Laser fluorescence spectroscopy and factor analysis in diagnostics of microbial diseases

Laser-induced fluorescence spectra of blood plasma are studied for patients suffering from microbial diseases. The spectra are measured on an experimental Spektrolyuks laser-fiber multichannel analyzer. A procedure for the statistical processing of the laser-fluorescence data bank is realized based on the method of factor analysis. The experimental results are presented for the learning and test groups. The appropriateness of the hybrid diagnostics in the detection and classification of pathologies with a statistical significance that is acceptable in practical applications is demonstrated.     

Expected accuracy in a measurement of the CKM angle α using a Dalitz plot analysis of B 0 → ρπ decays in the BTeV project

A precise measurement of the angle α in the CKM triangle is very important for a complete test of the Standard Model. A theoretically clean method to extract α is provided by B ⁰ → ρπ decays. Monte Carlo simulations to obtain the BTeV reconstruction efficiency and to estimate the signal-to-background ratio for these decays were performed. Finally the time-dependent Dalitz plot analysis, using the isospin amplitude formalism for tree and penguin contributions, was carried out. It was shown that, in one year of data taking, BTeV could achieve an accuracy on α better than 5°. The text was submitted by the authors in English     

First observation of spin flip in dμ-atoms via formation and back decay of ddμ molecules

We present the results of precision measurements of dμ spin-flip rates in pure D₂, in pure HD gas, and in the non-equilibrium and equilibrium H₂+D₂ gas mixtures. The experiments were performed at PSI in 1994-1996 using the high pressure ionization chamber from Gatchina as a 100% efficient detector of the charged fusion products. The measurements have been carried out in the temperature range 28-300 K, at gas density of 5% of LHD. In pure deuterium, the measured temperature dependence of the spin-flip rate allowed us to separate the two components (resonant and non-resonant) of the spin-flip processes. From the experiments in H/D mixtures we have measured the non-resonant spin-flip rate in collisions of dμ-atoms with HD molecules. Comparison with the theory revealed considerable disagreement in the case of non-resonant spin-flip in collisions of the dμ-atoms with D₂ molecules. This revised version was published online in August 2006 with corrections to the Cover Date.     

Stability islands in domains of separatrix crossings in slow-fast Hamiltonian systems

We consider a two-degrees-of-freedom Hamiltonian system with one degree of freedom corresponding to fast motion and the other corresponding to slow motion. The ratio of typical velocities of changes of the slow and fast variables is the small parameter ɛ of the problem. At frozen values of the slow variables, there is a separatrix on the phase plane of the fast variables, and there is a region in the phase space (the domain of separatrix crossings) where the projections of phase points onto the plane of the fast variables repeatedly cross the separatrix in the process of evolution of the slow variables. Under a certain symmetry condition, we prove the existence of many (of order 1/ɛ) stable periodic trajectories in the domain of separatrix crossings. Each of these trajectories is surrounded by a stability island whose measure is estimated from below by a value of order ɛ. So, the total measure of the stability islands is estimated from below by a value independent of ɛ. The proof is based on an analysis of asymptotic formulas for the corresponding Poincaré map.     

Hard X-ray compton polarimetry with the PENGUIN-M instrument in the spaceborne experiment CORONAS-PHOTON

We describe the main parameters of the PENGUIN-MD detector unit of the PENGUIN-M instrument designed to measure the degree of linear polarization of X-ray radiation from solar flares in the energy range 20–150 keV and the X-ray spectra of solar flares in the energy range 2–500 keV. The method for measuring the X-ray polarization employed in the PENGUIN-MD unit is based on registration of coincidences in an active scatterer and scattered-radiation detectors. This method makes it possible to substantially reduce the background and to increase the sensitivity and reliability of the measurements.     

Measurements of the ratio Rdp of the quasi-elastic nd \rightarrow p(nn) to the elastic np \rightarrow pn charge-exchange process yields at zero proton emission angle over the 0.55-2.0 GeV neutron beam energy region

New experimental results on the ratio R_dp of the quasi-elastic charge-exchange yield at the outgoing proton angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° for the nd $ \rightarrow$ p(nn) reaction to the elastic np $ \rightarrow$ pn charge-exchange yield are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8 and 2.0GeV. The intense neutron beam with small momentum spread was produced by break-up of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p _p approximately equal to the neutron beam momentum p _{n, beam} were detected in the directions close to the direction of incident neutrons, i.e. in the vicinity of the scattering angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° . Measured in the same data taking runs, the angular distributions of the charge-exchange reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident neutron beam direction. These corrected angular distributions for every of nd $ \rightarrow$ p(nn) and np $ \rightarrow$ pn charge-exchange processes were proportional to the differential cross-sections of the corresponding reactions. The data were accumulated by the Delta-Sigma set-up magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The new R_dp data are compared with the existing ones, which were obtained below 1GeV, and with the calculations which were made using the phenomenological NN amplitude sets.     

Nano-structured magnetic photonic crystals for magneto-optic polarization controllers at the communication-band wavelengths

We investigate the properties of optimized 1-D magnetic photonic crystal structures using doped iron garnet layers as magnetic constituents, for use in integrated-optics polarization controllers. We engineer the enhancement of Faraday rotation near 1,550 nm and describe a novel hysteresis-based driving scheme suitable for implementing ultra-fast polarization controllers.     

Experimental studies of very cold neutrons passing through solid deuterium

The studies of spectral dependences for neutrons passing through solid deuterium were carried out using a vertical beam of very cold neutrons with the wavelength λ～40–150 Å. The results show the dependence of the observed neutron scattering cross sections on the method of preparation of a solid deuterium sample and on the ortho-para composition of deuterium.     

Tailoring steep density profile with unstable points

The mesoscopic properties of a plasma in a cylindrical magnetic field are investigated from the view point of test-particle dynamics. When the system has enough time and spatial symmetries, a Hamiltonian of a test particle is completely integrable and can be reduced to a single degree of freedom Hamiltonian for each initial state. The reduced Hamiltonian sometimes has unstable fixed points (saddle points) and associated separatrices. To choose among available dynamically compatible equilibrium states of the one particle density function of these systems we use a maximum entropy principle and discuss how the unstable fixed points affect the density profile or a local pressure gradient, and are able to create a steep profile that improves plasma confinement.