http://dspace.nbuv.gov.ua:80/handle/123456789/116161 2026-04-11T11:27:15Z http://dspace.nbuv.gov.ua:80/handle/123456789/116928 A completely self-contained cryogen-free dilution refrigerator, the TritonDR™ Mikheev, V.A.; Noonan, P.G.; Adams, A.J.; Bateman, R.W.; Foster, T.J. Oxford Instruments have developed a new dilution refrigerator for ultralow temperatures down to below 35 mK. The TritonDRTM system is a continuous cryogenic cycle dilution refrigerator. The refrigerator is driven by a closed cycle cryocooler and hence requires no liquid cryogens. The system has a dedicated electronic control unit and software that provides full control of operation. 2008-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/116927 Electron attachment to atomic hydrogen on the surface of liquid ⁴He Arai, T.; Yayama, H.; Kono, K. We demonstrate a possibility that helium surface electrons at cryogenic temperatures can be used as a new source of very low energy electrons. Since both electrons (e¯) and hydrogen atoms (H) are bound on liquid helium surface, two-dimensional mixture gas of these two species is available on the surface. We found that low energy collision of e¯ and H drives electron attachment to form a negative hydrogen ion (H¯) in the mixture. From our temperature dependence measurement of the reaction rate, it was found that another H atom participate in the reaction. Namely, the reaction is expressed as H + H + e¯ → H¯ + H. Possible reaction mechanisms are discussed in terms of direct three-body process and dissociative attachment process. Measurements in applied magnetic field (B) show that the reaction rate coefficient is suppressed as ~ B⁻². This implies that electron spin singlet collision is relevant for electron attachment. 2008-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/116926 Dip-эффект в проводимости 2D-электронов на пленке гелия с шероховатой подложкой Лейдерер, П.; Назин, С.; Шикин, В. Обсуждается явление под общим названием dip-эффект в проводимости 2D-электронов на пленке гелия с шероховатой подложкой. Рассмотрен частный случай возникновения такого эффекта при движении 2D-электронов вдоль пленки гелия на периодически гофрированной подложке. Приведены аргументы за и против при использовании данного сценария для 2D-электронов на произвольной шероховатой подложке.; Обговорюється явище під загальною назвою dip-ефект у провідності 2D-електронів на плівці гелію із шорсткою підкладкою. Розглянуто окремий випадок виникнення такого ефекту при русі 2D-електронів уздовж плівки гелію на періодично гофрованій підкладці. Приведено аргументи за й проти при використанні даного сценарію для 2D-електронів на довільній шорсткій підкладці.; The phenomenon generally called the «dip-effect » in conduction of 2D electrons at a helium film on a rough substrate is discussed. A special case of the dip-effect appearing in moving 2D electrons along the helium film covering a periodically corrugated substrate is considered. Arguments for extending the outlined scenario to 2D electrons above the substrates with arbitrary corrugation on difficulties of this approach are presented. 2008-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/116925 Dynamical structure factor of two-dimensional electrons over a helium film Patricia Cristina Venturini; Nelson Studart; Jose Pedro Rino The dynamical structure factor of a two-dimensional electrons trapped to a helium film deposited on a solid substrate is determined through molecular dynamics simulations for different film thicknesses and two substrates. The phases of the system varying from the classical Wigner crystal to strong and intermediate- correlated electron liquid as well the influence of the film thickness and substrate are analyzed in the numerical experiments. 2008-01-01T00:00:00Z