Archivio Istituzionale della RicercaThe annihilation cross-sections at 66.4–68.9–71.4 MeV/c have been measured using the presently instrumented part of the OBELIX spectrometer. The results have been obtained at energies ( ≃ 2.5 MeV) by one order of magnitude smaller than in any existing experiment concerning the in-flight antiproton-proton annihilation. The average value obtained over the total interval 65.1–72.5 MeV/c, βσanT = 33.2 ± 1.7 (stat.) ±1.8 (syst.) mb, in agreement with a specific calculation, would favour for the spin-averaged S-wave scattering length the value (−0.7 + i0.8) fm. The branching ratios for the annihilations in two, four and six charged mesons turn out to be quite similar to those for annihilation at rest in liquid hydrogen.
Measurement of the anti-p p annihilation cross-sections at very low energies / Agnello, Michelangelo; F., Balestra; G., Belli; G., Bendiscioli; A., Bertin; P., Boccaccio; G. C., Bonazzola; T., Bressani; M., Bruschi; M. P., Bussa; L., Busso; D., Calvo; M., Capponi; M., Corradini; S., Costa; S., De Castro; D., D'Isep; I. V., Falomkin; L., Fava; A., Feliciello; L., Ferrero; V., Filippini; R., Garfagnini; U., Gastaldi; P., Gianotti; A., Grasso; C., Guaraldo; Iazzi, Felice; A., Lanaro; E., Lodi Rizzini; M., Lombardi; M. P., Macciotta; A., Maggiora; S., Marcello; U., Marconi; G. V., Margagliotti; G., Maron; M., Masala; A., Masoni; I., Massa; Minetti, Bruno; M., Morando; M., Morganti; D., Panzieri; G., Pauli; M., Piccinini; R., Piragino; M., Poli; G. B., Pontecorvo; G., Puddu; R. A., Ricc; A., Rotondi; A. M., Rozhdestvensky; P., Salvini; L., Santi; M. G., Sapozhnikov; G., Sartori; N., Semprini Cesari; S., Serci; F., Tosello; V. I., Tretyak; L., Vannucci; G., Vedovato; L., Venturelli; A., Vitale; A., Zenoni; A., Zoccoli; G., Zosi. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 256:3-4(1991), pp. 349-353.
Measurement of the anti-p p annihilation cross-sections at very low energies
AGNELLO, MICHELANGELO;IAZZI, Felice;MINETTI, Bruno;
1991
Abstract
The annihilation cross-sections at 66.4–68.9–71.4 MeV/c have been measured using the presently instrumented part of the OBELIX spectrometer. The results have been obtained at energies ( ≃ 2.5 MeV) by one order of magnitude smaller than in any existing experiment concerning the in-flight antiproton-proton annihilation. The average value obtained over the total interval 65.1–72.5 MeV/c, βσanT = 33.2 ± 1.7 (stat.) ±1.8 (syst.) mb, in agreement with a specific calculation, would favour for the spin-averaged S-wave scattering length the value (−0.7 + i0.8) fm. The branching ratios for the annihilations in two, four and six charged mesons turn out to be quite similar to those for annihilation at rest in liquid hydrogen.
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https://hdl.handle.net/11583/1799373
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