Cross Section for $\gamma n \to \pi^0 n$ measured at Mainz/A2

The A2 collaboration Briscoe, W.J. ; Hadžimehmedović, M. ; Kudryavtsev, A.E. ; et al.
Phys.Rev.C 100 (2019) 065205, 2019.
Inspire Record 1748263 DOI 10.17182/hepdata.116236

The $\gamma n \to \pi^0 n$ differential cross section evaluated for 27 energy bins span the photon-energy range 290-813 MeV (W = 1.195-1.553 GeV) and the pion c.m. polar production angles, ranging from 18 deg to 162 deg, making use of model-dependent nuclear corrections to extract pi0 production data on the neutron from measurements on the deuteron target. Additionally, the total photoabsorption cross section was measured. The tagged photon beam produced by the 883-MeV electron beam of the Mainz Microtron MAMI was used for the 0-meson production. Our accumulation of 3.6 x 10^6 $\gamma n \to \pi^0 n$ events allowed a detailed study of the reaction dynamics. Our data are in reasonable agreement with previous A2 measurements and extend them to lower energies. The data are compared to predictions of previous SAID, MAID, and BnGa partial-wave analyses and to the latest SAID fit MA19 that included our data. Selected photon decay amplitudes $N^* \to \gamma n$ at the resonance poles are determined for the first time.

21 data tables

Excitation function at pion c.m. angle THETA=18 deg as function of incident photon energy E. The uncertainties are statistical and systematic, combined in quadrature.

Excitation function at pion c.m. angle THETA=32 deg as function of incident photon energy E. The uncertainties are statistical and systematic, combined in quadrature.

Excitation function at pion c.m. angle THETA=41 deg as function of incident photon energy E. The uncertainties are statistical and systematic, combined in quadrature.

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High precision measurement of the associated strangeness production in proton proton interactions

The COSY-TOF collaboration Jowzaee, S. ; Borodina, E. ; Clement, H. ; et al.
Eur.Phys.J.A 52 (2016) 7, 2016.
Inspire Record 1393330 DOI 10.17182/hepdata.70735

A new high precision measurement of the reaction pp -> pK+Lambda at a beam momentum of 2.95 GeV/c with more than 200,000 analyzed events allows a detailed analysis of differential observables and their inter-dependencies. Correlations of the angular distributions with momenta are examined. The invariant mass distributions are compared for different regions in the Dalitz plots. The cusp structure at the N Sigma threshold is described with the Flatt\'e formalism and its variation in the Dalitz plot is analyzed.

9 data tables

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Proton-deuterium bremsstrahlung at 200 MeV

Pinston, J.A. ; Barneoud, D. ; Bellini, V. ; et al.
Phys.Lett.B 249 (1990) 402-405, 1990.
Inspire Record 1392683 DOI 10.17182/hepdata.29616

Double differential cross sections for photons above 20 MeV energy were measured for the p+d reaction at 200 MeV. A comparison is made with previous measurements at 140 and 197 MeV. Below 80 MeV photon energy the cross sections and the angular distribution are in reasonable agreement with a recent calculation of the free pnγ elementary process.

2 data tables

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Differential cross section for elastic n+d scattering and n+d break-up quasi free-scattering at 67 MeV

Balewski, J. ; Bodek, K. ; Jarczyk, L. ; et al.
Nucl.Phys.A 581 (1995) 131-144, 1995.
Inspire Record 1389771 DOI 10.17182/hepdata.36531

The differential cross sections for the n+d elastic scattering and for the 2H(n,np)n break-up reaction in the np quasi-free scattering configuration was measured at 67 MeV. The experimental data are compared with results of the calculations based on a rigorous solution of the three-nucleon Faddeev equations using meson-exchange potentials. Good agreement is found between experiment and theory for the n+d elastic-scattering cross section while in the case of np quasi-free scattering the theoretical predictions overestimate the data at neutron angles larger than 40° by about 30%.

6 data tables

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CROSS SECTION FOR THE N P QUASI-FREE SCATTERING CONFIGURATION.

CROSS SECTION FOR THE N P QUASI-FREE SCATTERING CONFIGURATION.

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Impact parameter dependence of high-energy gamma-ray production in argon induced reaction at 85 MeV/nucleon

Njock, M. Kwato ; Maurel, M. ; Monnand, E. ; et al.
Nucl.Phys.A 489 (1988) 368-380, 1988.
Inspire Record 1389759 DOI 10.17182/hepdata.37000

The double-differential cross sections for high-energy γ-rays were measured for collisions of 36Ar on C, Al, Cu, Ag, Tb, and Au at 85 MeV/nucleon. The system 36Ar+ 27Al has been studied in more detail in an exclusive experiment where the charged-particle multiplicity was measured in coincidence with high-energy γ-rays. A clear correlation between the hardness of the γ-spectra and the overlap distance of the two ions is observed. This correlation is interpreted as due to the spatial dependence of the Fermi momentum of the nucleons.

