The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data

M. Aglietta, B. Alessandro, P. Antonioli, Francesco Arneodo, L. Bergamasco, M. Bertaina, C. Castagnoli, A. Castellina, A. Chiavassa, G. Cini, B. D'Ettorre Piazzoli, G. di Sciascio, W. Fulgione, P. Galeotti, P. L. Ghia, M. Iacovacci, G. Mannocchi, C. Morello, G. Navarra, O. Saavedra & 115 others A. Stamerra, G. C. Trinchero, S. Valchierotti, P. Vallania, S. Vernetto, C. Vigorito, M. Ambrosio, R. Antolini, A. Baldini, G. C. Barbarino, B. C. Barish, G. Battistoni, Y. Becherini, R. Bellotti, C. Bemporad, P. Bernardini, H. Bilokon, C. Bower, M. Brigida, S. Bussino, F. Cafagna, M. Calicchio, D. Campana, M. Carboni, R. Caruso, S. Cecchini, F. Cei, V. Chiarella, B. C. Choudhary, S. Coutu, M. Cozzi, G. de Cataldo, H. Dekhissi, C. de Marzo, I. de Mitri, J. Derkaoui, M. de Vincenzi, A. di Credico, O. Erriquez, C. Favuzzi, C. Forti, P. Fusco, G. Giacomelli, G. Giannini, N. Giglietto, M. Giorgini, M. Grassi, A. Grillo, F. Guarino, C. Gustavino, A. Habig, K. Hanson, R. Heinz, E. Iarocci, E. Katsavounidis, I. Katsavounidis, E. Kearns, H. Kim, S. Kyriazopoulou, E. Lamanna, C. Lane, D. S. Levin, P. Lipari, N. P. Longley, M. J. Longo, F. Loparco, F. Maaroufi, G. Mancarella, G. Mandrioli, A. Margiotta, A. Marini, D. Martello, A. Marzari-Chiesa, M. N. Mazziotta, D. G. Michael, P. Monacelli, T. Montaruli, M. Monteno, S. Mufson, J. Musser, D. Nicolò, R. Nolty, C. Orth, G. Osteria, O. Palamara, V. Patera, L. Patrizii, R. Pazzi, C. W. Peck, L. Perrone, S. Petrera, V. Popa, A. Rainò, J. Reynoldson, F. Ronga, C. Satriano, E. Scapparone, K. Scholberg, A. Sciubba, P. Serra, M. Sioli, G. Sirri, M. Sitta, P. Spinelli, M. Spinetti, M. Spurio, R. Steinberg, J. L. Stone, L. R. Sulak, A. Surdo, G. Tarlè, V. Togo, M. Vakili, C. W. Walter, R. Webb

    Research output: Contribution to journalArticle

    Abstract

    The cosmic ray primary composition in the energy range between 1015 and 1016 eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 105 m2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nμ) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30°. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nμ-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Δγ= 0.7±0.4 at E0∼4×1015 eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.

    Original languageEnglish (US)
    Pages (from-to)641-652
    Number of pages12
    JournalAstroparticle Physics
    Volume20
    Issue number6
    DOIs
    StatePublished - Mar 1 2004

    Fingerprint

    primary cosmic rays
    cosmic ray showers
    muons
    electromagnetism
    kinematics
    energy
    rocks
    detectors
    zenith
    showers
    rigidity
    nuclei
    thresholds
    propagation
    interactions

    ASJC Scopus subject areas

    • Astronomy and Astrophysics

    Cite this

    Aglietta, M., Alessandro, B., Antonioli, P., Arneodo, F., Bergamasco, L., Bertaina, M., ... Webb, R. (2004). The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data. Astroparticle Physics, 20(6), 641-652. https://doi.org/10.1016/j.astropartphys.2003.10.004

    The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data. / Aglietta, M.; Alessandro, B.; Antonioli, P.; Arneodo, Francesco; Bergamasco, L.; Bertaina, M.; Castagnoli, C.; Castellina, A.; Chiavassa, A.; Cini, G.; D'Ettorre Piazzoli, B.; di Sciascio, G.; Fulgione, W.; Galeotti, P.; Ghia, P. L.; Iacovacci, M.; Mannocchi, G.; Morello, C.; Navarra, G.; Saavedra, O.; Stamerra, A.; Trinchero, G. C.; Valchierotti, S.; Vallania, P.; Vernetto, S.; Vigorito, C.; Ambrosio, M.; Antolini, R.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Erriquez, O.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Guarino, F.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longley, N. P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.

