Environmental dosimetry with the BeOSL personal dosimeter – State of the Art

In the course of this work, the possibility of the measurement of ambient dose equivalent H*(10) with the BeOSL dosimetry system was evaluated. Calculations for the energy response of the 2-element BeOSL dosimeter for irradiation with H*(10) were performed. The response doesn't fulfil the requirements of IEC 62387-1. Especially the response for photon energies of 60–100 keV is to low. It is possible to correct this under response using a modified BeOSL 2-element dosimeter and a linear algorithm. So the national requirements for a H*(10) dosimeter in Germany can be fulfilled. An incidence angle independent measurement is not possible because for several angles of incidences (>60°) the filters of the 2-element dosimeter doesn't shield the correct element. Another material which is more suitable for the H*(10) measurement was tested. So the doping of BeO with Lanthanum leads to an enhanced energy response for measurement of H*(10). Furthermore a higher OSL sensitivity was found for this material. Further tests on the influence of Lanthanum concentration on the dosimetric properties are necessary.     

Measurement of the tensor analyzing power components in the coherent photoproduction of a π 0 meson on a deuteron

The components of the tensor analyzing powers, T ₂₀, T ₂₁, and T ₂₂, of the coherent photoproduction of a π₀ meson on a deuteron have been measured for photon energies of 250–450 MeV and pion emission angles of 90°–145°. The results are compared with the theoretical predictions.     

The international Boltzmann project – the contribution of the PTB

To support new determinations of the Boltzmann constant, which have been requested by the International Committee for Weights and Measures (CIPM) and which are necessary for preparative steps towards new definitions of the kilogram, the ampere, the kelvin and the mole, an iMERAPlus joint research project is coordinating the European activities in this field in Spain (CEM), Denmark (DFM), France (LNE-INM/CNAM, University Paris North), Italy (INRiM, Universities of Naples and Milan), United Kingdom (NPL), Germany (PTB) and in the European Institute for Reference Materials and Measurements (IRMM). In this major European research project, the Boltzmann constant will be determined with various methods. The aims and the progress to date of the PTB contribution are reviewed in this article. To cite this article: B. Fellmuth et al., C. R. Physique 10 (2009).     

The power of distinguished limits: A comment on ‘On the two-dimensional instability of square-wave detonations’

The stability of both Chapman-Jouguet and overdriven square-wave detonations is investigated in the limit of a large detonation Mach number and a ratio of specific heats close to one.     

Differential analyzing power in pp′ scattering on a 28Si nucleus in the case of the excitation of high-spin particle-hole states

The experimental energy dependence of the differential analyzing power for 5 ₁ ^? , T=0 and 6 ₁ ^? , T=1 levels in the ²⁸Si nucleus is compared with the results of the calculations based on the DWBA-91 code. Information obtained for the nuclear structure from an analysis of inelastic scattering is discussed.     

Relaxation of the analyzing power of the (p, τX) and (p, αX) reactions in the continuum

The observed continuous decrease of the analyzing power for the reactions ($\text{p}$, τX) and ($\text{p}$, αX) on ⁹⁰Zr and ²⁰⁹Bi at E_p = 72 MeV as a function of the excitation energy of the final nucleus is described by a phenomenological relaxation process.     

Nobel Prizes in the “light” of Vavilov–Cherenkov radiation. To the 125th anniversary of the birth of S.I. Vavilov

The objective of this paper is not a detailed review or an analysis of the studies in the field of high-energy physics initiated by the discovery of Vavilov–Cherenkov radiation, occurred more than 80 years ago at the Lebedev Physical Institute, and awarded Nobel Prizes. The paper is written to emphasize the historical significance of the discovery of the effect and its key role in further studies in high-energy physics, commended by the high award of the Nobel committee. In 1958, 24 years after the first publication about the new phenomenon, i.e., emission of electrons moving in matter with the superlight speed, discovered by P.A. Cherenkov under the supervision by S.I. Vavilov, the Nobel Prize was awarded to a group of scientists of the Lebedev Physical Institute, P.A. Cherenkov, I.M. Frank, and I.E. Tamm “for the discovery and explanation of the Cherenkov effect”. Since then, practical application of Vavilov–Cherenkov radiation is widely spread.     

A feasible method for comparing the power dependent photostability of fluorescent proteins

A feasible method of combining the concept of fluorescence half-life and the power dependent photo- bleaching rate for characterizing the practical photostability of fluorescent proteins(FPs)was introduced. Furthermore,by using a fluorescent photostability standard,a relative comparison of the photostabilty of FPs from different research groups was proposed,which would be of great benefit for developing novel FPs with optimized emission wavelength,better brightness,and improved photostability.We used rho- damine B as an example to verify this method and evaluate the practical photostability of a far-red FP, mKate-S158C.Experimental results indicated good potential of this method for further study.     

