No abstract available

[en] In this paper the main principles of electron bombardment are discussed and an investigation is made of the most important factors which influence the emission and focussing of the electron source. Examples are given of the various types of electron guns which are developed for evaporation in vacuum, and the necessary accessories are mentioned. Furthermore, examples are discussed of various industrial applications of electron-beam evaporators. (Auth.)

[en] Reference materials of natural and isotopically enriched or depleted Li₂SO₄ are used for neutron cross section measurements. The detection limits of Sm, Eu, Gd, Dy and Cd in Li₂SO₄ by atomic emission spectroscopy (AES) and instrumental photon activation (IPA), correspond to a total contribution equivalent to the natural lithium (σ=70.5 barns), of 0.160% and 0.0213% respectively. MnSO₄ solutions are used for the calibration of neutron sources, e.g. ²⁵²Cf. The direct analysis of Sm, Eu, Gd, Dy, and Cd in MnSO₄ by AES and IPA, provides detection limits from which the total contributions equivalent to the manganese (σ=13.3 b) are respectively 2.38% and 0.395%. In order to improve the detection limits of Rare Earths, a method had been developed for the R.E/Mn chemical separation which is based on the coprecipitation of Rare Earths as fluorides by HF in the presence of ammonium after the addition of very pure Y as a carrier. A solution of sup(152+154)Eu(1.11x10⁵Bq) is used to monitor the recovery of the lanthanides. The Sc and Y are determined directly by AES or IPA. As an example, the contributions of Sm, Eu, Gd and Dy obtained by AES after the chemical separation of a solution containing 300 mg MnSO₄ per gram, are reduced to 0.0114%. The concentration of Cd found in this solution is 3.7 μg/g MnSO₄ and the total contribution of the 16 Rare Earths and Cd is <=0.107%

[en] An improved method to determine the thickness of thin toils, in the region of several μg cm^-2 to several mg cm^-2 by measuring the energy loss of α-particles traversing these foils is described. The method is particularly sensitive for monoenergetic α-particles of low energy. Using a simple experimental arrangement and applying a modified slightly asymmetrical Gaussian fit to the measured peaks, sensitivities in the determination of areal densities of a few tenths of a μg cm^-2 can be obtained. (orig.)

[en] The need for backscattering standards appears to be twofold and depends on the uses and requirements of the users. The first is as a calibrated reference by which samples of a similar nature to the standard may be absolutely compared. The second is as a means of intercomparing the relative results obtained by different laboratories using, as near as possible, identical samples. This type of comparison is of a relative nature and the absolute values are not necessarily required. In the present work the authors try to satisfy both needs by providing identical samples which have been absolutely calibrated to a high accuracy. Very thin copper and vanadium layers were evaporated onto bismuth implanted silicon crystals and on glass plates under carefully controlled conditions. The mass of the deposits was determined in situ using a sensitive UHV microbalance. In addition, two quartz oscillator monitors were used. The samples have been analysed by Rutherford backscattering and the absolute quantity of bismuth determined by a comparison with the known amounts of deposited material. (Auth.)

[en] The status of the Rutherford backscattering standards project comprising a dual implant of Au and Al in a vitreous carbon substrate is reported. The absolute Au and Al contents have been measured by Rutherford backscattering indepently of the charge Q on the target, or the solid angle Ω, by depositing absolutely calibrated thin uniform evaporated layers over the implanted targets. Photon activation analysis has also been used as an independent check on the implanted contents. High resolution Rutherford backscattering by electrostatic analysis has been used to deduce the range and profile of the implanted species and the effect of reversing the implantation sequence is reported. (orig.)

[en] In connection with a programme using non-destructive multielement photon activation analyses, especially for the determination of heavy elements, 22 natural elements are activated in the 44 MeV-bremsstrahlung produced by an electron linear accelerator, in order to evaluate the interferences. Using a rotating device, the element samples (4 or 5) and also the sample containing cobalt as reference element, are alternately irradiated under the same conditions during 16-18 hours with the bremsstrahlung produced by the impact of an electron beam (35-51 μA) on a platinum target. It is observed that photon activations at 44 MeV tend to favour the (γ,2n) and (γ,3n) reactions and interferences are important for some isotopes of neighbouring elements. From the results obtained for heavy elements, interferences are more severe in X-ray spectrometry than in γ-ray spectrometry. A figure of merit, A/sigma, is attributed to each photopeak and gives an indication of the photopeak sensitivity in practical conditions of photon activation analyses. (author)

No abstract available

[en] A method is presented which uses the backscattered yield from thin calibrated foils for monitoring MeV ion beam doses. It is totally independent of the target and permits ion beam doses to be obtained without the necessity of measuring the ion current. The effect of ion species, beam energy and current and carbon build-up have been investigated to determine their effect on the backscattered yield from and stability of the calibrated foils. (orig.)

No abstract available