Study of magnesium and MA2-1 alloy sublimation in chambers with cryogenic surfaces

Apparatus for studying the vaporization of metals and alloys in vacuo down to 4–10^–8 torr by a continuous weighing method is described. The vaporization rate of magnesium and MA2-1 alloy in the range 300–500 ° C is measured and the results compared with data on magnesium obtained by other authors. Protective films, preliminary treatment, the heater geometry, and the temperature of the screens surrounding the material are shown to play an important part.In conclusion the authors sincerely thank Dr. B. I. Verkin and Dr. I. M. Lyubarskii for their interest and valuable advice.     

Contributions from changes in various solar indices in cycles 20–23 and 24 to the modulation of cosmic rays

The modulation of cosmic rays (CRs) observed at neutron monitors during the minimum, growth, maximum, and beginning of the decay of solar activity (SA) of cycle 24 (2008–2015) is compared to the modulation of CRs in the same periods of SA of cycles 20–23. After a prolonged minimum of SA between cycles 23 and 24 in 2007–2009 and the maximum of CRs at the end of 2009, when CR intensity exceeded the previous four CR maxima, the SA growth phase displayed weaker modulation of CRs than in the corresponding periods of the previous cycles. The shorter variations in CRs (oscillations with variable periods and activity spikes) were clearer against the background of the reduction in the 11-year variation during SA growth in 2011–2014. The current SA cycle (24) saw a scenario with two SA maxima, and the CRs showed one minimum at the end of 2014 that differed from the maximum of 2009 by ≈12% for particles with a rigidity of 10 GV. CR modulation in the last cycle was the weakest since neutron monitors began operating. At the beginning of 2015, the CRs started to recover. Possible reasons for the unusually weak CR modulation are considered. Quantitative estimates are made of the contribution from different characteristics of the solar magnetic field to CR modulation in the period of cycle 24 under study and in the corresponding periods of solar cycles 20–23, and the estimates are compared.     

Long-Term Changes in Vertical Geomagnetic Cutoff Rigidities of Cosmic Rays

Physics of Atomic Nuclei - Vertical geomagnetic cutoff rigidities are obtained for the worldwide network of neutron monitors via trajectory calculations for the International Geomagnetic Reference...     

IR spectral fingerprints of carbonyl groups in graphite oxide: a theoretical study

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Tributylborane in the synthesis of graft copolymers of collagen and polymethyl methacrylate

Russian Chemical Bulletin - Graft copolymers of collagen and polymethyl methacrylate were synthesized in a suspension of an acetic acid dispersion of fish collagen and methyl methacrylate in the...     

Optimal deformation and ion irradiation modes for production of a uniform submicrograin structure in molybdenum

Transmission and scanning electron microscopy have been used to investigate the structure of molybdenum after complex processing: deformation and irradiation with accelerated argon ion beams. The analysis of the effect of deformation and radiation parameters on the structural transformations and mechanical properties of molybdenum allowed us to find the optimal mode of processing to form a submicrograin uniform-in-size structure.     

Single and double electron capture processes in slow Ne q+-He (q=10, 6) collisions

The cross sections for single and double electron capture to the states Ne⁹⁺ n) with n=3–6 and Ne⁸⁺(3l,n′l′), Ne⁸⁺(4l,n′l′) with n′⩾4 and also the cross sections for single electron capture to the states Ne⁵⁺(3) in collisions of Ne¹⁰⁺ and Ne⁶⁺ with He atoms are calculated for collision energies in the interval from 10 to 150 keV. The calculation is carried out in the multichannel Landau-Zener, Nikintin, and Landau-Zener-Chaplik models with allowance for the radial coupling of the channels at crossing points of the energies of the quasidiabatic twoelectron states of the quasimolecule. The energies of the two-electron states are calculated in the effective potential method to first order in perturbation theory in the residual electron-electron interaction. The energies of the adiabatic states in the neighborhoods of the crossings of quasidiabatic terms are determined by the configuration interaction method. It is found that in Ne¹⁰⁺-He collisions the electron is captured mainly to the n=5 state of the Ne⁹⁺ ion. The cross section for double electron capture to the 3lnl′ state (n⩾4) of the Ne⁸⁺ ion is an order of magnitude smaller than the cross section for single electron capture. The contribution to the total cross section for double electron charge transfer from the 4l4l′ 4l5l′, and 4l6l′ states is approximately 25%. The dependence of the cross sections for double electron charge transfer on the values of l and l′ is investigated. Zh. Tekh. Fiz. 69, 15–28 (January 1999)