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1. First Measurement of a Long-Lived π+π− Atom Lifetime

Author

P. Chliapnikov, Bernardo Adeva, V. D. Ovsiannikov, A. Romero Vidal, V.I. Rykalin, Tomáš Trojek, D. Fluerasu, O.E. Gorchakov, P. Prusa, C. Guaraldo, S.V. Trusov, Y. Yoshimura, E. Kulish, A. Sidorov, Masami Chiba, A. Lamberto, Tomáš Čechák, J. Kluson, M. Plo, A. Anania, D. Drijard, M. Pentia, J. Saborido, Yoshihisa Iwashita, L. Kruglova, Z. Hons, A. Gorin, V. Kruglov, V. Brekhovskikh, G.F. Rappazzo, M. Gugiu, R. Lednicky, T. Urban, J. Schacher, Fujio Takeutchi, A. Ryazantsev, P. Zrelov, V. Olchevskii, A. Benelli, A. Dudarev, A. I. Kulikov, J. Smolik, Masaki Kobayashi, V. Yazkov, J. Martincik, M. Hansroul, K. Okada, C. Marinas, D. Dumitriu, A. Penzo, K. Gritsay, L. Nemenov, M. Nikitin, T. Vrba, V. Karpukhin, P. Doskarova, Armando Lanaro, S. Aogaki, S. Horikawa, and L. Afanasyev

Subjects
Physics, Quantum chromodynamics, Scattering, Isoscalar, Dirac (software), General Physics and Astronomy, chemistry.chemical_element, 01 natural sciences, chemistry, Orders of magnitude (time), 0103 physical sciences, Atom, Beryllium, Atomic physics, 010306 general physics, Ground state
Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π+π- atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 μm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, nAL=436-61+157|tot, the lifetime of the 2p state is found to be τ2p=(0.45-0.30+1.08|tot)×10-11 s, not contradicting the corresponding QED 2p state lifetime τ2pQED=1.17×10-11 s. This lifetime value is three orders of magnitude larger than our previously measured value of the π+π- atom ground state lifetime τ=(3.15-0.26+0.28|tot)×10-15 s. Further studies of long-lived π+π- atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

Published
2019
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2. Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Author

K. Gritsay, A.V. Kuptsov, Carlos Marinas, V. Kruglov, A. Ryazantsev, Masaaki Kobayashi, Y. Yoshimura, A. Sidorov, V.I. Rykalin, P. Chliapnikov, Bernardo Adeva, Tomáš Trojek, D. Fluerasu, Claude Amsler, P. Prusa, A. Anania, A. I. Kulikov, J. Smolik, Yoshihisa Iwashita, M. Plo, M. Nikitin, P. Doskarova, S. Constantinescu, M. Gugiu, J. Saborido, J. Martincik, M. Hansroul, L. Afanasyev, G. Caragheorgheopol, M. Pentia, R. Lednicky, L. Nemenov, Armando Lanaro, J. Schacher, O.E. Gorchakov, A. Penzo, L. Kruglova, Z. Hons, Y. Allkofer, A. Romero Vidal, O. Ullaland, C. Ciocarlan, L. Tauscher, V. Karpukhin, T. Vrba, Masami Chiba, D. Dumitriu, M. Duma, M. Zhabitsky, V. Brekhovskikh, C. Guaraldo, T. Urban, A. Lamberto, V. Olchevskii, S.V. Trusov, S. Horikawa, Tomáš Čechák, S. Aogaki, A. Benelli, C. Detraz, E. Kulish, D. Drijard, A. Gorin, Fujio Takeutchi, V. Yazkov, J. Kluson, P. Zrelov, K. Okada, A. Dudarev, and G.F. Rappazzo

Subjects
Physics, Nuclear and High Energy Physics, Spectrometer, Meson, 010308 nuclear & particles physics, Hadron, Dirac (software), 01 natural sciences, Particle identification, Nuclear physics, Excited state, 0103 physical sciences, Atom, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics, Ground state, Instrumentation, Particle Physics - Experiment
Abstract

The DIRAC spectrometer installed at CERN PS was upgraded in order to study simultaneously A2π and AπK atoms, namely the bound states of two π mesons, and of π and K mesons, respectively. The detector system can now accept a high intensity beam of 2–6×1011 primary protons per second. The electronics and the data-acquisition system can handle a very large amount of data to identify π, K, p, e and µ, allowing the selection of ππ and πK pairs in the offline analysis. The resolution of the longitudinal and transverse components of the relative momentum Q of each meson pair in their center-of-mass system with respect to the direction of the pair was substantially improved. The analysis of their distributions allowed an reliable separation between the meson pairs originating from hadronic atoms and the backgrounds permitting the measurement of the lifetimes of hadronic atoms in the ground state and π–π, π–K s-wave scattering lengths. The upgraded setup also allowed the study of the long-lived excited states of ππ atoms.

