Elastic domains in antiferromagnets

We consider periodic domain structures which appear due to the magnetoelastic interaction if the antiferromagnetic crystal is attached to an elastic substrate. The peculiar behavior of such structures in an external magnetic field is discussed. In particular, we find the magnetic field dependence of the equilibrium period and the concentrations of different domains

Ion-Acoustic Solitons in Bi-Ion Dusty Plasma

The propagation of ion-acoustic solitons in a warm dusty plasma containing two ion species is investigated theoretically. Using an approach based on the Korteveg-de-Vries equation, it is shown that the critical value of the negative ion density that separates the domains of existence of compressi- on and rarefaction solitons depends continuously on the dust density. A modified Korteveg-de Vries equation for the critical density is derived in the higher order of the expansion in the small parameter. It is found that the nonlinear coefficient of this equation is positive for any values of the dust density and the masses of positive and negative ions. For the case where the negative ion density is close to its critical value, a soliton solution is found that takes into account both the quadratic and cubic nonlinearities. The propagation of a solitary wave of arbitrary amplitude is investigated by the quasi-potential method. It is shown that the range of the dust densities around the critical value within which solitary waves with positive and negative potentials can exist simultaneously is relatively wide.Comment: 17 pages, 5 figure

Growth, crystal structure, and properties of Cu2Zn1-xCdxSnS4 solid solutions

The phase diagram of the Cu 2 CdSnS 4 –Cu 2 ZnSnS 4 system was constructed using data on differential thermal, X-ray phase and microstructure analysis methods. The diagram can be attributed to the first type according to the Rosebohm classification. The Cu 2 CdSnS 4 –Cu 2 ZnSnS 4 solid solution single crystals were grown by chemical vapor transport using iodine as a transport agent. Their structure and unit cell parameters as well as compositional dependences of lattice parameters, pycnometric, X-ray densities and microhardness were determined. It was found that the Vegard's law is fulfilled in solutions studied

Evidence for Cold-stream to Hot-accretion Transition as Traced by Ly alpha Emission from Groups and Clusters at 2 < z < 3.3

We present Keck Cosmic Web Imager observations of giant Ly alpha halos surrounding nine galaxy groups and clusters at 2 < z < 3.3, including five new detections and one upper limit. We find observational evidence for the cold-stream to hot-accretion transition predicted by theory by measuring a decrease in the ratio between the spatially extended Ly alpha luminosity and the expected baryonic accretion rate (BAR), with increasing elongation above the transition mass (M-stream). This implies a modulation of the share of BAR that remains cold, diminishing quasi-linearly (logarithmic slope of 0.97 +/- 0.19, 5 sigma significance) with the halo to M-stream mass ratio. The integrated star formation rates (SFRs) and active galactic nucleus (AGN) bolometric luminosities display a potentially consistent decrease, albeit significant only at 2.6 sigma and 1.3 sigma, respectively. The higher scatter in these tracers suggests the Ly alpha emission might be mostly a direct product of cold accretion in these structures rather than indirect, mediated by outflows and photoionization from SFR and AGNs; this is also supported by energetics considerations. Below M-stream (cold-stream regime), we measure L (Ly alpha) /BAR = 10(40.51 +/- 0.16) erg s(-1) M-circle dot(-1) yr, consistent with predictions, and SFR/BAR = 10(-0.54 +/- 0.23): on average, 30(-10)(+20) M-stream (hot-accretion regime), L-Ly alpha is set by M-stream (within 0.2 dex scatter in our sample), independent of the halo mass but rising 10-fold from z = 2 to 3.Peer reviewe

Ускоренные испытания транзисторов большой мощности на длительную наработку при решении задач прогнозирования их надежности методом имитационных воздействий

