Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ and $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV

The GlueX collaboration Al Ghoul, H. ; Anassontzis, E.G. ; Austregesilo, A. ; et al.
No Journal Information, 2017.
Inspire Record 1511149 DOI 10.17182/hepdata.76745

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

2 data tables

Measurement of the beam asymmetry $\Sigma$ for $\pi^0$ photoproduction on the proton at $E_\gamma = 9$ GeV. The uncorrelated systematic errors (syst) are given in the table below along with a correlated normalization uncertainty (norm) of 3.6% due to the beam polarization.

Measurement of the beam asymmetry $\Sigma$ for $\eta$ photoproduction on the proton at $E_\gamma = 9$ GeV. The uncorrelated systematic errors (syst) are given in the table below along with a correlated normalization uncertainty (norm) of 3.6% due to the beam polarization.


Measurements of Exclusive Photoproduction Processes at Large Values of t and u from 4-GeV to 7.5-GeV

Anderson, Robert L. ; Gustavson, D. ; Ritson, D. ; et al.
Phys.Rev. D14 (1976) 679, 1976.
Inspire Record 108061 DOI 10.17182/hepdata.4592
18 data tables

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Angular dependence of the recoil proton polarization from the reaction $\gamma p \to \pi^0 p$ for photon energies between 360-MeV and 1200-MeV

Blum, P. ; Brinckmann, P. ; Brockmann, R. ; et al.
Conference Paper, 1970.
Inspire Record 1085812 DOI 10.17182/hepdata.70500
6 data tables

No description provided.

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Polarization of recoil protons from neutral pion photoproduction

Lundquist, David Eugene ;
PhD Thesis, Stanford U., 1967.
Inspire Record 1408653 DOI 10.17182/hepdata.16895
1 data table

Polarised target asymmetry for pi-zero photoproduction at 4 gev.

Booth, P.S.L. ; Boyes, E. ; Court, G.R. ; et al.
Conf.Proc. C710830 (1971) 213-215, 1971.
Inspire Record 1093328 DOI 10.17182/hepdata.70366
1 data table

No description provided.


PROTON COMPTON EFFECT

Nagashima, Yorikiyo ;
No Journal Information, 1964.
Inspire Record 1101996 DOI 10.17182/hepdata.69229
2 data tables

No description provided.

No description provided.


Forward Photoproduction of Neutral Pions on Polarized Protons in the Third Resonance Region

Herr, H. ; Husmann, D. ; Jansen, W. ; et al.
Nucl.Phys. B125 (1977) 157-161, 1977.
Inspire Record 118996 DOI 10.17182/hepdata.50398
3 data tables

No description provided.

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The Photoproduction of Neutral Pions from Protons Between 0.7-GeV and 1.7-GeV

Barton, J.S. ; Booth, P.S.L. ; Carroll, L.J. ; et al.
Nucl.Phys. B84 (1975) 449-466, 1975.
Inspire Record 90496 DOI 10.17182/hepdata.32128
9 data tables
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The Photoproduction of Neutral Pions from Protons at Forward Angles in the Resonance Region

Booth, P.S.L. ; Carroll, L.J. ; Holt, J.R. ; et al.
Nucl.Phys. B84 (1975) 437-448, 1975.
Inspire Record 90412 DOI 10.17182/hepdata.32127
1 data table

No description provided.


Polarization of recoil protons from neutral pion photoproduction

Hayakawa, Satio ; Horikawa, Naoaki ; Kajikawa, Ryoichi ; et al.
J.Phys.Soc.Jap. 25 (1968) 307-318, 1968.
Inspire Record 1393542 DOI 10.17182/hepdata.38539
1 data table

No description provided.


Asymmetry of the cross section of the reaction $\gamma$P $\rightarrow$ P$\pi^{0}$ in the energy interval 0.9-1.65 GeV at $\theta _{\pi}^{0 cms}$ = 110°

Abramyan, L.O. ; Avakyan, R.O. ; Akopov, N.Z. ; et al.
JETP Lett. 23 (1976) 375-378, 1976.
Inspire Record 1393126 DOI 10.17182/hepdata.39803
2 data tables

THE ERRORS INCLUDE THE 10 PCT ERROR IN THE EFFECTIVE PHOTON POLARIZATION.

No description provided.


$\pi$$^{0}$ PHOTOPRODUCTION FROM THE DEUTERON AT FORWARD ANGLES IN THE ENERGY RANGE FROM 900-MeV TO 1400-MeV

Clinesmith, Carl R. ;
PhD Thesis, Caltech, 1967.
Inspire Record 51564 DOI 10.17182/hepdata.37172

The cross section for the reaction [...] was measured at the Caltech synchrotron. The [...] was detected by measuring its decay gamma rays with two lead glass, total absorption Cherenkov counters. The results are three angular distributions at k = 911, 1180, and 1390 MeV, at forward angles from 3 degrees to 90 degrees. The deuteron/proton ratio differs significantly from 2.0, but final state effects from the use of a deuteron target make impossible quantitative conclusions about the neutron cross section.

