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The mean heat capacity of a sample of powdered beryllium carbide, a possible moderator material for a nuclear reactor, was determined as a function of temperature. A thin-walled stainless steel capsule containing the material was heated in an electric furnace and dropped into a water calorimeter. The following linear equation for mean heat capacity over the temperature range 50 f C-T f C as a function of temperature, T, was derived from the data by the method of least squares: C/sub p/ = 0.299 + 2.16 x 10/sup -4/ T f C el temperatures 0.005 cal gm/sup -1/( f C)/sup -1/. The numerical value of C/sub p/ expressed by this equation is also equal to the mean heat capacity in Btu lb/sup -1/( f F)/sup -1/. (auth)

Analytical methods are given for determining the composition and impurities of beryllium carbide. A summary of the experimental work leading to these procedures and supporting data are also presented. Analytical procedures for the determination of free and combined carbon, moisture, nitrogen, beryllium oxide, silica, iron, total beryllium, and beryllium metal are outlined. Diagrams of special apparatus used are included. (auth)

The mean heat capacity of a sample of powdered U/sub 3/O/sub 8/ was determined as a function of temperature from measurements of heat content. A thin-walled nickel capsule containing the material was heated in an electric furnace and dropped into a water calorimeter The Mean heat capacity values calculated from the experimental data were nearly constant over the temperature range, room temperture to 250-975 deg C (482-1790 deg F). The average value was 0.074 plus or minus 0.004 cal gm/sup -1EDE/C/sup -2/ (0.074 plus or minus 0.004 Btu lb/sup -1 deg F/du p -1/). From 975-1100 deg C (1790-2012 deg F) a small rise was observed. (auth)

Included in this semi-monthly report written in 1943 are progress with neutron beams, neutron absorption in enriched materials, equipment operation and maintenance reports of the cyclotron neutron source facility, and instrumentation maintenance activities of individuals in the cyclotron group. (GHT)

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.

A comparison of the decay constants of Be{sup 7} in beryllium oxide and in beryllium fluoride has given {lambda}{sub BeO}-{lambda}{sub BeF{sub 2}} = (+1.375 {+-} 0.053)10{sup -3}{lambda}{sub BeO} thus showing a definite effect of the chemical binding on the radioactive decay constant.

Excitation functions have been measured, using a 38-Mev alpha-beam and a 19-Mev deuteron beam for the following reactions: Bi({alpha},2n)At{sup 211}, Bi({alpha},3n)At{sup 210}, Bi(d,p)Ra E, Bi(d,n)Po{sup 210}, and Bi(d,3n)Po{sup 209}. The results are summarized in Figs. 4 and 5 and Tables I and II. A new isotope of astatine, At{sup 210}, has been identified; this isotope has a half life of 8.3 hr., decaying by K-capture to Po{sup 210} with the emission of a 1.0-Mev gamma-ray and a few conversion electrons.

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.

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.

In an early continuation of the investigation of the radioactive isotopes of element number 43 (technetium) Segre and Seaborg produced by the deuteron and neutron bombardment of molybdenum the isotope Tc{sup 99}, which they observed to decay by means of an isomeric transition with a half-life of 6.6 hours to a lower isomeric state with a half-life greater than 40 years. The upper isomeric state of this isotope was observed by Segre and C. S. Wu to be produced in the fission of uranium and more recently R. P. Schumann and also D. C. Lincoln and W. H Sullivan working on the Plutonium Project of the Manhattan District have independently observed the beta-particles of half-life about 10 years due to the lower isomeric state. Later work by E. E. Motta and G. E. Boyd sets a more accurate value of 9.4 x 10{sup 5} years for this half-life. Since this isotope is formed in rather large amounts, namely, a fission yield of 6.2%, in the slow neutron induced fission of uranium it is now possible to isolate technetium in weighable amounts and in rather substantial quantities. For example, a uranium pile operating at a power level of 10{sup 5} kw …

In an attempt to detect a possible influence of the atomic electrons on the radioactive decay constant of Be{sup 7} they have measured {lambda}{sub Be}-{lambda}{sub BeO} and found (-3.0 {+-} 1.8) 10{sup -4} {lambda}{sub Be}. They describe also a method to measure mean lives of radioactive substances in a time short compared with the mean life.

The dark fixation of carbon dioxide by green algae has been investigated and found to be closely related to photosynthesis fixation. By illumination in the absence of carbon dioxide followed by treatment with radioactive carbon dioxide in the dark, the amount fixed has been increased ten to twenty fold. This rate of maximum fixation approaches photosynthesis maximum rates. The majority of the radioactive products formed under these conditions have been identified and isolated and the distribution of labeled carbon determined. From these results a tentative scheme for the mechanism of photosynthesis is set forth.

This paper reports on the following programs: (1) 184-inch Cyclotron Program; (2) 60-inch Cyclotron Program; (3) Synchrotron Program; (4) Linear Accelerator Program; (5) Experimental Physics; (6) Theoretical Physics; (7) Isotope Separation Program; (8) Chemistry; and (9) Medical Physics.