    In: Astroparticle Physics, Vol. 20, No. 6, 01.03.2004, p. 641-652.

    Research output: Contribution to journalArticle

    Aglietta, M, Alessandro, B, Antonioli, P, Arneodo, F, Bergamasco, L, Bertaina, M, Castagnoli, C, Castellina, A, Chiavassa, A, Cini, G, D'Ettorre Piazzoli, B, di Sciascio, G, Fulgione, W, Galeotti, P, Ghia, PL, Iacovacci, M, Mannocchi, G, Morello, C, Navarra, G, Saavedra, O, Stamerra, A, Trinchero, GC, Valchierotti, S, Vallania, P, Vernetto, S, Vigorito, C, Ambrosio, M, Antolini, R, Baldini, A, Barbarino, GC, Barish, BC, Battistoni, G, Becherini, Y, Bellotti, R, Bemporad, C, Bernardini, P, Bilokon, H, Bower, C, Brigida, M, Bussino, S, Cafagna, F, Calicchio, M, Campana, D, Carboni, M, Caruso, R, Cecchini, S, Cei, F, Chiarella, V, Choudhary, BC, Coutu, S, Cozzi, M, de Cataldo, G, Dekhissi, H, de Marzo, C, de Mitri, I, Derkaoui, J, de Vincenzi, M, di Credico, A, Erriquez, O, Favuzzi, C, Forti, C, Fusco, P, Giacomelli, G, Giannini, G, Giglietto, N, Giorgini, M, Grassi, M, Grillo, A, Guarino, F, Gustavino, C, Habig, A, Hanson, K, Heinz, R, Iarocci, E, Katsavounidis, E, Katsavounidis, I, Kearns, E, Kim, H, Kyriazopoulou, S, Lamanna, E, Lane, C, Levin, DS, Lipari, P, Longley, NP, Longo, MJ, Loparco, F, Maaroufi, F, Mancarella, G, Mandrioli, G, Margiotta, A, Marini, A, Martello, D, Marzari-Chiesa, A, Mazziotta, MN, Michael, DG, Monacelli, P, Montaruli, T, Monteno, M, Mufson, S, Musser, J, Nicolò, D, Nolty, R, Orth, C, Osteria, G, Palamara, O, Patera, V, Patrizii, L, Pazzi, R, Peck, CW, Perrone, L, Petrera, S, Popa, V, Rainò, A, Reynoldson, J, Ronga, F, Satriano, C, Scapparone, E, Scholberg, K, Sciubba, A, Serra, P, Sioli, M, Sirri, G, Sitta, M, Spinelli, P, Spinetti, M, Spurio, M, Steinberg, R, Stone, JL, Sulak, LR, Surdo, A, Tarlè, G, Togo, V, Vakili, M, Walter, CW & Webb, R 2004, 'The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data', Astroparticle Physics, vol. 20, no. 6, pp. 641-652. https://doi.org/10.1016/j.astropartphys.2003.10.004
    Aglietta, M. ; Alessandro, B. ; Antonioli, P. ; Arneodo, Francesco ; Bergamasco, L. ; Bertaina, M. ; Castagnoli, C. ; Castellina, A. ; Chiavassa, A. ; Cini, G. ; D'Ettorre Piazzoli, B. ; di Sciascio, G. ; Fulgione, W. ; Galeotti, P. ; Ghia, P. L. ; Iacovacci, M. ; Mannocchi, G. ; Morello, C. ; Navarra, G. ; Saavedra, O. ; Stamerra, A. ; Trinchero, G. C. ; Valchierotti, S. ; Vallania, P. ; Vernetto, S. ; Vigorito, C. ; Ambrosio, M. ; Antolini, R. ; Baldini, A. ; Barbarino, G. C. ; Barish, B. C. ; Battistoni, G. ; Becherini, Y. ; Bellotti, R. ; Bemporad, C. ; Bernardini, P. ; Bilokon, H. ; Bower, C. ; Brigida, M. ; Bussino, S. ; Cafagna, F. ; Calicchio, M. ; Campana, D. ; Carboni, M. ; Caruso, R. ; Cecchini, S. ; Cei, F. ; Chiarella, V. ; Choudhary, B. C. ; Coutu, S. ; Cozzi, M. ; de Cataldo, G. ; Dekhissi, H. ; de Marzo, C. ; de Mitri, I. ; Derkaoui, J. ; de Vincenzi, M. ; di Credico, A. ; Erriquez, O. ; Favuzzi, C. ; Forti, C. ; Fusco, P. ; Giacomelli, G. ; Giannini, G. ; Giglietto, N. ; Giorgini, M. ; Grassi, M. ; Grillo, A. ; Guarino, F. ; Gustavino, C. ; Habig, A. ; Hanson, K. ; Heinz, R. ; Iarocci, E. ; Katsavounidis, E. ; Katsavounidis, I. ; Kearns, E. ; Kim, H. ; Kyriazopoulou, S. ; Lamanna, E. ; Lane, C. ; Levin, D. S. ; Lipari, P. ; Longley, N. P. ; Longo, M. J. ; Loparco, F. ; Maaroufi, F. ; Mancarella, G. ; Mandrioli, G. ; Margiotta, A. ; Marini, A. ; Martello, D. ; Marzari-Chiesa, A. ; Mazziotta, M. N. ; Michael, D. G. ; Monacelli, P. ; Montaruli, T. ; Monteno, M. ; Mufson, S. ; Musser, J. ; Nicolò, D. ; Nolty, R. ; Orth, C. ; Osteria, G. ; Palamara, O. ; Patera, V. ; Patrizii, L. ; Pazzi, R. ; Peck, C. W. ; Perrone, L. ; Petrera, S. ; Popa, V. ; Rainò, A. ; Reynoldson, J. ; Ronga, F. ; Satriano, C. ; Scapparone, E. ; Scholberg, K. ; Sciubba, A. ; Serra, P. ; Sioli, M. ; Sirri, G. ; Sitta, M. ; Spinelli, P. ; Spinetti, M. ; Spurio, M. ; Steinberg, R. ; Stone, J. L. ; Sulak, L. R. ; Surdo, A. ; Tarlè, G. ; Togo, V. ; Vakili, M. ; Walter, C. W. ; Webb, R. / The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data. In: