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[en] The author examines the methods utilized for separating artificial radio-elements and describes a few preparations (phosphorus 32, iodine 131, arsenic 76, fission products). He describes also various industrial applications of the radioactive elements, which make use of their radiation products. Reprint of a paper published in 'Industrie chimique belge', T. XIX, No. 8-1954, p. 785-788.
[fr]On indique quelles sont les methodes utilisees pour la preparation des radioelements artificiels et l'on decrit quelques preparations (phosphore-32, iode-131, arsenic-76, produits de fission). On decrit egalement quelques applications industrielles des radioelements qui utilisent les produits de leurs rayonnements. Reproduction d'un article publie dans l'Industrie chimique belge, T. XIX, No. 8-1954, p. 785-788.
[en] The authors studied 34S/32S isotopic ratios of ten samples of native sulfur and three of pyrite. Extreme variations of 5 pc have been observed. The obtained values are related to those published by H. Thode in a previous study; the method of sample preparation is presented and the obtained spectra is discussed. Reprint of a paper published in 'Journal de Chimie Physique', t. 49, no. 2, Feb 1952.
[fr]Les auteurs ont etudie les rapports isotopiques 34S/32S de dix echantillons de soufre natif et de trois de pyrite. Des variations extremes de 5 pc ont ete observees. Les valeurs obtenues ont ete reliees a celles publiees par THODE. Ils donnent la methode de preparation des echantillons et discutent les spectres obtenus. Reproduction d'un article publie dans le 'Journal de Chimie Physique', t. 49, no. 2, Feb 1952.
[en] The author reports an attempt to use the Bohr model formalism to approximately process, within the frame of the layer model, the interaction between a single nucleon of an even-odd nucleus with incomplete (or not surely incomplete) layers which contain an even number of nucleons. These incomplete pair layers are replaced by the oscillating surface of the Bohr's model. Other nucleons interacting with this surface are treated according to the Pauli principle. Reprint of a paper published in 'Journal de Physique et le Radium', t. 14, Nov 1953, p. 635-636.
[en] The fine structure of 234U α spectra has been studied by the impulse ionisation chamber technique, with determination of the energy of the α1 line. A second α0 line is determined at about 170 keV. Reprint of a paper published in 'Comptes Rendus des Seances de l'Academie des Sciences', t. 237, sitting of Dec 21, 1953, p. 1673-1675.
[fr]Etude de la structure fine α de 234U par la technique de la chambre d'ionisation a impulsion. Determination de l'energie de la raie α1. Mise en evidence d'une seconde raie a environ 170 keV de α0. Reproduction d'un article publie dans les 'Comptes Rendus des Seances de l'Academie des Sciences', t. 237, seance du 21 decembre 1953, p. 1673-1675.
[en] Countries with large stock of fissile material and producing large quantity of nuclear pure 235U and 239Pu are able to allocate part of the stock to non military research. For countries with low stock of fissile material, all the stock is allocated to military research. An economical and technical solution has to be find to dedicate a part of fissile material to non military research and develop the atomic energy industry. It stated the industrial and economical problems and in particular the choice between the use of enriched fuel with high refining cost or depleted fuel with low production cost. It discusses of four possible utilizations of the natural resources: reactors functioning with pure fissile material (235U or 239Pu) or concentrated material (235U mixed with small quantities of 238U after an incomplete isotopic separation), breeder reactors functioning with enriched material mixed with 238U or Thorium placed in an appropriate spatial distribution to allow neutrons beam to activate 238U or Thorium with the regeneration of fissile material in 239Pu, reactors using natural uranium or low enriched uranium can also produce Plutonium with less efficiency than breeder reactors and the last solution being the use of natural uranium with the only scope of energy production and no production of secondary fissile material. The first class using pure fissile material has a low energy efficiency and is used only by large fissile material stock countries to accumulate energy in small size fuel for nuclear engines researches for submarines and warships. The advantage of the second class of reactors, breeder reactors, is that they produce energy and plutonium. Two type of breeder reactor are considered: breeder reactor using pure fissile material and 238U or breeder reactor using the promising mixture of pure fissile material and Thorium. Different projects are in phase of development in United States, England and Scotland. The third class of reactor using natural uranium as fuel are presented as a possibility for double-function reactor with the production of plutonium and energy, but the neutron balance is lower than with breeder reactor. One solution is to increase the temperature of functioning but it induces to change the structure materials and moderators. Different solutions are discussed about the utilization of graphite or heavy water as moderators. The last class of reactors using natural uranium and producing only energy is considered by countries with no uranium stock, the energy efficiency and balance, as well as the costs, are then of more importance. Finally, it presented conclusions about the different economic strategies about the industrial development of atomic energy in countries with and without fissile material resources. (M.P.)
