Cherenkov Telescope Array—CTA

Gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. Cherenkov Telescope Array (CTA) is an international initiative to build the next-generation ground-based gamma-ray observatory which will have a factor of 5–10 improvement in sensitivity in the 100-GeV–10-TeV range and an extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the Northern and another in the Southern Hemisphere) for full sky coverage and will be operated as an open observatory. It will provide a deep insight into the non-thermal high-energy Universe. In this talk, we will briefly present the major design concepts of CTA as well as its vast science case.     

Spin-rotating magnet for the ΔσL(np) experiment at LHEP JINR

The spin rotating magnet (SRM) is purposed for the orientation rotation of the nucleon spins in the polarized beam from the transverse (T) direction with respect to the nucleon beam momentum to the longitudinal (L) one. The longitudinally polarized neutron beam was used in the experiment for measuring the total cross section difference Δσ_L(np) with parallel and antiparallel orientation of the participant L polarization. To perform the nucleon spin rotation in the polarized nucleon beam through the angle of 90° over the beam momentum region of ～1.8–5.5 GeV/c, a proper spin rotation device had to be prepared. For this purpose, the necessary calculations of corresponding values of the magnetic induction integral were carried out. Using the calculations the dipole magnet SP 57 type was chosen for the Δσ_L(np) experiment and the required reconstruction of its pole tips was also accomplished. After the SRM installation at the neutron beam line the appropriate apparatus set for the magnetic measurements was prepared and the precise measurements of the whole set of the SRM characteristics were performed. The obtained results for the SRM magnetic field parameters were successfully used during the Δσ_L(np) experimental runs to specify the current at this magnet coil corresponding to the calculated magnetic induction integral for the given neutron beam momentum.     

Search for η-mesic nuclei in the reaction d + C at JINR

Results of a search for quasi-bound states of the η-meson and a target nucleus obtained during several years using the internal target at the Nuclotron d-beam are presented. Formation of η-mesic nuclei was studied in the reaction d + C in the energy interval 1.5 to 2.2 GeV/nucl. Decay products of S₁₁ resonances excited by η-mesons captured by nucleons in the nuclear target have been analyzed. Measurements were performed with a scintillation spectrometer SCAN. Analysis of obtained data is presented.     

Assessment of the 200-μm Atmospheric Window for Ground-Based Astronomy

Submillimetre astronomy with ground-based instruments is currently restricted to spectral windows below 1 THz where the atmosphere is not very opaque. Recently, it was shown that supra-terahertz windows also unfold under very good atmospheric conditions, and could be explored for this effect. In particular, the 200 m window (1.5 THz) can transmit up to 30% on exceptionally dry weather at high-altitude sites. This study was conducted in parallel with the designs of THUMPER, a Two Hundred Micron Photometer for the James Clerk Maxwell Telescope, in Hawaii. Here we consider the weather conditions required and how often they arise, both by modelling the spectral transmittance of the atmosphere at 200 m and by analysing opacity data at 225 GHz. Implications for submillimetre astronomy are discussed. This study could benefit the ongoing analysis of other observation sites.     

Atmospheric Neutrinos as a Tool for Exploring the Earth’s Inner Parts

Investigation of the Earth’s inner parts requires developing new methods. It is well known that atmospheric neutrinos traverse the Earth, undergoing virtually no interaction. The change in the neutrino flux is due exclusively to neutrino oscillations, which are enhanced by the effect of Earth’s matter. At the present time, there are two projects outside Russia (PINGU and ORCA) that are aimed at detecting atmospheric neutrinos that traversed the Earth, which are supposed to be used for purposes of Earth’s tomography. The creation of a large neutrino detector on the basis of a liquid scintillator is planned at the BaksanNeutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) in the North Caucasus. After testing this detector, there will arise the possibility of employing it as part of the worldwide network of neutrino detectors for studying the Earth’s inner parts.     

NIR Spectroscopy and Imaging Techniques for Evaluation of Fish Quality—A Review

Abstract

Fish is a highly perishable product and it is particularly important to pay attention to its quality changes. Maintenance of the high quality of fish and fishery products necessitates development of means for precise and rapid quality evaluation. Near-infrared (NIR) spectroscopy and imaging techniques are proven technologies that can provide useful information for the estimation of quality attributes in fish and fishery products due to fast speed, noninvasiveness, ease of use, and minimal sample preparation. The aim of this review is to communicate perspectives and aspects relating to NIR spectroscopy and imaging techniques with regard to evaluation of chemical composition (fat, protein, and moisture), microbiological (freshness, spoilage, and nematodes), and sensory (flavor, texture, and color) attributes of fish and fishery products. Moreover, the usefulness of NIR spectroscopy and imaging techniques for fish authentication and classification are presented. Finally, some viewpoints on the current situation and suggestions for future research directions are proposed.     

Direct search for dark matter—striking the balance—and the future

Weakly Interacting Massive Particles (WIMPs) are among the main candidates for the relic dark matter (DM). The idea of the direct DM detection relies on elastic spin-dependent (SD) and spin-independent (SI) interaction of WIMPs with target nuclei. In this review paper the relevant formulae for WIMP event rate calculations are collected. For estimations of the WIMP-proton and WIMP-neutron SD and SI cross sections the effective low-energy minimal supersymmetric standard model is used. The traditional one-coupling-dominance approach for evaluation of the exclusion curves is described. Further, the mixed spin-scalar coupling approach is discussed. It is demonstrated, taking the high-spin ⁷³Ge dark matter experiment HDMS as an example, how one can drastically improve the sensitivity of the exclusion curves within the mixed spin-scalar coupling approach, as well as due to a new procedure of background subtraction from the measured spectrum. A general discussion on the information obtained from exclusion curves is given. The necessity of clear WIMP direct detection signatures for a solution of the dark matter problem, is pointed out.     

