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A Measurement of the Beam Asymmetry Parameter Sigma for Neutral Pion Photoproduction in the Energy Range 1.2-GeV-2.8-GeV

Bussey, P.J. ; Raine, C. ; Rutherglen, J.G. ; et al.

Nucl.Phys.B 104 (1976) 253-276, 1976.

Inspire Record 100818 DOI 10.17182/hepdata.8492

An experiment has been completed at the Daresbury synchrotron to measure the asymmetry in the photoproduction cross section of neutral pions on hydrogen, for photons polarised normal to and in the production plane. The source of polarised photons was coherent bremsstrahlung of electrons traversing the lattice structure of diamond and the polarisation P of the γ beam was calculated from the measured intensity of the coherent spike. The asymmetry parameter Σ, defined as Σ = ( σ ⊥ − σ |)/( σ ⊥ + σ |) where σ ⊥( σ |) are the cross sections for photons polarised perpendicular (parallel) to the production plane, has been measured over a range of photon energies from 1.2 to 2.8 GeV and over a range of − t (the square of the four-momentum transfer) from 0.13 (GeV/ c ) 2 to 1.4 (GeV/ c ) 2 . A marked energy variation in the value of Σ is found over the energy region 1.6–1.8 GeV.

38 data tables

Table 1

Axis error includes +- 0.0/0.0 contribution (?////).

Table 2

Axis error includes +- 0.0/0.0 contribution (?////).

Table 3

Axis error includes +- 0.0/0.0 contribution (?////).

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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.B 84 (1975) 437-448, 1975.

Inspire Record 90412 DOI 10.17182/hepdata.32127

Differential cross sections for the photoproduction of pi-zero mesons from protons have been measured at angles between 10° and 70° c.m. in the energy range 0.85 GeV to 1.30 GeV. The values are compared with the fits to pion photoproduction data from three recent partial-wave analyses.

1 data table

Table 1

Differential cross-sections for the photoproduction of eta mesons from protons near 2 gev

Booth, P.S.L. ; Carroll, L.J. ; Holt, J.R. ; et al.

Nucl.Phys.B 71 (1974) 211-216, 1974.

Inspire Record 94714 DOI 10.17182/hepdata.32321

Differential cross sections for the process γ p → p η have been measuredd at c.m. angles of 28°, 35° and 42° at incident energies between 2 GeV and 2.8 GeV. Data from an earlier experiment below 2 GeV have been re-analysed and corrected. The whole set of data is compared with the form ( s − M 2 ) 2 d σ /d t , which fits data at higher energies. There is good agreement above 2 GeV, particularly at the largest angle, but strong departures below.

2 data tables

Table 1

No description provided.

Table 2

THESE DATA ARE A REANALYSIS OF THOSE REPORTED IN P. S. L. BOOTH ET AL., NP B25, 510 (1971). THE CORRECTED RESULTS ARE IN GENERAL ABOUT TWICE THE OLD VALUES.