[en] This short paper shows that the isotope 67 of zinc, concentrated at 75 pc, emits α rays under the action of thermal neutrons. The cross section of the 67Zn (n, α)64Ni reaction is 5.5 x 10-30 cm2 and the energy of the α is about 7.5 MeV. For isotopes 66 and 68, σ(n, α) < 2.10-29 cm2 and for nickel σ(n, α) < 2.10-30 cm2. Reprint of a paper published in 'Comptes Rendus des Seances de l'Academie des Sciences', t. 235, sitting of Aug 11, 1952, p. 425-427.
[fr]Nous avons montre que l'isotope 67 du zinc, concentre a 75 pc, emet des rayons α sous l'action des neutrons thermiques. La section efficace de la reaction 67Zn (n, α) 64Ni est de 5,5.10-30 cm2 et l'energie des α est d'environ 7,5 MeV. Pour les isotope 66 et 68, σ (n, α) < 2.10-29 cm2 et pour le nickel σ (n, α) < 2.10-30 cm2. Reproduction d'un article publie dans les 'Comptes Rendus des Seances de l'Academie des Sciences', t. 235, seance du 11 aout 1952, p. 425-427.
[en] A significant separation of gallium isotopes is obtained with a DC current applied to the molten metal. Reprint of a paper published in 'Comptes rendus des seances de l'Academie des Sciences', T. 239, Sitting of July 12 1954, p. 162-164.
[fr]Une separation appreciable des isotopes du gallium est obtenue sous l'action d'un courant continu passant dans le metal fondu. Reproduction d'un article publie dans les Comptes rendus des seances de l'Academie des Sciences, T. 239, seance du 12 juillet 1954, p. 162-164.
[en] The purpose of these notes is to give an account of some attempts at interpreting the observed values of nuclear magnetic moments. There is no attempt at a complete summary of the field as that would take much more space than is used here. In many cases the arguments are only outlined and references are given for those interested in further details. A discussion of the theory of nuclear magnetic moments necessitates many excursions into the details of the nuclear models because the magnetic moments have a direct bearing on the validity of these models. However the main emphasis here is on those features which tend to explain the magnetic moments and other evidence is not discussed unless it has a direct bearing on the problem. In the first part of the discussion the Shell Model of the nucleus is used, as this model seems to correlate a large body of data relating to the heavier nuclei. Included here are the modifications proposed to explain the fact that the experimental magnetic moments do not fit quantitatively with the exact predictions of the Shell Model. The next sections deal with some of the more drastic modifications introduced to explain the large nuclear quadrupole moments and the effect of these modifications on the magnetic moments. Finally we turn to more detailed investigations of the light nuclei, in particular the - Conjugate nuclei. (author)
[en] With the increasing use of radioactive isotopes by industry, the medical profession, and research laboratories, it is essential that certain minimal precautions be taken to protect the users and the public. The recommendations contained in this Handbook represent what is believed to be the best available opinions on the subject as of this date. As our experience with radioisotopes broadens, we will undoubtedly be able to improve and strengthen the recommendations for their safe handling, utilization, and disposal of wastes. Comments on those recommendations will be welcomed by the committee. One of the greatest difficulties encountered in the preparation of this Handbook lay in the uncertainty regarding permissible radiation exposure levels, particularly for ingested radioactive materials. The establishment of sound figures for such exposure still remains a problem of high priority for many conditions and radioactive substances. Such figures as are used in this report represent the best available information today. If, in the future, these can be improved upon, appropriate corrections will be issued. The subject will be under continuous study by the subcommittees mentioned above. The best available information on permissible radiation levels and permissible quantities of ingested radioactive material may be found in the Recommendations of the International Commission on Radiological Protection and the Supplement to these recommendations in NBS Handbook 47. It should be borne in mind, however, that even the values given in that Handbook may be subject to change. As the problem of the disposal of radioactive wastes varies over such wide limits, depending upon the usage to which the isotopes are put, the committee has decided that it will not be feasible to incorporate in one volume broad recommendations covering all situations and materials. This is the first of a series of such reports. The present Handbook has been prepared by the Subcommittee on Waste Disposal and decontamination
