Single-Pion Production in pp Collisions at 0.95-GeV/c (I)

The COSY-TOF collaboration El-Samad, S.Abd ; Bilger, R. ; Brinkmann, K. -Th. ; et al.
Eur.Phys.J.A 30 (2006) 443-453, 2006.
Inspire Record 725793 DOI 10.17182/hepdata.43429

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.

8 data tables

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+.

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Cross sections of the p p --> p p pi0 reaction between 310-MeV and 425-MeV

Bilger, R. ; Brodowski, W. ; Calén, H. ; et al.
Nucl.Phys.A 693 (2001) 633-662, 2001.
Inspire Record 566664 DOI 10.17182/hepdata.36159

None

1 data table

ABSOLUTE TOTAL CROSS SECTIONS.


Anisotropy in the pion angular distribution of the reaction pp -> pp pi0 at 400 MeV

Thorngren Engblom, P. ; Negasi Keleta, S. ; Cappellaro, F. ; et al.
Phys.Rev.C 76 (2007) 011602, 2007.
Inspire Record 725409 DOI 10.17182/hepdata.31500

The reaction pp -> pp pi0 was studied with the WASA detector at the CELSIUS storage ring. The center of mass angular distribution of the pi0 was obtained by detection of the gamma decay products together with the two outgoing protons, and found to be anisotropic with a negative second derivative slope, in agreement with the theoretical predictions from a microscopic calculation.

2 data tables

Acceptance corrected centre of mass PI0 angular distribution, normalized to 92.3 +- 7.2 MUB (Bilger et al.).

Acceptance corrected centre of mass PI0 angular distribution for relative proton momenta < 53 MeV, normalized to Bilger et al... Statistical errors only.


Study of the reaction p p --> p p pi0 within 10-MeV above the threshold.

The COSY-TOF collaboration AbdEl Samad, S. ; Bilger, R. ; Bohm, A. ; et al.
Eur.Phys.J.A 17 (2003) 595-606, 2003.
Inspire Record 605377 DOI 10.17182/hepdata.43625

Kinematically complete measurements of the $pp\to pp\pi^{0}$ reaction were performed for beam energies in the range $292 - 298 $MeV. By detecting both protons in coincidence with the large acceptance COSY-TOF spectrometer set up at an external beam line of the proton synchrotron COSY-Julich, total and differential cross sections and energy distributions were obtained. A strong enhancement is observed in the Dalitz plots resulting from the final state interaction between the outgoing proton pair: the data are well reproduced by Monte Carlo simulations with standard parameters for scattering length $a_0$=-7.83 fm and effective range $r_0$=2.8 fm. The total cross sections exceed the ones measured recently in internal target experiments at IUCF and CELSIUS by roughly 50%. Arguments are presented which link this discrepancy with the effect of the final state interaction pushing yield into the very small-angle region and the near-impossibility of an internal target experiment to cover just this range.

1 data table

Total P P --> P P PI0 cross section.


The p p ---> p p pi0 reaction near the kinematical threshold

Bondar, A. ; Calén, H. ; Carius, S. ; et al.
Phys.Lett.B 356 (1995) 8-12, 1995.
Inspire Record 406944 DOI 10.17182/hepdata.28488

The reaction pp → pp π 0 has been measured using electron-cooled protons incident on an internal gas-jet target at seven different incident beam energies, from 280.7 MeV (1 MeV above the reaction threshold) up to 310.2 MeV. The pions were measured by their decay photons. In the overlapping energy region, the measured total cross sections agree with those measured in a recent Indiana experiment. The angular distributions are consistent with a 3 P 0 → 1 S 0 s 0 transition in the full energy range studied. The kinematical distributions are well described when taking into account the final state and the Coulomb interactions.

1 data table

AN OVERALL 5 PCT ERROR IN NORMALIZATION IS NOT INCLUDED.


Measurement of the $p p$ Cross-sections in the Momentum Range 0.9-2.0 GeV/c

Shimizu, F. ; Kubota, Y. ; Koiso, H. ; et al.
Nucl.Phys.A 386 (1982) 571-588, 1982.
Inspire Record 11839 DOI 10.17182/hepdata.37042

The pp total, elastic, and all the inelastic cross sections were measured at 11 momenta in the range 0.9–2.0 GeV/c. No clear structure was observed in their momentum dependences. The momentum dependence of the total cross section agrees quite well with the result of a phase-shift analysis by Arndt. Our measurement of the ppπ 0 and pnπ + cross sections served to normalize the earlier systematic but relative and extrapolated measurements of these cross sections over a narrower momentum range. Calculations by König and Kroll based on a pion exchange model including the effect of an I = 1 dibaryon did not fit the single-pion production cross sections.

4 data tables

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Total cross-section for p + p ---> p + p + pi0 near threshold measured with the Indiana cooler

Meyer, H.O. ; Ross, M.A. ; Pollock, R.E. ; et al.
Phys.Rev.Lett. 65 (1990) 2846-2849, 1990.
Inspire Record 305682 DOI 10.17182/hepdata.19936

The total cross section for the reaction pp→ppπ0 was measured at nine center-of-mass energies from 1.5 to 23 MeV above threshold. The experiment was carried out with the Indiana Cooler, a recently constructed storage ring. The experimental advantages of an electron-cooled proton beam were utilized. The data cover an energy range where only the lowest possible angular momentum state contributes in the exit channel. The measured energy dependence of the total cross section is not compatible with that predicted by models of s-wave pion production and rescattering.

1 data table

No description provided.