2 data tables

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Scaling of the $^{4}$He(γ,p)t reaction in the $E_\gamma$ = 80–160 MeV region

Schmieden, H. ; MacGregor, I.J.D. ; Owens, R.O. ; et al.
Phys.Lett.B 314 (1993) 284-288, 1993.
Inspire Record 1389619 DOI 10.17182/hepdata.28840

The 4 He( γ ,p) 3 H reaction cross section has been measured with tagged photons of energy 81–158 MeV. Protons were detected over the angular range 55°–125°. The scaling of the data as a function of momentum mismatch has been examined for two reaction models, the modified quasideuteron mechanism and quasifree knockout. Both models show clear scaling behaviour but comparison of the predicted and measured scaling function shapes favours the modified quasideuteron mechanism at momenta up to ≈500 MeV/ c .

7 data tables

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Scattering of positrons and electrons from protons

Bartel, W. ; Dudelzak, B. ; Krehbiel, H. ; et al.
Phys.Lett.B 25 (1967) 242-245, 1967.
Inspire Record 1389651 DOI 10.17182/hepdata.29449

The ration R = σ(e + = p)/σ(e − + p) of the elastic scattering cross section of positrons and electrons on protons was measured at momentum transfers of 11.66 fm −2 and 35.1 fm −2 . The results are consistent with R = 1.

1 data table

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Photoproduction of positive pions on hydrogen between 200 and 450 MeV

Althoff, K. ; Fischer, H. ; Paul, W. ;
Z.Phys. 175 (1963) 19-33, 1963.
Inspire Record 1385261 DOI 10.17182/hepdata.16824

Mit einem magnetischen Spektrometer wurde am Bonner 500 MeV-Elektronen-Synchrotron die Reaktionγ+p→π ++n für Photonenenergien zwischen 200 und 450 MeV untersucht. Es wurden Anregungskurven für die Lab

19 data tables

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Measurement of the g p -> K^0 Sigma^+ reaction with the Crystal Ball/TAPS detectors at the Mainz Microtron

The A2 collaboration Aguar-Bartolome, P. ; Annand, J.R.M. ; Arends, H.J. ; et al.
Phys.Rev.C 88 (2013) 044601, 2013.
Inspire Record 1237227 DOI 10.17182/hepdata.64391

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. In the present experiment, this reaction was searched for in the 3pi^0 p final state, by assuming K^0_S -> pi^0 pi^0 and Sigma^+ -> pi^0 p. The experimental results include total and differential cross sections as well as the polarization of the recoil hyperon. The new data significantly improve empirical knowledge about the g p -> K^0 Sigma^+ reaction in the measured energy range. The results are compared to previous measurements and model predictions. It is demonstrated that adding the present g p -> K^0 Sigma^+ results to existing data allowed a better description of this reaction with various models.

4 data tables

The differential cross section for photon energies 1125, 1175 and 1225 MeV.

The differential cross section for photon energies 1275, 1325, 1375 and 1425 MeV.

The recoil polarization of the SIGMA+ for photon energy 1125, 1175 and 1225 MeV.

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Photoproduction of Neutral Pions off Protons

The CBELSA/TAPS collaboration Crede, V. ; Sparks, N. ; Wilson, A. ; et al.
Phys.Rev.C 84 (2011) 055203, 2011.
Inspire Record 917921 DOI 10.17182/hepdata.61486

Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction $\gamma p\to p\pi^0$ for photon energies between 0.85 and 2.50 GeV. The $\pi^0$ mesons are observed in their dominant neutral decay mode: $\pi^0\to\gamma\gamma$. For the first time, the differential cross sections cover the very forward region, $\theta_{\rm c.m.}<60^\circ$. A partial-wave analysis of these data within the Bonn-Gatchina framework observes the high-mass resonances $G_{17}$(2190), $D_{13}$(2080), and $D_{15}$(2070).

82 data tables

Differential cross section for the process GAMMA P --> PI0 P as a function of the cosine of the centre-of-mass scattering angle of the PI0 for photon energies from 0.850 to 0.875 GeV.

Differential cross section for the process GAMMA P --> PI0 P as a function of the cosine of the centre-of-mass scattering angle of the PI0 for photon energies from 0.875 to 0.900 GeV.

Differential cross section for the process GAMMA P --> PI0 P as a function of the cosine of the centre-of-mass scattering angle of the PI0 for photon energies from 0.900 to 0.925 GeV.

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