GAMMA P --> P PI0
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Backward photoproduction of neutral pions off hydrogen at photon energies between 0.4 and 2.2 gev

Becks, H. ; Feller, P. ; Menze, D. ; et al.
Nucl.Phys.B 60 (1973) 267-276, 1973.
Inspire Record 83927 DOI 10.17182/hepdata.6749

The differential cross section has been measured for the reaction γ +p→p+ π o at the Bonn 2.5 GeV electron synchrotron in the energy range from 0.4 to 2.2 GeV for a c.m. angle of 150 degrees. The protons were detected in a magnetic spectrometer system. The excitation curve shows a distinct resonance structure. The total corrections to the counting rate are about 3%. The contribution of the process γ +p→p+2 π was separated. The uncertainty of this separation leads to an error of about 4% in the cross section.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


MEASUREMENT OF ASYMMETRY IN CROSS-SECTION OF GAMMA P ---> P PI0 REACTION IN THE RESONANCE REGION. (IN RUSSIAN)

Avakian, R.O. ; Avetisian, A.E. ; Bagdasaryan, A.S. ; et al.
Yad.Fiz. 38 (1983) 1196-1198, 1983.
Inspire Record 200187 DOI 10.17182/hepdata.17731

None

1 data table
Table 1

Axis error includes +- 0.0/0.0 contribution (?////DUE TO ERRORS IN PHOTON POLARIZATION).


MEASUREMENT OF POLARIZATION OF PROTONS FROM REACTION GAMMA P ---> P PI0 IN THE THIRD RESONANCE. (IN RUSSIAN)

Bratashevsky, A.S. ; Zybalov, A.A. ; Karasev, S.P. ; et al.
Yad.Fiz. 41 (1985) 1515-1519, 1985.
Inspire Record 227501 DOI 10.17182/hepdata.17615

None

2 data tables
Table 1

No description provided.

Table 2

No description provided.


MEASUREMENT OF POLARIZATION OF PROTONS FROM THE REACTION GAMMA P ---> P PI0 AT THETA (PI) = 110-DEGREES C.M. IN THE RANGE OF THE SECOND AND THIRD RESONANCES. (IN RUSSIAN)

Bratashevsky, A.S. ; Zybalov, A.A. ; Karasev, S.P. ; et al.
Yad.Fiz. 42 (1985) 658-663, 1985.
Inspire Record 221959 DOI 10.17182/hepdata.17612

None

1 data table
Table 1

No description provided.


MEASUREMENT OF POLARIZATION OF PROTONS IN THE REACTION GAMMA P ---> P PI0 IN A PHOTON LINEARLY POLARIZED BEAM. (IN RUSSIAN)

Avakian, R.O. ; Avakian, E.O. ; Avetisian, A.E. ; et al.
Yad.Fiz. 36 (1982) 393-399, 1982.
Inspire Record 183654 DOI 10.17182/hepdata.17730

None

1 data table
Table 1

Axis error includes +- 0.0/0.0 contribution (?////ERROR IN POLARIZATION OF INITIAL GAMMAS IS NOT GIVEN).


MEASUREMENT OF POLARIZATION OF RECOIL PROTONS IN PI0 PHOTOPRODUCTION FOR THETA* (PI0) = 60-degrees IN RESONANCE REGION. (IN RUSSIAN)

Avakian, R.O. ; Avakian, E.O. ; Avetisian, A.E. ; et al.
Sov.J.Nucl.Phys. 37 (1983) 199-201, 1983.
Inspire Record 183972 DOI 10.17182/hepdata.17739

None

1 data table
Table 1

Axis error includes +- 0.0/0.0 contribution (?////NO DISCUSSION OF ERRORS AT ALL).


MEASUREMENT OF THE ASYMMETRY OF THE REACTION gamma p ---> p pi0 CROSS-SECTION FOR PION PRODUCTION ANGLES IN CMS 65-degrees TO 80-degrees IN THE RESONANCE ENERGY RANGE

Avakian, R.O. ; Bagdasaryan, A.S. ; Vartapetian, G.A. ; et al.
Sov. J. Contemp. Phys. 19 ( 1984) No. 1 46-48. ( Izv. Akad. Nauk Arm. SSR 19 ( 1984) No. 1 50-53) and Erevan Phys. Inst. - EFI-674(64)-83 (83,REC.JAN.84) 13p, 1983.
Inspire Record 195991 DOI 10.17182/hepdata.18465

None

3 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.


Measurement of polarization observables $\textbf{T}$, ${\textbf{P}}$, and ${\textbf{H}}$ in $\mathbf {\pi ^0}$ and $\mathbf {\eta }$ photoproduction off quasi-free nucleons

The CBELSA/TAPS collaboration Jermann, N. ; Krusche, B. ; Metag, V. ; et al.
Eur.Phys.J.A 59 (2023) 232, 2023.
Inspire Record 2712592 DOI 10.17182/hepdata.145075

The target asymmetry T, recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive $\pi ^0$ and $\eta $ photoproduction off quasi-free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the $\gamma p \rightarrow \pi ^0 p$ and $\gamma p \rightarrow \eta p$ reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the $\eta n$ system at $W = 1.68\ \textrm{GeV}$. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the $S_{11}(1535)$ and $S_{11}(1650)$ resonances within the $S_{11}$-partial wave.

4 data tables
Figure 4 (a)

Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma p \to \pi^0 p$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.

Figure 4 (b)

Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma n \to \pi^0 n$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.

Figure 5 (a)

Target asymmetry T, recoil asymmetry P, and polarization observable H for $\gamma p \to \eta p$ as a function of the polar center-of-mass angle for bins at the given centroid c.m. energies.

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Measurement of the Helicity Asymmetry $E$ for the reaction $ \gamma p\to \pi^0 p$

The CBELSA/TAPS collaboration Gottschall, M. ; Afzal, F. ; Anisovich, A.V. ; et al.
Eur.Phys.J.A 57 (2021) 40, 2021.
Inspire Record 1731795 DOI 10.17182/hepdata.100433

A measurement of the double-polarization observable $E$ for the reaction $\gamma p\to \pi^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C$_4$H$_9$OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $E_\gamma =600$~MeV to $E_\gamma =2310$~MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

1 data table
Figure 11

Double-polarization observable E for different beam energies from 600 to 2310 MeV


Measurement of the cross section asymmetry of the reaction gamma p --> pi0 p in the resonance energy region E(gamma) = 0.5-GeV - 1.1-GeV.

Adamian, F.V. ; Bunyatyan, A.Yu. ; Frangulian, G.S. ; et al.
Phys.Rev.C 63 (2001) 054606, 2001.
Inspire Record 536542 DOI 10.17182/hepdata.31424

The cross section asymmetry Sigma has been measured for the photoproduction of pi0-mesons off protons, using polarized photons in the energy range Eg = 0.5 - 1.1 GeV. The CM angular coverage is Theta = 85 - 125 deg with energy and angle steps of 25 MeV and 5 deg, respectively. The obtained Sigma data, which cover the second and third resonance regions, are compared with existing experimental data and recent phenomenological analyses. The influence of these measurements on such analyses is also considered.

9 data tables
Table 1

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

Table 2

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

Table 3

Axis error includes +- 3/3 contribution (Due to accuracy of the linear polarization calculations).

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