Published
2016
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3. Measurement of the πK atom lifetime and the πK scattering length

Author

L. Nemenov, L. Tauscher, Claude Amsler, P. Federicova, E. Kulish, P. Chliapnikov, Bernardo Adeva, D. Fluerasu, R. Lednicky, A. Anania, Y. Allkofer, V.I. Rykalin, J. Schacher, P. Zrelov, S. Horikawa, A. Romero Vidal, T. Vrba, C. Guaraldo, S. Aogaki, K. Gritsay, S.V. Trusov, P. Prusa, Carlos Marinas, M. Zhabitsky, A. Lamberto, A. Gorin, Yoshihisa Iwashita, Masaki Kobayashi, A. Penzo, M. Plo, A. Dudarev, Y. Yoshimura, M. Gugiu, A. Sidorov, Masami Chiba, V. Yazkov, L. Afanasyev, M. Pentia, V. Brekhovskikh, K. Okada, Fujio Takeutchi, Tomáš Čechák, G.F. Rappazzo, D. Dumitriu, L. Kruglova, Tomáš Trojek, M. Nikitin, J. Saborido, A. Benelli, V. Karpukhin, J. Kluson, J. Martincik, M. Hansroul, O.E. Gorchakov, Z. Hons, A.V. Kuptsov, A. Ryazantsev, D. Drijard, Armando Lanaro, V. Kruglov, A. I. Kulikov, J. Smolik, T. Urban, and V. Olchevskii

Subjects
Physics, Particle physics, Crystallography, 010308 nuclear & particles physics, 0103 physical sciences, Atom, Pi, Scattering length, 010306 general physics, 01 natural sciences
Abstract

After having announced the statistically significant observation ($5.6\ensuremath{\sigma}$) of the new exotic $\ensuremath{\pi}K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $\ensuremath{\pi}K$ data sample: $\ensuremath{\tau}=(5.{5}_{\ensuremath{-}2.8}^{+5.0})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}\text{ }\text{ }\mathrm{s}$. By means of a precise relation ($\ensuremath{\approx}1%$) between atom lifetime and scattering length, the following value for the $S$-wave isospin-odd $\ensuremath{\pi}K$ scattering length ${a}_{0}^{\ensuremath{-}}=\frac{1}{3}({a}_{1/2}\ensuremath{-}{a}_{3/2})$ has been derived: $|{a}_{0}^{\ensuremath{-}}|=(0.07{2}_{\ensuremath{-}0.020}^{+0.031}){M}_{\ensuremath{\pi}}^{\ensuremath{-}1}$.

Published
2017
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4. Observation ofπ−K+andπ+K−Atoms

Author

E. Kulish, L. Tauscher, M. Nikitin, V. Olchevskii, L. Kruglova, L. Afanasyev, V. Brekhovskikh, T. Urban, A. I. Kulikov, J. Smolik, A. Romero Vidal, M. Zhabitsky, A. Gorin, D. Fluerasu, A. Lamberto, Fujio Takeutchi, V. Karpukhin, O.E. Gorchakov, M. Pentia, T. Trojek, Y. Allkofer, A. Penzo, T. Vrba, K. Gritsay, J. Saborido, R. Lednicky, A. Anania, Masami Chiba, Masaaki Kobayashi, A.V. Kuptsov, V. Yazkov, A. Ryazantsev, C. Guaraldo, Z. Hons, Yoshihisa Iwashita, M. Plo, S.V. Trusov, V. Kruglov, M. Gugiu, D. Drijard, S. Horikawa, J. Martincik, M. Hansroul, K. Okada, Tomáš Čechák, S. Aogaki, P. Doskarova, D. Dumitriu, Y. Yoshimura, C. Marinas, A. Sidorov, Armando Lanaro, P. Chliapnikov, Bernardo Adeva, V.I. Rykalin, Claude Amsler, P. Prusa, A. Benelli, J. Kluson, G.F. Rappazzo, P. Zrelov, and A. Dudarev

