Photodisintegration of Polarized Deuterons: Measurement of Angular Distributions at $e (\gamma$) = 450-{MeV}, 550-{MeV} and 650-{MeV}

Althoff, K.H. ; Anton, G. ; Bock, B. ; et al.
Z.Phys.C 43 (1989) 375, 1989.
Inspire Record 277082 DOI 10.17182/hepdata.15455

At the Bonn 2.5 GeV electron synchrotron an angular distribution of the target asymmetry of the reaction γ+d↑→p+n has been measured at photon-lab-energies of 450 and 650 MeV and at proton-CM-angles between 25° and 155°. At 550 MeV the data of our previous run [1] have been improved. Using deuterated ammonia as material for the polarized deuteron target a maximum vector polarization of 44% could be achieved. At 450 and 650 MeV the data are consistent with a smooth sin 2Θ-like distribution. The evidence for a structure around 90° at 550 Mev remains. This might be due to the influence of a higher momentum state (like a dibaryon). The feasibility of measuring the tensor asymmetry of the deuteron photodisintegration with a polarized target has been shown for the first time. Data were taken in a short run for one kinematical setting.

1 data table

Errors contain both statistics and systematics.


Deuteron Photodisintegration at Photon Energies Between 200-{MeV} and 700-{MeV} in Backward Direction

Althoff, K.H. ; Anton, G. ; Bour, D. ; et al.
Z.Phys.C 21 (1983) 149, 1983.
Inspire Record 192906 DOI 10.17182/hepdata.50170

The differential cross section of the deuteron photodisintegration was measured at a protion c.m. angle of 180 degrees and for photon energies between 180 and 730 MeV. The protons were detected in a magnetic spectrometer. The proton energy resolution varied between 30 MeV and 50 MeV FWHM. Since these are the first data at 180 degrees in this energy range a comparison can only be done with data from other laboratories extrapolated to 180 degrees and with theoretical predictions. The agreement with existing calculations is poor. Contributions of dibaryons to the cross section seem not to improve the situation.

1 data table

BEAM ERROR D(E) = 50.000 MEV.


Measurement of gamma p --> K+ Lambda and gamma p --> K+ Sigma0 at photon energies up to 2-GeV .

The SAPHIR collaboration Tran, M.Q. ; Barth, J. ; Bennhold, C. ; et al.
Phys.Lett.B 445 (1998) 20-26, 1998.
Inspire Record 483236 DOI 10.17182/hepdata.27074

Associated strangeness production in the reactions γp → K + Λ and γp → K + Σ 0 was measured with the SAPHIR detector at the electron stretcher ring ELSA at Bonn. Data on total and differential cross sections and on hyperon polarizations are presented. The total cross section for Λ production shows a strong threshold enhancement whereas the Σ 0 data have a maximum at about E γ =1.45 GeV. Along with the angular decomposition of the differential cross section into polynomials, this suggests resonance production. However, the angular distributions of both hyperon polarizations vary only slightly with the photon energy. Λ and Σ 0 polarizations show opposite signs and change sign over the angular range.

10 data tables

Total cross section for the reaction GAMMA P --> K+ LAMBDA.

Total cross section for the reaction GAMMA P --> K+ SIGMA0.

Differential cross section for the reaction GAMMA P --> K+ LAMBDA in the GAMMA energy range 0.90 to 1.10 GeV in three energy bins.

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TARGET ASYMMETRY MEASUREMENT OF DEUTERON PHOTODISINTEGRATION AT A PHOTON ENERGY OF 550-MEV

Althoff, K.H. ; Anton, G. ; Bock, B. ; et al.
Z.Phys.C 26 (1984) 175-179, 1984.
Inspire Record 214987 DOI 10.17182/hepdata.16199

The target asymmetry of the deuteron photodisintegration was measured at a photon energy of 550±50 MeV and at proton center-off-mass angles between 25 and 155 degrees.D-butanol andND3 were used as target material yielding a maximum deuteron polarization of 41%. Proton and neutron were detected in coincidence. The data show a structure which cannot be described by the existing analyses.

1 data table

Axis error includes +- 8/8 contribution (UNCERTAINTY IN THE DETERMINATION OF THE TARGET POLARIZATION//OTHER SYSTEMATIC ERRORS ARE FROM COMPETING PROCESSES (<2 PCT) AND OTHERS (<1 PCT)).