3 data tables

No description provided.

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Measurement of the angular dependence of the polarization of the recoil protons from the photoproduction of neutral pions on hydrogen at proton energies between 240 and 420 MeV

Althoff, K.H. ; Finken, D. ; Minatti, N. ; et al.
Phys.Lett. B26 (1968) 677-678, 1968.
Inspire Record 1392747 DOI 10.17182/hepdata.29304

New measurements of the polarization of the recoil protons from the reaction γ + p → π o + p are reported for the region of the first resonance. These measurements are an extension of earlier experiments, done on the 500 MeV-electron-synchroton. More data have been taken at photon energies of 240, 300, 360 and 420 MeV.

1 data table

No description provided.


Some cross-sections for the photo-production of neutral Pi-mesons from hydrogen at energies from 360 to 938 MeV

Dougan, P. ; Kivikas, T. ; Lugner, K. ; et al.
Z.Phys. A274 (1975) 73-78, 1975.
Inspire Record 1385254 DOI 10.17182/hepdata.16654

Some cross-sections for the photo-production of ~z~ from hydrogen for pion c.m. angles in the range 60~ ~ are presented. The data have been obtained by measuring proton yields from a hydrogen target, thus permitting separation of single-pion production from the strong background caused by double-pion production. The values, which extend from 360 to 938 MeV, show reasonable agreement with the results of a recent phase-shift analysis

1 data table

No description provided.


The photoproduction of $\pi^{0}$ mesons in hydrogen

Miller, D.B. ; Bellamy, E.H. ;
Proc.Phys.Soc. 81 (1963) 343-348, 1963.
Inspire Record 1393356 DOI 10.17182/hepdata.26953
1 data table

No description provided.


Single photoproduction of neutral $\pi$-mesons on hydrogen at small angles between 4 and 5.8 GeV

Braunschweig, M. ; Braunschweig, W. ; Husmann, D. ; et al.
Phys.Lett. B26 (1968) 405-409, 1968.
Inspire Record 1389637 DOI 10.17182/hepdata.29336

The differential cross-section of the reaction γ + p → p + π 0 was measured at the Deutsches Elektronen-Synchrotron, Hamburg, at mean photon energies of 4.0, 5.0 and 5.8 GeV and pion center of mass angles between 0° and 60°. The results are compared wiht theoretical calculations based on Reggeized vector meson exchange.

6 data tables

Axis error includes +- 7/7 contribution.

Axis error includes +- 7/7 contribution.

Axis error includes +- 7/7 contribution.

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PHOTOPRODUCTION OF pi0 FROM NEUTRONS AT 4-Gev

Bolon, G.C. ; Bellenger, D. ; Lobar, W. ; et al.
Phys.Rev.Lett. 27 (1971) 964, 1971.
Inspire Record 67576 DOI 10.17182/hepdata.29303
1 data table

No description provided.


The ratio of π° photoproductions from neutrons and protons in deuterium in the energy range of 700 to 1100 mev.

Chang, Tseng-Hsu ;
PhD Thesis, Caltech, 1962.
Inspire Record 44258 DOI 10.17182/hepdata.37218

The ratio of the cross sections for photoproduction of neutral pions from neutrons to that from protons has been obtained at average photon energies of 750, 875, and 1050 mev at a pion CM angle of 60° and at average photon energies of 875 and 1050 mev at a pion CM angle of 90°. The experimental technique required simultaneous detection of both the pions and the nucleons. Pions were detected by three scintillation counters. Lead plates of 2.4 radiation lengths and 1.2 radiation lengths were placed in front of the second and third counters. Neutral pions were identified by the absence of output in the first counter and the large outputs in the second and third counters. Nucleons were detected in two scintillation counters. The second of the two counters is 11” thick and has approximately 20% efficiency of detecting neutrons. Neutrons were identified by the absence of output in the first counter. The energy of the incident photons was determined by synchrotron subtraction. Since the statistical accuracy of synchrotron subtraction is poor, a system of three fast coincidence circuits was used as a time-of-flight instrument to reduce the number of events initiated by low energy photons. The statistical errors assigned to the ratio range between 15-30%. The results of this experiment agree with the results of Bingham within statistical errors, but show a general tendency for the σ^(no)/ σ^o ratio to lower. The ratio of σ^(no)/ σ^o obtained in this experiment ranges between 0.4 and 0.8. The cross sections for neutral pion photoproduction from neutrons are derived from the σ^(no)/ σ^o ratio and the Caltech data on neutral pion photoproduction from hydrogen.