Subjects
Physics, Large Hadron Collider, Meson, 010308 nuclear & particles physics, General Physics and Astronomy, chemistry.chemical_element, Scattering length, 01 natural sciences, Nickel, chemistry, Fragmentation (mass spectrometry), Ionization, 0103 physical sciences, Atom, Physics::Atomic and Molecular Clusters, Physics::Atomic Physics, Atomic physics, Nuclear Experiment, 010306 general physics, Platinum
Abstract

The observation of hydrogenlike πK atoms, consisting of π^{-}K^{+} or π^{+}K^{-} mesons, is presented. The atoms are produced by 24 GeV/c protons from the CERN PS accelerator, interacting with platinum or nickel foil targets. The breakup (ionization) of πK atoms in the same targets yields characteristic πK pairs, called "atomic pairs," with small relative momenta Q in the pair center-of-mass system. The upgraded DIRAC experiment observed 349±62 such atomic πK pairs, corresponding to a signal of 5.6 standard deviations. This is the first statistically significant observation of the strange dimesonic πK atom.

Published
2016
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5. Production and decay of $\eta^{\prime}(958)$ and $\eta (1440)$ in $\bar p p$ annihilation at rest

Author

M. Corradini, F. Nichitiu, A.M. Rozhdestvensky, G. Pauli, Paolo Montagna, Paola Salvini, M. Lombardi, Massimo Piccinini, El Rizzini, Roberto Spighi, F. Tosello, Ableev, A. Vitale, S. Decastro, O.E. Gorchakov, D. Galli, A M Rosca, C. Guaraldo, Lucherini, M.G. Sapozhnikov, Alberto Masoni, G. Maron, D. Calvo, L. Santi, O. Y. Denisov, Bruno Minetti, Antonietta Donzella, Felice Iazzi, Armando Lanaro, L. Fava, G. Bendiscioli, Umberto Marini Bettolo Marconi, C. Scoglio, F. Balestra, Nicola Semprini-Cesari, L. Busso, Filippini, C. Cicalo, A. Grasso, E. Rossetto, M. Capponi, M. Poli, Mauro Villa, L. Ferrero, G. Vedovato, L. Vannucci, P. Gianotti, S. Serci, S. Tessaro, Benedetto Giacobbe, Alberto Rotondi, A. Collamati, Tullio Bressani, F. Vigotti, C. Petrascu, D. Panzieri, U. Gastaldi, D. Parena, C. Cavion, Aldo Zenoni, G. Puddu, R. Garfagnini, S. Costa, Elena Botta, Michelangelo Agnello, S.N. Prakhov, Antonio Zoccoli, P. Cerello, A. Bertin, A. Lai, L. Musa, Antonio Ferretti, A. Filippi, R. Donà, A. Feliciello, Andrea Fontana, Mp Bussa, V.I. Tretyak, A. Maggiora, A. Saino, Stefania Vecchi, Marco Bruschi, L. Valacca, L. Venturelli, P.P. Temnikov, A. Vezzani, G. L. Usai, and S. Marcello

Subjects
Quantum chromodynamics, Rest (physics), Physics, Particle physics, Physics and Astronomy (miscellaneous), Glueball, Partial wave analysis, Pi, State (functional analysis), Engineering (miscellaneous), Pseudovector
Published
2004
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6. On the formation and decay of the atomcule

Author

F. Balestra, C. Petrascu, L. Santi, Antonietta Donzella, Armando Lanaro, M.P. Bussa, Germano Bonomi, C. Guaraldo, O. Y. Denisov, V. Lucherini, A.M. Rozhdestvensky, E. Lodi Rizzini, A. Grasso, M. Maggiora, Gianfranco Zosi, L. Busso, G. Piragino, G. V. Margagliotti, M.L. Colantoni, S.N. Prakhov, R. Vilar, M. Corradini, F. Tosello, S. Tessaro, L. Ferrero, G. Gomez, Andrea Bianconi, P. Gianotti, R. Garfagnini, L. Venturelli, V.I. Tretyak, A. Maggiora, and O.E. Gorchakov

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Microsecond, Large Hadron Collider, Metastability, Atomic physics, Nanosecond, Exotic atom, Bar (unit)
Abstract

Up to now it has been observed that a fraction of about 3% of the p 's stopped in a dense He target survives for a surprisingly long time (tens of microseconds). As suggested by Condo in 1964 the long lifetime of p 's in He is explained by the existence of metastable states of the exotic atom p He + . An analysis of data from p 's stopped in He targets at 3 bar pressure by the Obelix apparatus at the LEAR decelerator at CERN is presented. We do not observe any significative amount of “prompt” annihilations (few nanoseconds) after the p 's capture.

