The effect of contaminants (H-2, N2, Ne, Ar, Xe) on the time distribution of delayed annihilations (average delay time about 3 mus) 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'' sigmaBAR, that is different for the different contaminants. For hydrogen and xenon at low concentrations, sigmaBAR 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 Annihilations Delay-time Distribution of Stopped Antiprotons In Helium Gas, Due To Contaminants .1.

BALESTRA, Ferruccio;BONAZZOLA, Giancarlo;BRESSANI, Tullio;BUSSA, Maria Pia;BUSSO, Luigi;COSTA, Sergio;FERRERO, Livio;GARFAGNINI, Raffaello;GRASSO, Antonino;MARCELLO, Simonetta;PANZIERI, Daniele;PIRAGINO, Guido;ZOSI, Gianfranco
1994-01-01

Abstract

The effect of contaminants (H-2, N2, Ne, Ar, Xe) on the time distribution of delayed annihilations (average delay time about 3 mus) 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'' sigmaBAR, that is different for the different contaminants. For hydrogen and xenon at low concentrations, sigmaBAR 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.
1994
107
1325
1337
25.43; antiproton annihilation delay; antiproton-He-4 annihilation; antiproton annihilation at rest
V. G. ABLEEV;A. ADAMO;M. AGNELLO;F. BALESTRA;G. BELLI;G. BENDISCIOLI;A. BERTIN;P. BOCCACCIO;G. C. BONAZZOLA;T. BRESSANI;M. BRUSCHI;M. P. B...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/105679
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