We intend to study a new class of cosmological models in f(R, T) modified theories of gravity, hence
define the cosmological constant Λ as a function of the trace of the stress energy-momentum-tensor T and
the Ricci scalar R, and name such a model Λ(R, T) gravity where we have specified a certain form of
Λ(R, T). Λ(R, T) is also defined in the perfect fluid and dust case. Some physical and...
The NEVOD-EAS array for the detection of extensive air showers in the energy range 10^15−10^17 eV is being created in MEPhI on the basis of the Experimental complex NEVOD. It is aimed at independent estimations of the size, axis position and arrival direction of EAS registered with other detectors of the complex.
Since the NEVOD-EAS is being created at a densely built territory and detecting...
A four-layer gaseous detector for electrons and other charged particles is developed. A charged particle passing through a thin window produces ionization in four consecutive gas gaps separated by absorbers. The gas gain about of $10^{4}$ allows one to determine four signal amplitudes under the control of any combination of these signals. Simultaneous measurement of the ionization losses of...
We developed a new ring neutron detectors based on ZnS/LiF scintillators and solid-state photomultipliers (SiPM) for powder neutron difractometers. This detector can capture full Sherrer's ring and therefore can provide the most effective regustration of scaterred by sample neutrons. The design of the detector allows completely avoiding blind areas. The developed detectors consisst from...
It is supposed that in a black hole unlike the routine world of coordinate and time are constants, and an impulse and energy are variables. In work some possibilities of driving of a particle of matter in these conditions are considered. For their consideration the principle of ab inititio but not traditional minimization of expression of action through a Lagrangian is used.
In this work at...
The existence of axionlike particles (ALPs) is predicted by many extensions of the Standard Model. ALPs represent very probable and well motivated candidate for the role of dark matter. ALPs may manifest themselves through interaction with photons – particularly, through photon-ALP conversion in magnetic fields. This hypothetical process is able to solve a big astrophysical problem of an...
Modern existing and being developed Cherenkov water detectors for neutrino astrophysics have a cubic-kilometers volume. These detectors are deployed at great depths of water or ice and, in addition to neutrinos, register atmospheric muons with a high energy threshold (hundreds GeV). The energy spectrum of muons with energies above 100 TeV is extremely poorly studied. Knowing the spectrum will...
The perspective space project SOLARIS involves research on board a spacecraft launched at Lagrange L1 point, which should provide long-term continuous complex observations of the Sun in various ranges of the electromagnetic spectrum. The complex of scientific devices developed by NRNU MEPhI is designed to study active nonstationary processes on the Sun in a wide range of X-ray and gamma...
The attachment of electrons to electronegative impurities in condensed phases is the most important process limiting performance of two-phase emission detectors. These impurities are also responsible for some other processes that degrade the efficiency of the detector, such as reducing energy of electrons during drift and absorbing UV radiation. We present a complex method for preparing...
Primary particles of cosmic rays originate in outer space and when they reach the Earth, they cause a series of nuclear reactions with the molecules and particles presented in the Earth’s atmosphere and therefore, lead to the creation of many secondary particles in the form of extensive air showers. By the increase in altitude, the layer of the protective atmosphere being thinner and...
The original ideas of new theory – “Non-Inflationary Cosmology” (NIC) – and its consequences are manifested: 1. Global hierarchy of Bose-Einstein statistics’ (BES) at earliest Universe guarantees the formation of Bose-Einstein condensate in Matter Era (ME). 2. New phenomenon – Cosmological Small-Bang – has been disclosed as a consequence of further phase-transition process from BES to FDS in...
The conducting of physical experiments at large accelerator facilities, of the FAIR (Germany) type requires the provision of readout and processing of signals from a large number of detectors. To solve these tasks there are used complicated electronic units, which are designed as application specific integrated circuits (ASIC). The design process is subject to hard requirements, bound with...
