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The polarization of the proton from the process γ+p→p+$\pi^{0}$ in the region of the higher resonances

Querzoli, R. ; Salvini, G. ; Silverman, A. ;

Nuovo Cim. 19 (1961) 53-76, 1961.

Inspire Record 1185001 DOI 10.17182/hepdata.37767

The polarization of the recoil proton in the photoproduction process γ+p→p+π0 has been measured with the beam of the Frascati electrosynchrotron at an angle of 90° in the c.m. system, in the energy interval (500÷900) MeV. A counter technique has been used, and the polarization of the proton was revealed by the left to right asymmetry in the elastic scattering of the protons in a carbon target. The experimental results are given in Table III and in Fig. 10. A definite polarization is found, always of the same sign and equal to −0.4±.14, −0.63±.23, −0.6±.25, −0.57±.12, −0.38±.09, −0.5±.17, −0.5±.22 at the γ-ray energies of 560, 610, 650, 700, 750, 800, 850 MeV respectively. The discussion of these experimental results, together with the data of angular dstributions, allows to conclude that they are in agreement with the hypothesis that the second resonance is a transition (E 1,d 3/2) and the third one is a transition (E 2,f 3/2).

1 data table

Table 1

No description provided.

Polarization in proton-beryllium and proton-proton scattering at 1.7 GeV

Bareyre, P. ; Detoeuf, J.F. ; Van Rossum, L. ; et al.

Nuovo Cim. 20 (1961) 1049-1066, 1961.

Inspire Record 1185005 DOI 10.17182/hepdata.37750

The polarization in p-Be and p-p scattering has been measured by counter techniques at a proton kinetic energy of 1.74 GeV. The maximum polarization in p-Be scattering was found to beP max==0.19±0.04 and occurs at an angleθ max⩾3.5°. Inelastic scatters were rejected when the inelastic momentum loss was more than about 1% in the first scatter (magnetic analysis) or more than about 5% in the second scatter (Čerenkov threshold counter). The maximum polarization in p-p scattering isP max=0.30±0.09 and occurs at an angle 35°<θ max<<55° (c.m.). The angular dependence of the polarization is consistent with a distribution proportional to sin 2θ within large statistical errors. Optical model calculations applied to the data on p-Be scattering yield an almost all imaginary central potential of about 43 MeV and a spin-orbit potential of between 0.9 MeV and 2.0 MeV which is also almost all imaginary, in contrast with the predominantly real spin-orbit potential needed to explain the large polarization in the region of several hundred MeV.

2 data tables

Table 1

'1'. '2'. '3'. '4'.

Table 2

'1'. '2'. '3'. '5'.

Measurement of the polarization of the recoil proton in $\gamma+p \to p + \pi^{0}$ using a propane-ethane bubble chamber

Bertanza, L. ; Mannelli, I. ; Santucci, S. ; et al.

Nuovo Cim. 24 (1962) 734-745, 1962.

Inspire Record 1187694 DOI 10.17182/hepdata.37757

The polarization of the recoil proton in γ + p → p + π0 has been measured at photon energies of 725 MeV and 900 MeV for centerof-mass angles near 90° using a small propane-ethane gas bubble chamber. Protons emerging from a liquid hydrogen target are momentum-analysed with a magnet, and the scattering from carbon observed in the bubble chamber. A counter telescope rejects pions and electrons, and protons from multiple pion processes are discriminated against by keeping the peak bremsstrahlung energy just above the mean photon energy. The visual method of observing scattering asymmetries has the advantage of being insensitive to systematic asymmetries in the incoming proton flux. It also quickly eliminates strongly inelastic scatters (stars), and provides a complete angular distribution from which the fraction of scatters which are inelastic can be deduced. The effect of inelastic scatters upon the scattering asymmetry is large when the energy-loss resolution is poor, an inherent problem with bremsstrahlung beams. The counting rate for this small chamber (3.4g/cm2 carbon scatterer) was 11 scatters/hour using every 5th synchrotron pulse; larger chambers with more dense scatterers (such as Freon) could give higher counting rates. Results are fork = 725MeV and ϑ (pion) = 87° (cm.), P=0.74±0.20, and for k=900MeV and ϑ (pion) = 70°, P=.51±.7. P is taken to be positive along the directionK xp, wherep is the momentum of the outgoing proton.

1 data table

Table 1

No description provided.

Negative Pion Production from Neutrons by Polarized gamma Rays

Nishikawa, T. ; Hiramatsu, S. ; Kimura, Y. ; et al.

Phys.Rev.Lett. 21 (1968) 1288-1291, 1968.

Inspire Record 944914 DOI 10.17182/hepdata.38534

The differential asymmetry ratio for the process γ+n→p+π− was measured at 90° in the center-of-mass system and for incident photon energies from 352 to 550 MeV. The observed asymmetries are larger than the values predicted from the theory by Berends, Donnachie, and Weaver. A smaller M1- amplitude gives better agreement between the experiment and the theory.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

PROTON POLARIZATION IN THE PHOTODISINTEGRATION OF THE DEUTERON BY LINEARLY POLARIZED 400-MEV AND 500-MeV GAMMA RAYS

Bratashevsky, A.S. ; Gorbenko, V.G. ; Gushchin, V.A. ; et al.

JETP Lett. 35 (1982) 605-607, 1982.

Inspire Record 184506 DOI 10.17182/hepdata.16942

None

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

Polarization measurements in $π^−$p charge exchange scattering from 618 MeV/c to 2267 MeV/c

Brown, Robert M. ; Clark, A.G. ; Davies, J.K. ; et al.

AIP Conf.Proc. 35 (1976) 189-197, 1976.

Inspire Record 117337 DOI 10.17182/hepdata.76257

Results are presented of measurements of the polarisation parameter for the reaction π−p→π°n : π°→γγ at 22 incident momenta in the resonance region. These results are generally in agreement with those of previous measurements and in qualitative agreement with predictions of phase shift analyses.

22 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.