Large-angle cross sections for γd→π0d are systematically measured in the photon energy range between 500 and 1000 MeV. A good fit is obtained by use of a Glauber-model calculation which includes the dibaryon resonances F33(2.26) and G41(2.51), but the fit has an unusual nature in the role of resonance and nonresonance contributions.
Liquid hydrogen target for final calibration.
The π − p→n γ and π − p→n π ° differential cross sections have been measured for −0.9< cos θ ∗ <−0.45 (θ ∗ c.m. scattering angle) at 475 MeV/ c and 550 MeV/ c incident momenta. The π − p→n γ measurement is a good check of the detailed balance principle in the electromagnetic interactions of hadrons at these energies and is in good agreement with Walker's analysis. On the other hand the π − p→ π °n extrapolated values of 180° allows one to verify that the phases of the A 1 2 and A 3 2 amplitudes are equal.
No description provided.
No description provided.
BACKWARD CROSS SECTION ESTIMATED BY LEGENDRE POLYNOMIAL FIT.
The reaction gamma p --> K0 Sigma+ was measured in the photon energy range from threshold up to 2.6 GeV with the SAPHIR detector at the electron stretcher facility, ELSA, in Bonn. Results are presented on the reaction cross section and the polarization of the Sigma+ as a function of the kaon production angle in the centre-of-mass system, cos(Theta_K^{c.m.}), and the photon energy. The cross section is lower and varies less with photon energy and kaon production angle than that of gamma p --> K+ Sigma0. The Sigma+ is polarized predominantly at cos(Theta_K^{c.m.}) \approx 0. The data presented here are more precise than previous ones obtained with SAPHIR and extend the photon energy range to higher values. They are compared to isobar model calculations.
Polarization parameter of the SIGMA+ as a function of angle in two photon energy ranges.
The ep -> e'pi^+n reaction was studied in the first and second nucleon resonance regions in the 0.25 GeV^2 < Q^2 < 0.65 GeV^2 range using the CLAS detector at Thomas Jefferson National Accelerator Facility. For the first time the absolute cross sections were measured covering nearly the full angular range in the hadronic center-of-mass frame. The structure functions sigma_TL, sigma_TT and the linear combination sigma_T+epsilon*sigma_L were extracted by fitting the phi-dependence of the measured cross sections, and were compared to the MAID and Sato-Lee models.
Structure functions for Q**2 = 0.30 GeV**2 and W = 1.31 GeV.
Structure functions for Q**2 = 0.30 GeV**2 and W = 1.33 GeV.
Structure functions for Q**2 = 0.30 GeV**2 and W = 1.35 GeV.
The electroproduction of π0-mesons on protons has been measured with electrons of 1.7 and 2.1 GeV energy in the region of the nucleon resonances at\(W = \sqrt {(q + p)^2 }= 1,400 - 2,000MeV\) at rather low values of |q2|=|(e−e′)2|=0.01–0.1 GeV2 but at high values of the nucleon recoil |t|=|(p−p′)2|≈0.6–2.2 GeV2 corresponding to\(\Theta _\pi ^{cm}\approx 145^ \circ- 180^ \circ\). Up toW≈1,650 MeV the cross section for π0-production with virtual photons of |q2|≈0.03 GeV2 is only slightly smaller than that with real photons. ForW≳1,700 MeV the cross section at |q2|≈0.03 GeV2 is on average a factor of 2 smaller than that atq2=0 but only slightly higher than that at |q2|≈0.3–1 GeV2.
INCLUDING RADIATIVE CORRECTIONS.
The process $ep \to e^{\prime}p^{\prime}\pi^0$ has been measured at $Q^2$ = 6.4 and 7.7 \ufourmomts in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center of mass frame considering the process $\gamma^{\ast}p \to p^{\prime}\pi^0$. Various details relating to the background subtractions, radiative corrections and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well known $\Delta(1232)$ resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios $R_{EM}$ and $R_{SM}$ along with the magnetic transition form factor $G_M^{\ast}$. It is found that the rapid fall off of the $\Delta(1232)$ contribution continues into this region of momentum transfer and that other resonances
Differential cross sections at Q**2=6.212 GeV**2, EPSILON=0.4411, W=1.312 GeV and COS(THETA(*))=-0.9 for the small SOS spectrometer.
Differential cross sections at Q**2=6.212 GeV**2, EPSILON=0.4411, W=1.312 GeV and COS(THETA(*))=-0.7 for the small SOS spectrometer.
Differential cross sections at Q**2=6.212 GeV**2, EPSILON=0.4411, W=1.312 GeV and COS(THETA(*))=-0.5 for the small SOS spectrometer.
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