Design approach and structure of an Application-Specific Integrated Circuit (ASIC) for multichannel Gas Electron Multiplier (GEM) detectors are presented. This ASIC is designed for use in tracking and calorimetric systems of large physical experiments such as CBM (FAIR, Darmstadt) and MPD (NICA, Dubna).
The amount of data to be processed by ASIC is related to the channel event rate, ADC...
Possible study of hadron production at small angles with respect to beam
at the Large Hadron Collider (LHC) is being actively discussed now.
Apart from a better understanding of the fundamental QCD processes,
the study of high energy particle production in the forward direction
is an extremely important topic for cosmic ray physics.
Such measurements could remove uncertainties in physics...
Using the Monte Carlo method (GEANT4), energy deposit distributions were obtained for incident gamma photons with energy from $256$ MeV up to $8192$ MeV interacting with the various parts of the spaghetti calorimeter (SPACAL). The SPACAL consists of nine scintillation single crystal gallium-gadolinium garnet (GGG) rods with dimensions $3\times3\times100$ $\text{mm}^3$ forming a $3\times3$...
Dissipative interactions between neutrinos and the environment in which they propagate lead to quantum decoherence. Such an environment is predicted by quantum gravity models featuring a 'foamy' space-time structure. Environmental decoherence degrades the interference between neutrino states that is responsible for neutrino oscillations, resulting in exponential damping of oscillation...
Using back tracing we research galactic cosmic ray propagation in a moving magnetic cloud having the shape of magnetic loop. It is obtained that the inductive electric field of an extended magnetic cloud decreases particle energy. Both energy losses and long particle trapping by a magnetic loop produce Forbush decrease. The calculation results of particle density and the components of uni- and...
The possibility of generating and detecting high-frequency gravitational waves based on parametric optical processes in dielectric media at their excitation by intense laser radiation of visible or ultraviolet ranges is analyzed. The theory predicts the feasibility of the Hertz gravitational laboratory experiment in which the parametric conversion of intense laser pulses with frequency ω0 to a...
Higgs boson production cross-sections via the gluon–gluon fusion and vector-boson fusion modes are measured in the $H \rightarrow WW^{*}\rightarrow е\nu\mu\nu$ decay channel in the ATLAS experiment at the LHC. The $H \rightarrow WW^{*}$ decay channel has the second largest branching fraction and allows to measure Higgs boson production cross-section with good precision. The analysis is based...
The High Altitude Water Cherenkov (HAWC) observatory is a wide-field-of-view (2sr) and high duty cycle (>95%) gamma-ray detector array, which is sensitive to gamma rays from 500 GeV - 100 TeV. HAWC operates at an altitude of 4100 meters in the state of Puebla, Mexico, since HAWC observes 2/3 of the sky 24 hours a day, it is a well-suited instrument to perform indirect dark matter searches by...
During the development of large fast scintillation detectors with silicon photomutipliers (SiPM) for the satellite based gamma-ray telescope GAMMA-400, the properties of the SiPM allowed to measure the number of photoelectrons detected. The minimum of photoelectrons detected is calculated for effective particles selection. The functions of the detector response to SiPM with a different number...
We study the properties of a certain class of solutions of a relativistic model with the logarithmic nonlinearity. We show that such a model have two types of solutions: topologically trivial (gaussons) and topologically non-trivial (kinks). For the kink-antikink scattering, we have found a critical value of the initial velocity $v_\mathrm{cr}$, which separates two different scenarios of...
During the upcoming Long Shutdown 2 the accelerator complex at CERN will implement significant improvements to the performance of the collider including the increase of the luminosity such that it is expected a sustain interaction rates up to 1MHz for p-p collisions and 50 kHz for Pb-Pb collisions. In order to remain operational during the Run 3 and Run 4 ALICE has to upgrade many of its...
Detectors based on organic scintillators are widely used in the tasks when fast neutrons in the presence of gamma radiation are necessary to detect. Such tasks are control of spent nuclear fuel, measurement of the yield of fast neutrons from neutron generators, monitoring of neutron and gamma background in underground low-background experiments (neutrino and dark matter detectors), and...
