First exclusive data for the $pp \to nn\pi^+\pi^+$ reaction have been obtained at CELSIUS with the WASA detector setup at a beam energy of $T_p$ = 1.1 GeV. Total and differential cross sections disagree with theoretical calculations, which predict the $\Delta\Delta$ excitation to be the dominant process at this beam energy. Instead the data require the excitation of a higher-lying $\Delta$ state, most likely the $\Delta(1600)$, to be the leading process.
Total cross section.
Distribution of the invariant mass of the PI+PI+ system.
Distribution of the cosine of the PI+_PI+ opening angle DELTA at an incident kinetic energy of 1.1 GeV.
pp interactions at 11 momenta in the range 0.9 to 2.0 GeV/ c have been studied. The elastic angular distributions, covering the c.m. angular range 22°–90°, agree in general with Hoshizaki's phase-shift analysis which shows the looping 1 D in and 3 F 3 amplitudes in the Argand diagram. About 80% of pn π + events come from the n Δ ++ state at all momenta above 1.2 GeV/ c . The behavior of the density matrix elements of the Δ ++ show no momentum or angular dependence. A large fraction of pp π 0 events also come from the p Δ + state at all momenta above 1.2 GeV/ c . The behavior of the Δ + density matrix elements is similar to that for the case of Δ ++ .
No description provided.
No description provided.
No description provided.
The total and differential p¯p charge-exchange cross sections were obtained at seven momenta in the range 480 to 728 MeV/c. The total cross sections are roughly consistent with other data. The momentum dependences of the Legendre coefficients a1a0, a2a0, and a3a0 of the differential cross sections do not agree well with the predictions of the Bryan-Phillips model, unlike the case of elastic scattering.
TWO SETS OF DATA ARE GIVEN. THIS FIRST IS THAT PREFERRED USING THE CROSS SECTIONS OF BIZZARI ET AL.
SECOND SET USING BURROWS ET AL., CROSS SECTIONS.
DATA NORMALIZED TO THE CROSS SECTIONS OF HAMILTON ET AL., PRL 44, 1179 (1980).
p p elastic total and differential cross sections were measured at 17 incident momenta in the range 374–680 MeV/ c . No prominent feature was seen in them to clearly indicate the existence of the S-meson. There is, however, a small enhancement at the S-meson mass, which is equivalent to the elastic total cross section of 4.6 ± 2.1 mb. The behavior of the Legendre expansion coefficients of the angular distributions with incident momentum agrees well the predictions of the OBE model of Bryan and Phillips.
METHOD OF MOMENTS AND LEAST SQUARES FITS GAVE SIMILAR RESULTS.
No description provided.
No description provided.
A measurement of the differential cross section for the reaction np→ π 0 d has been made at the Lawrence Radiation Laboratory 184-inch cyclotron. A neutron beam with kinetic energies up to 720 MeV was incident on a liquid hydrogen target. The angle and momentum of the deuterons were measured using an analyzing magnet and wire spark chambers with a magnetostrictive readout. Deuterons were separated from protons by time-of-flight. The photons from the decaying π 0 were not detected. The neutron energy was calculated from the measured deuteron angle and momentum.
No description provided.
No description provided.
No description provided.
Forum