Angular Distribution of Charge Exchange and Inelastic Neutrons in $\pi^- - p$ Interactions at 313 and 371 MeV

Lind, Don L. ; Barish, Barry C. ; Ku, Richard J. ; et al.
Phys.Rev. 138 (1965) B1509-B1517, 1965.
Inspire Record 1186787 DOI 10.17182/hepdata.467

Neutron angular distributions from the charge-exchange (π0n) and inelastic modes (π0π0n,π+π−n) of the π−−p interaction have been investigated at 313 and 371 MeV incident-pion kinetic energy. The data were obtained with an electronic counter system. Elastic and inelastic neutrons were separated in the all-neutral final states by time of flight. At both energies the charge-exchange differential cross section at the forward neutron angles differs from that determined by Caris et al. from measurements of the π0-decay gamma distributions, but generally agrees with the phase-shift-analysis calculations of Roper. The distribution of inelastic neutrons from both modes shows a strong preference for low center-of-mass neutron energies. The distribution of these neutrons does not correspond to that expected from the I=0, π−π interaction (ABC effect) suggested to account for the anomaly in p−d collisions observed by Abashian et al. Finally, all available charge-exchange differential-cross-section data from this and other experiments were combined by at least-squares fit to a Legendre expansion of the form dσdΩ*(cosθπ0*)=Σl=0NalPl(cosθπ0*) with the following results (in mb/sr):

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Elastic Scattering of Negative Pions by Protons at 230, 290, 370, and 427 Mev

Goodwin, Lester K. ; Kenney, Robert W. ; Perez-Mendez, Victor ;
Phys.Rev. 122 (1961) 655-664, 1961.
Inspire Record 944985 DOI 10.17182/hepdata.26809

The elastic differential cross section for the scattering of negative pions by hydrogen was measured at laboratory-system pion kinetic energies of 230, 290, 370, and 427 Mev. The elastically scattered pions were detected by a counter telescope which discriminated against recoil protons and inelastic pions on the basis of range. Differential cross sections were obtained at nine angles for each energy and were fitted by a least-squares program to a series of Legendre polynomials. At the three higher energies, D waves are required to give satisfactory fits to the data. The real parts of the forward-scattering amplitudes calculated from this experiment are in agreement with the predictions of dispersion theory. The results of this experiment, in conjunction with data from other pion-nucleon scattering experiments, support the hypothesis of charge independence at these higher energies.

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Total Cross Sections for Negative Pions on Protons at 230, 290, 370, 427, and 460 Mev

Caris, John C. ; Goodwin, Lester K. ; Kenney, Robert W. ; et al.
Phys.Rev. 122 (1961) 262-264, 1961.
Inspire Record 944986 DOI 10.17182/hepdata.26810

Total cross sections for negative pions on protons were measured at laboratory energies of 230, 290, 370, 427, and 460 Mev. The measurements were made in the same pion beams as and at energies identical with those of our π−−p differential scattering experiments. Comparisons of the total and differential scattering can be made with the dispersion theory at a given energy without introducing the systematic errors that would normally enter due to uncertainties in the parameters of more than one pion beam. The measured total cross sections are found to agree within statistics with other measured values, and with the sums of elastic, inelastic, and charge-exchange cross sections measured at this laboratory. The results are:

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Charge-Exchange Scattering of Negative Pions by Hydrogen at 230, 260, 290, 317, and 371 Mev

Caris, John C. ; Kenney, Robert W. ; Perez-Mendez, Victor ; et al.
Phys.Rev. 121 (1961) 893-904, 1961.
Inspire Record 944987 DOI 10.17182/hepdata.805

The differential cross section for charge-exchange scattering of negative pions by hydrogen has been observed at 230, 260, 290, 317, and 371 Mev. The reaction was observed by detecting one gamma ray from the π0 decay with a scintillation-counter telescope. A least-squares analysis was performed to fit the observations to the function dσdω=Σl=15alPl−1(cosθ) in the c.m. frame. The best fit to our experimental measurements requires only s- and p-wave scattering. The results (in mb) are: The least-squares analysis indicates that d-wave scattering is not established in this energy range.

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