When evaluating the individual reliability of semiconductor devices by gradual failures for a given operating time, the value of the electrical parameter of a particular instance for this operating time is predicted using the simulation method. To obtain a prediction of an electrical parameter, it is necessary to have a simulation model in the form of a function of the relationship between a given operating time and the level of simulation impact. The simulation model is obtained with the help of preliminary studies (training experiment) of a training sample of semiconductor devices of the type of interest with the volume of approximately 50 ... 100 copies. The application of the model is reduced to the calculation of the level of simulation impact corresponding to a given operating time. The result of measuring the electrical parameter at the calculated level of the imitation impact in a new specimen of the same type that did not take part in the training experiment should be considered as a prediction of this parameter for a given operating time. An integral part of the preliminary research to obtain a simulation model is the testing of semiconductor devices of the training set for a long operating time, which can be tens of thousands of hours, which necessitates planning and conducting accelerated tests. The article substantiates the conditions for conducting accelerated forced tests in relation to high-power bipolar transistors of the KT872A type. The increased temperature and the reverse voltage applied to the collector junction of the transistors are chosen as factors accelerating the tests. The test acceleration coefficient is calculated relative to the operating mode of the transistors. Based on the results of the accelerated tests for the electrical parameter (collector-emitter saturation voltage), a mathematical model was obtained in the form of a dependence of its average value on the operating time. The presence of this model is necessary to determine the function of recalculating the given operating time of transistors to the value of the simulation impact.При оценке индивидуальной надежности полупроводниковых приборов по постепенным отказам для заданной наработки прогнозируют значение электрического параметра конкретного экземпляра для этой наработки, используя метод имитационных воздействий. Для получения прогноза электрического параметра надо иметь имитационную модель в виде функции связи заданной наработки с уровнем имитационного воздействия. Имитационную модель получают с помощью предварительных исследований (обучающего эксперимента) обучающей выборки полупроводниковых приборов интересующего типа объемом примерно 50…100 экземпляров. Применение модели сводится к расчету уровня имитационного воздействия, соответствующего заданной наработке. Результат измерения электрического параметра при рассчитанном уровне имитационного воздействия у нового однотипного экземпляра, не принимавшего участия в обучающем эксперименте, следует считать прогнозом этого параметра для заданной наработки. Составной частью предварительных исследований по получению имитационной модели являются испытания полупроводниковых приборов обучающей выборки на длительную наработку, которая может составлять десятки тысяч часов, что обусловливает необходимость планирования и проведения ускоренных испытаний. В статье обоснованы условия проведения ускоренных форсированных испытаний применительно к биполярным транзисторам большой мощности типа КТ872А. В качестве факторов, ускоряющих испытания, выбраны повышенная температура и обратное напряжение, прикладываемое к коллекторному переходу транзисторов. Рассчитан коэффициент ускорения испытаний относительно рабочего режима работы транзисторов. По результатам ускоренных испытаний для электрического параметра (напряжение насыщения коллектор–эмиттер) получена математическая модель в виде зависимости его среднего значения от наработки. Наличие этой модели необходимо для определения функции пересчета заданной наработки транзисторов на значение имитационного воздействия

Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR

Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel $\bar p p \to e^+ e^-$ is studied on the basis of two different but consistent procedures. The suppression of the main background channel, $\textit{i.e.}$ $\bar p p \to \pi^+ \pi^-$, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance

A super-linear 'radio-AGN main sequence' links mean radio-AGN power and galaxy stellar mass since z similar to 3

Mapping the average active galactic nucleus (AGN) luminosity across galaxy populations and over time reveals important clues regarding the interplay between supermassive black hole and galaxy growth. This paper presents the demography, mean power, and cosmic evolution of radio AGN across star-forming galaxies (SFGs) of different stellar masses (M).We exploit deep VLA-COSMOS 3 GHz data to build the rest-frame 1.4 GHz AGN luminosity functions at 0:1 z 4:5 hosted in SFGs. Splitting the AGN luminosity function into different M bins reveals that, at all redshifts, radio AGN are both more frequent and more luminous in higher M than in lower M galaxies. The cumulative kinetic luminosity density exerted by radio AGN in SFGs peaks at z 2, and it is mostly driven by galaxies with 10:5 log(M=M ) < 11. Averaging the cumulative radio AGN activity across all SFGs at each (M,z) results in a ‘radio-AGN main sequence’ that links the time-averaged radio-AGN power hLAGN 1:4 i and galaxy stellar mass, in the form: log h[LAGN 1:4 /WHz1]i = (20.97 0.16) + (2.51 0.34) log(1+z) + (1.41 0.09) (log[M /M ] – 10). The super-linear dependence on M , at fixed redshift, suggests enhanced radio-AGN activity in more massive SFGs as compared to star formation. We ascribe this enhancement to both a higher radio AGN duty cycle and a brighter radio-AGN phase in more massive SFGs. A remarkably consistent M dependence is seen for the evolving X-ray AGN population in SFGs. This similarity is interpreted as possibly driven by secular cold gas accretion fuelling both radio and X-ray AGN activity in a similar fashion over the galaxy’s lifetime.The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation, the Villum Fonden, European Union’s Horizon research and innovation program under the Marie Skłodowska-Curie grant and the Italian Ministry of University and Research.http://www.hanspub.org/Journal/AAS.htmlam2023Physic