Experimental realization of a Coulomb blockade refrigerator

We present an experimental realization of a Coulomb blockade refrigerator (CBR) based on a single-electron transistor (SET). In the present structure, the SET island is interrupted by a superconducting inclusion to permit charge transport while preventing heat flow. At certain values of the bias and gate voltages, the current through the SET cools one of the junctions. The measurements follow the theoretical model down to ∼80 mK, which was the base temperature of the current measurements. The observed cooling increases rapidly with decreasing temperature, in agreement with the theory, reaching about a 15 mK drop at the base temperature. The CBR appears as a promising electronic cooler at temperatures well below 100 mK.Peer reviewe

Analisys of experience foreign universities in implementation of master’s programms with distance technologies

На основе проведенного исследования рассматриваются особенности применения дистанционных технологий в реализации магистерских программ зарубежных университетов-партнеров Томского государственного университета: описываются различные модели организации обучения, структура и функционирование электронной информационно-образовательной среды вуза, подразделений, обеспечивающих применение ИКТ в учебном процессе. Результаты исследования могут быть использованы российскими вузами для разработки механизмов реализации магистерских программ с применением дистанционных технологий и привлечением зарубежных партнеров.The article is based on the research of the use specifics of distance educational technologies in realization of Master’s programs of 14 foreign partner universities of National Research Tomsk State University: there are described various learning organization models, structure and activity of electronic informational and educational environment of the higher education institutions and of the departmentswhich are responsible for ICT implementation in learning process. The perceived conclusions may be used in Russian higher education institutions for organization of Master’s programs with foreign partners using distance technologies.Работа выполнена в рамках проектов: «Развитие электронного обучения и дистанционных технологий, в том числе для реализации совместных образовательных программ и индивидуализации обучения» Программы повышения конкурентоспособности ТГУ; «Разработка и апробация методики создания и внедрения вузами магистерских программ с модулями в виде дистанционных курсов с участием иностранных профессоров» (договор №14078 от 22.12.2014, заказчик – ФГАНУ «Социоцентр»)

Primary thermometry in the intermediate Coulomb blockade regime

We investigate Coulomb blockade thermometers (CBT) in an intermediate temperature regime, where measurements with enhanced accuracy are possible due to the increased magnitude of the differential conductance dip. Previous theoretical results show that corrections to the half width and to the depth of the measured conductance dip of a sensor are needed, when leaving the regime of weak Coulomb blockade towards lower temperatures. In the present work, we demonstrate experimentally that the temperature range of a CBT sensor can be extended by employing these corrections without compromising the primary nature or the accuracy of the thermometer.Comment: 8 pages, 4 figure

Search for Axionlike and Scalar Particles with the NA64 Experiment

We carried out a model-independent search for light scalar (s) and pseudoscalar axionlike (a) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through the Primakoff effect in interactions of hard bremsstrahlung photons generated by 100 GeV electrons in the NA64 active dump with virtual photons provided by the nuclei of the dump. The a(s) would penetrate the downstream HCAL module, serving as shielding, and would be observed either through their $a(s)\to\gamma \gamma$ decay in the rest of the HCAL detector or as events with large missing energy if the a(s) decays downstream of the HCAL. This method allows for the probing the a(s) parameter space, including those from generic axion models, inaccessible to previous experiments. No evidence of such processes has been found from the analysis of the data corresponding to $2.84\times10^{11}$ electrons on target allowing to set new limits on the $a(s)\gamma\gamma$-coupling strength for a(s) masses below 55 MeV.Comment: This publication is dedicated to the memory of our colleague Danila Tlisov. 7 pages, 5 figures, revised version accepted for publication in Phys. Rev. Let