The participation of phosphorus in biological oxidation-reduction reactions of the type found in glycolysis ADP + PO{sub 4}H{sup -} + 3-phosphoglyceraldehyde + DPN{sup +} = 3-phosphoglycerate{sup -} + 2H{sup +} + DPNH + ATP has suggested theories in which similar reactions are proposed for photosynthesis. In these theories the reducing power of photosynthesis is utilized not only for reduction of carbon dioxide but also, by means of coupled oxidations, for the generation of high-energy phosphate bonds, or in the last reference directly for the generation of high-energy phosphate. Since in these theories acyl phosphate is formed from inorganic phosphate, they are amenable to proof without isolation of particular intermediates, by means of radioactive phosphorus. It would be expected that the rate of conversion of inorganic phosphate to organic phosphate would be greater in light than in the dark. They have investigated this possibility under a variety of conditions and are unable to substantiate the theories.

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. …

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 …

The authors have produced and identified two new series of alpha-particle emitting radioactive elements; one is a 'collateral' branch of the actinium (4n + 3) radioactive family and the other is collateral to the thorium (4n) family. The series are of considerable interest in that they are the first whose early members lie on the neutron deficient side of beta stability. They have been produced in high yield of irradiation of thorium with deuterons of energy about {sup 80}Mev in the Berkeley 184-inch cyclotron. So far as the present observations are concerned both of these series begin with isotopes of protactinium (atomic number 91), although progenitors with higher atomic numbers are to be expected and will possibly be produced and identified. These protactinium isotopes are Pa{sup 227} and Pa{sup 228} formed by d,7n and d,6n reactions respectively.

This report gives a short summary of each of the following programs: (1) 184-inch Cyclotron Program; (2) 60-inch Cyclotron Program; (3) Synchrotron Program; (4) Linear Accelerator Program; (5) Experimental Physics; (6) Theoretical Physics; (7) Chemistry; (8) Medical Physics; and (9) Health Physics and Chemistry.

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.

In the course of a rather cursory examination of the elution of tetra-positive ions from the cation exchange resin Dowex 50 with hydrochloric acid solutions, the authors have discovered a very effective method of separating zirconium from hafnimu. In view of the great labor involved in preparing even reasonably pure hafnium compounds by existing methods, they feel that this procedure will prove very valuable to those interested in obtaining hafnium compounds free of zirconium. Although the conditions which give satisfactory separation were first worked out using microgram amounts of material and the radioactive tracer technique, the run described here, involving milligrams of material, illustrates the applicability of the method to the production of significant amounts of pure hafnium and zirconium.

Fireman(1) has reported the results of a rather difficult beta-particle coincidence counting experiment in which the decay of Sn{sup 124} by the simultaneous emission of two negative beta-particles, with a half-life between 0.4 x 10{sup 16} years and 0.9 x 10{sup 16} years, seems to have been observed. This note reports the results obtained from a different and somewhat simpler method of looking for the phenomenon of simultaneous emission of two beta-particles. These results are negative so far and show that this process is considerably less probable in the case chosen by us than in that reported by Fireman. The method consists of looking in uranium samples for 90-year Pu{sup 238} which would come from U{sup 238} by the double beta-particle mechanism since Np{sup 238} is heavier than U{sup 238}, which in turn is substantially heavier than Pu{sup 238}, in the isobaric triplet {sub 92}U{sup 238}-{sub 93}Np{sup 238}-{sub 94}Pu{sup 238}. This chemical method of investigation is particularly applicable to this isobaric triplet because there appears to be no other mechanisms to account for the Pu{sup 238} should it be found. The energetics of the situation are summarized in the following diagram, where the disintegration energies are derived from sources which …

Magnetic susceptibilities per gram atomic weight of elements 92 to 95 in most of their oxidation states were measured on 0.1 ml of solution which was 0.007 to 0.09 M in heavy element. The values obtained (all paramagnetic) in c.g.s. units x 10{sup 6} were: U(IV), 3690; Np(VI), 2060; Np(V), 4120; Np(IV), 4000; Pu(IV), 1610; Pu(III), 370; Am(III), 720. The results could be interpreted only on the basis of electronic configurations 5f{sup n}, even though susceptibilities were generally lower than the theoretical values and lower than experimental values for corresponding lanthanide cations. The lower values should be expected as a result of the Stark effect produced by fields of anions and of water dipoles. Failure of the Russell-Saunders approximation to the coupling between electrons may account for some of the error in the theoretical calculations. Wider multiplet splitting in the actinides accounts for the fact that the susceptibilities of Pu(III) and Am(III) are many-fold lower than those of Sm(III) and Eu (III) respectively.

The decay scheme of a 4.2 second neutron emitter has been investigated in detail. Chemical and physical evidence shows that it is N{sup 17}, which emits beta rays to a broad excited state of O{sup 17}, which then breaks up into a neutron plus O{sup 16}. The energy spectrum of the neutrons is determined by measuring the energies of the O{sup 16} recoils in a proportional counter. The neutrons have a most probable energy of 0.9 Mev, a 'half width' of less than .5 Mev, and an upper limit of about 2 Mev. {beta}-recoil coincidences are observed, as predicted by the Bohr-Wheeler theory, and the {beta}-ray energy is measured by absorption. The beta rays in coincidence with neutrons have an upper limit of 3.7 {+-} 0.2 Mev. Beta-rays directly to the ground stat of O{sup 17} are not observed because of high background effects, but should have an energy of 8.7 Mev. Some evidence is presented to show that energy is conserved in the {beta}-n transition through the broad excited state in O{sup 17}.