Classical Trajectory Monte Carlo simulation of coincidence experiments in electron impact ionization of helium

The state-to-state (exchange) interference of the autoionizing resonances of helium is studied in (e,2e) experiments. These studies are disturbed by the coincidence events caused by the direct ionization, so their decrease is desirable. For this reason, to mimic the experimental observation, we performed four-body classical trajectory Monte Carlo calculations. The calculations were done for 93.15 eV primary energy, where the exchange interference of the 2s2(1S) and 2p2(1D) autoionizing states of helium is expected. The yields of non-coincidence and coincidence events detected in various combinations of scattering geometry were calculated and compared with the experimental observations

A Fizikai Intézet Ra-Be neutronforrásának felhasználása és eltemetése

A 44 éven át oktatási célra használt laboratóriumi rádium-226-berillium neutronforrás felhasználási ideje lejárt, eltemetése szükségessé vált. A forrás szétszerelése, temetésre előkészítése egyedülálló, szakmailag komoly feladatot jelentett. A cikkben beszámolunk a feladat előírások szerinti végrehajtásáról. A mérési eredmények alapján a radioaktív hulladéktemetőnek egy sértetlen, teljesen zárt izotópot adtunk át

Laboratory Experiments on the Radiation Astrochemistry of Water Ice Phases

Water (H2O) ice is ubiquitous component of the universe, having been detected in a variety of interstellar and Solar System environments where radiation plays an important role in its physico-chemical transformations. Although the radiation chemistry of H2O astrophysical ice analogues has been well studied, direct and systematic comparisons of different solid phases are scarce and are typically limited to just two phases. In this article, we describe the results of an in-depth study of the 2 keV electron irradiation of amorphous solid water (ASW), restrained amorphous ice (RAI) and the cubic (Ic) and hexagonal (Ih) crystalline phases at 20 K so as to further uncover any potential dependence of the radiation physics and chemistry on the solid phase of the ice. Mid-infrared spectroscopic analysis of the four investigated H2O ice phases revealed that electron irradiation of the RAI, Ic, and Ih phases resulted in their amorphization (with the latter undergoing the process more slowly) while ASW underwent compaction. The abundance of hydrogen peroxide (H2O2) produced as a result of the irradiation was also found to vary between phases, with yields being highest in irradiated ASW. This observation is the cumulative result of several factors including the increased porosity and quantity of lattice defects in ASW, as well as its less extensive hydrogen-bonding network. Our results have astrophysical implications, particularly with regards to H2O-rich icy interstellar and Solar System bodies exposed to both radiation fields and temperature gradients

Resolution and ambiguity studies for a series expansion based multilayer refraction inversion method

The paper discusses the characteristics and feasibility of a multilayer kinematic refraction inversion method that is applicable to estimate the — even laterally changing — parameters of a geological model in the simultaneous evaluation of refraction data. The studied method has been developed at the Department of Geophysics of the University of Miskolc for the interpretation of parameters (layer thicknesses and seismic velocities) using series expansion based on adequately chosen basis functions. Besides revealing its resolution properties, ambiguity studies are also presented on synthetic data sets. In the terminology of refraction inversion uncertain and ambiguous results are frequently encountered problems in multilayer cases when all parameters (or all coefficients describing the parameters) are estimated simultaneously in the same inversion procedure. Results of resolution and ambiguity analyses of synthetic data sets and field examples are shown in this study