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Il Nuovo Cimento (1955-1965)

, Volume 3, Issue 4, pp 731–748 | Cite as

K-mesons in emulsions exposed to a 6.2 GeV proton beam

  • J. Ceussard
  • V. Fouché
  • J. Hennessy
  • G. Kayas
  • L. Leprince-Binguet
  • D. Morellet
  • F. Renard
Article

Summary

A large emulsion stack has been exposed in the 6.2 GeV proton beam of the Berkeley Bevatron. 414 K+ decaying at rest have been observed. Their probable time of flight is ~5-10-10s. 57 flat secondaries at or near minimum ionization have been extensively measured. The proportions of Kμ,Ξ, Kβ,ξ, τ and τ′ are found to be respectively around 54%, 26%, 8%, 4%, 7% and 1%. They are not significantly different from the proportions in stacks exposed to the K+ focused beam of the bevatron or to cosmic radiation, which indicates similarity in lifetimes and in relative frequencies of production for the different types of K’s. The average range of 8 stopping secondaries of Kµ and of 4 stopping secondaries of κ are respectively 202.0±1.9 mm and 118.8±1.7 mm. The masses of Kµ and κ deduced from these ranges are very close to the masses found by direct measurement in the K beam. Two κ events with secondaries of 61.5 and 90.5 MeV have been observed. The whole evidence on κ-mesons in large emulsion stacks is examined: it is felt that the results are so far consistent with the κ →π° +µ+v scheme. Five K--events have been found and are described.

Riassunto

Un grosso pacco di emulsioni è stato esposto al fasoio protonico di 6.2 GeV del bevatrone di Berkeley. Sono stati osservati 414 K+ disintegranti a riposo. Il loro probabile tempo di volo è ~ 5-10-10 s. Sono stati misurati in dettaglio 57 secondari piani al minimo o prossimi al minimo di ionizzazione. Le proporzioni di Kβ, κ, Kµ, κ,τ e τ’ risultano rispettivamente del 54%, 26%, 8%, 4%, 7% e 1%. Non differiscono, cioè, in modo significativo dalle proporzioni riscontrate in pacchi esposti al fascio focheggiato di K+ del bevatrone o alla radiazione cosmica, il che è indice di similitudine nella vita media e nelle frequenze relative di produzione dei differenti tipi di K. I range medi di 8 secondari di Kµ e di 4 secondari di κ giunti a riposo sono rispettivamente 202 ± 1.9 mm e 118.8 ± 1.7 mm. Le masse del Kµ e del κ dedotte da questi range sono assai prossime a quelle risultanti dalla misura diretta nel fascio dei K. Sono stati osservati 2 eventi κ con secondari di 61.5 e 90.5 MeV. Si esaminano tutti i dati noti sui κ nei grossi pacchi di emulsioni; si esprime il parere che finora i risultati sono compatibili con lo schema κ → π°+µ+v. Si sono trovati e si descrivono 5 eventi K-.

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Copyright information

© Società Italiana di Fisica 1956

Authors and Affiliations

  • J. Ceussard
    • 1
  • V. Fouché
    • 1
  • J. Hennessy
    • 1
  • G. Kayas
    • 1
  • L. Leprince-Binguet
    • 1
  • D. Morellet
    • 1
  • F. Renard
    • 1
  1. 1.Laboratoire de Physique de l’ École PolytechniqueParis

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