Astroparticle Physics. 2004 ; Vol. 20, No. 6. pp. 641-652.
    @article{3be118e7a4cc4c338bc90750f7730c9d,
    title = "The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data",
    abstract = "The cosmic ray primary composition in the energy range between 1015 and 1016 eV, i.e., around the {"}knee{"} of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 105 m2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nμ) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30°. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nμ-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Δγ= 0.7±0.4 at E0∼4×1015 eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the {"}standard{"} galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.",
    author = "M. Aglietta and B. Alessandro and P. Antonioli and Francesco Arneodo and L. Bergamasco and M. Bertaina and C. Castagnoli and A. Castellina and A. Chiavassa and G. Cini and {D'Ettorre Piazzoli}, B. and {di Sciascio}, G. and W. Fulgione and P. Galeotti and Ghia, {P. L.} and M. Iacovacci and G. Mannocchi and C. Morello and G. Navarra and O. Saavedra and A. Stamerra and Trinchero, {G. C.} and S. Valchierotti and P. Vallania and S. Vernetto and C. Vigorito and M. Ambrosio and R. Antolini and A. Baldini and Barbarino, {G. C.} and Barish, {B. C.} and G. Battistoni and Y. Becherini and R. Bellotti and C. Bemporad and P. Bernardini and H. Bilokon and C. Bower and M. Brigida and S. Bussino and F. Cafagna and M. Calicchio and D. Campana and M. Carboni and R. Caruso and S. Cecchini and F. Cei and V. Chiarella and Choudhary, {B. C.} and S. Coutu and M. Cozzi and {de Cataldo}, G. and H. Dekhissi and {de Marzo}, C. and {de Mitri}, I. and J. Derkaoui and {de Vincenzi}, M. and {di Credico}, A. and O. Erriquez and C. Favuzzi and C. Forti and P. Fusco and G. Giacomelli and G. Giannini and N. Giglietto and M. Giorgini and M. Grassi and A. Grillo and F. Guarino and C. Gustavino and A. Habig and K. Hanson and R. Heinz and E. Iarocci and E. Katsavounidis and I. Katsavounidis and E. Kearns and H. Kim and S. Kyriazopoulou and E. Lamanna and C. Lane and Levin, {D. S.} and P. Lipari and Longley, {N. P.} and Longo, {M. J.} and F. Loparco and F. Maaroufi and G. Mancarella and G. Mandrioli and A. Margiotta and A. Marini and D. Martello and A. Marzari-Chiesa and Mazziotta, {M. N.} and Michael, {D. G.} and P. Monacelli and T. Montaruli and M. Monteno and S. Mufson and J. Musser and D. Nicol{\`o} and R. Nolty and C. Orth and G. Osteria and O. Palamara and V. Patera and L. Patrizii and R. Pazzi and Peck, {C. W.} and L. Perrone and S. Petrera and V. Popa and A. Rain{\`o} and J. Reynoldson and F. Ronga and C. Satriano and E. Scapparone and K. Scholberg and A. Sciubba and P. Serra and M. Sioli and G. Sirri and M. Sitta and P. Spinelli and M. Spinetti and M. Spurio and R. Steinberg and Stone, {J. L.} and Sulak, {L. R.} and A. Surdo and G. Tarl{\`e} and V. Togo and M. Vakili and Walter, {C. W.} and R. Webb",
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    TY - JOUR

