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Coal Deposits of the Santa Clara District Near Tonichi, Sonora, Mexico

Description: From abstract: The Santa Clara coal district is 7 to 10 kilometers west of Tonichi, a small town on the Rio Yaqui, in southeastern Sonora, Mexico. Tonichi was the terminus of a branch railroad from Corral until May 1945, when the end of the line was removed. The coal deposits were developed by the Southern Pacific Railroad from the 1890's until about 1911, when the mines were abandoned, partly because the coal was found unsuitable for use in locomotives. Other coal deposits, near Los Bronces and San Javier, west of the Santa Clara district, were mined for a number of years to provide coal for a silver smelter at San Javier which was abandoned sometime during the 1920's. Since 1942 the Santa Clara deposits have been reopened; through 1945 about 50,000 tons of coal had been shipped, at first to the Boleo copper smelter at Santa Rosalia, Baja California, and more recently to Guadalajara, Jalisco, for the manufacture of calcium carbide.
Date: 1949
Creator: Wilson, Ivan F. & Rocha, Victor S.

Manganese Resources of the Artillery Mountains Region, Mohave County, Arizona

Description: From introduction: The sampling on which the estimates of ore reserves in this report are partly based was done by Lasky and Roberts. The text was written by Lasky, who, except where otherwise noted, is responsible for any descriptions, comments, and conclusions concerning the area beyond the limits of the Hanna holdings, as well as for all statements concerning reserves and recommendations for future prospecting.
Date: 1949
Creator: Lasky, Samuel G. & Webber, B. N. (Benjamin Nevitt), 1899-

Antimony Deposits of El Antimonio District Sonora, Mexico

Description: From introduction: This is one of a series of detailed studies of the antimony deposits of Mexico, which were investigated by the United States Geological Survey and the Instituto de Geologia de Mexico. The investigation was part of a cooperative program sponsored by the Interdepartmental Committee for Scientific and Cultural Cooperation, under the auspices of the Department of State.
Date: 1949
Creator: White, Donald Edward & Guiza, Reinaldo

Range Energy Relation for Protons in Nuclear Emulsions

Description: An experimental range-energy relation in Ilford C-2 emulsion has been obtained for proteins up to 39.5 Mev. In the region from 17 to 33 Mev the relation for dry emulsion is fitted by the empirical equation E{sub (MeV)} = 0.251 R{sub ({mu})} 0.581. Variations in water content due to changes in atmospheric humidity make several percent difference in range. The range in Ilford glass is found to be 18 {+-} 4 percent longer than in dry C-2 emulsion.
Date: September 9, 1949
Creator: Bradner, H.; Smith, F.M.; Barkas, W.H. & Bishop, A.S.

Electronics Accomplishment Report

Description: Group 10 - The following items were shipped to Scioto Laboratory: 6 Thyratron Heater Controls (TR-1-A), 2 Switch Boxes (for P & E), 1 Log Amplifier (AM-1); 1 Pulse Generator (PG-1-B). The following are completed, tested, and awaiting transportation: 3 Two-Input B-wall Mixers (MX-2-A), 1 Pulse Generator (PG-1-B),1 Regulation Checker (RC-1) (for plating control power supplies), 1 Preamplifier (AM-2) (for Berkeley decimal scaler). The following are under construction: 6 Pulse Generators (PG-1-B) (for Health Division) (EO-508) 90%, 10 Switch Boxes (8 for P & E, Scioto, 2 for P& E, "T" Building) 85%, 6 Junction Boxes (for P&E, "T" Building, EO-486) 90%, 2 Four-Input G. M. Mixers. One on EO-17, one from Unit III. The mixers have been finished and tested for some time. The scalers (Nuclear Instrument Model 161-G) have just been received and are being modified for use with the mixers. A prototype preamplifier for the Berkeley decimal scaler was constructed and tested. Group 11 - A special pulse generator having output pulses fixed in time, and adjacent pulses variable in time with respect to the fixed pulse is under development. An initial mock-up of such a generator showed promise in that the variable pulses could be shifted in time, but there was considerable "jitter" of the pulses. A method of obtaining more positive triggering of the pulse generating circuits is being worked out. Group 12 - Three service calls were made during this period for defective G. E. induction heaters used by Group 31. Group 14- Routine counting this period included 5990 counts.
Date: September 30, 1949
Creator: Heyd, J. W. & Ohmart, P. E.

