On the possibility of measuring the temperature by the luminescence of a probe with intramolecular proton transfer

The temperature dependences of the fluorescence characteristics of three forms (normal, tautomeric, and anionic) of 3-hydroxyflavone in methanol upon selective excitation in different UV ranges are studied. The fluorescence of all the forms undergoes temperature quenching, whose efficiency depends on the excitation energy. It is found that the intensity ratio of the fluorescence of different forms also varies with temperature; the excitation regions in which these variations are most pronounced are determined. The highest temperature sensitivity is observed for the luminescence intensity ratio of the normal and tautomeric forms upon excitation in the region of 280 nm, this ratio continuously increasing from 0.5 to 1.0 in the temperature range of 20–70°C. The dependence found allows one to measure the temperature of the solution in some temperature regions with an error of ～1 ± 0.5% with the help of a standard Hitachi F-2500 spectrofluorimeter.     

On double polarization asymmetries in the elastic electron-proton scattering

Double polarization asymmetry D_p^(M) for the process of elastic electroweak scattering of the longitudinally polarized electrons by polarized proton target is considered with account of anapole G_1p and electric dipole moment (EDM) G_2p proton form factors. This asymmetry is only due to T-parity violating form factor G_2p, but does not directly depend on it, and having a significant value, allows to confirm the existence of the EDM of the proton.     

Measurement of the polarization correlation parameter C nn in the pp elastic scattering with an unpolarized proton target and an unpolarized 1-GeV proton beam

The polarization correlation parameter C _nn in the elastic proton-proton scattering was for the first time measured with a high statistical accuracy at 1 GeV using an unpolarized proton beam incident on an unpolarized proton target. Both outgoing protons from the reaction were detected in coincidence by means of a two-arm focusing magnetic spectrometer installed at nonsymmetric angles corresponding to the center-of-mass scattering angle Θ_cm = 62.25°. The correlation parameter C _nn , as well as polarizations P ₁ and P ₂ of the secondary protons, were measured by means of multiwire proportional chamber polarimeters placed at the focal planes of each spectrometer arm. The obtained data are compared with the predictions of the phase-shift analysis. The connection with the experiment on C _nn and polarization measurements in the (p, 2p) reaction on ⁴He and other light nuclei in similar kinematics is discussed     

Neutron scattering by inhomogenous distribution of proton polarization produced by the dynamic nuclear polarization

The coherent neutron scattering from polarized proton clusters was observed. Clusters of polarized protons were formed in dicychrohexyl 18-crown-6 (C₂₀H₃₆D₆) molecules. The proton polarization in the molecule was produced by the dynamic nuclear polarization (DNP). The proton polarization distribution in the DNP process was also measured in propanediol. In the stationary state, no inhomogenous distribution was found.     

On the problem of measuring the degree of polarization of synchrotron radiation

The possibility for determining the degree of polarization of synchrotron radiation by measuring linear dichroism in stepwise ionization of an autoionization state of an atom with a known total momentum is considered.     

Measuring the transverse polarization of quarks in the proton

The transverse spin polarization distribution of quarks in a proton contributes at leading twist to the angular distribution of lepton pair production in doubly polarized proton-proton collisions. Although this distribution is straightforward to define in the QCD-improved parton model and represents a fundamental quark degree of freedom, it has never been measured. Moreover, deeply inelastic electroproduction experiments are only sensitive to this distribution at the higher twist level, and then mix this contribution with others, including the one coming from multiparton initial states. Reviewing this, we conclude that the Drell-Yan process is the best way to measure the quark transverse spin polarization distribution.Unité propre du CNRS     

Definitions of the degree of polarization of a light beam

A necessary and sufficient condition is derived for certain ad hoc expressions that are frequently used in the literature to represent correctly the degree of polarization of a light beam.     

On the possibility of measuring the mass of the neutrino with a low energy electron beam

The neutrino mass sensitivity of the cross section just above threshold in the reaction \(_Z^A X(\bar e,v_e )_{Z - 1}^A X\) is investigated. By general arguments we find the ₃₄ ⁷⁷ Se and ₅₁ ¹²¹ Sb as the most appropriate candidates for and eventual experiment.     

Flavour separation by means of transverse beam polarization in high-energy e+e- annihilation

Transverse beam polarization is in e⁺e^- annihilation at high energies shown to lead to a strong azimuthal variation in the flavour composition of the produced quark-antiquark pairs. We describe, in the SU(2) × U(1) model, a way in which this could be used to obtain flavour-specific information on the quark fragmentation functions. In inclusive charged particle rates the effect might be much reduced, but still observable.     