A search for resonant absorption of the solar axion by $^1$$^6$$^9$Tm nuclei will be performed using the Tm-containing bolometers installed inside the low-background setup at the underground laboratory. The thulium crystal Tm$_3$Al$_5$O$_1$$_2$ have been grown and tested for the first time as a bolometric detector. The expected sensitivity of 1 kg Tm-bolometer to axion-photon g$_A$$_γ$ and...
We analyze observational signatures that may arise from a cosmological epoch corresponding to the simple harmonic universe, which consists of positive curvature, a negative cosmological constant, and one or more matter sources with an intermediate equation of state, which then tunnels and/or evolves into inflation and radiation-dominated eras. We find that the effects on the cosmic microwave...
In our previous publications [1–3] we have discussed new original effect appeared at crossing of the metal foils by fission fragments (FFs). We have observed significant mass deficit in the total mass Ms of the FFs detected in coincidence with ions knocked out from the foil. In series of the recent more detailed experiments we have compared event by event the mass of the FF before (Mtt) and...
For the experiments with irradiation of cylindrical targets by intense ion beams which are actual in some fundamental and applied researches (laboratory astrophysics, medicine, etc) it is necessary to shape the irradiating beam with hollow geometry. Among the various methods of hollow beam formation the wobbling is of interest. The deflecting plates or RF-cavities with phase shift of...
Elementary particle processes in the extreme astrophysical conditions, such as strong magnetic fields, require knowledge of the exact propagators. There are known expressions for the propagators of scalar, Dirac and massive vector fields in the presence of the constant magnetic field both in the coordinate and in the momentum spaces. In general they require either following the tedious...
The Compressed Baryonic Matter (CBM) experiment at the future Facility for
Antiproton and Ion Research (FAIR) aims to study the properties of nuclear
matter at high net-baryon densities and moderate temperatures.
The Silicon Tracking System (STS) is the key detector to reconstruct with
a high efficiency up to 1000 charged particle trajectories created in heavy-ion
collisions at interaction...
Measurements of the directed and elliptic flow of strange and multi-strange hadrons are an important part of the physics program of the Compressed Baryonic Matter experiment (CBM) at the future accelerator complex FAIR in Darmstadt, Germany. It was shown recently by studies from the RHIC BES program that $dv_1/dy|y=0$ and the difference between $v_2$ of particles and antiparticles in the...
The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the QCD phase diagram at high net baryon densities and moderate temperatures using collisions of heavy ions at center-of-mass energies of a few GeV per nucleon. Anisotropic transverse flow is among the key observables to study the properties of matter created in such collisions.
The CBM performance for anisotropic flow...
In this talk the phase structure of the dense baryonic/quark matter has been investigated in the presence of baryon, isospin, chiral and chiral isospin chemical potentials in the framework of Nambu--Jona-Lasinio model. It has been shown that in the large-Nc limit there exist several dualities of the phase portrait. One of the key conclusions of our studies is the fact that chiral imbalance...
To apply force-free magnetic field models we present and discuss properties and feathers of the following models: Miller and Turner solution, modified Miller and Turner solution, Romashets and Vandas solution, Integral model, Krittinatham and Ruffolo model. These models can be used to interpret in-situ observations of the magnetic flux rope, study Forbush decrease in magnetic clouds or...
Supersource of ultracold neutrons on the basis of superfluid helium is under construction in PNPI NRC KI. It must provide UCN density 2-3 orders of magnitude
higher than existing sources. For the new source we propose an experiment on search for neutron–antineutron oscillations based on the storage of ultracold neutrons in a material trap. The sensitivity of the experiment mostly depends on...
We investigate the processes of radiative transitions of electrons between the Landau levels, $e_{(\ell)} \to e_{(n)} + \gamma$, in a moderately strong magnetic field. Under such conditions, it is necessary to take into account transitions in which both the initial and final electrons can be in states corresponding to arbitrary Landau levels. The results obtained can be used in calculating the...
