Multiple ionization of neon by soft X-rays at ultrahigh intensity

At the free-electron laser FLASH, multiple ionization of neon atoms was quantitatively investigated at 93.0 eV and 90.5 eV photon energy. For ion charge states up to 6+, we compare the respective absolute photoionization yields with results from a minimal model and an elaborate description. Both approaches are based on rate equations and take into acccout a Gaussian spatial intensity distribution of the laser beam. From the comparison we conclude, that photoionization up to a charge of 5+ can be described by the minimal model. For higher charges, the experimental ionization yields systematically exceed the elaborate rate based prediction.Comment: 10 pages, 3 figure

Magneto-Optical Trap for Thulium Atoms

Thulium atoms are trapped in a magneto-optical trap using a strong transition at 410 nm with a small branching ratio. We trap up to $7\times10^{4}$ atoms at a temperature of 0.8(2) mK after deceleration in a 40 cm long Zeeman slower. Optical leaks from the cooling cycle influence the lifetime of atoms in the MOT which varies between 0.3 -1.5 s in our experiments. The lower limit for the leaking rate from the upper cooling level is measured to be 22(6) s$^{-1}$. The repumping laser transferring the atomic population out of the F=3 hyperfine ground-state sublevel gives a 30% increase for the lifetime and the number of atoms in the trap.Comment: 4 pages, 6 figure

A perturbation of DC electric field caused by light ion adhesion to aerosols during the growth in seismic-related atmospheric radioactivity

International audienceThe influence of variations in conductivity and external electric current variations in the lower atmosphere on DC electric field over a seismic region is investigated. The external current is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. This effect is related with the occurrence of ionization source due to seismic-related emanation of radon and other radioactive elements into the lower atmosphere. An increase in atmosphere radioactivity level results in the appearance of additional sources of ionization, and altitude dependence of the ion formation rate is calculated. Ionization source varies the atmospheric conductivity and the external current through appearance of ions with equilibrium number density and their adhesion to aerosols. We have calculated the perturbation of conductivity and external electric current as a function of altitude. Variation of conductivity and external current in the lower atmosphere leads to a perturbation of electric current which flows in the global atmosphere-ionosphere circuit. Finally, perturbations of DC electric field both on the Earth's surface and in the ionosphere are estimated

The detection of lengthened objects by pulse altimeter

The algorithm of lengthened objects detection is based on statistical processing of reflected pulse altimeter signal. We use method of maximum posteriori probability to make a decision. Minimum of maximum posteriori probability accorded with lengthened objects position. We use this fact to detect their position. This algorithm allows to realize autonomic navigation. In this paper it is shown two cases of the algorithm realization. The first method is based on the typical regime of radar altimeter and the second is based on the application of the Doppler’s filtration. The results of flight experiments are introduced in this article, which approved the correctness of the created algorithm.Алгоритм обнаружения протяженных объектов основан на статистической обработке отраженного сигнала импульсного радиовысотомера. Для принятия решения используется метод максимума апостериорной вероятности. Минимум максимума апостериорной вероятности определяет положение границ протяженного объекта. В статье показаны два режима, реализующие разработанный алгоритм: типовой режим работы РВС и режим доплеровской фильтрации. Приведены результаты натурных испытаний, подтвердившие правильность разработанного алгоритма