Modification of thin films induced by slow heavy ions analysed with PIXE and SRIM

In the present work the particle induced X-rays (PIXE) emitted during interaction of inert and active slow heavy (HI) ions with specially prepared thin films were measured. Kinematics of the interaction was simulated numerically with SRIM in grazing incident-exit angle geometry and in time sequence in order to determine dynamics of formation of the subsurface region damaged through implantation, sputtering and interface mixing. It was shown that the structure and composition of films and surfaces are not stable against HI irradiation due to preferential sputtering and implantation of ions and recoils and that dynamics of such a modification can be in-situ monitored with PIXE and analyzed with SRIM

RBS simulations studies of SIMOX structure

In the paper we present the short description of physical phenomena related to the motion of ion inside the crystal. The form of this description makes it possible and easy to construct the calculation procedures. The final results are the simulation and experimental data for the Si(001)-Si02-Si(001 (SIMOX) structure. The comparison of the results obtained shows that the problem of energy losses of fast ion moving inside such well ordered structure like single crystal is the fundamental one in order to good understand the quality of Si-Si02 interface and its location under the surface of sample. Only for a very thin amorphous layers thickness' and for the energies of incident ion close to the maximum of energy losses the assumption about the linear dependence between the energy loss and the penetration depth is right. If the direction of incidence of ion lies along one of main crystallographic directions the analytical models proposed in literature give results, which are in bad agreement with experimental data. The correct results were, however, obtained using simulation of successive collisions with the nearest atom of crystallographic lattice with impact parameter dependent energy losses and helium ion charge state taken into consideration. This attempt significantly lengthened simulation time but allowed for good reconstruction of the shape of energetic spectra as to show slight perturbations of SIMOX structure

Ophthalmological and obstetric management in pregnant women with retinal disorders

Objectives: To analyze the clinical significance of ophthalmological assessment in pregnant women affected with degenerative retinal lesions, and the lesions’ clinical relevance in determining the obstetric management and delivery method.  Material and methods: 69 pregnant women affected with retinal degenerative lesions were included in our study. In each patient, the risk of ophthalmological complications during vaginal delivery was evaluated. After the woman’s delivery, alignment between the ophthalmological recommendations and the obstetric management were analyzed. Each case where the management plan differed from the clinical proceedings was thoroughly investigated to determine the cause.  Results: In 69 pregnant women the risk of ophthalmological complications was evaluated, and in 24 cases (35%) assessed as low, as medium in 37 cases (54%) and as high in 8 cases (11%). Among the 69 patients, 42 of women delivered vaginally and the remaining 27 underwent caesarean section. In the high-risk group, the rate of caesarean section was 87%, while in both the low- and medium-risk groups the rate of vaginal births was 75%. Two years of postnatal ophthalmological follow-up did not reveal any complications that could have been associated with the delivery.  Conclusions: Every pregnant woman should undergo ophtalmological examination to assess peripartum risk of complications and determine the method of delivery.

ROOT - A C++ Framework for Petabyte Data Storage, Statistical Analysis and Visualization

ROOT is an object-oriented C++ framework conceived in the high-energy physics (HEP) community, designed for storing and analyzing petabytes of data in an efficient way. Any instance of a C++ class can be stored into a ROOT file in a machine-independent compressed binary format. In ROOT the TTree object container is optimized for statistical data analysis over very large data sets by using vertical data storage techniques. These containers can span a large number of files on local disks, the web, or a number of different shared file systems. In order to analyze this data, the user can chose out of a wide set of mathematical and statistical functions, including linear algebra classes, numerical algorithms such as integration and minimization, and various methods for performing regression analysis (fitting). In particular, ROOT offers packages for complex data modeling and fitting, as well as multivariate classification based on machine learning techniques. A central piece in these analysis tools are the histogram classes which provide binning of one- and multi-dimensional data. Results can be saved in high-quality graphical formats like Postscript and PDF or in bitmap formats like JPG or GIF. The result can also be stored into ROOT macros that allow a full recreation and rework of the graphics. Users typically create their analysis macros step by step, making use of the interactive C++ interpreter CINT, while running over small data samples. Once the development is finished, they can run these macros at full compiled speed over large data sets, using on-the-fly compilation, or by creating a stand-alone batch program. Finally, if processing farms are available, the user can reduce the execution time of intrinsically parallel tasks - e.g. data mining in HEP - by using PROOF, which will take care of optimally distributing the work over the available resources in a transparent way

Thermal induced structural and magnetic transformations in Fe_{73.5−x}Ce_{x=0,3,5,7}Si_{13.5}B_9Nb_3Cu_1 amorphous alloy

Structural and magnetic properties of amorphous and partly crystallized Fe_{73.5−x}Ce_{x=0,3,5,7}Si_{13.5}B_9Nb_3Cu_1 alloys, were analysed in the temperature ranging from RT to 800 °C with scanning calorimetry and magnetometry. The Fe(Si) and Fe(B) structures were identified and characterised with set of crystallization temperatures and activation energies. Also, Curie temperatures for amorphous and for crystalline structures were determined and analysed as functions of Ce content

Stopping of Slow H-, He-, Li- and Be-Like Projectiles in Electron Gas

Results of calculations of the electronic stopping power and the energy loss straggling for low velocity H-, He-, Li- and Be-like projectiles in the degenerate electron gas are reported. The Hartree-Fock-Slater description of the projectile and the dielectric function method were used. The size parameter Z_$\text{}_{min}$ of the charge distributions calculated from a variational principle depends on the characteristics of the medium. The stopping and straggling effective charges Z$\text{}_{ef}$ of a projectile were analysed. They were found to differ with each other and to depend on the one-electron radius r$\text{}_{s}$, on the projectile atomic number Z$\text{}_{i}$ and on the number of electrons N$\text{}_{i}$ carried by the projectile

Effective Ion Charge

The impact parameter dependent energy transfer and random stopping power for ions carrying electrons were determined within the first-order Born approximation. The ion and atom were described by many-electron ground states. The excitations and ionizations of both collision partners were taken into account, but exchange of electrons was neglected. With the Bethe sum rule and closure relation, the random stopping was shown to have the Bethe form. For the Moliere form factors the analytical results were obtained. The effective charge was discussed in the random and channelling conditions. Comparison with some previous calculations was carried out

Energy Loss of Excited Slow Ions in Electron Gas

The electronic energy loss and the straggling of the energy loss of the degenerate electron gas for excited H*-, He*-, He**-, and Li*-like ions were calculated. The results were compared with the corresponding characteristics for ions kept in the ground state. The linear response theory was used. The ion was described by the Hartree-Fock-Slater formalism and the medium by the dielectric function. The stopping and straggling effective charges Z$\text{}_{ef}$ for the energy loss were analysed and they were found to differ from each other and to depend on the one-electron radius r$\text{}_{s}$, on the ion atomic number Z$\text{}_{i}$, and on the number of electrons N$\text{}_{i}$ carried by the ion

ACTA PHYSICA POLONICA A EFFECTIVE ION CHARGE

The impact parameter dependent energy transfer and random stopping power for ions carrying electrons were determined within the first-order Born approximation. The ion and atom were described by many-electron ground states. The excitations and ionizations of both collision partners were taken into account, but exchange of electrons was neglected. With the Bethe sum rule and closure relation, the random stopping was shown to have the Bethe form. For the Moliere form factors the anaJytical results were obtained. The effective charge was discussed in the random and channelling conditions. Comparison with some previous calculations was carried out