[en] An extensive project of measuring spin-dependent quantities in the elastic scattering of neutrons on protons and of measuring the spin dependence of production of pions in inelastic neutron-proton interactions within the neutron kinetic energy region of 230 to 590 MeV is being implemented by using a high-intensity beam of polarized neutrons, which was obtained by a charge exchange reaction of longitudinally polarized 590 MeV protons, ¹²C(p,n)X, under an angle of 0 deg. The experiments use non-polarized targets of CH₂, C, and LH₂, and a polarized proton target based on the ³He-⁴He refrigerator. The spectrometric instrumentation makes it possible to measure quantities which depend on the spin of one, two, and three particles in np interactions within the scattering angle range from 60 deg to 180 deg in a centre-of-gravity system. Following the first stage of study of inelastic interactions, a spectrometric system was set up for the detection of the np → ppp^- process. The experiments dealing with elastic np scattering provided over 1300 values of 17 spin-dependent quantities. The results will enable the matrix parameters of elastic NN scattering to be determined in a model-independent way

[en] In experiments on the measurement of values of spin observables in elastic neutron-proton (np) interaction in the neutron energy range 230–590 MeV using polarized neutron beams and polarized proton targets at the Paul Scherrer Institute (PSI), 16 spin observables have been investigated: analyzing power A_00n0; polarization of recoil particles P_0n00; polarization correlation coefficients A_00nn, A_00ss, A_00sk, A_00kk; polarization transfer coefficients K_0nn0, K_0ss0, K_0sk0; depolarization coefficients D_0n0n, D_0s0s, D_0s0k; and three-index spin coefficients N_0nkk, N_0skn, N_0ssn, N_0sns for scattering angles in the center of mass system of 60°–164°. Results: of these investigations present a complete set of precision data on elastic np scattering, which together with the complete set of data for elastic proton-proton (pp) scattering obtained earlier makes the basis for unambiguous determination of the amplitudes of the elastic nucleon-nucleon (NN) scattering matrix for the channel with the isotopic spin I = 0 and provides a possibility of description of the process of NN interaction in a model-independent way.

[en] Short communication. 1 fig

[en] Short communication. 2 refs., 3 figs

[en] Directional distribution of gamma rays following the decay of ¹⁵²Tb oriented in a gadolinium host at low temperature has been studied. The gamma-ray anisotropies of transitions in ¹⁵²Gd were measured and multipole mixing ratios δ(E2/M1) were determined. Part of our results is presented here and attention is paid to investigation of the EO multipolarity admixtures which were observed in many ΔI = 0 transitions of ¹⁵²Gd. Among them the E2/M1 mixing ratios for 2 → 2 and 4 → 4 transitions from the β-vibrational (K^π - 0⁺) and γ-vibrational (K^π - 2⁺) bands to the ground-state band were observed, and the E0/E2 probability ratios, X(E0/E2), were determined. (author)

[en] Based on the state of the art of technological achievements, new complementary nuclear orientation facilities - the SPIN facilities - will be developed and constructed at the Joint Institute for Nuclear Research (JINR) in Dubna and at the Faculty of Mathematics and Physics of Charles University in Prague. These facilities together with the existing and planned JINR radioactive beam complexes YASNAPP and DRIBs will open new horizons for many new experiments with oriented nuclei in a broad range of atomic and mass numbers and nuclear half-lives. This will enable to accomplish a rich program in nuclear and solid state physics research - the SPIN program at JINR. (author)

[en] First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized ⁶LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors

[en] Gamma ray induced transparency changes of different scintillating and light guide fibres were measured on-line in static and dynamic bremsstrahlung gamma radiation fields produced when irradiating W target by 21 MeV electron beam from a microtron accelerator. Dose rate used was 140 Gy/min for about 30 minutes. Transmission spectra were measured on-line in time intervals 30-60 s for both the excitation and the recovery processes. The results confirmed that different types of fibers studied have different radiation hardness. (author)

[en] The reaction np→ppπ^- has been studied in a kinematically complete measurement with a large acceptance time-of-flight spectrometer for incident neutron energies between threshold and 570 MeV. The proton-proton invariant mass distributions show a strong enhancement due to the pp(¹S₀) final state interaction. A large anisotropy was found in the pion angular distributions in contrast to the reaction pp→ppπ⁰. At small energies, a large forward/backward asymmetry has been observed. From the measured integrated cross section σ(np→ppπ^-), the isoscalar cross section σ₀₁ has been extracted. Its energy dependence indicates that mainly partial waves with Sp final states contribute. (orig.)

[en] The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π^-π^-π⁺ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420 000 events taken at values of the squared 4-momentum transfer t^' between 0.1 and 1 GeV²/c². The well-known resonances a₁(1260), a₂(1320), and π₂(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J^PC=1^-+ at 1.66 GeV/c² decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J^PC=2^-+ and 1⁺⁺ waves. From a mass-dependent fit a resonance mass of (1660±10_-64⁺⁰) MeV/c² and a width of (269±21_-64⁺⁴²) MeV/c² are deduced, with an intensity of (1.7±0.2)% of the total intensity.