Gadolinium-based hybrid ultra-low-background material for protecting the darkside20k dark matter detector from background neutrons

A laboratory technique was developed for obtaining an ultra-low-background hybrid material based on organic glass - polymethyl methacrylate (PMMA). 157Gd nuclei are used as an efficient absorber of thermal neutrons in the hybrid material. A uniform distribution of gadolinium in the PMMAmatrix is achieved by introducing he gadolinium in the form of a coordination compound -gadolinium acetylacetonate- into the hybrid materia

Thermodynamic properties and electrical conductivity of strongly correlated plasma media

We study thermodynamic properties and the electrical conductivity of dense hydrogen and deuterium using three methods: classical reactive Monte Carlo (REMC), direct path integral Monte Carlo (PIMC) and a quantum dynamics method in the Wigner representation of quantum mechanics. We report the calculation of the deuterium compression quasi-isentrope in good agreement with experiments. We also solve the Wigner-Liouville equation of dense degenerate hydrogen calculating the initial equilibrium state by the PIMC method. The obtained particle trajectories determine the momentum-momentum correlation functions and the electrical conductivity and are compared with available theories and simulations

Глубокая очистка теллура для производства материалов электроники и фотоники

The regularities of impurity distribution between the distillate and the still as well as the spatial  distribution of impurities  along  the distillate length have been studied. We conclude that some impurities such as s−metals, Zn, Ni, V and rare metals distribute uniformly along the distillate length (20 cm). Contrarily, Se tends to concentrate in the distant (from the still) region  of distillate with more  than one order  of magnitude higher concentration compared to the nearest region.Для проведения процесса получе ния высокочистого теллура методом вакуумной  дистилляции предложена конструкция реактора из высокочистых кварцевого стекла и графита. В ходе процесса расплав теллура испаряется, пар переносится из горячей части системы в более холодную и конденсируется в виде твердой фазы (дистиллята) без образования жидкости. Изучены закономерности перераспределения примесей между дистиллятом и кубовым остатком, а также пространственное распределение примесей в дистилляте при проведении очистки металлического теллура. Установлено, что часть примесей, например щелочные металлы, Zn, Ni, V, редкоземельные металлы распределены равномерно по длине  дистиллята (20  см). В то же время концентрация Se в дальней (от перегонного куба) части дистиллята превышает концентрацию в ближней части на порядок

The EnMAP Mission Planning System

The Environmental Monitoring and Analysis Program mission (EnMAP) is a German hyperspectral Earth observation mission, currently scheduled for launch in 2020. The EnMAP Mission Planning System (MPS), developed and operated by the German Space Operations Center (GSOC), is one of 15 subsystems constituting the EnMAP Ground Segment. Its main task is to compile and maintain a conflict-free timeline for routine operations that does not violate any constraints of the spacecraft (e.g. regarding power or onboard memory); this timeline will regularly be commanded to the spacecraft. This paper gives an overview of the current EnMAP MPS design, including the special requirements of the EnMAP mission, the components of the MPS and its most important external interfaces. The design of the EnMAP MPS largely builds on our experience gathered during the TerraSAR-X/TanDEM-X mission and has been developed further. Novel technologies include the Reactive Planning framework, which particularly stands out due to its high responsiveness to user input. Particular attention is furthermore paid to the inclusion of cloud coverage and sunglint information into the planning process -- two challenges which are specific to EnMAP observing in the optical and near infrared part of the spectrum

Properties of very n -rich He isotopes

Low-energy spectra of the 8, 10He nuclei were investigated in the (t, p) -type reactions at small centre-of-mass angles using ∼ 25 AMeV beams of 6He and 8He nuclei. The 0+ ground state (g.s.) of 8He and excited states, 2+ at 3.6-3.9MeV and (1+) at 5.3-5.5MeV, were populated with cross-sections of 200, 100-250, and 90-125μb/sr, respectively. To account for a near-threshold anomaly observed in the 8He spectrum the population of a 1- continuum (soft dipole excitation) was considered. The lowest-energy group of events in the 10He spectrum was observed at ∼ 3 MeV with a cross-section of ∼ 140 μb/sr. This result is consistent with the previously reported observation of 10He providing a new g.s. position for 10He at about 3MeV

Markov-modulated M/G/1 type queue in heavy traffic and its application to time-sharing disciplines

International audienceThis paper deals with a single-server queue with modulated arrivals, service requirements and service capacity. In our first result, we derive the mean of the total workload assuming generally distributed service requirements and any service discipline which does not depend on the modulating environment. We then show that the workload is exponentially distributed under heavy-traffic scaling. In our second result, we focus on the discriminatory processor sharing (DPS) discipline. Assuming exponential, class-dependent service requirements, we show that the joint distribution of the queue lengths of different customer classes under DPS undergoes a state-space collapse when subject to heavy-traffic scaling. That is, the limiting distribution of the queue-length vector is shown to be exponential, times a deterministic vector. The distribution of the scaled workload, as derived for general service disciplines, is a key quantity in the proof of the state-space collapse