The associated charged particle multiplicity of high-pT π0 and single-photon events

M. Diakonou*, C. Kourkoumelis, L. K. Resvanis, T. A. Filippas, E. Fokitis, S. Karpathopoulos, A. M. Cnops, E. C. Fowler, D. M. Hood, T. Killian, T. Ludlam, R. B. Palmer, D. C. Rahm, P. Rehak, I. Stumer, D. Cockerill, C. W. Fabjan, A. Hallgren, M. Kreisler, D. LissauerI. Mannelli, W. Molzon, P. Mouzourakis, B. S. Nielsen, Y. Oren, L. Rosselt, W. J. Willis, O. Botner, H. Bøggild, E. Dahl-Jensen, I. Dahl-Jensen, G. Damgaard, K. H. Hansen, J. Hooper, R. Møller, S. Nielsen, B. Schistad, T. Akesson, S. Almehed, G. von Dardel, S. Henning, G. Jarlskog, B. Lörstad, A. Melin, U. Mjörnmark, A. Nilsson, L. Svensson, M. G. Albrow, N. A. McCubbin, O. Benary, S. Dagan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The associated charged particle multiplicities of high-pT π0 and single-photon events were measured at the CERN intersecting storage rings using lead/liquid-argon calorimeters and a scintillation counter array placed around the intersection region. The average multiplicity on the trigger side for the single-photon events was found to be significantly lower than that for the π0 events. The away-side multiplicity for both π0 and single-photon events increases with the trigger particle pT, but, at a fixed pT, the direct photon sample was found to have a slightly lower average multiplicity. The differences in the event structure can be explained if a large fraction of the single photons are produced via qg → γq constituent scattering.

Original languageEnglish
Pages (from-to)301-306
Number of pages6
JournalPhysics Letters B
Issue number2
StatePublished - 7 Apr 1980
Externally publishedYes


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