Summary
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»,\(\bar \sigma \), that is different for the different contaminants. For hydrogen and xenon at low concentrations,\(\bar \sigma \) 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.
Similar content being viewed by others
References
M. Ywasaki et al.:Phys. Rev. Lett.,67, 1246 (1991).
Interim report of PS205Collaboration (T. Yamasaki et al.): May 18, 1992.
A. Adamo et al.:Nucl. Phys. A,558, 665c (1993).
G. T. Condo et al.:Phys. Lett.,9, 65 (1964).
J. F. Russel:Phys. Rev. A,1, 721, 742 (1970).
L. Bracci andE. Zavattini: CERN-EP/89-48;Phys. Rev. A,41, 2352 (1990).
K. Richter et al.:Phys. Rev. Lett.,66, 149 (1991).
M. Agnello et al.:Phys. Lett. B,256, 349 (1991);A. Adamo et al.: Phys. Lett. B,285 15 (1992).
P. Buttazzo, G. V. Margagliotti, G. Pauli, C. Rizzo, S. Tessaro andE. Zavattini: Internal report OBX/TS/91/01.
Author information
Authors and Affiliations
Consortia
Rights and permissions
About this article
Cite this article
Ableev, V.G., Adamo, A., Agnello, M. et al. Changes in the Annihilation’s delay time distribution of stopped antiprotons in helium gas, due to contaminants.—I. Nuov Cim A 107, 1325–1337 (1994). https://doi.org/10.1007/BF02775771
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF02775771