Some results of the growth of semiconductor crystals in microgravity conditions (to the 50th anniversary of Yuri Gagarin’s flight into space)

The history of the growth of semiconductor crystals aboard space vehicles and their subsequent investigation has been described shortly. It has been shown using Ge(Ga), GaSb(Si), and GaSb(Te) crystals as an example that the formation of segregation growth striations can be avoided during their recrystallization by the vertical Bridgman method in conditions of physical simulation of microgravity on the Earth, mainly due to the essential weakening of the thermal gravitation convection. By their structure and impurity distribution, they approach the crystals grown in space. The investigation of recrystallization of Te has made it possible to determine the role of the detachment effect characteristic of the microgravity conditions and the features of the microstructure of the samples that crystallize with a free surface. The analysis of the results obtained from experiments in space allows us to better understand the processes occurring during the crystallization of the melts and to improve the crystal growth in terrestrial conditions.     

The discovery of polyacetylene film – the dawning of an era of conducting polymers

This lecture is not directly related to our discovery and development of conducting polymers to which the Nobel Prize in Chemistry 2000 was awarded. However, I would like to present my previous work that I had carried out just before we reached the discovery of chemical doping. I do hope my talk will be of use for you the audience to deepen your understandings by learning what had happened before and how we did reach the idea of chemical doping.     

The Influence of the Composition on the Atomic Structure of Bi1 – xYxFeO3 Ceramics

Technical Physics - The variation of the Bi1 – xYxFeO3 ceramics atomic structure with yttrium concentration x = 0, 0.10, 0.15, and 0.20 has been analyzed. Ceramic samples have been prepared...     

A theoretical perspective of the nature of hydrogen-bond types – the atoms in molecules approach

Hydrogen bonds and their strength were analysed based on their X–H proton–donor bond properties and the parameters of the H–Y distance (Y proton acceptor). Strong, moderate and weak interactions in hydrogen-bond types were verified through the proton affinities of bases (PA), deprotanation enthalpies of acids (DPE) and the chemical shift (σ). The aromaticity and anti-aromaticity were analysed by means of the NICS (0) (nucleus-independent chemical shift), NICS (1) and ΔNICS (0), ΔNICS (1) of hydrogen-bonded molecules. The strength of a hydrogen bond depends on the capacity of hydrogen atom engrossing into the electronegative acceptor atom. The correlation between the above parameters and their relations were discussed through curve fitting. Bader's theory of atoms in molecules has been applied to estimate the occurrence of hydrogen bonds through eight criteria reported by Popelier et al. The lengths and potential energy shifts have been found to have a strong negative linear correlation, whereas the lengths and Laplacian shifts have a strong positive linear correlation. This study illustrates the common factors responsible for strong, moderate and weak interactions in hydrogen-bond types.     

Determination of the Avogadro constant – A contribution to the new definition of the mass unit kilogram

An improved attempt of several national metrology institutes to replace the present definition of the kilogram with the mass of a certain number of ¹²C atoms is described. This requires the determination of the Avogadro constant, N _A, via the silicon route with a relative uncertainty better than 2 ⋅ 10^-8. Previously, the limiting factor is the measurement of the average molar mass. Consequently, a world-wide collaboration has been set up, to produce, approximately, 5 kg of ²⁸Si single-crystal with an enrichment factor greater than 99.985% to be used for an improved determination of N _A. The first successful tests of all technological steps (enrichment of SiF₄, purification and synthesis of silane, deposition of polycrystalline ²⁸Si, single crystal growth) for the production of high-purity ²⁸Si are described.     

Characterization of radiated electromagnetic fields using equivalent sources – Application to the EMC of power printed circuit boards

This article presents an original methodology to characterize electromagnetic disturbances radiated from power electronic devices. The method is based on the substitution of the power device by an equivalent set of elemental dipoles (electric and magnetic dipoles). The set of dipoles radiates the same near-field. The dipoles are determined from a near field cartography of the fields obtained with a measurement bench. The dipoles parameters are determined by solving an inverse problem using a genetic algorithm. The efficiency of the approach is demonstrated on an academic DC-DC converter. Finally some results about the chopper are presented. The methodology has two advantages: first it allows one to define some threshold limitations for electromagnetic fields on the surroundings and secondly it gives the location of the real source distribution. To cite this article: L. Beghou et al., C. R. Physique 10 (2009).