Natural Isotopic Mixture Research Articles

Spectrum of protons from n, p reactions at 13.4 and 17.5 MeV

In this paper measurements are presented on the energy distribution of protons emitted in n, p reactions on Al and Ni in the natural isotopic mixture. These measurements have been taken with neutrons of energy of 17.5 and 13.4 MeV, to the purpose of studying how the proton energy distribution varies with the incoming neutron energy, in order to establish which process is responsible for the n, p reaction. The results give evidence to the fact that the statistical evaporation theory is insuitable for explaining the proton spectra obtained, and that the spectrum shape does not depend on the residual nucleus excitation energy but seems more determined by the energy of emitted protons.

Infrared Spectra and Molecular Constants of Gaseous Tritium Bromide and Tritium Chloride

The infrared spectra of TCl35, TCl37, and TBr79,81 have been observed using a CaF2 prism. Throughout this paper the notation TBr79,81 indicates the natural isotopic mixture of Br79 and Br81, and lack of spectral resolution of the two isotopes. A least squares treatment of the data yielded the following molecular constants for TBr79,81, TCl35, and TCl37, respectively: ν0=1519.26, 1739.10, 1735.51 cm−1Be= 2.899, 3.746, 3.723 cm−1αe= 0.046, 0.061, 0.066 cm−1De= 4.5×10−5 7.7×10−5 6.8×10−5 cm−1

Excitation Functions for Spallation Reactions on Cu

Excitation functions have been measured for 190-Mev deuterons from the 184-inch Berkeley cyclotron on the natural isotopic mixture of ${\mathrm{Cu}}^{63}$ and ${\mathrm{Cu}}^{65}$. Chemical separation of Zn, Cu, Ni, Co, Fe, and Mn has been performed and the yields of several of the radioactive isotopes of these elements have been measured as a function of deuteron energy. The results seem to be in agreement with Serber's theory of high energy processes and with other information on the yields of nuclear reactions at these energies.

The properties of the condensed phase of the light helium isotope

Using the principles of the law corresponding states, adapted to the quantum theory in previous papers 1), a number of properties of He 3 can be predicted as to their order of magnitude, which may be of interest for further attempts to separate He 3 from the natural isotopic mixture. The critical temperature and pressure are roughly 3.2 to 3.5°K and 0.9 to 1.2 atm respectively. The density at 0°K is about 65% and the internal energy about 35% of the value of He 4. The vapour pressure formula should be 10 log P cm = — 1.12/T + 5 2 log T + 1.01 giving at 0.3°K still a vapour pressure of 10 −3 mm Hg. Finally the concentration ratios of a dilute mixture of He 3 in He 4 of vapour and liquid have been calculated and are compared with the experiments of Fairbank, Lane, Aldrich and Nier 5).

The Optimal Dimensions of a Clusius-Dickel Isotope Separator

A Clusius-Dickel isotope separator is treated on basis of the theory of Furry, Jones and Onsager. The dependence on the dimensions of the apparatus of $H$, $A$, $\frac{{K}_{d}}{K}$ and ${P}_{c}$ are derived without any assumption regarding the intermolecular forces in the isotope mixture. The problem treated is: How to choose the dimensions of the apparatus in order to obtain, at the smallest possible cost, a given quantity of isotope mixture, containing one isotope in a given concentration. The costs are assumed to consist of the costs of the power expended and the costs of the apparatus, the latter costs being proportional to the surface of the tubes. We need not include costs, which are independent of the dimensions of the apparatus, as, e.g., the cost of the natural isotope mixture. The question of how to choose the dimensions in order to obtain the output with the minimal power expenditure or with the minimal surface of the tubes is a special case of the general problem. The problem is solved for a single-stage apparatus, in which the concentration of the isotope in question always is small compared with unity. Formulae are given for the distance between the tubes, the mean circumference of the annular space between them and the length of the tubes, as well as for the minimum costs. Similarly, the problem is treated for an "ideal" multi-stage apparatus consisting of very many stages. In this case, the relative abundance of the isotope in question is not restricted to small values. It is shown that the costs are a minimum if the distance between the tubes has a constant value for all stages, this value being the same as for single-stage operation. The mean circumference however is different for different stages. Both in the single- and the multi-stage operation an increase in the pressure reduces the costs somewhat. The production of ${\mathrm{C}}^{13}$ is given as a numerical example.