HEPData Search

Interactions of 683-MeV/c negative pions with protons were investigated using the BNL 14-in. hydrogen bubble chamber in a 17-kG field. Two thousand elastic scatterings were analyzed, yielding a cross section of 18.9±1.0 mb. No evidence for powers of cosθ higher than the second was observed in the elastic angular distribution. The angular distribution obtained was dσdω=(0.384±0.026)+(1.70±0.06)cosθ+(3.36±0.11)cos2θ mb/sr. The single-pion production reactions π−+p→π−+π0+p and π−+p→π−+π++n were studied in detail. A total of 441 π0 productions and 833 π+ productions were analyzed giving cross sections of 3.99±0.50 and 7.50±0.80 mb, respectively. The differential distributions for these inelastic processes are presented and compared with the predictions of the model of Olsson and Yodh. The distribution of events on the Dalitz plots for π0 production is accounted for by the model. However, for the π+ reaction, the model (so far developed) does not describe adequately the distribution of events on the Dalitz plot. In particular, the model fails to account for the enhancement at high (π+π−) effective masses in ππ mass distribution. The center-of-mass angular distributions for π0 and π+ production reactions are presented and compared with the model.

3 data tables

Table 1

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pi++p Interactions at 646 MeV

Oliver, John D. ; Nadelhaft, I. ; Yodh, G.B. ;

Phys.Rev. 147 (1966) 932-938, 1966.

Inspire Record 944954 DOI 10.17182/hepdata.26654

A 14-in. liquid-hydrogen-filled bubble chamber in a 17.5-kG magnetic field was exposed to a beam of negative pions produced by the Cosmotron at Brookhaven National Laboratory. About 26 000 pictures were taken and examined for the following final states: (1) elastic scattering (π−p); (2) π+ production (π−π+n); (3) π0 production (π−π0p); (4) neutrals. Values for the cross sections for these processes are σ(elastic)=17.56±0.43 mb, σ(π+)=7.14±0.23 mb, σ(π0)=4.65±0.17 mb. The elastic-scattering angular dependence in the c.m. system is fitted by a power-series expansion in cosθ and gives the following coefficients: a0=0.27±0.02, a1=1.48±0.11, a2=3.86±0.22, a3=−0.29±0.53, a4=−0.65±0.28, a5=1.69±0.52 (units: mb/sr). Cross sections for multiple-pion production were also measured: σ(π−π+π0n)=0.33±0.04 mb, σ(π−π+π−p)=0.08±0.02 mb. The total neutral cross section was σ(neutrals)=11.78±0.43 mb; the total charged events cross section was σ(charged)=29.76±0.69 mb; and the total cross section was σ(total)=41.54±0.82 mb. For single-pion production events, two-body mass distributions and angular distributions were compared with the predictions of the Olsson-Yodh isobar model.

1 data table

Table 1

Axis error includes +- 0.0/0.0 contribution (?////STATISTICAL YIELD DOMINATES).

Pion production in $\pi^-$ - $p$ interactions at energies 790, 830, and 870 {MeV}

Cason, N.M. ; Derado, I. ; Lamsa, J.W. ; et al.

Phys.Rev. 150 (1966) 1134-1140, 1966.

Inspire Record 50370 DOI 10.17182/hepdata.26587

Single-pion production has been studied in the reactions π−p→π−π+n and π−p→π−π0p at 790, 830, and 870 MeV. A total of 4193 events in these two channels, divided approximately equally between the three energies, have been identified. The most interesting feature of the data is the tendency for events to concentrate at high values of mππ and low values of four-momentum transfer. These effects are discussed in terms of conventional isobar models and a model involving two-pion exchange. Partial cross sections for the reactions studied are reported for each energy.

1 data table

Table 1

No description provided.

Large-Angle Pion-Proton Elastic Scattering at High Energies

Orear, J. ; Rubinstein, R. ; Scarl, D.B. ; et al.

Phys.Rev. 152 (1966) 1162-1170, 1966.

Inspire Record 50774 DOI 10.17182/hepdata.407

Differential cross sections for elastic π±−p scattering have been measured at lab momenta of 8 and 12 GeV/c in a momentum-transfer region corresponding to 1.2≤−t≤6 (GeV/c)2. Also, differential cross sections near 180° were measured for 4 and 8 GeV/c pions. At momentum transfers greater than −t=2 (GeV/c)2, the π−p cross sections drop much faster with increasing angle than the corresponding p−p cross sections. Also, in the region −t≃1.3 (GeV/c)2, there is structure in the π−p angular distribution but not in the p−p angular distribution. At −t≃3 (GeV/c)2, the drop in cross section appears to stop and from then on the angular distribution is consistent with isotropy. But in the angular region 170° to 180°, the cross sections have become much larger, and sharp backward peaks are observed. Information is given on the energy and charge dependences and widths of these backward peaks.

22 data tables

Table 1

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Differential Pion Charge-Exchange Scattering and $\eta$ Production: $\pi^-+p\to \pi^0 + n$ from 2.4 to 3.8 GeV/c, at 6 GeV/c and at 10 GeV/c, $\pi^-+p\to \eta^0 + n$ at 10 GeV/c

Wahlig, M.A. ; Mannelli, I. ;

Phys.Rev. 168 (1968) 1515-1526, 1968.

Inspire Record 1186784 DOI 10.17182/hepdata.749

Small-angle differential cross sections are presented here for π−+p→π0+n charge-exchange scattering between 2.4 and 3.8 GeV/c. The differential cross section near t=0 displays two minima and one maximum in this momentum interval, reflecting the presence of the N32*(2420), N32*(2850), and N12*(2650) resonances; at larger t values, the cross sections fall off exponentially as a function of t, just as has been previously observed for charge-exchange scattering above 6 GeV/c. The pion-charge-exchange data reported here at 6 and 10 GeV/c extend out to large angles, showing a maximum near t=0, followed by an exponential falloff as e10t, a minimum near −t=0.6 (GeV/c)2, and then a second maximum near −t=1.0 (GeV/c)2. The π−+p→η0+n differential cross section shows a maximum near t=0, followed by an exponential falloff as e4t, much less steep than the π0 slope. These data are compared to our previously published data and to those of the Saclay-Orsay group.

15 data tables

Table 1

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Measurement of Polarization in pi-p Elastic Scattering from 229 to 390 MeV

Arens, John F. ; Chamberlain, Owen ; Dost, Helmut E. ; et al.

Phys.Rev. 167 (1968) 1261-1267, 1968.

Inspire Record 944940 DOI 10.17182/hepdata.26509

The polarization parameter in elastic π−p scattering has been measured, at the Berkeley 184-in. synchrocyclotron, with the use of a polarized proton target. At 318-, 337-, and 390-MeV incident pion kinetic energy, the angular range from 70° to 180° in the center-of-mass system was covered. At 229 MeV, polarization measurements were made in the angular range 150° to 180°. Phase-shift analyses, using these and other published data, were made at the two lowest energies.

4 data tables

Table 1

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