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Il Nuovo Cimento (1955-1965)

, 18:623 | Cite as

Central and peripheric interactions of 7.3 GeV negative pions in emulsions

  • E. M. Friedländer
  • M. Marcu
  • M. Spîrchez
Article

Summary

534 interactions of 7.3 GeV negative pions in an emulsion stack have been studied. Average multiplicities of heavy prongs and shower particles were obtained. Individual Lorentz factorsγc were computed for 395 showers withns⩾3. A detailed study is made of theγc-spectrum of events from light nuclei. This spectrum appears structured into head-on collisions with one or two nucleons and peripheric collisions involving one or two pions in the struck nucleon’s meson cloud. Pion-pion collisions show a marked « two-centre » structure, attributed tentatively to the formation and isotropic two pion decay of pionic resonant (isobaric) states of mass ∼3 μ. The e-e+-pair spectrum from π0-decay has been measured and yields an average inelasticity of ∼ 75% in π-nucleus collisions.

Riassunto

Si sono studiate 534 interazioni di pioni negativi a 7.3 GeV in un pacco di emulsioni. Si sono ottenute le molteplicità medie dei rami pesanti e delle particelle dello sciame. Si sono calcolati i fattori individuali di Lorentzγc per 395 sciami conns⩾3. Si è fatto uno studio dettagliato dello spettroγc di eventi da nuclei leggeri. Questo spettro risulta composto di collisioni centrali con uno o due nucleoni e collisioni periferiche che coinvolgono uno o due pioni nella nuvola mesonica del nucleone urtato. Le collisioni pione-pione presentano una marcata struttura a due centri, attribuita, in via di tentativo, alla formazione ed al decadimento isotropico in due pioni di stati pionici risonanti (isobarici) di massa ∼3 μ. Lo spettro della coppia e-e+ da decadimento π0 è stato misurato e dà una anelasticità media di ∼75% in collisioni π-nucleo.

References

  1. (1).
    E. M. Friedländer:Nuovo Cimento,14, 796 (1959).CrossRefGoogle Scholar
  2. (2).
    N. Birger andYu. Smorodin:Žurn. Ėksp. Theor. Fiz.,37, 1355 (1959).Google Scholar
  3. (3).
    R. Brown, U. Camerini, P. Fowler, N. Heitler, D. King andC. Powell:Phil. Mag.,40, 307 (1949).CrossRefGoogle Scholar
  4. (4).
    C. Castagnoli, G. Cortini, C. Franzinetti, A. Manfredini andD. Moreno:Nuovo Cimento,10, 1539 (1953).CrossRefMATHGoogle Scholar
  5. (5).
    E. M. Friedländer:Nuovo Cimento,12, 483 (1959).CrossRefGoogle Scholar
  6. (*).
    The validity of the correction formula derived in (5) has been proved by recent measurements (6,7).CrossRefMATHGoogle Scholar
  7. (6).
    P. Jain, E. Lohrmann andM. Teucher:Phys. Rev.,115, 643 (1959).ADSCrossRefGoogle Scholar
  8. (7).
    H. Winzeler, B. Klaiber, W. Koch, M. Nikolić andM. Schneeberger: preprint (1960).Google Scholar
  9. (8).
    E. Edwards, J. Losty, D. Perkins, K. Pinkau andJ. Reynolds:Phil. Mag.,3, 237 (1958).ADSCrossRefGoogle Scholar
  10. (9).
    N. Duller andW. Walker:Phys. Rev.,93, 215 (1954).ADSCrossRefMATHGoogle Scholar
  11. (*).
    Comparison of these amplitudes yields an interaction cross-section in nuclear matter for the incident pions ∼0.83 times the geometrical one. This corresponds to an interaction mean free path of 32.5 cm of emulsion, in good agreement with previous results (10) under similar conditions.CrossRefGoogle Scholar
  12. (10).
    P. Abrahamson, J. Ben-Arieh, G. Yekutieli andG. Alexander:Nuovo Cimento,12, 27 (1959).CrossRefGoogle Scholar
  13. (11).
    P. Ciok, J. Coghen, J. Gierula, R. Hołinsky, A. Jurak, M. Mięsowicz, J. Saniewska andJ. Pernegr:Nuovo Cimento,10, 741 (1958).CrossRefGoogle Scholar
  14. (12).
    G. Cocconi:Phys. Rev.,111, 1699 (1958).ADSCrossRefGoogle Scholar
  15. (13).
    F. Cerulus:Nuovo Cimento,14, 827 (1959);E. Eberle:Nuovo Cimento,8, 610 (1958);T. Gotō:Nuovo Cimento,8, 625 (1958);F. Cerulus andJ. von Behr:Nuovo Cimento,16, 1046 (1960);M. Manimenko:Žurn. Ėksp. Theor. Fiz.,38, 306 (1960).CrossRefGoogle Scholar
  16. (14).
    D. King:Phys. Rev.,109, 1344 (1958).ADSCrossRefGoogle Scholar
  17. (15).
    G. Bayatian, I. Gramenitzky, A. Nomofilov, M. Podgoretzky, andE. Skrzypczak:Žurn. Ėksp. Theor. Fiz.,36, 690 (1959).Google Scholar
  18. (16).
    G. B. Zhdanov:Žurn. Ėksp. Theor. Fiz.,34, 856 (1958).Google Scholar
  19. (17).
    E. M. Friedländer: to be published.Google Scholar

Copyright information

© Società Italiana di Fisica 1960

Authors and Affiliations

  • E. M. Friedländer
    • 1
  • M. Marcu
    • 1
  • M. Spîrchez
    • 1
  1. 1.Cosmic Ray LaboratoryInstitute of Atomic PhysicsBucharest

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