π--meson photoproduction on neutrons by polarized photons in the 0.9-1.65 GeV energy range

The asymmetry of the cross section of the π--meson photoproduction on neutron in the energy range Esub(γ)=0.9-1.65 GeV and of π--meson escape angles THETAsub(π)sup(*)--30 deg-60 deg in the center-of-mass system has been measured. The experiment was carried out on a beam of linearly-polarized photons. Linearly polarized photons were generated in a single crystal diamond target at an electron energy of 4.6 GeV. π+--meson detection was realized by means of a magnetic spectrometer. For detecting recoil protons and neutrons a time-of-flight spectrometer with 12 block scintillation counters was employed. The experimental set up was operating on-line with a computer complex. A typical spectrum of polarized photons and the calculated curve of polarization, a table of calculated and measured asymmetries and graphs of energy and angular dependences of asymmetry of the π-production cross section are presented. The results of measurements are compared with the predictions of phenomenological analyses and of the quark model. A conclusion has been drawn that in the π-meson photoproduction on nucleons at Esub(γ) approximately 1.5 GeV alongside with F37 (1950) resonance other resonances with isospin I=3/2 (for instance, F35 (1890), P31 (1950), D35 (2000)) also take part