The two outermost layers of the ALICE inner tracking system are composed of about 1800 AC-coupled double-sided silicon microstrip detectors. More than two thousand sensors have been delivered by ...three manufacturers, which amount to the largest production of this type of devices undertaken so far. Sensor testing and quality control has been performed at INFN Trieste. By careful optimization of the testing procedure, a complete static characterization of the large number of sensors has been possible without making use of fully automatic test stations, which are difficult to adapt to handling diced double-sided detectors. The paper presents some aspects of the experience gained from the testing and qualification of the sensors. The test procedures and the statistics of results will be briefly illustrated, and some problems encountered will be discussed.
In order to extend the direct observation of high-energy cosmic rays up to the PeV region, highly performing calorimeters with large geometrical acceptance and high energy resolution are required. ...Within the constraint of the total mass of the apparatus, crucial for a space mission, the calorimeters must be optimized with respect to their geometrical acceptance, granularity and absorption depth. CaloCube is a homogeneous calorimeter with cubic geometry, to maximise the acceptance being sensitive to particles from every direction in space; granularity is obtained by relying on small cubic scintillating crystals as active elements. Different scintillating materials have been studied. The crystal sizes and spacing among them have been optimized with respect to the energy resolution. A prototype, based on CsI(Tl) cubic crystals, has been constructed and tested with particle beams. Some results of tests with different beams at CERN are presented.
The modes of the instant prognosis of earthquakes and tsunami with probability greater than 0.95 are offered. These modes are based on the principal idea of a simultaneous measurement of elastic and ...electromagnetic waves from the underground center of earthquakes. Electromagnetic waves with frequency from 1 Hz up to 1000 Hz transmit well on the surface of the Earth, bottom of ocean and in open space. The time of arrival of an electromagnetic wave at three (or more) points can be used to determine coordinates of the center of the earthquakes. The measurement of intensity of an electromagnetic signal is an informative indication about arrival of disastrous elastic waves. The mode of fall of energy of elastic waves in a seismic center is developed by an exposure to electromagnetic waves within 30-50 days in one year.
•Hysteresis losses in a nanocrystalline alloy with uniaxial induced anisotropy.•Formulas for calculation of hysteresis losses in a wide region of the magnetic field.•Relation of magnetization ...processes in the Rayleigh region to the correlation length.•Hysteresis associated with irreversible magnetization rotation in ferromagnetic clusters.
The hysteresis losses and their relation to the parameters of the minor static hysteresis loops were investigated in the nanocrystalline Fe67.5Co5Cu1Nb2Mo1.5Si14B9 alloy with magnetic-field-induced anisotropy. The analysis of experimental data was performed using a power function, which approximated the dependencies between the hysteresis parameters. It is shown that all the experimental dependences in cores with magnetic-field-induced anisotropy in a weak magnetic field are consistent with the formulas derived from the Rayleigh law. It is also shown, that in a nanocrystalline alloy with uniaxial induced anisotropy, certain empirical relationships obtained earlier for isotropic materials are not met, particularly, for the relation of the hysteresis losses to the remanence and the maximal magnetic induction. It has been found, that samples with longitudinal induced anisotropy demonstrate low initial permeability, and the magnetization process in the Rayleigh region is carried out by the domain walls’ displacement at distances comparable to the correlation length Lex. A magnetic hysteresis mechanism associated with the irreversible magnetization rotation in ferromagnetic clusters of nanocrystalline alloys is proposed. Formulas are proposed to calculate hysteresis losses in a soft magnetic nanocrystalline material with a different magnetic anisotropy.
