installed are now being run. Calorimeter 40 was found to be unstable, and is to be disassembled and examined for the trouble. Calorimeter 46 was finished and placed in operation. Construction details are discussed. Six Logac samples were run in Calorimeter 38. Tests of this calorimeter are in Table 1. Comparison of Calorimeter 38 in a water bath and in an ice bath is shown in Table 2. Good results were obtained for such a drastic change in environment. Calorimeter 38 was turned over to Calorimetric Assay marking the end of the tests of this particular microcalorimeter. Calorimeter 44 was completed and installed in the ice bath. Table 4 shows the results of tests. The zero bridge potential is small and is very stable compared to Calorimeter 38. The comparison of the values with those from Calorimetric Assay is summarized in Table 3. The characteristics of Calorimeter 44 are shown in Table 5. Construction details are given for the platinum-manganin bridge-type thermometer. An instrument was needed that could be …

Apparatus for measuring the resistivity of polonium is described. This equipment has been built and tested. No resistivity measurements were made, however, because the method of determining the purity of the sample has not been perfected.

Experimental use of sodium radiophosphate (P32)in treatment of polycythemia is described. Treatment history is 66 patients treated with P32 alone, 32 patients treated with P32 followed within 4 months by venesections, 21 patients treated with P32 followed more than 4 months later by venesections, 6 patients treated exclusively by venesections, and 9 patients treated and followed elsewhere.

Considerable study has been given to the problem of a cathode-follower coupling circuit for matching a B-wall tube to a properly terminated coaxial cable. A matched circuit makes it possible to obtain faster counting rates independent of practical cable lengths. A breadboard circuit has been built and first results indicate that a two millivolt signal at the input of the cathode-follower will operate the Model 162 Instrument Development Laboratory Scaling Unit when adjusted for maximum gain. This is comparable to the voltage available when the B-wall tube is coupled to its amplifier through a coaxial cable. Shielded room measurements have been completed in the ``R`` Building. One log-amplifier (EL-257) was delivered to group 32, one scaler-multiplier (EL-252) to group 34, one four-input GM mixer (EL-247 to Group 24, and the plating control regulation checker (EL-258) plus the portable pulse generator (EL-261) to Group 12. The scaler-multiplier (EL-253)is 20 per cent complete and the motor-driven slide wire and the four-input gamma mixer (EL-262) are 95 per cent complete. The manufacturing specifications for plating controls and the instruction book for the portable pulse generator (EL-2561) have been submitted for duplication and should be completed by January 31, 1949. The two (2) 6 …

The Purpose of this manual is to describe preparation of bismuth powder for use in process operations. Bismuth powder is to be prepared in Room 232 of ``T`` Building where all necessary apparatus is installed.

This document is a March 1949 Ad Interim Report from the Mound Laboratory on the solution chemistry of polonium. A consideration of the valences of the elements of the Group VI-A would indicate that the oxidation states of -2, 2, 4, and 6 might be expected for polonium. From the decrease in stability of the hydrides of these elements with increase in atomic number, one would expect that the compound H{sub 2} Po would be very unstable and that the oxidation state of -2 would not occur in solution. Furthermore, the stability of the oxidation state +6 as well as the stability of the highest oxidation state of a given element decreases as the atomic number increases in Group VI-A and Period VI respectively. For these reasons, the oxidation state +6 for polonium would be expected to occur only in a strongly oxidizing medium. The +4 state would be expected to be stable. The work discussed herein indicates that polonium exists as PoO{sup ++} in a nonoxidizing or reducing medium.

Progress is reported on the quartz fiber microbalance design and research. The mechanism for drawing the quartz fibers and the measurements of the properties of the fibers are described. Design and construction of a mass spectrograph and a cloud chamber is presented. Refilling B-wall tubes is investigated.

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This report is a descriptive journey of the Activation Analysis of the Rare Earths.