    T1 - The cosmic ray primary composition between 1015 and 1016 eV from Extensive Air Showers electromagnetic and TeV muon data

    AU - Aglietta, M.

    AU - Alessandro, B.

    AU - Antonioli, P.

    AU - Arneodo, Francesco

    AU - Bergamasco, L.

    AU - Bertaina, M.

    AU - Castagnoli, C.

    AU - Castellina, A.

    AU - Chiavassa, A.

    AU - Cini, G.

    AU - D'Ettorre Piazzoli, B.

    AU - di Sciascio, G.

    AU - Fulgione, W.

    AU - Galeotti, P.

    AU - Ghia, P. L.

    AU - Iacovacci, M.

    AU - Mannocchi, G.

    AU - Morello, C.

    AU - Navarra, G.

    AU - Saavedra, O.

    AU - Stamerra, A.

    AU - Trinchero, G. C.

    AU - Valchierotti, S.

    AU - Vallania, P.

    AU - Vernetto, S.

    AU - Vigorito, C.

    AU - Ambrosio, M.

    AU - Antolini, R.

    AU - Baldini, A.

    AU - Barbarino, G. C.

    AU - Barish, B. C.

    AU - Battistoni, G.

    AU - Becherini, Y.

    AU - Bellotti, R.

    AU - Bemporad, C.

    AU - Bernardini, P.

    AU - Bilokon, H.

    AU - Bower, C.

    AU - Brigida, M.

    AU - Bussino, S.

    AU - Cafagna, F.

    AU - Calicchio, M.

    AU - Campana, D.

    AU - Carboni, M.

    AU - Caruso, R.

    AU - Cecchini, S.

    AU - Cei, F.

    AU - Chiarella, V.

    AU - Choudhary, B. C.

    AU - Coutu, S.

    AU - Cozzi, M.

    AU - de Cataldo, G.

    AU - Dekhissi, H.

    AU - de Marzo, C.

    AU - de Mitri, I.

    AU - Derkaoui, J.

    AU - de Vincenzi, M.

    AU - di Credico, A.

    AU - Erriquez, O.

    AU - Favuzzi, C.

    AU - Forti, C.

    AU - Fusco, P.

    AU - Giacomelli, G.

    AU - Giannini, G.

    AU - Giglietto, N.

    AU - Giorgini, M.

    AU - Grassi, M.

    AU - Grillo, A.

    AU - Guarino, F.

    AU - Gustavino, C.

    AU - Habig, A.

    AU - Hanson, K.

    AU - Heinz, R.

    AU - Iarocci, E.

    AU - Katsavounidis, E.