2 data tables

No description provided.

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PHOTOPRODUCTION OF NEUTRAL PIONS ON HYDROGEN BELOW 500-MeV. 3. CROSS-SECTION MEASUREMENTS BETWEEN THE FIRST AND THE SECOND RESONANCE

Genzel, H. ;
Z.Phys. 268 (1974) 37-41, 1974.
Inspire Record 80489 DOI 10.17182/hepdata.2

Differential cross sections of neutral pion photoproduction on hydrogen were measured in the region between the first and the second nucleon resonance at photon energies of 400–500 MeV and were compared with results of an energy-independent multipole analysis.

1 data table

No description provided.


Cross-Sections for the Photoproduction of pi0 Mesons from Hydrogen from 238-MeV to 922-MeV

Dougan, P. ; Ramsay, V. ; Stiefler, W. ;
Z.Phys. A276 (1976) 155-160, 1976.
Inspire Record 99794 DOI 10.17182/hepdata.16656
1 data table

No description provided.


Single photoproduction of neutral π-mesons on hydrogen at small angles between 1.3 and 3 GeV

Braunschweig, M. ; Husmann, D. ; Lübelsmeyer, K. ; et al.
Phys.Lett. 22 (1966) 705-708, 1966.
Inspire Record 1389452 DOI 10.17182/hepdata.753

The differential cross section of the reaction γ + p → p + πo has been measured at the Deutsches Elektronen- Synchrotron, Hamburg, at mean phonon energies of 1.36, 2.0 and 3.0 GeV and pion center of mass angles between 0o and 70o. The results are compared with some theoretical calculations based on elementary and reggeized 1- meson exchange.

4 data tables

Axis error includes +- 12/12 contribution.

Axis error includes +- 12/12 contribution.

Axis error includes +- 12/12 contribution.

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Isospin amplitudes for $S$-state pion photoproduction on nucleons

Govorkov, B.B. ; Denisov, S.P. ; Minarik, E.V. ;
Sov.J.Nucl.Phys. 4 (1967) 265-270, 1967.
Inspire Record 1392561 DOI 10.17182/hepdata.18381
1 data table

NEUTRAL MESON PHOTOPRODUCTION FROM HYDROGEN AT FORWARD ANGLES IN THE PHOTON ENERGY RANGE 750-MeV - 1500-MeV

Hatch, G.Laurie ;
PhD Thesis, Caltech, 1966.
Inspire Record 50286 DOI 10.17182/hepdata.37214

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Measurements have been made of the cross-sections for neutral meson photoproduction from protons at angles in the forward hemisphere for photon energies near 911, 1182, and 1390 MeV. The experimental method consists of detecting the decay gamma-rays of the neutral meson in two pb-glass total absorption Cerenkov counters. The results agree very well with the existing data where the same points have been measured. The striking feature of the angular distributions at 1182 and 1390 MeV is the small 0[degree] cross-section and the peak near 30[degrees] to 40[degrees] in the CMS. Using as a model for the cross-section calculation a vector meson X[degrees] exchange plus background, we find the product [...] for M[subscript X] = 788 MeV. Fits made without the vector meson pole are not inconsistent with a resonance model for the cross-section.

4 data tables

No description provided.

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Photoproduction of $\pi$$^\circ$'S from protons in the forward direction in the region of the second and third resonances

Talman, Richard Michael ;
PhD Thesis, Caltech, 1963.
Inspire Record 44255 DOI 10.17182/hepdata.37170

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The cross section for photoproduction of neutral pions from protons has been measured at energies near 750, 915 and 1150 Mev and over most of the forward-going [...] C.M. hemisphere. The experimental technique consisted of detecting both of the [...] decay photons with lead glass total absorption counters and, when convenient, the recoil proton with a single scintillation counter. The method is subject to rather large systematic errors but, within these, our results are consistent with other experiments wherever there are overlapping points. Our data has the striking feature that the cross section is very small at [...] in the region of the second and third pion nucleon resonances. Also, although the data is not inconsistent with a simple first, second and third resonance model, it appears likely that above the third resonance the pole process consisting of the exchange of a single vector meson is becoming important or even dominant. The evidence at this time mildly suggests that this behaviour is largely due to [...] mesons and under that hypothesis we are able to estimate some [...] meson coupling constants. For example, using a prescription of Gell-Mann and Zachariasen, we estimate the partial width for the decay [...] to be 240 Kev.

1 data table

No description provided.