Published
2001
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7. Study of η and η′ production in annihilations

Author

Alberto Masoni, D. Calvo, A. Grasso, A.M. Rozhdestvensky, A. Filippi, O.E. Gorchakov, M. Capponi, Tullio Bressani, R. Donà, Germano Bonomi, Maurizio Piccinini, R. Spighi, S. Mauro, S. De Castro, Piergiorgio Cerello, C. Guaraldo, M. Poli, Michelangelo Agnello, S. Serci, Stefania Vecchi, Paolo Montagna, D. Panzieri, Bruno Minetti, Mauro Villa, M.G. Sapozhnikov, V. Filippini, Paola Salvini, E. Lodi Rizzini, V. Vagnoni, V.I. Tretyak, A. Maggiora, S.N. Prakhov, V. Lucherini, Aldo Zenoni, V.G. Ableev, G. Puddu, G. Bendiscioli, N. Semprini Cesari, F. Balestra, L. Venturelli, Maria Pia Bussa, L. Busso, U. Marconi, R. Garfagnini, B. Giacobbe, Antonio Zoccoli, S. Costa, Elena Botta, Marco Bruschi, A. Feliciello, A. Panzarasa, O. Y. Denisov, L. Vannucci, Andrea Bianconi, G. L. Usai, I. Massa, S. Marcello, F. D'Isep, Armando Lanaro, A. Vitale, G. Vedovato, Paola Gianotti, A. Bertin, D. Galli, Adriano Fontana, N. Mirfakhraee, F. Tosello, S. Tessaro, Felice Iazzi, Corrado Cicalo, Alberto Rotondi, and C. Petrascu

Subjects
Quark, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, P wave, Pseudoscalar meson, Nuclear physics, Pseudoscalar, Production (computer science), Mixing (physics), Line (formation)
Abstract

The annihilation fractions and cross sections for the n p annihilation reaction in flight (∼50–400 MeV/c) into ηπ+ and η′π+ final states have been measured. The first ones follow the trend expected for P wave annihilations. From the ratios of the yields an evaluation of the pseudoscalar mixing angle in the standard form is possible. The value found shows that for pseudoscalar meson production from P wave the Quark Line Rule is not grossly violated.

Published
1999
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8. and annihilation cross sections at very low energy

Author

N. Semprini Cesari, D. Galli, Andrea Bianconi, G. L. Usai, M.P. Bussa, Piergiorgio Cerello, S. Costa, G. Bendiscioli, Paola Salvini, Stefania Vecchi, R. A. Ricci, S.N. Prakhov, Adriano Fontana, I. Massa, N. Mirfakhrai, S. Marcello, L. Ferrero, L. Venturelli, C. Guaraldo, Maurizio Piccinini, R. Garfagnini, R. Spighi, F. D'Isep, Alberto Rotondi, Armando Lanaro, U. Marconi, M. Corradini, M. Capponi, A. Panzarasa, C. Petrascu, F. Tosello, S. Tessaro, G. Puddu, Tullio Bressani, A. Grasso, S. De Castro, A. Vitale, Elena Botta, U. Gastaldi, Antonio Zoccoli, S. Mauro, V.I. Tretyak, Alberto Masoni, S. Serci, M. Poli, Antonietta Donzella, A. Feliciello, V. Lucherini, D. Calvo, B. Giacobbe, Mauro Villa, V. Vagnoni, Paola Gianotti, Felice Iazzi, Corrado Cicalo, O.E. Gorchakov, Germano Bonomi, D. Panzieri, Michelangelo Agnello, A.M. Rozhdestvensky, A. Filippi, R. Donà, E. Lodi Rizzini, Aldo Zenoni, A. Bertin, Bruno Minetti, Marco Bruschi, F. Balestra, L. Vannucci, O. Y. Denisov, Paolo Montagna, and L. Busso

