Prediction for a Four-Neutron Resonance Shirokov, A M; Papadimitriou, G; Mazur, A I ...
Physical review letters,
10/2016, Letnik:
117, Številka:
18
Journal Article
Recenzirano
Odprti dostop
We utilize various ab initio approaches to search for a low-lying resonance in the four-neutron (4n) system using the JISP16 realistic NN interaction. Our most accurate prediction is obtained using a ...J-matrix extension of the no-core shell model and suggests a 4n resonant state at an energy near E_{r}=0.8 MeV with a width of approximately Γ=1.4 MeV.
Abstract
We define a new class of functions of variable smoothness that are analytic in the unit disc and continuous in the closed disc. We construct the theory of the Nevanlinna outer-inner ...factorization, taking into account the influence of the inner factor on the outer function, for functions of the new class.
TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of ...the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ∼100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44ˆ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.
The origin and nature of extreme energy cosmic rays (EECRs), which have energies above the
5
⋅
10
19
eV
—the Greisen-Zatsepin-Kuzmin (GZK) energy limit, is one of the most interesting and complicated ...problems in modern cosmic-ray physics. Existing ground-based detectors have helped to obtain remarkable results in studying cosmic rays before and after the GZK limit, but have also produced some contradictions in our understanding of cosmic ray mass composition. Moreover, each of these detectors covers only a part of the celestial sphere, which poses problems for studying the arrival directions of EECRs and identifying their sources. As a new generation of EECR space detectors, TUS (Tracking Ultraviolet Set-up), KLYPVE and JEM-EUSO, are intended to study the most energetic cosmic-ray particles, providing larger, uniform exposures of the entire celestial sphere. The TUS detector, launched on board the Lomonosov satellite on April 28, 2016 from Vostochny Cosmodrome in Russia, is the first of these. It employs a single-mirror optical system and a photomultiplier tube matrix as a photo-detector and will test the fluorescent method of measuring EECRs from space. Utilizing the Earth’s atmosphere as a huge calorimeter, it is expected to detect EECRs with energies above
10
20
eV
.
It will also be able to register slower atmospheric transient events: atmospheric fluorescence in electrical discharges of various types including precipitating electrons escaping the magnetosphere and from the radiation of meteors passing through the atmosphere. We describe the design of the TUS detector and present results of different ground-based tests and simulations.
We develop the numerical method of moments for solving an integral equation that describes the distribution of the charge along a thin finite-length antenna wire in an anisotropic medium in the ...quasistatic approximation. It is shown that the method of moments can be used to calculate the electrodynamic characteristics of such an antenna under the conditions where the kernel of the integral equation has a singularity related to the resonance cone. The influence of the ratio between the elements of the dielectric permittivity tensor and the method of partitioning of the antenna surface on the calculation accuracy is analyzed. It is shown that the relative error of calculations of the antenna characteristics is a fairly small value of about 1% if the antenna wire is divided into ten segments.
The influence of the reamer’s elastic guide plates on the quality of the machined hole is studied by means of a mathematical model. Recommendations are made for reducing the defects (fracturing) to ...an acceptable level.
The convergence of bound-state calculations performed via the oscillator basis expansions by means of locating
-matrix poles for bound states within the HORSE and SS-HORSE approaches is examined. The ...convergence in question is studied both in the case of a sharp truncation of the potential matrix in the harmonic-oscillator space and in the case of smoothed matrix elements of the potential. As a result, a new method of extrapolation to the case of the infinite-dimensional model space is proposed. This method makes it possible to predict, on the basis of variational calculations, binding energies and asymptotic normalization coefficients for bound states to a high accuracy and to estimate the uncertainties of these predictions.
The influence of the structure of a 3D spatial mesh on the quality of numerical modeling of viscous compressible gas flow at a Mach number equal to 3 around a forward-facing part of a rectangular ...cylinder is demonstrated. The results obtained show that the mesh structure critically affects the shape and the intensity of the head shock wave, and its influence can exceed that of other mesh-related effects. The calculations are performed using a finite volume method implemented for regularized or quasi-gas dynamic equations.
Music plays a more important role in our life than just being an entertainment. For example, it can be used as an anti-anxiety therapy of human and animals. However, the unsafe listening of loud ...music triggers hearing loss in millions of young people and professional musicians (rock, jazz and symphony orchestra) owing to exposure to damaging sound levels using personal audio devices or at noisy entertainment venues including nightclubs, discotheques, bars and concerts. Therefore, it is important to understand how loud music affects us. In this pioneering study on healthy mice, we discover that loud rock music below the safety threshold causes opening of the blood-brain barrier (OBBB), which plays a vital role in protecting the brain from viruses, bacteria and toxins. We clearly demonstrate that listening to loud music during 2 h in an intermittent adaptive regime is accompanied by delayed (1 h after music exposure) and short-lasting to (during 1-4 h) OBBB to low and high molecular weight compounds without cochlear and brain impairments. We present the systemic and molecular mechanisms responsible for music-induced OBBB. Finally, a revision of our traditional knowledge about the BBB nature and the novel strategies in optimizing of sound-mediated methods for brain drug delivery are discussed.
Hole Accuracy in Reaming Zheleznov, G. S.; Shirokov, A. V.
Russian engineering research,
03/2023, Letnik:
43, Številka:
3
Journal Article
Recenzirano
Analytical formulas are derived for the discrepancy in hole diameter on reaming due to the misalignment of the reaming and rotating axes, with rigid attachment of the reamer to the machine tool. ...These formulas may be used to optimize the input parameters in reaming and hence to obtain accurate holes.
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