    AU - Katsavounidis, I.

    AU - Kearns, E.

    AU - Kim, H.

    AU - Kyriazopoulou, S.

    AU - Lamanna, E.

    AU - Lane, C.

    AU - Levin, D. S.

    AU - Lipari, P.

    AU - Longley, N. P.

    AU - Longo, M. J.

    AU - Loparco, F.

    AU - Maaroufi, F.

    AU - Mancarella, G.

    AU - Mandrioli, G.

    AU - Margiotta, A.

    AU - Marini, A.

    AU - Martello, D.

    AU - Marzari-Chiesa, A.

    AU - Mazziotta, M. N.

    AU - Michael, D. G.

    AU - Monacelli, P.

    AU - Montaruli, T.

    AU - Monteno, M.

    AU - Mufson, S.

    AU - Musser, J.

    AU - Nicolò, D.

    AU - Nolty, R.

    AU - Orth, C.

    AU - Osteria, G.

    AU - Palamara, O.

    AU - Patera, V.

    AU - Patrizii, L.

    AU - Pazzi, R.

    AU - Peck, C. W.

    AU - Perrone, L.

    AU - Petrera, S.

    AU - Popa, V.

    AU - Rainò, A.

    AU - Reynoldson, J.

    AU - Ronga, F.

    AU - Satriano, C.

    AU - Scapparone, E.

    AU - Scholberg, K.

    AU - Sciubba, A.

    AU - Serra, P.

    AU - Sioli, M.

    AU - Sirri, G.

    AU - Sitta, M.

    AU - Spinelli, P.

    AU - Spinetti, M.

    AU - Spurio, M.

    AU - Steinberg, R.

    AU - Stone, J. L.

    AU - Sulak, L. R.

    AU - Surdo, A.

    AU - Tarlè, G.

    AU - Togo, V.

    AU - Vakili, M.

    AU - Walter, C. W.

    AU - Webb, R.

    PY - 2004/3/1

    Y1 - 2004/3/1

    N2 - The cosmic ray primary composition in the energy range between 1015 and 1016 eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 105 m2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nμ) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30°. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nμ-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Δγ= 0.7±0.4 at E0∼4×1015 eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.

    AB - The cosmic ray primary composition in the energy range between 1015 and 1016 eV, i.e., around the "knee" of the primary spectrum, has been studied through the combined measurements of the EAS-TOP air shower array (2005 m a.s.l., 105 m2 collecting area) and the MACRO underground detector (963 m a.s.l., 3100 m w.e. of minimum rock overburden, 920 m2 effective area) at the National Gran Sasso Laboratories. The used observables are the air shower size (Ne) measured by EAS-TOP and the muon number (Nμ) recorded by MACRO. The two detectors are separated on average by 1200 m of rock, and located at a respective zenith angle of about 30°. The energy threshold at the surface for muons reaching the MACRO depth is approximately 1.3 TeV. Such muons are produced in the early stages of the shower development and in a kinematic region quite different from the one relevant for the usual Nμ-Ne studies. The measurement leads to a primary composition becoming heavier at the knee of the primary spectrum, the knee itself resulting from the steepening of the spectrum of a primary light component (p, He) of Δγ= 0.7±0.4 at E0∼4×1015 eV. The result confirms the ones reported from the observation of the low energy muons at the surface (typically in the GeV energy range), showing that the conclusions do not depend on the production region kinematics. Thus, the hadronic interaction model used (CORSIKA/QGSJET) provides consistent composition results from data related to secondaries produced in a rapidity region exceeding the central one. Such an evolution of the composition in the knee region supports the "standard" galactic acceleration/propagation models that imply rigidity dependent breaks of the different components, and therefore breaks occurring at lower energies in the spectra of the light nuclei.

    UR - http://www.scopus.com/inward/record.url?scp=1242351107&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=1242351107&partnerID=8YFLogxK

    U2 - 10.1016/j.astropartphys.2003.10.004

    DO - 10.1016/j.astropartphys.2003.10.004

    M3 - Article

    VL - 20

    SP - 641

    EP - 652

    JO - Astroparticle Physics

    JF - Astroparticle Physics

    SN - 0927-6505

    IS - 6

    ER -