Cheng, C.P.
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Isospin invariance in the reaction n p ---> pi0 d

Wilson, S.S. ; Longo, M.J. ; Young, K.K. ; et al.
Phys.Lett.B 35 (1971) 83-86, 1971.
Inspire Record 69283 DOI 10.17182/hepdata.28477

A measurement of the differential cross section for the reaction n + p → d + π° has been made using a neutron beam with kinetic energies up to 720 MeV. The angle and momentum of the deuterons were measured using an analyzing magnet and wire spark chambers with a magnetostrictive readout. The photons from the decaying π° were not detected. The neutron energy was calculated from the measured deuteron angle and momentum. The cross sections are compared to those for the reaction π + + d ⇆ p + p as a test of isotopic spin invariance in strong interactions. The symmetry of the cross sections about 90° is also investigated, and an upper limit of about 1% is placed on the real part of the ratio of isospin-violating to isospin-conserving amplitudes.

1 data table
Table 1

EKIN IS 325 TO 675 MEV.


pi-p Interactions at 460 MeV

Poirier, C.P. ; Tilger, C.A. ; Alyea, E.D. ; et al.
Phys.Rev. 148 (1966) 1311-1314, 1966.
Inspire Record 50913 DOI 10.17182/hepdata.26590

A total of 1589 two-prong events were observed in an exposure of the Brookhaven National Laboratory 14-in. bubble chamber at the Cosmotron. The fit to the elastic angular distribution requires terms through cos4θc.m.. The ratio of the inelastic cross sections σ(π−p→π−π+n)σ(π−p→π−π0p) is 3.75±0.46. The π−p→π−π+n reaction is dominated by formation of the π−n isobar and an enhancement in the di-pion mass spectrum previously reported by Kirz. The π−p→π−π0p reaction shows no structure in the effective-mass spectra.

1 data table
Table 1

No description provided.


$\pi^+p$ interactions at $T_\pi = 781$ MeV

Tilger, C.A. ; Poirier, C.P. ; Alyea, E.D., Jr. ; et al.
Phys.Rev. 142 (1966) 972-976, 1966.
Inspire Record 944956 DOI 10.17182/hepdata.26684

Interactions of 781-MeV π+ mesons with protons were investigated using the Brookhaven National Laboratory 14-in. hydrogen bubble chamber. A total of 2305 events was observed. The data were normalized to a total cross section of 22.2 mb, giving partial cross sections σ(π+p→π+p)=9.5±0.5 mb, σ(π+p→π+pπ0)=9.3±0.5 mb, σ(π+p→π+π+n)=2.15±0.17 mb, and a multiple-pion-production cross section of 1.15±0.17 mb. The elastic angular distribution was obtained and is dσdω=(0.25±0.03)+(0.90±0.11)cosθc.m.+(2.57±0.24)cos2θc.m.+(0.19±0.22)cos3θc.m.−(1.73±0.34)cos4c.m.. The kinetic-energy and angular distributions of the outgoing particles in single-pion production are given. The data are compared with other experiments in this energy region and their relevance to the shoulder in the π+p total cross section near 830 MeV is discussed.

1 data table