Archivio Istituzionale della RicercaThe effect of contaminants (H2, N2, Ne, Ar, Xe) on the time distribution of delayed annihilations (average delay time about 3 μs) of antiprotons stopped in helium gas, at 3 atm and room temperature, has been experimentally investigated. The annihilation rate is expressed in terms of an empirical «quenching cross-section», σ ¯ , that is different for the different contaminants. For hydrogen and xenon at low concentrations, σ ¯ is around 3.5·10−16 cm2, and is more than ten times larger than for the other contaminants. It has been observed that the addition of a contaminant, with the exception of neon, gives also rise to a delayed annihilation’s component that decays with an average time of some hundreds of nanoseconds. It seems that this fast component increases and its average time decreases as the contaminant concentration increases.
Changes in the annihilation’s delay time distribution of stopped antiprotons in helium gas, due to contaminants. I / V. G., Ableev; A., Adamo; 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; B., Cereda; P., Cerello; C., Cicalo; M., Corradini; S., Costa; S., De Castro; Denisov, O. Y. u.; F., D’Isep; A., Donzella; L., Fava; A., Feliciello; L., Ferrero; A., Filippi; V., Filippini; D., Galli; R., Garfagnini; U., Gastaldi; B., Giacobbe; P., Gianotti; A., Grasso; C., Guaraldo; Iazzi, Felice; A., Lai; A., Lanaro; E., Lodi Rizzini; M., Lombardi; V., Lucherini; A., Maggiora; S., Marcello; U., Marconi; G. V., Margagliotti; G., Maron; A., Masoni; I., Massa; Minetti, Bruno; P., Montagna; M., Morando; L., Musa; F., Nichitiu; D., Panzieri; G., Pauli; M., Piccinini; G., Piragino; M., Poli; S. N., Prakhov; G., Puddu; R. A., Ricci; C., Rizzo; E., Rossetto; A., Rotondi; A. M., Rozhdestvensky; P., Salvini; L., Santi; M. G., Sapozhnikov; N., Semprini Cesari; S., Serci; R., Spighi; P., Temnikov; S., Tessaro; F., Tosello; V. I., Tretyak; G. L., Usai; L., Vannucci; S., Vecchi; G., Vedovato; L., Venturelli; M., Villa; A., Vitale; E., Zavattini; A., Zenoni; A., Zoccoli; G., Zosi. - In: NUOVO CIMENTO DELLA SOCIETÀ ITALIANA DI FISICA. A, NUCLEI, PARTICLES AND FIELDS. - ISSN 1124-1861. - 107:8(1994), pp. 1325-1337. [10.1007/BF02775771]
Changes in the annihilation’s delay time distribution of stopped antiprotons in helium gas, due to contaminants. I
AGNELLO, MICHELANGELO;IAZZI, Felice;MINETTI, Bruno;
1994
Abstract
The effect of contaminants (H2, N2, Ne, Ar, Xe) on the time distribution of delayed annihilations (average delay time about 3 μs) of antiprotons stopped in helium gas, at 3 atm and room temperature, has been experimentally investigated. The annihilation rate is expressed in terms of an empirical «quenching cross-section», σ ¯ , that is different for the different contaminants. For hydrogen and xenon at low concentrations, σ ¯ is around 3.5·10−16 cm2, and is more than ten times larger than for the other contaminants. It has been observed that the addition of a contaminant, with the exception of neon, gives also rise to a delayed annihilation’s component that decays with an average time of some hundreds of nanoseconds. It seems that this fast component increases and its average time decreases as the contaminant concentration increases.
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https://hdl.handle.net/11583/1845553
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