Recrystallization processes in snte thin films implanted with the nobel gas ions (Kr,Xe)

Abstract

The results of investigation of the quasi-Cherenkov (parametric) X-ray emission of 4.5 GeV electrons in diamond and quartz crystals are presented. A noticeable increase in X-ray photons yield has been observed under the influence of external factors (acoustic waves, temperature gradient).     

210Pb in magnesium dietary supplements

The idea behind this study was to investigate the most popular magnesium dietary supplements as a potential additional source of ²¹⁰Pb in the human diet. The paper presents the results of ²¹⁰Pb activities determined in different magnesium supplements, as well as an estimation of the annual effective radiation doses from ²¹⁰Pb decay. The results showed that the highest value of ²¹⁰Pb activity was found in a magnesium supplement of natural origin (dolomite) with a value of 2.97?±?0.18 mBq g^–1. The highest annual radiation dose from ²¹⁰Pb obtained from the magnesium daily recommended value (0.4 g of pure Mg) was calculated for dolomite tablets as 3.71?±?0.02 µSv·year^–1.     

The secondary X-ray fluorescence and absorption near the interface of multi-material: Case of EDS microanalysis

A simple model is proposed to take into account secondary X-ray fluorescence and absorption effects near the interface. This model is based on the investigation of the shape change of the first derivative equation that can fit the sigmoidal EDS profile obtained when a high vacuum electron beam passes through the interface of two adjacent materials. The contribution of the photoelectric absorption of primary X-rays (characteristic and Bremsstrahlung) and the secondary fluorescence on the degradation of the X-ray spatial resolution can be easily quantified. The close agreement between the simulated (Monte Carlo simulation using the Casino software) and the experimental data serves to assess the reliability of this developed model.     

Radiometrische Bandwaage mit Rechnerschaltkreis zur Signalaufbereitung

Es wird eine radiometrische Bandwaage zur Koksaustragsmengen-Messung in BHT-Kokereien beschrieben. Voranstellend werden einige analytische Ausdrücke zur theoretischen Behandlung dieses Bandwaagentyps mitgeteilt. Die Waage zeichnet sich durch hohe Stabilität der Anzeige, durch die Möglichkeit des routinemäßigen Umsetzens von Meßstelle zu Meßstelle innerhalb kurzer Zeit und durch einen relativ kleinen Wägefehler (Meßunsicherheit ≦ 2,9%) aus. Die Signalaufbereitung innerhalb der Elektronik erfolgt durchgängig digital unter Verwendung eines Rechnerschaltkreises.     

A CARBON-13 NMR STUDY OF POLAR-(NITRO)TRIMETHYLENEDIAMINE-N,N,N′-TRIACETATOCOBALTATE(III) ION

Abstract

The complex ion [Co(1,3-pd3a)NO₂]^? (pd3a=trimethylenediamine-N,N,N′-triacetate ion) was prepared from equatorial-skew-[Co(1,3-pd3a)H₂ O]. The absorption spectrum and the ¹³C NMR spectrum show the nitro product to be a polar isomer. The diamine backbone ring is believed to have the chair conformation.     

Quellenformen für γ-Bestrahlungsanlagen mit Reaktorbrennelementen

Wesentliche Bedeutung für die Strahlenausnutzung in γ-Bestrahlungsanlagen mit Reaktorbrennelementen hat die Quellenform, wobei der besonderen Quelldichteverteilung Rechnung zu tragen ist. Es wurden Bewertungskenngröβen abgeleitet, mit deren Hilfe Optimalvarianten der Quellenform für verschiedene Bestrahlgutbedingungen bestimmt werden können. Für fünf Quellen-grundformen sind Formeln zur Berechnung der Strahlenfelder angegeben. Mit Hilfe der ermittelten Kenngröβen wurden die verschiedensten Quellenformen verglichen. Die hieraus abgeleiteten Optimalbedingungen sind abschlieβend zusammengefaβt.     

Flux and fluence dependence of disorder produced during implantation of 11B in silicon

The flux and fluence dependence of disorder produced in silicon during the implantation of ¹¹B has been investigated at room temperature, -50°C. and -120°C. Implantations were carried out with 200 keV ¹¹B ions using current densities in the range from 0.06μA/cm² to 15μA/cm², and the disorder monitored by measuring the energy spectra of backscattered protons which were incident on the sample at 450 keV parallel to a (110) axis. Significant differences in the dependence of the disorder on ¹¹B flux and fluence were observed between the implantations performed at room temperature and those carried out at the two lower temperatures.     

Binary collision simulations of ion transmission through silicon single crystal films

Abstract

Computer simulation studies of the energy distribution of transmitted ions such as alpha-particles, He-, and B-ions through crystalline silicon, using the enhanced binary-collision cascade simulator MARLOWE, will be reviewed. The enhancement includes an additional electronic-energy loss (EEL) model which takes into account explicitly both the target electron density variation via the structure factors and the electron density of the projectile. Investigations of the stopping power for He ions and protons in silicon, at intermediate- and high-energies, based on the adapted EEL model and a velocity-dependent effective charge will be presented. The overall agreement between the calculated and experimentally determined stopping power data and the simulated and measured transmission spectra will be demonstrated. Effects of energy-loss straggling, core-electron contribution to the energy loss at high-energies and charge-state effects at low energies on the transmission spectra will also be discussed.     

Computed positron lifetimes in vacancies and vacancy-iron clusters in gold

Annihilation characteristics are calculated for positrons trapped in clean and impurity decorated vacancy clusters in Au. The positron lifetime depends strongly on the structure of the clusters. In a strongly relaxed vacancy cluster, the lifetime can become smaller than the lifetime in a single vacancy. The substitution of some neighbour atoms of a vacancy cluster by Fe atoms has only a minor effect on the positron lifetimes.     

Approximant crystals of icosahedral Mg–(Ga,Al)–Zn alloys

The zero field cooled (ZFC) and field cooled (FC) low-field magnetic moment m of a dense frozen ferrofluid containing Fe₅₅Co₄₅ particles of size 4.6nm in hexane exhibits irreversibility at temperatures T?T _b≈ 30?K. FC in μ ₀ H ≤ 1?T gives rise to shifted minor hysteresis loops below T _b. At T _c≈ 10?K, sharp peaks of m ^ZFC and of the ac susceptibility χ ′, a kink of the thermoremanent magnetic moment m ^TRM, a sizeable reduction of the coercive field H _c, and the appearance of a spontaneous moment m ^SFM indicate a phase transition with near mean-field critical behaviour of both m ^SFM and χ ′ . These features are explained within a core-shell model of nanoparticles, whose strongly disordered shells gradually become blocked below T _b, while their soft ferromagnetic cores couple dipolarly and become superferromagnetic (SFM) below T _c.