Measurement of gamma p ---> K+ Lambda and gamma p ---> K+ Sigma0 at photon energies up to 1.47-GeV

Bockhorst, M. ; Burbach, G. ; Burgwinkel, R. ; et al.
Z.Phys.C 63 (1994) 37-47, 1994.
Inspire Record 380478 DOI 10.17182/hepdata.14114

The reactions γp→K+ Λ and γp→K+ Σ0 have been measured with the multiparticle detector system SAPHIR at ELSA in Bonn. Besides the differential cross sections the Λ polarization and, for the first time, the Σ0 polarization have been determined in a photon induced reaction. All data are presented as functions of the photon energy (from threshold up to 1.47 GeV) and of the kaon production angle (0°–180°). The polarization of both Λ and Σ0 is substantial at all energies and varies strongly with the production angle.

8 data tables

Differential cross sections.

Total cross sections.

Differential cross sections.

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Positive Pion Photoproduction From Hydrogen at Photon Energies Between 500-{MeV} and 1400-{MeV} in Forward Direction

Althoff, K.H. ; Anton, G. ; Bock, B. ; et al.
Z.Phys.C 18 (1983) 199, 1983.
Inspire Record 189703 DOI 10.17182/hepdata.16352

The differential cross section of the reactionγ+p→π+ was measured at pion CM-angles of 20° and 30° for photon energies between 500 MeV and 1,400 MeV. The pions were detected in a magnetic spectrometer. By measuring each pion trajectory and by offline calculation of the initial pion parameters an energy resolution of about 2.5% FWHM was achieved. The results complete a set of data which were measured in recent years at the Bonn 2.5 GeV synchrotron. In comparison to photoproduction analyses two effects were revealed: The η cusp appears in the energy dependence of the cross section as a sharp drop atKγ=710 MeV. In the region of the third resonance the data show a greater enhancement than predicted by most of the analyses.

1 data table

No description provided.


Measurement of the proton structure function F2 in e p scattering at HERA

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 316 (1993) 412-426, 1993.
Inspire Record 357414 DOI 10.17182/hepdata.28804

This paper presents our first measurement of the F 2 structure function in neutral-current, deep inelastic scattering using the ZEUS detector at HERA, the ep colliding beam facility at DESY. The data correspond to an integrated luminosity of 24.7 nb −1 . Results are presented for data in range of Q 2 from 10 GeV 2 to 4700 GeV 2 and Bjorken x down to 3.0 × 10 −4 . The F 2 structure function increases rapidly as x decreases.

7 data tables

No description provided.

No description provided.

No description provided.

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Search for excited electrons using the ZEUS detector

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 316 (1993) 207-218, 1993.
Inspire Record 355574 DOI 10.17182/hepdata.45106

This paper reports a search for excited electrons at the HERA electron-proton collider. In a sample corresponding to an integrated luminosity of 26 nb − , no evidence was found for any resonant state decaying into e − γ , ν W − or e − Z 0 . Limits on the coupling strength of an excited electron have been determined for masses between 45 and 225 GeV. This study also reports the observation of the wide-angle e γ Compton scattering process.

1 data table

No description provided.


Observation of hard scattering in photoproduction at HERA

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 297 (1992) 404-416, 1992.
Inspire Record 339388 DOI 10.17182/hepdata.45149

We report a study of electron proton collisions at very low Q 2 , corresponding to virtual photoproduction at centre of mass energies in the range 100–295 GeV. The distribution in transverse energy of the observed hadrons is much harder than can be explained by soft processes. Some of the events show back-to-back two-jet production at the rate and with the characteristics expected from hard two-body scattering. A subset of the two-jet events have energy in the electron direction consistent with that expected from the photon remnant in resolved photon processes.

1 data table

No description provided.


A Measurement of sigma(tot) (gamma p) at s**(1/2) = 210-GeV

The ZEUS collaboration Derrick, M. ; Krakauer, D. ; Magill, S. ; et al.
Phys.Lett.B 293 (1992) 465-477, 1992.
Inspire Record 339275 DOI 10.17182/hepdata.45171

The total photoproduction cross section is determined from a measurement of electroproduction with the ZEUS detector at HERA. The Q 2 values of the virtual photons are in the range 10 −7 < Q 2 <2×10 −2 GeV 2 . The γp total cross section in the γp centre of mass energy range 186–233 GeV is 154 ± 16 (stat.) ± 32 (syst.) μ b.

1 data table

Scattered electron in range 10 to 16 GeV.