Determination of <Superscript>131</Superscript>I based dose equivalents for emissions of short-lived iodine isotopes

The coefficients required for evaluating the inhalation dose from short-live iodine isotopes entering the human body during a radiation accident associated with a spontaneous chain reaction are validated computationally. Such coefficients make it possible to reduce the effect of a collection of iodine isotopes to that of an equivalent amount of ¹³¹I. The dose inhalation load from an iodine emission aerosol cloud and the site contamination with ¹³¹I are evaluated for a spontaneous chain reaction in systems consisting of enriched metallic uranium with 10¹⁹ fissions with no localizing facilities present. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 311–315, May, 2007.     

Cross-section measurements for short-lived isotopes of 46Ti, 75As and 92Mo at the neutron energies from 13.6 to 14.9 MeV

Cross-sections were measured at neutron energies from 13.6 to 14.9 MeV for the reactions ⁴⁶Ti(n,p) ^46mSc, ⁷⁵As(n,p) ^75mGe and ⁹²Mo(n,2n) ^91mMo leading to short-lived products. Corrections were made for the effects of gamma ray attenuation, coincidence summing, pulse pile-up, dead time, neutron flux fluctuations and scattered low energy neutrons. Statistical model calculations taking into account precompound effects were also performed.     

Methods of obtaining a uniform volume concentration of implanted ions

Three simple practical methods of irradiation with high energy particles (>5 MeV/n), providing the conditions of obtaining a uniform volume concentration of the implanted ions in the massive samples are described in the present paper. Realization of the condition of two-sided irradiation of a plane sample during its rotation in the flux of the projectiles is the basis of the first method. The use of free air as a filter with varying absorbent ability due to the movement of the irradiated sample along ion beam brought to the atmosphere is at the basis of the second method of uniform ion alloying. The third method of obtaining a uniform volume concentration of the implanted ions in a massive sample consists of sample irradiation through the absorbent filter in the shape of a foil curved according to the parabolic law moving along its surface. The first method is the most effective for obtaining a great number of the samples, for mechanical tests, for example, the second one – for irradiation in different gaseous media, the third one – for obtaining high concentration of the implanted ions under controlled (regulated) thermal and deformation conditions.     

Experiments on the synthesis of neutron-deficient isotopes of kurchatovium in reactions with accelerated50Ti ions

Conclusions A number of conclusions can be drawn from the aggregate of experimental results.The method of synthesis of transfermium elements in the irradiation of lead isotopes with ions with mass A_I40 atomic units, investigated earlier [12] for the example of the reaction Pb(⁴⁰Ar, xn)Fm, is also extremely effective using⁵⁰Ti ions. The reactions Pb(⁴⁰Ar, 2n)Fm and Pb(⁵⁰Ti, 2n)Ku have approximately equal cross sections, which might have been expected on the basis of theoretical estimates. This permits us to hope that this method can be used successfully for the synthesis of heavier elements in the reactions induced by⁵⁴Cr,⁵⁵Mn, and⁵⁸Fe ions.In all probability, the substantial changes in the systematics of the half-lives for even-even isotopes of kurchatovium are associated with the structure of the barriers to fission of these nuclei. From this standpoint, it seems important to investigate the properties of more neutron-deficient isotopes of kurchatovium, using, in particular, the reactions with²⁰⁴Pb, and to attempt to advance into the region of elements with Z 106. On the other hand, a detailed theoretical analysis must be made of the data obtained on the basis of the modern theory of nuclear fission, which, in our opinion, will aid in a more reliable prediction of the properties of heavy and ultraheavy elements.Translated from Atomnaya Énergiya, Vol. 38, No. 6, pp. 382–390, June, 1975.     

Operating conditions of cascades for separating isotopes

Scientific Research Institute of Stable Isotopes. Translated from Atomnaya Énergiya, Vol. 73, No. 4, pp. 328–331, October, 1992.     

Method for precision measurement of the masses of short-lived nuclides with application of stable isobars

The distinction of the suggested scheme of the experiment is the application of the isobaric doublets method in determining the masses of short-lived nuclides by means of a high-resolution mass spectrometer. This method enables us to considerably decrease the systematic errors of the measurement results in comparison with the previously applied isotopic reference method.

The work was carried out on an experimental complex, the main component of which was a prism mass spectrometer (PMS) with resolution R = 3 × 10⁴, installed on-line with a mass separator and a synchrocyclotron of the LNPI of the Academy of Sciences of Russia. On this installation we measured the masses of the isotopes ^91–97Rb. Samples containing stable reference isotopes ^91,92,94,96Zr, ⁹³Nb or ^95,97Mo were introduced into the ionizer of the PMS for calibration of the mass scale, that was ensured by their ionization simultaneously with radioactive isotopes of rubidium coming from the mass separator. The values of the masses of the stable isotopes used as reference in the suggested method are known with a very high precision (ΔM/M 3×10⁻⁸), therefore they made a negligible contribution to our experimental errors.