Abstract. The pixel recovery time of the Hamamatsu SiPM linear assembly was measured. The assembly contains eight SiPMs of 2.8 mm active area diameter; pixel size is 15 x 15 mkm2. The assembly is used in calorimeters of the CMS experiment.
The measurements were made for two groups of pixels: 49 and 17 pixels. Recovering time was found as 7 ns and 6 ns respectively.
The amplifier of 40 db and...
The exact Reissner-Nordstr\"om solution of the Maxwell and Einstein equations corresponding the electromagnetic field configuration
localized in the region with the range of about $10^{-34}$ cm is considered as a model for the classical electron. It is shown that in
the tetrad representation, in spite of singularities of the electromagnetic and gravitational fields, there are solutions with...
The TUS experiment is designed to investigate the ultra high energy cosmic ray (UHECR) at energy ~ 100 EeV from the space orbit by the UV radiation measurement of extensive air showers (EAS). It was launched on board the “Lomonosov” satellite from the Vostochny Cosmodrome on April 28, 2016 for 5 years of data taking. It is the first orbital telescope aimed for such measurements. The main mode...
The inside energy content of the extended particle obeys Umov’s estimate of 1873 mc^2/γ ≈ mc^2 (1-0.5β^2) ≤ mc^2 under low velocities despite γmc^2 ≈ mc^2 (1+0.5β^2) ≥ mc^2 for the total kinetic energy. Geodesic auto-accelerations in mechanics / gravitation of nonlocal energy fluxes drive the probe body toward equipartition of kinetic energies of inside chaos, mc^2/γ, and its ordered...
Simulation of Gamma-400 calorimeter physical characteristics with considering processes of generation, propagation and detection of optical photons in scintillation crystal was performed using Geant4 toolkit with G4OpticalPhoton library, which contains the characteristics of processes with participation of optical photons and its processing procedures. Including of optical processes into...
There are several problems in the numerical simulation of jets of young stars: the results of calculations depend very much on the initial conditions, most of which are unknown from observational data. Analytical approaches, based on the solution of the Grad-Shafranov equation, can only provide a stationary one-dimensional picture of what is happening.
The purpose of this work is to combine...
Detectors consisting of a high Z converter and a hodoscope type particle detector behind it are often used in HEP experiments for e,γ/hadron and γ/π0 separations and for e,γ coordinate and energy measurements. The most popular converter materials are Pb and W, while Fe or Cu are used less frequently. The converter thickness is often close to tmax that corresponds to the maximum flux of charge...
Associated Higgs boson production in pp collisions can be a powerful tool for searches for CP violation in the Higgs sector. In this study we analyze CP sensitive observables constructed for a four lepton final state. It is shown that azimuthal angle distributions of leptons in this process demonstrate a strong sensitivity to CP violation at the current limits on Higgs boson coupling...
Primordial black holes (PBH) attracted particular attention last time. They are possible candidates not only to dark matter, but to supermassive black holes, gravitational waves events from black hole merger and others. However, recently there appeared constraints on PBH abundance from different observations (including those from gravitational microlensing). The present work is devoted to the...
We consider a model of $OHe$ atomic dark matter formed by Coulomb binding of the stable double charged massive $O^{--}$ particles with nuclei of primordial helium. Such dark matter can be captured by ordinary matter forming superheavy nuclei. We discuss $O$-nuclearites formed by multiple capture of $O^{--}$ particles by heavy nuclei and effect of accumulation of $OHe$ atoms in stellar evolution.
Prototype detector based on long BC-408 scintillators with SiPM readout for space-based gamma-telescope GAMMA-400 was tested in 100-300 MeV secondary positron beam of synchrotron C-25P «PAKHRA» of Lebedev Physical Institute. The measurement setup, design concepts for the prototype detector and chosen solutions together with some test results are discussed.
Considered the numerical simulation technique which providing optimum beam parameters at the transport channel output of electron accelerator. The KATRAN channels design environment used for this purpose has a modular structure includes the basic beam focusing blocks. This allows enabling create and configure the optical system of the accelerator fast and efficiently if a given topology of the...
