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- 作者：Joachim Ullrich and Alexander Voitkiv
- 刊名：The European Physical Journal A - Hadrons and Nuclei
- 出版年：2003
- 出版时间：August 2003
- 年：2003
- 卷：17
- 期：4
- 页码：595-605
- 全文大小：644 KB
文摘
Kinematically complete measurements of the pp ? ppp0pp \to pp\pi^0 reaction were performed for beam energies in the range 292-298 MeV. We detected both protons in coincidence by using the large-acceptance COSY-TOF spectrometer and an external proton beam at COSY-JÃ&frac;lich; thus, we measured total and differential cross-sections and energy distributions. A strong enhancement was observed in the Dalitz plots due to the final-state interaction between the two outgoing protons; the data are well reproduced by Monte Carlo simulations using a standard scattering length of a0=-7.83 fm and effective range of r0=2.8 fm. Our measured total cross-sections are roughly 50 % 50\ % larger than those of recent internal-target experiments at IUCF and CELSIUS. This discrepancy may be due to the final-state interaction pushing some events into the very small-angle region which is almost inaccessible to an internal-target experiment. In the angular distributions we found only very slight deviations from isotropy. The analysis of our momentum distributions yielded a small fraction of 5¡À5 % 5\pm 5 \ % for Ps or Pp wave contributions.