Results of experiments aimed at amplification of the pressure of laser-induced shock wave on the passage from low- to high-density target material via vacuum gap are presented. During the action of ...nanosecond laser pulse of terawatt power on plane composite targets comprising a layer of laser radiation absorber of low-density (0.01–0.025 g/cm
3
) spaced by vacuum gap from a layer of aluminum, the shock-wave velocity in aluminum reached 25–29 km/s and a pressure jump at the aluminum layer boundary was 1.2–1.5 times as large as that observed in experiments on the cumulative transition of laser-induced shock wave into a solid. The obtained experimental data are compared to results of the numerical calculations performed using hydrodynamic programs in which the shock-wave generation and propagation was modeled with allowance for the interaction of laser pulses with partly homogenized plasma of the porous material. Based on the results of experiments, numerical calculations, and their theoretical analysis, the efficiency of using low-density porous media in the targets intended for their equation of state investigations and inertial confinement fusion ignition is considered.
Solving the ecological problems of big cities is made difficult by the fact that their activities are built on the concentration of many kinds of resources. The economic foundation for their ...prosperity is made up of scientific, manufacturing, and cultural opportunities. At the same time, negative externalities occur, and natural and technological restrictions come into effect. The lessons of the COVID-19 pandemic require seeking out new methods of managing metropolitan areas. Global cities are unique in their constant influx of people - tourists, expats, students, and so on. This paper presents a way to solve the problems relating to regulating the inflow of visitors. A dynamic model of the spread of the infection is put together, the arguments for which are the restrictive and quarantine measures. At the same time, the problem of finding an economically sound balance between ecological externalities and the capacity of limited resources is solved. When solving these two problems using computer simulation, it becomes possible to use information flows of smart city systems, while the results of the calculations provide the basis for adopting the optimal set of administrative and technical solutions.
The shaping of astrophysical outflows into bright, dense, and collimated jets due to magnetic pressure is here investigated using laboratory experiments. Here we look at the impact on jet collimation ...of a misalignment between the outflow, as it stems from the source, and the magnetic field. For small misalignments, a magnetic nozzle forms and redirects the outflow in a collimated jet. For growing misalignments, this nozzle becomes increasingly asymmetric, disrupting jet formation. Our results thus suggest outflow/magnetic field misalignment to be a plausible key process regulating jet collimation in a variety of objects from our Sun's outflows to extragalatic jets. Furthermore, they provide a possible interpretation for the observed structuring of astrophysical jets. Jet modulation could be interpreted as the signature of changes over time in the outflow/ambient field angle, and the change in the direction of the jet could be the signature of changes in the direction of the ambient field.
Magnetized laser-produced plasmas are central to many novel laboratory astrophysics and inertial confinement fusion studies, as well as in industrial applications. Here we provide the first complete ...description of the three-dimensional dynamics of a laser-driven plasma plume expanding in a 20 T transverse magnetic field. The plasma is collimated by the magnetic field into a slender, rapidly elongating slab, whose plasma-vacuum interface is unstable to the growth of the "classical," fluidlike magnetized Rayleigh-Taylor instability.
Collective processes in plasmas often induce microinstabilities that play an important role in many space or laboratory plasma environments. Particularly notable is the Weibel-type current ...filamentation instability, which is believed to drive the creation of collisionless shocks in weakly magnetized astrophysical plasmas. Here, this instability class is studied through interactions of ultraintense and short laser pulses with solid foils, leading to localized generation of megaelectronvolt electrons. Proton radiographic measurements of both low- and high-resistivity targets show two distinct, superimposed electromagnetic field patterns arising from the interpenetration of the megaelectronvolt electrons and the background plasma. Particle-in-cell simulations and theoretical estimates suggest that the collisionless Weibel instability building up in the dilute expanding plasmas formed at the target surfaces causes the observed azimuthally symmetric electromagnetic filaments. For a sufficiently high resistivity of the target foil, an additional resistive instability is triggered in the bulk target, giving rise to radially elongated filaments. The data reveal the growth of both filamentation instabilities over large temporal (tens of picoseconds) and spatial (hundreds of micrometres) scales.In the interaction of ultraintense, short laser pulses with solid targets, the collisionless Weibel instability is observed. For a sufficiently high resistivity of the target, an additional resistive instability appears.
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