Donaldson, G
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Measurement of the analyzing power $A_y$ in neutron-proton radiative capture at $E_n$ = 68 MeV

Tuccillo, M. ; Fritschi, D. ; Götz, J. ; et al.
Nucl.Phys.A 580 (1994) 253-262, 1994.
Inspire Record 1389770 DOI 10.17182/hepdata.36513

The vector analyzing power Ay for the reaction Full-size image (<1 K) has been measured at five angles between 60° and 140° in the lab at an incident neutron energy of 67.7 MeV. The measurement is of a presision never before acheived (ΔAy ⩽ 0.01, statistical) for this observable. This precision makes possible a quantitative comparison with meson-exchange theories, thus enhancing our understanding of the role of non-nucleonic degrees of freedom.

1 data table
Table 1

No description provided.


Differential cross section and recoil polarization measurements for the gamma p to K+ Lambda reaction using CLAS at Jefferson Lab

The CLAS collaboration McCracken, M.E. ; Bellis, M. ; Meyer, C.A. ; et al.
Phys.Rev.C 81 (2010) 025201, 2010.
Inspire Record 840934 DOI 10.17182/hepdata.54967

We present measurements of the differential cross section and Lambda recoil polarization for the gamma p to K+ Lambda reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+ p pi- and K+ p (missing pi -) final-state topologies/ results from these analyses were found to exhibit good agreement. These differential cross section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300 MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500 MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of non-resonant K+ Lambda photoproduction mechanisms at all production angles.

241 data tables
Table 1

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.62-1.63 GeV.

Table 2

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.63-1.64 GeV.

Table 3

Differential cross section as a function of COS(THETA(K)) for the centre-of-mass range 1.64-1.65 GeV.

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Measurement of eta photoproduction on the proton from threshold to 1500-MeV

The GRAAL collaboration Bartalini, O. ; Bellini, V. ; Bocquet, J.P. ; et al.
Eur.Phys.J.A 33 (2007) 169-184, 2007.
Inspire Record 755415 DOI 10.17182/hepdata.51526

Beam asymmetry and differential cross section for the reaction gamma+p->eta+p were measured from production threshold to 1500 MeV photon laboratory energy. The two dominant neutral decay modes of the eta meson, eta->2g and eta->3pi0, were analyzed. The full set of measurements is in good agreement with previously published results. Our data were compared with three models. They all fit satisfactorily the results but their respective resonance contributions are quite different. The possible photoexcitation of a narrow state N(1670) was investigated and no evidence was found.

45 data tables
Table 1

Measured beam asymmetry at photon energy 724 MeV as a function of the ETA centre of mass angle.

Table 2

Measured beam asymmetry at photon energy 761 MeV as a function of the ETA centre of mass angle.

Table 3

Measured beam asymmetry at photon energy 810 MeV as a function of the ETA centre of mass angle.

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Measurement of the beam asymmetry in eta photoproduction off the proton.

The CBELSA & TAPS collaborations Elsner, D. ; Anisovich, A.V. ; Anton, G. ; et al.
Eur.Phys.J.A 33 (2007) 147-155, 2007.
Inspire Record 744568 DOI 10.17182/hepdata.43430

The beam asymmetry, $\Sigma$, was measured at ELSA in the reaction $\vec \gamma p \to \eta p$ using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range $E_\gamma = 800$ to 1400 MeV with the maximum polarisation of $P_\gamma = 49$ % obtained at 1305 MeV. Both dominant decay modes of the $\eta$ into two photons and $3\pi^0$ were used to extract the beam asymmetry from the azimuthal modulation of the cross section. The measurements cover the angular range $\Theta_\text{cm}\simeq 50$ -- 150 degrees. Large asymmetries up to 80 % are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn--Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly.

6 data tables
Table 1

Photon asymmetry for eta photoproduction at incident photon energy of 850 MeV.

Table 2

Photon asymmetry for eta photoproduction at incident photon energy of 950 MeV.

Table 3

Photon asymmetry for eta photoproduction at incident photon energy of 1050 MeV.

