Differential cross sections for single photoproduction of neutral pion on neutron have been measured at different c.m. angles for photon energies, between 450–800 MeV.
No description provided.
None
No description provided.
None
No description provided.
Cross sections for the photoproduction of neutral pions have been measured at the 1.1-GeV Frascati electron synchrotron for bombarding photon energies k between 400 and 800 MeV and for π0 c.m. angles of θπ*=90∘, 120∘, and 135∘. The main feature of the experiment is good resolution in incident photon energy. The results are in good agreement with the existing theories in the energy range of 450 to 550 MeV. The cross sections exhibit a smooth behavior as a function of energy for k=400−600 MeV. No immediate evidence is found of a contribution of the P11 resonance. An anomaly at the limit of statistical significance appears for k≃700−740 MeV, indicating a possible structure of the so-called second resonance. We attempt to interpret the observed anomaly as a reflection of the sharp opening of the η production channel (η cusp effect).
No description provided.
None
No description provided.
Pions from the reaction γ + p → π + + n were analysed in the backward direction by a magnetic spectrometer. The photon energy region of 0.394 GeV to 1.397 GeV was covered by 19 different momentum settings. Data reduction resulted in 74 measured differential cross sections with statistical uncertainties typically from 4% to 8%. The systematic uncertainty was estimated to be ±5%. The data are compared to other recent experiments and predictions of phenomenological analyses.
No description provided.
New results are presented on the differential cross-section for the reaction α+p→π0+p, at energies between 600 and 1000 MeV, and c.m. pion angles Θ*π=40° and Θ*π=60°. The present data, together with that at Θ*π=40° already published (11), show an angle-independent position of the second resonance at about 750 MeV. Rather flat angular distributions in the forward c.m. hemisphere are also favoured by these data. On comparing the cross-sections obtained when detecting both the neutral pion and the recoil proton, and when detecting only the latter, estimates of the background of «ghost protons» are obtained, in agreement with the empirical curve proposed in ref. (11).
No description provided.
The polarization of the recoil proton in the photoproduction process γ+p→p+π0 has been measured with the beam of the Frascati electrosynchrotron at an angle of 90° in the c.m. system, in the energy interval (500÷900) MeV. A counter technique has been used, and the polarization of the proton was revealed by the left to right asymmetry in the elastic scattering of the protons in a carbon target. The experimental results are given in Table III and in Fig. 10. A definite polarization is found, always of the same sign and equal to −0.4±.14, −0.63±.23, −0.6±.25, −0.57±.12, −0.38±.09, −0.5±.17, −0.5±.22 at the γ-ray energies of 560, 610, 650, 700, 750, 800, 850 MeV respectively. The discussion of these experimental results, together with the data of angular dstributions, allows to conclude that they are in agreement with the hypothesis that the second resonance is a transition (E 1,d 3/2) and the third one is a transition (E 2,f 3/2).
No description provided.
Forum