[en] Acceleration of polarized proton beams and experiments with them at RHIC require fast and reliable measurements of the polarization. The polarimeter presented here uses very high figure of merit of the elastic pC scattering at very low momenta transfer since the cross section is large. Small (a few percent) analysing power of the reaction makes it necessary to collect about 10⁷ events per measurement. A dead-timeless DAQ system for the polarimeter is discussed in this paper. It is based on the waveform digitizer modules with 'on-board' event analysis, resulting in typical polarization measurement times of several tens of seconds. During winter 2001/2002 RHIC polarized run several dedicated data runs were taken by the polarimeter to extract the form of the analyzing power dependence as a function of the momentum transferred at beam energies 24 and 100 GeV. This dependence is extremely important for the theoretical understanding of the CNI process including the contribution of the spin-flip hadronic amplitude. The new data may become an input to some theoretical models predicting the energy dependence of the analyzing power. (author)

[en] The paper presents the experimental results on measurements of carbon analyzing power for polarized protons at momenta 1.36, 1.60, 1.78, 2.02 GeV/c and the carbon thickness 4.9, 19.4, 36.5 g/cm². The data shows that the analyzing power does not depend on the thickness in the interval 19-36 g/cm². The results of this experiment for carbon thickness 19.4 and 36.5 g/cm² together with the Saclay data were used for parametrization over the momentum and the scattering angle. Proton polarization in the quasielastic scattering on carbon at 10.5 deg. was also measured. The experiment was completed at the ITEP accelerator. (author)

[en] The authors report results of systematic measurements of the asymmetry of elastic π^-p scattering into the backward hemisphere at 1.4-2.1 GeV/c and also of a test of the isospin invariance of the existing set of experimental data on πp scattering in the investigated interval of momenta. At 1.98 and 2.07 GeV/c the isodoublet scattering amplitudes are established. The data obtained, the results of the isospin analysis, and the reconstruction of the amplitudes are compared with the predictions of current phase-shift analyses

[en] We present the results of an experimental study of the reaction of dipion production by a beam of negative pions with momentum 17.78 GeV/c on polarized proton and liquid hydrogen targets. The experiment covers the region of dipion masses near the mass of the ρ-meson and small transferred momenta vertical bar t vertical bar < 0.2 (GeV/c)². The complete set of spin density matrix elements was reconstructed and model-independent and model-dependent amplitude analyses of the reaction were performed. The experiment allows us to exclude the ambiguity of the amplitude analysis existing at high energies. The results contain evidence in favour of the existence of a σ(750) 00⁺⁺. The data also allows us to estimate the intercept of the a₁-meson Regge trajectory. The experiment was performed at the ITEP proton synchrotron, Moscow

[en] The analyzing power of carbon for polarized protons has been experimentally studied for momenta of 1.36, 1.60, 1.78, and 2.02 GeV/c at scatterer thicknesses of 4.9, 19.4, and 36.5 g/cm2. This analyzing power has been shown to be independent of the carbon thickness in the range 19-36 g/cm2. The results for carbon thicknesses of 19.4 and 36.5 g/cm2, combined with those of Saclay experiments, have been used to fit data obtained for various momenta and scattering angles. The polarization of protons in quasielastic scattering on carbon at an angle of 10.5 deg. has been measured. The experiments have been performed at the accelerator installed at the Institute of Theoretical and Experimental Physics (ITEP, Moscow, Russia)

[en] Results of systematic measurements of the asymmetry parameter in the elastic scattering of pions on polarized protons at 1.4-2.1 GeV/c in the backward hemisphere are presented together with a test of the isospin invariance of the data set available on pion-proton scattering in the investigated momentum range. The transversity isodoublet amplitudes at 1.98 and 2.07 GeV/c are reconstructed. The obtained data, the isospin analysis and amplitude reconstruction results are compared with the current phase-shift analysis predictions. (orig.)

[en] Dipion production by a beam of 1.78-GeV/ c negative pions on polarized-proton and liquid-hydrogen targets has been studied experimentally. The experimental searches covering the region of low momentum transfers have been performed for dipion-mass values close to the ρ-meson mass. The complete set of the spin-density-matrix elements has been found, and model-independent and model-dependent amplitude analyses of the reaction have been carried out. The experiment makes it possible to remove the high-energy ambiguity in the solution obtained from amplitude analyses. The data from this experiment support the existence of σ(750)00⁺⁺with mass M_σ=744±5MeV and width Γ_σ=77±22MeV and make it possible to estimate the intercept of the a₁-meson trajectory. The experiment has been performed at the accelerator installed at ITEP (Moscow)

[en] Recent measurements of spin-rotation parameters in elastic π⁺p scattering are in marked disagreement with predictions of the Carnegie-Mellon-Berkeley and Karlsruhe-Helsinki analyses. Using the method of Barrelet, we show how this discrepancy can be removed. We then show how this Barrelet transformation alters the partial-wave amplitudes. The effect of unitarity and analyticity constraints is also considered. copyright 1997 The American Physical Society

[en] For ¹²C ⁹Be interactions at a kinetic beam energy of 3.2 GeV per nucleon, the spectra of photons at laboratory angles in the range 55^o-73^o were measured off the kinematical region available to the interaction of single nucleons within colliding nuclei. The use of a fast trigger for selecting events involving the production of high-transverse-momentum photons made it possible to measure spectra off the kinematical boundary of four-nucleon interaction. It is shown that the proposed procedure is adequate to the problem of searches for and investigation of flucton-flucton interaction. In the kinematical region where flucton-flucton interaction can manifest itself, the cross sections in question are on the same order of magnitude as respective model predictions. In order to draw definitive conclusions on the role of flucton-flucton interaction, it is highly desirable to extend the angular range of the measurements toward smaller angles.

[en] Acceleration of polarized proton beams and experiments with them at RHIC require fast and reliable measurements of the polarization. The polarimeter presented here uses very high figure of merit of the elastic pC scattering at very low momenta transfer since the cross section is large. Small (a few percent) analyzing power of the reaction makes it necessary to collect about 10⁷ events per measurement. A deadtimeless DAQ system for the polarimeter is discussed in this paper. It is based on the waveform digitizer modules with ''on-board''' event analysis, resulting in typical polarization measurement times of several tens of seconds. During winter 2001/2002 RHIC polarized run several dedicated data runs were taken by the polarimeter to extract the form of the analyzing power dependence as a function of the momentum transferred at beam energies 24 and 100 GeV. This dependence is extremely important for the theoretical understanding of the CNI process including the contribution of the spin-flip hadronic amplitude. The new data may become an input to some theoretical models predicting the energy dependence of the analyzing power