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Analyzing powers for pi p elastic scattering between 57 and 139 MeV

Patterson, J.D. ; Hofman, G.J. ; Brack, J.T. ; et al.
Phys.Rev.C 66 (2002) 025207, 2002.
Inspire Record 594648 DOI 10.17182/hepdata.25268

Analyzing powers for πp elastic scattering at bombarding energies below the Δ(1232) resonance were measured at TRIUMF using the CHAOS spectrometer and a polarized spin target. This work presents π− data at six incident energies of 57, 67, 87, 98, 117, and 139 MeV, and a single π+ data set at 139 MeV. The higher energy measurements cover an angular range of 72°<~θc.m.<~180° while the lower energies were limited to 101°<~θc.m.<~180°. There is a high degree of consistency between this work and the predictions of the VPI/GWU group’s SM95 partial wave analysis.

9 data tables
Table 1

Analysing power measurements for a 139 GeV PI+ beam (standard track).

Table 2

Analysing power measurements for a 139 GeV PI- beam (standard track).

Table 3

Analysing power measurements for a 117 GeV PI- beam (standard track).

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Measurement of K- p --> eta Lambda near threshold

The Crystal Ball collaboration Starostin, A. ; Nefkens, B.M.K. ; Berger, E. ; et al.
Phys.Rev.C 64 (2001) 055205, 2001.
Inspire Record 569202 DOI 10.17182/hepdata.25269

We present measurements of the differential and total cross sections and the Λ polarization for the reaction K−p→ηΛ from threshold to pK−=770MeV/c, with much better precision than previous measurements. Our cross-section data show a remarkable similarity to the SU(3) flavor-related π−p→ηn cross-section results. The reaction K−p→ηΛ at threshold is dominated by formation of the intermediate Λ(1670)12− state.

5 data tables
Table 1

Total cross section measurement for K- P --> ETA LAMBDA. Errors shown are statistical only.

Table 2

Differential cross sections DSIG/DOMEGA for K- P --> ETA LAMBDA. Errors shown are statistical only.

Table 3

Differential cross sections DSIG/DOMEGA for K- P --> ETA LAMBDA. Errors shown are statistical only.

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Measurement of the vector analyzing power in elastic electron proton scattering as a probe of double photon exchange amplitudes.

The SAMPLE collaboration Wells, S.P. ; Averett, T. ; Barkhuff, D. ; et al.
Phys.Rev.C 63 (2001) 064001, 2001.
Inspire Record 524209 DOI 10.17182/hepdata.31444

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.

1 data table
Table 1

Polarized beam.


Analyzing powers and partial wave decomposition of p n --> p p((1)S(0)) pi- at low energies.

Hahn, H. ; Duncan, F.A. ; Aclander, J. ; et al.
Phys.Rev.Lett. 82 (1999) 2258-2261, 1999.
Inspire Record 500174 DOI 10.17182/hepdata.19495

Analyzing powers for p→n→pp(S01)π− were measured at beam energies 353, 404, and 440 MeV by extracting the quasifree process from p→d→pppπ−. Partial wave amplitude analysis yields a significant contribution from the isospin 1, s-wave channel. This contribution is relatively much larger than that expected from theoretical models which have been successful in describing the isospin 1, s-wave channel behavior of pp→ppπ0 cross sections at threshold.

3 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 (?////).


The Spin Correlation Parameter and Analyzing Power in $n p$ Elastic Scattering at Intermediate-energies

Abegg, R. ; Ahmad, M. ; Bandyopadhyay, D. ; et al.
Phys.Rev.C 40 (1989) 2684-2696, 1989.
Inspire Record 281880 DOI 10.17182/hepdata.26220

In order to improve existing I=0 phase shift solutions, the spin correlation parameter ANN and the analyzing powers A0N and AN0 have been measured in n-p elastic scattering over an angular range of 50°–150° (c.m.) at three neutron energies (220, 325, and 425 MeV) to an absolute accuracy of ±0.03. The data have a profound effect on various phase parameters, particularly the P11, D23, and ε1 phase parameters which in some cases change by almost a degree. With the exception of the highest energy, the data support the predictions of the latest version of the Bonn potential. Also, the analyzing power data (A0N and AN0) measured at 477 MeV in a different experiment over a limited angular range [60°–80° (c.m.)] are reported here.

10 data tables
Table 1

The beam analysing power at incident kinetic energy 220 MeV. Additional systematic uncertainty of +- 0.015 and a scalar error of 3.5 PCT.

Table 2

The beam analysing power at incident kinetic energy 325 MeV. Additional systematic uncertainty of +- 0.018 and a scalar error of 3.1 PCT.

Table 3

The beam analysing power at incident kinetic energy 425 MeV. Additional systematic uncertainty of +- 0.022 and a scalar error of 3.3 PCT.

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