[en] The optical spectrum of plutonium was excited in a hollow cathode discharge tube provided with 7 mg Pu-oxide. Highly purified argon was circulated through the tube. During 7 hours the spectrum of neutral plutonium was very bright at 400 V, 150 mA. By means of a Steinheil 3 prism glass spectrograph it could be photographed in 15 minutes in the region 7000-3700 A. The strongest Pu II-lines are also present on the spectrograms. The spectrum was examined under high resolution in the region 6500-4000 A by means of Fabry-Perot standards placed in front of the spectrograph. The interference fringes were focused on the slit by means of a 33.3 cm achromat. Exposure times of 3 hours yielded spectrograms of sufficient density to study several Pu-lines in detail. Two such spectrograms could be made, one with silvered etalon plates 19 mm a part, and the second with aluminized plates at a distance of 28 mm. The interferometer spectrograms revealed the existence of a narrow doublet structure in 28 lines. The doublet components have nearly equal intensities in most cases. In the region 6420-5520 A 30 Pu-lines are strong enough to be studied and 13 of them turn out to be doublets, while some other lines are definitely broadened. Since the sample practically does not contain any other isotope than 239Pu, the observed splitting must be interpreted as a magnetic hyperfine structure. Though the electronic structure of plutonium is unknown as yet it is certain that most strong lines are due to transitions between levels of high J. Moreover the J-values in the Pu I-spectrum are integer and even a 0-1-transition would show 3 components if the nuclear spin were > 3/2. Hence the 94239Pu-nuclide has a ground state spin I = 1/2. The nuclear magnetic moment cannot be determined as long as the electronic levels are unknown. Even its sign cannot be given, since one may expect transitions 5f5 6d 7s2 - 5f5 6d 7s 7p in which the high level has the largest hyperfine structure splitting and transitions 5/5 6d2 7s - 5f5 6d2 7p in which the low level will split widest. The nuclear spin found is rather unexpected in connection with the spin of 235U, which is probably 5/2, and with the regularities of the nuclear shell model. It has been assumed that in 235U the neutron state 6g9/2 is filled, while 7i11/2 lodges 6 neutrons and the odd neutron is in the 5d5/2-orbit. It would be quite natural if the 2 additional neutrons in 239Pu would occupy the 7i11/2-orbit and the final state would remain the same as in 235U. However, among odd neutron nuclei the tendency of the last neutron to occupy states of small momentum is well-known. The shell in question contains the 4s1/2-state. When the odd neutron in 239Pu prefers to occupy that state this means that 4s1/2 is lower than 7i11/2, 8k15/2, 5d5/2, 6g7/2 and 5d3/2 for single occupation in the region concerned. A similar situation is known in the foregoing period of the nuclear periodic system, where 111Cd (and subsequent nuclei) has a 3s1/2 ground state owing to 3s1/2 being lower than 4d5/2, 6h11/2 and 4d3/2 for single occupation. If the interpretation given is correct the magnetic moment of 239Pu should be negative. The plutonium used in this research had been extracted from the uranium pile at Chatillon, in the laboratories of the French Commissariat a l'energie atomique, with the help of Madame C. Lheureux. Seven milligrams of highly purified Pu in the form of its hydroxide were brought to Amsterdam where the hydroxide was dried and transformed into oxide in the chemical laboratory of the institute for nuclear research, with the help of Mr. L. Lindner. The investigation of the plutonium spectrum is being continued. Reprint of a paper published in 'Physica' XX, p. 37-38.