Tests for Hydrogen Cyanide and Hydrogen Sulfide

Description: A potential source of dangerous concentrations of hydrogen cyanide exists in the plating room of the Machine Shop where open plating baths containing cyanide salts are maintained and where solid cyanide salts are stored. Also the use of hydrogen sulfide in certain steps of the waste disposal process has lead to noticeable and sometimes objectionable concentrations of this gas in the air of the "WD" Building. In view of the toxic properties of these two gases, it was desirable to set up suitable tests to determine the actual concentrations present in the air of the respective working areas.
Date: August 24, 1949
Creator: Joy, E. F.

Carrier-free Radioisotopes from Cyclotron Targets I. Preparation and Isolation of Sn113 and In114 from Cadmium

Description: The cyclotron is the only practical source of many carrier-free radioisotopes. The preparation and radiochemical isolation of a number of these activities, produced in the 60-inch cyclotron of Crocker Laboratory, will be presented in this paper and in subsequent papers of this series. In most cases the carrier-free radioisotopes were prepared for use in biological systems and the final preparations were in the form of isotonic saline solutions at a range of pH from 5 to 8. The present paper reports the radiochemical isolation of carrier-free Sn{sup 113} and In{sup 114} produced by bombarding cadmium with 38 Mev alpha-particles. At this energy, Sn{sup 113} and In{sup 114} are produced in a thick target by the nuclear reactions; Cd{sup 110}({alpha},n)Sn{sup 113}, Cd{sup 111}({alpha},2n)Sn{sup 113}, Cd{sup 112}({alpha},3n)Sn{sup 113}, Cd{sup 111}({alpha},p)In{sup 114}, Cd{sup 112}({alpha},pn) In{sup 114}. The shorter-lived tin and indium activities together with the possible radioisotopes of silver produced by (n,p) reactions, were allowed to decay out prior to the chemical separations.
Date: August 11, 1949
Creator: Maxwell, R.D.; Haymond, H.R.; Bobmberger, D.R.; Garrison, W.M. & Hamilton, J.G.

Low Mass Francium and Emanation Isotopes of High AlphaStability

Description: Isotopes of francium with 126 or fewer neutrons have been looked for in bombardments of Th{sup 232} with 350 Mev protons from the 184-inch cyclotron. Fr{sup 212} with an apparent half-life of 19.3 minutes for branching decay by alpha emission (44%) to At{sup 208} and by orbital electron capture (56%) to Em{sup 212} has been found. Em{sup 212} is shown to be a 23-minute alpha-emitter. At{sup 208} decays primarily (99.5%) by orbital electron capture to Po{sup 208}, but shows 0.5% alpha-branching. The francium and emanation isotopes have alpha half-lives completely out of line with the predictions based on the previously known isotopes of these elements. Their high alpha stability is believed to be due to a closed shell of 126 neutrons in analogy to the behavior of elements 83-85. The non-existence of long-lived francium in nature is discussed in the terms of this and other recent work on francium isotopes.
Date: October 10, 1949
Creator: Hyde, E.K.; Ghiorso, A. & Seaborg, G.T.

New Low Mass Isotopes of Emanation (Element 86)

Description: Among the spallation products obtained from the 350-Mev proton bombardment of Th{sup 232} they have identified two gaseous alpha-emitters which apparently do not decay into any presently known alpha-decay chains. The half-lives observed for the decay of the alpha-activities are 23 minutes and 2.1 hours. These half-lives may be principally determined by an unknown amount of orbital electron capture. At least one alpha-emitting daughter (about 4 hours half-life) has been observed to grow from a gaseous parent, but it has not been determined whether it arises from alpha-decay or electron-capture. Since these gaseous atoms emit alpha-particles it is assumed that they are isotopes of element 86 (emanation or radon) rather than a lighter rare gas. if they were heavy isotopes such as Em{sup 221} or Em{sup 223}, both unknown, they would decay into known alpha-decay series, the neptunium and actinium series, respectively, and so would grow known short lived alpha-emitters which would have been detected. It thus appears reasonable that they must be lighter than the known emanation isotopes.
Date: September 5, 1949
Creator: Ghiorso, A.; Meinke, W.W. & Seaborg, G.T.

Nitrogen 12

Description: N{sup 12} is shown to have a half life of 12.5 {+-} 1 milliseconds, and a positron upper limit of 16.6 {+-} 0.2 Mev. It is produced by the reaction C{sup 12}(p,n)N{sup 12}, and has a threshold proton energy of 20.0 Mev. This indicates that N{sup 12} is within about 200 Kev of being unstable against proton emission. The mass of N{sup 12} is 12.0228 {+-} 0.00015, and the beta transition is allowed.
Date: January 19, 1949
Creator: Alvarez, Luis W.