Peculiarities of induced radiation and controlled dechanneling of relativistic particles in crystals under the Cherenkov—Vavilov extreme condition

Peculiarities of induced radiation and absorption of hard electromagnetic radiation are considered on the basis of the channeling of relativistic particles in crystals under the Vavilov—Cherenkov extreme condition. It is shown that the consistent inclusion of quantum recoil in the relativistic region makes it possible to produce a number of anomalous effects having no analogs in optics. In particular, it is predicted that it is possible to simultaneously cool the beam of fast particles during radiation and absorption and to create a tandem laser for which successive radiation of quasicharacteristic-radiation quanta at the normal and anomalous Doppler effect leads to the restoration of the initial state of the quantum system and to the multiple repetition of the radiation cycle. It is shown that the main difficulties preventing these effects from being produced directly in the X-and gamma-ray spectral regions are related to the necessity to use media with positive dispersion. It is considered that such dispersion can be produced by changing the effective susceptibility of the medium in the case of radiation diffraction.     

Six—Parameter Exponential—Type Potential and the Identity for the Exponential—Type Potentials

We propose a six-parameter exponential-type potential (SPEP),which has been shown to be a shapeinvariant potential with a translation of parameters.For this reducible potential,the exact energy levels are obtained by using the supersymmetric shape invariance technique.Choosing appropriate parameters,four classes of exponential-type potentials and their exact energy spectra are reduced from the SPEP and a general energy level formula,respectively.Each class shows the identity except for the different definitions of parameters.     

A new proposal for the discretization of the Griffin—Wheeler—Hartree—Fock equations

A polynomial expansion is proposed as a new way to discretize the Griffin-Wheeler-Hartree-Fock equations of the Generator Coordinate Hartree-Fock method. The implementation of the polynomial expansion in the Generator Coordinate Hartree-Fock method discretizes the Griffin-Wheeler-Hartree-Fock equations through a numerical mesh which is not equally spaced. This procedure makes the optimization of Gaussian exponents in the Generator Coordinate Hartree-Fock method more flexible and more efficient. The results obtained with the polynomial expansion for atomic Hartree-Fock energies show this technique is very powerful when employed in the design of compact and high accurate Gaussian basis sets used in ab initio non-relativistic (Hartree-Fock) and relativistic (Dirac-Fock) calculations.     

Parametric analysis of Cherenkov light LDF from EAS in the range 30–3000 TeV for primary gamma rays and nuclei

A simple “knee-like” approximation of the Lateral Distribution Function (LDF) of Cherenkov light emitted by EAS (extensive air showers) in the atmosphere is proposed for solving various tasks of data analysis in HiSCORE and other wide angle ground-based experiments designed to detect gamma rays and cosmic rays with the energy above tens of TeV. Simulation-based parametric analysis of individual LDF curves revealed that on the radial distance 20?500 m the 5-parameter “knee-like” approximation fits individual LDFs as well as a mean LDF with a very good accuracy. In this paper we demonstrate the efficiency and flexibility of the “knee-like” LDF approximation for various primary particles and shower parameters and the advantages of its application to suppressing proton background and selecting primary gamma rays.     

A 210–280 GHz sis heterodyne receiver for the James Clerk Maxwell Telescope part I: Design and performance

We describe the design and performance of a 210–280 GHz SIS heterodyne receiver built for use on the Maxwell Telescope. The mixer utilises a lead alloy SIS tunnel junction, mounted in 41 reduced height rectangular waveguide, and is tuned with a backshort in 21 reduced height guide. The receiver has a receiver noise temperature of <200K (DSB) across the RF band from 210–270 GHz, with a best noise temperature measured in the laboratory of 113K (DSB) at 231 GHz. A prototype version of this receiver was successfully operated on the telescope in May 1989. By direct intercalibration with a Schottky diode receiver we deduced a best receiver noise temperature of 140K (DSB) at 245 GHz. Discrepancies between this figure and that derived from broad band thermal load calibration are discussed in the accompanying paper (Little et al., 1992, this issue).     

Mean—Field Calculations for the Three—Dimensional Holstein Model

The electron-phonon Holstein model is studied in three spatial dimensions.It is argued that this model can be used to account for major features of the high-Tc BaPb1-xBixO3 and BaxK1-xBiO3 systems.Mean-field calculations are performed via a path integral representation of the model.Charge-density-wave order parameters and transition temperatures are obtained.     

Exact Solution of the Milburn Equation for the Two—Mode Two—Photon Jaynes—Cummings Model

We adopt an algebraic method to study the two-mode two-photon Jaynes-Cummings model governed by the Milburn equation and find an exact solution of Milburn equation of the system.The influence of the intrinsic decoherence on the nonclassical effects of the system is also discussed.     

Infrared magnetooptic — A tool for the determination of the effective mass

The analysis of the magnetooptical effects of heavily doped materials at the plasma edge yields the concentration dependence of the effective cyclotron mass. Therefore these experiments support the general diskussion about the nonparabolicity of a band, the position of the Fermi level at high degenerated semiconductors and the determination of the dispersion function. Experimental results of the magnetooptical determinedm _c ^* (N) function are compared with coresponding band structure calculations. A matrix calculation model, which describes the symmetrical magnetooptical transmission effects as well as the asymmetrical magnetooptical reflection effects of arbitrary successions of coherent films and incoherent substrates consitently, is used to determine free carrier density profilesN (z) of inhomogeneously doped semiconductors non-destructively. This application of the matrix formalism requires the knowledge of them ^* (N)-function. The influence of the effective cyclotron mass on thedifferential magnetooptical interference structures caused by buried density profiles is discussed.