A system for measuring a low-intensity proton beam

A system for measuring proton beam intensity and energy for the medical channel of the Institute for Nuclear Research, Russian Academy of Sciences, at energies of 70–280 MeV and an average current of about 1 nA is presented. The reaction of elastic scattering of primary beam protons on the polyethylene target is used in the system to determine the intensity and energy of a therapeutic proton beam with accuracies of 1% and 1 MeV, respectively.     

Acoustic scattering of a high-order Bessel beam by an elastic sphere

The exact analytical solution for the scattering of a generalized (or “hollow”) acoustic Bessel beam in water by an elastic sphere centered on the beam is presented. The far-field acoustic scattering field is expressed as a partial wave series involving the scattering angle relative to the beam axis and the half-conical angle of the wave vector components of the generalized Bessel beam. The sphere is assumed to have isotropic elastic material properties so that the nth partial wave amplitude for plane wave scattering is proportional to a known partial-wave coefficient. The transverse acoustic scattering field is investigated versus the dimensionless parameter ka(k is the wave vector, a radius of the sphere) as well as the polar angle θ for a specific dimensionless frequency and half-cone angle β. For higher-order generalized beams, the acoustic scattering vanishes in the backward (θ = π) and forward (θ = 0) directions along the beam axis. Moreover it is possible to suppress the excitation of certain resonances of an elastic sphere by appropriate selection of the generalized Bessel beam parameters.     

Quantum measurement of the degree of polarization of a light beam

We demonstrate a coherent quantum measurement for the determination of the degree of polarization (DOP). This method allows us to measure the DOP in the presence of fast polarization state fluctuations, difficult to achieve with the typically used polarimetric technique. A good precision of the DOP measurements is obtained using eight type II nonlinear crystals assembled for spatial walk-off compensation.     

Computation and analysis of the Bessel beam scattering by a submerged elastic sphere

Taking an elastic sphere for example,the acoustic scattering of a submerged object illuminated by a Bessel beam is studied.The partial wave series representation for an elastic sphere has been extended to the case of Bessel beam scattering.Referring to the scattering of a plane wave,the peak to peak intervals in backscattering form function caused by the interference of the specular wave and the Franz wave have been analyzed in geometry.The influence of the characteristic parameterβof a Bessel beam on the peak to peak intervals has been indicated,and a predictive formula of the peak to peak intervals has been established for the first time.Meanwhile the elastic scattering of each partial wave has been separated based on the Resonance Scattering Theory.The influence ofβon the pure elastic resonance has been studied further.The results show that selecting specificβcan reduce the contribution of a certain partial wave.Therefore the resonance at the corresponding frequency and the nearby region in the backscattering is remarkably suppressed.The work of this paper could be helpful to the applications of Bessel beams on the acoustic detection of submerged objects.     

Vacuum polarization effects in elastic scattering of protons by nuclei

Sensitivity of spin observables in elastic proton scattering by nuclei to the vacuum polarization correction δϱ_VAC is explored. The Dirac optical potential is calculated from a complete set of Lorentz invariant amplitudes, Dirac-Hartree densities and the existing estimate of δϱ_VAC based on quantum hadrodynamics.     

Coulomb effects in polarization transfer in elastic antiproton and proton electron scattering at low energies

The influence of Coulomb distortion on the polarization transfer in elastic proton and antiproton electron scattering at low energies is calculated in a distorted-wave Born approximation. For antiproton electron scattering Coulomb effects reduce substantially the polarization transfer cross-section compared to the plane-wave Born approximation, whereas for proton electron scattering they lead to a dramatic increase for kinetic proton lab energies below about 20keV.     

Polarized deuteron elastic scattering from a polarized proton target

Measurements are reported of the spin correlation parameter C_y,y for the elastic scattering of 10.0 MeV vector polarized deuterons from a polarized proton target at five CM angles (76°, 85°, 98°, 115°, 132°). The experimental results are compared with different predictions. A Faddeev type calculation on the basis of local potentials also including approximate Coulomb distortion is favoured by our experimental results.     

Phase shift analysis of elastic proton scattering by12C

Angular distributions of the polarization and cross section in¹²C (p,p)¹²C were measured at 24 energies between 9.95 and 10.90 MeV. A phase shift analysis of the data was carried out. The results show four resonances in¹³N atE _x =11.40, 11.64, 11.67 and 11.82 MeV with spins 5/2⁺, 5/2^?, 3/2^? and 3/2⁺.     

Proton-electron elastic scattering and the proton charge radius

It is suggested that proton elastic scattering on atomic electrons allows a precise measurement of the proton charge radius. The main advantage is that inverse kinematics allows one to access with a huge cross section very small values of transferred momenta, up to four orders of magnitude smaller than the ones presently achieved.