Systematics of Alpha-Radioactivity

Description: Correlations of alpha-decay energies in terms of mass number and atomic number have been made for all of the alpha-emitting species now numbering over 100. For each element isotopes show increase in alpha-energy with decrease in mass number except in the region of 126 neutrons where there is an explainable reversal. This reversal has the effect of creating a region of relatively low alpha-energy and long half-life at low mass numbers for such elements as astatine, emanation, francium, and possibly higher elements as had been noted already for bismuth and polonium. Methods and examples of using alpha-decay data to define the energy surface in the heavy element region are discussed. The regularities in alpha-decay are used for predictions of nuclear properties including prediction of the beta-stable nuclides among the heavy elements. The half-life vs. energy correlations show that the even-even nuclides conform well with existing alpha-decay theory, but all nuclear types with odd nucleons show prohibited decay. The reason for this prohibition is not found in spin changes in the alpha-emission but in the assembly of the components of the alpha particle, and this theory is discussed further in terms of observations made on nuclides having two or more alpha-groups. Using most of the even-even nuclei to define 'normal nuclear radius' calculations are now able to show the shrinkage in the regions of lead and of 126 neutrons to amount to about 10%. The much greater change in 'effective radius' for bismuth isotopes can be dissociated into the effects of odd nucleons superimposed on the actual decrease in nuclear radius. The simple expression r = 1.48 A{sup 1/3} {center_dot} 10{sup -13} cm seems to fit the data for the even-even nuclei outside of the region of 126 neutrons better than more complex functions.
Date: September 12, 1949
Creator: Perlman, I.; Ghiorso, A. & Seaborg, G.T.

Production for Mesons by X-rays

Description: At the spring, 1949, meeting of the National Academy of Sciences(l) a preliminary account was given of some observations of mesons produced by the 335 Mev x-ray beam from the Berkeley synchrotron. The present paper is a progress report of this work; no claim is made for completeness, but sufficient new data are available to make publication at this time worth while, especially since some of the numerical results given in the earlier report require revision. The x-ray beam, produced by the impact of 335 Mev electrons on a 20 mil thick platinum target, has a width at half maximum of 0.0135 radian (about 1 inch at 6 feet from the target). In all but the earliest experiments the beam was further defined by a 1 inch hole in a lead block, then passed through a piece of carbon which served as the meson source. The x-ray intensity at one meter from the target was about 3500 r per hour (measured behind 1/8 inch of lead) under the best running conditions; the average was about half this. The actual exposures at the carbon meson source (6 feet from the target) ranged from 500 to 2000 r in the later runs. Mesons were recorded on Ilford nuclear plates; the highest density of meson endings observed was about 100 per square centimeter in a 100 micron emulsion. In the following sections the experimental conditions and some of the results are described in more detail.
Date: September 15, 1949
Creator: McMillan, Edwin M.; Peterson, Jack & White, R. Stephen

A Proposed Experimental Test of the Neutrino Theory

Description: The experiment outlined in this proposal has the possibility of giving an answer to the important question, 'Does the neutrino exist'? It is unfortunate that at the present time, there is no convincing experimental that neutrinos exist. Two recent articles review the status of various experiments which could give information about neutrinos. In general, these experiments give results in agreement with the predictions of beta decay theory. But actually, if even the most complete of the 'recoil type' experiments could be performed satisfactorily, all that could be concluded would be the following: the energy and momentum relationships in beta decay are consistent with the theory that the known energy deficit is carried away by a single particle. But to emphasize the fact that this would not constitute a proof of the real existence of that particle, the following quotations from the review articles should be noted. Crane says, 'All of the evidence about the neutrino is, as already pointed out, indirect in character since neutrinos have not yet been caught after leaving the nucleus. It can, of course, be argued on very general grounds that, if energy is not conserved between nucleus and electron, momentum should not be expected to be conserved either, and in consequence of this, it has often been remarked that the recoiled experiments add nothing that is really new to their knowledge'. Allen concludes his article by saying, 'Practically all the experimental evidence indicates that there is an apparent non-conservation of momentum in the beta decay process, and that the neutrino hypothesis is at least one explanation of the missing momentum'.
Date: April 18, 1949
Creator: Alvarez, Luis W.