The gamma-quanta background count rate model in the energy range from 0.1 MeV up to several MeV for high inclination satellites is presented. The AVS-F instrument (Amplitude-Time Spectrometry of the Sun) was installed onboard the specialized automatic station CORONAS-F functioning in time interval since July, 2001 up to December, 2005 on the orbit with initial parameters: altitude ~500 km,...
strong text The four-dimensional non-stationary model of a bunch of the particles interacting with own field is studied. For the description of behavior of a bunch the "Meshchersky's integral" allowing to give completely self-consistent kinetic description in 8-dimensional phase space is used. In the considered task the self-coordinated potential determines interaction forces in...
For Jiangmen Underground Neutrino Observatory the requirements < 1 % energy scale uncertainty and 3 % at 1 MeV energy resolution are crucial in order to determine neutrino Mass Hierarchy. Several effects determine the energy scale and response function of the detector. To measure two of them, ionization quenching and intrinsic energy resolution, small-scale laboratory setup was developed....
Expected energy spectra calculations for large volume liquid scintillation detectors to inverse $\beta$-decay for anti-neutrinos produced by $^{144}$Ce - $^{144}$Pr artificial source have been performed.
The calculations were carried out through Monte-Carlo method within GEANT4.10 framework and were purposed to search for neutrino oscillation to sterile eigenstate.
The analysis of relative...
In this talk the description of possible realisation of NLO Mateix Element Method is presented and probed with the Higgs boson decays. The comparison of LO and NLO approaches is demonstrated and the separation power of each approach is estimated.
The experiment was done to study $^{11}$B($^{3}$He,d)$^{12}$C reaction with energy E($^{3}$He) = 25 MeV.
The aim of the experiment is to determine the properties of $^{12}$C states at high excitation energies and in particular to verify which of the conflicting spin-parity assignments of the 13.35 MeV state (2¯ or 4¯) is consistent with the data and optical model predictions.
The...
Preliminary results of measurements of the total reaction cross sections σR for weakly bound 4He, 6He, 8He, 7Li, 8Li, 9Li, 11Li, 7Be, 9Be, 10Be, 11Be, 12Be, 8B, 10B, 11B and 12B nuclei at energy range (10-45) A MeV with 28Si and 181Ta target are presented. The secondary beams of light nuclei were produced by bombardment of the 15N (50 A MeV) primary beam on Be target and separated by COMBAS...
We calculate two-loop massless correlator $G(n_1,n_2,n_3,n_4,n_5;x,y;D)$ of two composite vertexes with Bjorken fractions $x$ and $y$, arbitrary indices $n_i$, and arbitrary space-time dimension, $D$. A closed-form expression for this two-loop kite Feynman diagram with composite vertexes is given in terms of a twofold hypergeometric series. In some special cases it reduces to a sum of...
In the light of the latest data by LHCf collaboration of the LHC on leading neutrons spectra it is possible to obtain total pion-proton cross-sections in the TeV energy region. In this work the exact extraction procedure is shown. Final numbers for the pion-proton cross-section are collected at several different values of the colliding energy and compared with some popular theoretical...
In last few years, several cosmologists have been used different equation of states (EOS) (namely, Phantom energy, generalized Chaplygin gas, Vander Walls quintessence EOS etc ) to explain the present accelerated expansion of the Universe. By using the same EOS, some theoretical physicists have been trying to construct traversable wormholes. Recently, Ananda and Bruni...
Приводятся результаты поиска событий, регистрируемых детектором LVD, совпадающих с гравитационными сигналами от источников GW150914, GW151226, GW170104, GW170608, GW170814 и GW170817.
Single-channel compact noise-proof spectrometer (Ø 5х10 mm) is based on the absorption filter method. Spectrometer is an assembly of thermoluminescent detectors made of lithium fluoride LiF, that are placed one after another, which are also used as filters for X-ray spectrum selection. Spectrometer has been developed for measuring X-ray spectra of micropinch-discharge plasma in the energy...
