E. A. Filimonov

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.

Backward asymmetry measurements in the elastic pion-proton scattering at resonance energies

The asymmetry parameter P was measured for the elastic pion-proton scattering in the very backward angular region of

EPECUR setup for the search for narrow baryon resonances in pion-proton scattering

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Study of π−p charge exchange scattering for forward angles

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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

150 - 170° at several pion beam energies in the invariant-mass range containing most of the pion-proton resonances. The general goal of the experimental program was to provide new data for partial wave analyses in order to resolve their uncertainties in the baryon resonance region to allow the unambiguous baryon spectrum reconstructions. Until recently the parameter P was not measured in the examined domain that might be explained by the extremely low cross-section. At the same time the predictions of various partial wave analyses are far from agreement in some kinematic areas and specifically those areas were chosen for the measurements where the disagreement is most pronouncing. The experiment was performed at the ITEP U-10 proton synchrotron, Moscow, by the ITEP-PNPI Collaboration in the latest 5 years.

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

The EPECUR experimental setup has been designed to search for narrow resonant states by precisely measuring differential and total reaction cross sections for pion-nucleon interactions with 1-MeV pion energy steps. Over the 5 years that passed from the submission of the idea of the experiment to the start of data taking in April 2009, a non-magnetic spectrometer with a liquid hydrogen target based on the large-aperture multiwire drift chambers with a hexagonal structure has been built at the universal beamline 322 of the U-10 proton synchrotron at the Alikhanov Institute for Theoretical and Experimental Physics. Owing to the unique properties of the beamline, the beam particle momentum can be measured with an accuracy of 0.1% or better using 1-mm-pitch proportional chambers located at the first focus of the beamline. The design of numerous subsystems of the setup is based on modern electronic components including microprocessors and field programmable gate arrays. All the subsystems have been tuned and tested both individually and as parts of the whole setup. The distributed data acquisition system is based on the widely spread USB and Ethernet protocols, which help achieve high performance characteristics and take full advantage of the industrial solutions.

Measurement of the Polarization Parameter P in π-p Elastic Scattering in the Energy Range 450–600 MeV

Differential cross sections for the reaction π−p → π0n were measured for nearly forward scattering angles. The experiment was performed at the pion channel of the synchrocyclotron installed at the Petersburg Nuclear Physics Institute (PNPI, Gatchina), the incident-pion momenta ranging between 417 and 710 MeV/c. The measurements, which involved recording both photons from the decay process π0 → 2γ, employed the neutral-pion spectrometer developed at the PNPI. A description of the experimental facility is given, and the results of the measurements are presented.

Investigation of near-threshold eta-meson production in the reaction π − p→ ηn

Differential cross sections of reaction π−p→π°n are measured for forward scattering angles. The experiment is carried out at the pion channel of the PNPI synchrocyclotron in Gatchina at ten momenta of incident pions in the range from 417 to 710 MeV/c. Measurements were made using the PNPI π°‐spectrometer by detecting both photons from the decay π°→2γ. A brief description of the experimental setup is given, and results obtained are presented.

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