V. V. Abaev

Measurement of the spin rotation parameter A+ in the elastic scattering of positive pions on a longitudinally-polarized proton target in the second resonance region

Abstract The ITEP-PNPI collaboration presents the first results of the spin rotation parameter A+ measurements in the second resonance region. The experiment was performed at the ITEP accelerator at a positive pion beam momentum 1.43 GeV/c for scattering angles θcm = 127° and 133°. The setup was based on a polarized proton target and a carbon-plate polarimeter. The obtained data is compared with the predictions of the existing partial-wave analyses.

Measurement of the spin rotation parameters R and A in πp elastic scattering and a test of πN partial-wave analyses in the region of low-lying P11, S11 and D13 resonances

Abstract This paper presents the results of an experiment in which the spin rotation parameters R and Ain π − p elastic scattering have been measured at energies 450, 530, 560 and 600 MeV. The experiment was performed on a pion channel of the PNPI synchrocyclotron. The main parts of the setup were a polarized proton target with horizontal spin orientation and a carbon-plate polarimeter consisting of multigap optical spark chambers with television read-out. A comparison of the obtained results with partial-wave analyses is given.

Measurement of the polarization parameterP inπ+p elastic scattering in the region of low-lying pion-nucleon resonances

This paper presents the results of an experiment in which the polarization parameterP in π+p elastic scattering has been measured in the energy range from 335 to 580 MeV. The experiment was performed on a pion channel of the LNPI synchrocyclotron using a polarized proton target and wire spark chambers with magnetostrictive read-out. The results have substantially higher precision in comparison with the most of other experiments in this energy range and allow to determine unambiguously the shape of angular dependenceP(θ*) in the whole investigated region. New phase-shift analysis of π+p scattering data has been performed. The results of this experiment were used also to check isospin invariance.

Measurement of the spin rotation parameters R and A in π‐p‐elastic scattering in the region of pion‐nucleon resonances

First measurement of the spin rotation parameters R and A in {pi}-p elastic scattering in the region of pion-nucleon resonances has been performed at the Leningrad Nuclear Physics Institute. The experiment was carried out on a pion channel of the LNPI synchrocyclotron using a polarized target with LNPI synchrocyclotron using a polarized target with horizontally oriented polarization vector and a multi-plate carbon polarimeter consisting of optical spark chambers with television read-out. Results at the energies 450 and 560 MeV are given in comparison with the predictions of phase-shift analyses.

Measurement of the total cross section of the reaction K{sup -}p{yields}{sigma}{sup 0}{gamma} between 514 and 750 MeV/c

We report the first measurements of the total cross section of the reaction K{sup -}p{yields}{sigma}{sup 0}{gamma} at eight beam momenta from 514 to 750 MeV/c. The data were obtained at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory using the Crystal Ball detector consisting of 672 NaI crystals. All charged particles were vetoed by a barrel of plastic scintillators, resulting in a study of only the neutral decays of the {sigma}{sup 0}. The prompt photon and the photons from the decay products of {sigma}{sup 0} were detected for each reconstructed event; the neutron was also detected in a small fraction of the events.

Measurement of the K{sup -}p{yields}{sigma}{sup 0}{pi}{sup 0} reaction between 514 and 750 MeV/c

The reaction K{sup -}p{yields}{sigma}{sup 0}{pi}{sup 0}{yields} neutrals was studied with the Crystal Ball detector at the BNL Alternating Gradient Synchrotron for beam momenta between 514 and 750 MeV/c. The photons from {sigma}{sup 0} and {pi}{sup 0} decays were detected, as well as the neutron in a small fraction of the events. The differential cross section and the {sigma}{sup 0} polarization are reported at eight momenta and nearly the full angular range. Total cross sections are derived from Legendre polynomial fits to the data. The measurements presented are of considerably higher precision than previous results.The reaction K- p → Σ 0 π 0 → neutrals was studied with the Crystal Ball detector at the BNL Alternating Gradient Synchrotron for beam momenta between 514 and 750 MeV/c. The photons from Σ0 and π 0 decays were detected, as well as the neutron in a small fraction of the events. The differential cross section and the Σ 0 polarization are reported at eight momenta and nearly the full angular range. Total cross sections are derived from Legendre polynomial fits to the data. The measurements presented are of considerably higher precision than previous results.

Measurement of spin rotation parameter A+ in π +p elastic scattering

Abstract The ITEP-PNPI collaboration presents first results of the spin rotation parameter A+ measurements in the second resonance region. The experiment was performed on ITEP accelerator at positive pion beam momentum 1·43 GeV/c (√s= 1·90 GeV/c) for scattering angles 0cm = 127° and 133°. Main parts of the setup were a polarized proton target and a carbon-plate polarimeter. The results of measurements are in agreement with the predictions of the partial-wave analysis VPI and in contradiction with the predictions of PWAs KH and CMB.

Measurement of the Spin Rotation Parameters R and A in πp Elastic Scattering in the Energy Range from 450 to 600 MeV

Interest to the investigation of ℛP scattering in the resonance region has recently increased due to the development of various theoretical models predicting spectra of baryons. To make choice among these models one has to know baryon spectra with high precision.