The angular and energy distributions of pions produced by 650-MeV protons and pion-nucleon correlations were studied using a liquid hydrogen bubble chamber. The present investigation indicates that the experimental angular distributions of neutral and charged pions are consis- tent with the assumption of isotopic spin conservation. The contributions of rrN subsystem states with isospin T 11'N = 7' 2 and % are measured; the contribution of the latter is 72 ± 3%.
No description provided.
The single-pion production reactions $pp\to d\pi^+$, $pp\to np\pi^+$ and $pp\to pp\pi^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The implementation of a central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight and angle measurements. Thus all pion production channels were recorded with 1-4 overconstraints. The total and differential cross sections obtained are compared to previous data and theoretical calculations. Main emphasis is put on the discussion of the $pp\pi^0$ channel, where we obtain angular distributions different from previous experimental results, however, partly in good agreement with recent phenomenological and theoretical predictions. In particular we observe very large anisotropies for the $\pi^0$ angular distributions in the kinematical region of small relative proton momenta revealing there a dominance of proton spinflip transitions associated with $\pi^0$ $s$- and $d$-partial waves and emphasizing the important role of $\pi^0$ d-waves.
Total cross section measurements.. Errors are mainly systematic.
Measured angular distribution for elastic P P scattering in the CM system normalised to the data in the SAID database (Arndt et al. PR C62,034005(2000). This measurement is made to determine the luminosity.
The measured pion angular distribution in the CM system in the reaction P P --> DEUT PI+.
The present data support a large anisotropy in accordance with phase shift predictions and in contrast to another recent experiment.
Measured deuteron angular distribution in the c.m. system. The errors shown are statistical only and there is an additional 10 PCT systematic uncertainty on the overall normalisation.
Legendre polynomial coefficients from a second order and fourth order fit.
Total cross section from second order fit.
The three polarization tensor components of the deuteron produced in the H( p , d )π + reaction have been measured for the first time. The experiment was performed using a vertically polarized proton beam produced by the SATURNE accelerator. The deuteron polarization was measured with the POLDER polarimeter. The three polarizing powers t 20 00 , t 21 00 and t 22 00 and the three spin-transfer observables t 20 11 , t 22 11 and t 22 11 have been extracted at a proton kinetic energy of 580 MeV over a wide angular range and at two fixed center-of-mass angles, 132° and 151°, between 800 and 1300 MeV. The six observables, calculated in the C.M. helicity frame, have been compared with predictions of the most refined partial-wave analyses and also with the predictions of a theoretical coupled-channel model which includes the NN-NΔ transition. The comparison between the data and the theory/partial-wave analyses shows some discrepancies which get worse with increasing proton energy. Adding these data to the world database should improve significantly future partial-wave analyses. The A y 0 analyzing power has also been measured over the same kinematical range. The partial-wave analysis predictions are in good agreement with this observable.
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Inclusive measurements of the pion differential cross sections and analyzing powers have been carried out for the pp→pnπ+ reaction at 420 and 500 MeV using the SASP spectrometer at TRIUMF. Pion energies from the onset of the continuum down to about 25 MeV were covered in the angular range from 23° to 100° (lab). Total cross sections of 0.750±0.075 mb and 2.77±0.28 mb were determined for the pp→pnπ+ reaction at 420 and 500 MeV, respectively. The experimental results are presented and discussed within the framework of a partial wave analysis. Theoretical predictions from a covariant one-boson-exchange model that includes final state interactions, provide a good description of the data. The pion spectra, in the region corresponding to low relative np energies, are also well described by a final state interaction model that uses the pp→dπ+ cross sections as input. Details of the determination of the background corrections and detector efficiencies will be discussed.
No description provided.
Only statistical errors are given.
Only statistical errors are given.
The p+p→π++d reaction is studied at excess energies between 0.275 and 3.86 MeV. Differential and total cross section were measured employing a magnetic spectrometer with nearly 4π acceptance in the center of mass system. The measured anisotropies between 0.008 and 0.29 indicate that the p wave is not negligible even so close to threshold. The data are compared to other data offering no evidence for charge symmetry breaking or time reversal violation. The s-wave and p-wave contributions at threshold are deduced.
The CONST is p-wave contribution to the cross section. The differential cross section is fitted usig the relations 4*pi*D(SIG)/D(OMEGA) = SIG + CONST*P2(COS(THETA)), where P2 denotes the Legendre polynomial.
We have measured angular distributions of differential cross sections and analyzing powers ( A y ) of the reaction p p → d π + at six incident proton energies between 1.3 and 2.4 GeV. They confirm the rapid variations at √ s = 2.65 GeV suggested by earlier experiments. Deviations from a monotonic behavior are also found in the excitation functions of the differential cross section at t = 0 or where Θ π + (c.m.) = 0°. Structures clearly appear at √ s = 2.4 and 2.65 GeV, in some coefficients of the associated Legendre function expansions of A y .
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The first spin-transfer observables for the πd→pp reaction have been measured at a number of energies spanning the Δ resonance in this system. These parameters correspond to KSL and KSS of the pp→dπ reaction for incident proton energies ranging from 600 to 800 MeV. Such data can provide an important constraint on the determination of the partial-wave amplitudes describing this fundamental reaction. The discrepancies between our data, theoretical predictions, and values calculated from published partial-wave amplitudes demonstrate the need for further work in this area.
No description provided.
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Forward angular distributions of the analysing power for the pp→d π + reaction have been measured at six energies T p =1.2, 1.4, 1.6, 1.8, 2.0, 2.3 GeV. A strong energy dependence is observed for A y 0 ( t =0) and A y 0 ( θ CM π =90°). The data are compared with the backward angular distributions previously published and suggest the existence of a resonant state in the pp system at the approximate energy of 2.7 GeV.
No description provided.
No description provided.
No description provided.
The differential cross section and analyzing power of the reaction pp → d π + were measured for nine incident proton energies between 725 and 1000 MeV. A magnetic spectrometer was used to detect either deuterons or pions. Cross-section and analyzing-power angular distributions were respectively fitted with Legendre polynomial and associated Legendre function expansions, the coefficients of which were found to vary smoothly with energy in the vicinity of the alleged 3 F 3 dibaryon resonance.
Data present here in form of Legendre polynomial fit.
Legendre Polynomial fit to cross section.
Legendre polynomial fit to analysing power.
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