Subjects
Nuclear physics, Momentum, Physics, Nuclear and High Energy Physics, Cross section (physics), Low energy, Annihilation, Deuterium, Nuclear Experiment
Abstract

The p D and p 4 He total annihilation cross sections have been measured with the Obelix apparatus at LEAR at, respectively, three and two values of the p incident momentum between 70 MeV/c and 36 MeV/c. The values of the p D annihilation cross section, at such low energies, are in agreement with a surprising result obtained in a recent low statistics measurement of the antiprotonic deuterium K α X-rays [M. Augsburger et al., Phys. Lett. B 461 (1999) 417] (see following article), concerning the unexpected narrow width of the antiprotonic deuterium 1s level.

Published
1999
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9. Evidence for two pseudoscalar states in the 1.4–1.5 GeV mass region

Author

R. Spighi, A. Masoni, Germano Bonomi, L. Venturelli, V.I. Tretyak, V. Lucherini, D. Galli, A. Filippi, Bruno Minetti, A. Feliciello, Petar Temnikov, Antonio Zoccoli, D. D'Isep, M. Capponi, Tullio Bressani, R. Garfagnini, A. Grasso, S. Costa, A. Maggiora, M. Lombardi, L. Ferrero, O.E. Gorchakov, Elena Botta, A. De Falco, F. Tosello, S. Tessaro, Michelangelo Agnello, I. Massa, Mauro Villa, S.N. Prakhov, A. Panzarasa, S. Marcello, R. Donà, Sergio Serci, Alberto Rotondi, V. Filippini, F. Balestra, G. Vedovato, B. Giacobbe, U. Marconi, Vincenzo Vagnoni, C. Petrascu, Felice Iazzi, M. Bruschi, V.G. Ableev, D. Panzieri, Piergiorgio Cerello, A. Vitale, Aldo Zenoni, Stefania Vecchi, Adriano Fontana, M. Poli, Corrado Cicalo, G. Puddu, M. Piccinini, D. Calvo, C. Guaraldo, P. Montagna, N. Semprini Cesari, Paola Gianotti, Andrea Bianconi, G. L. Usai, S. Mauro, E. Lodi Rizzini, Paola Salvini, A.M. Rozhdestvensky, N. Mirfakhrai, Armando Lanaro, S. De Castro, O. Y. Denisov, L. Busso, and A. Bertin

Subjects
Pseudoscalar, Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics
Abstract

A confirming evidence for two pseudoscalar states with masses M 1 =1405±5, Γ 1 =50±4 MeV/ c 2 and M 2 =1500±10, Γ 2 =100±20 MeV/ c 2 is reported. The second pseudoscalar fills the nonet and leaves the first as an outsider supporting the hypothesis for its exotic nature.

Published
1999
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10. Study of φ and f′2(1525) meson production in annihilation at rest

Author

M. Capponi, Tullio Bressani, U. Gastaldi, A. Feliciello, S. Mauro, Paola Salvini, Armando Lanaro, V. Vagnoni, L. Valacca, D. D'Isep, L. Fava, G. Puddu, M. Poli, L. Venturelli, G. Vedovato, Paola Gianotti, U. Marconi, A. Filippi, A.M. Rozhdestvensky, C. Scoglio, S. De Castro, R. Donà, D. Galli, S. Costa, A. Vitale, Alberto Masoni, S.N. Prakhov, L. Ferrero, R. Spighi, S. Serci, D. Calvo, M. Corradini, F. Nichitiu, Alberto Rotondi, C. Petrascu, V.P. Nomokonov, B. Giacobbe, O.E. Gorchakov, N. Semprini Cesari, A M Rosca, D. Panzieri, N. Mirfakhrai, G. Pauli, A. Panzarasa, S. Marcello, L. Santi, V. Filippini, Maurizio Piccinini, Marco Bruschi, Antonio Zoccoli, Elena Botta, Piergiorgio Cerello, C. Cavion, V.I. Tretyak, Michelangelo Agnello, M.P. Bussa, A. Maggiora, V. Lucherini, Aldo Zenoni, L. Busso, Stefania Vecchi, L. Vannucci, Petar Temnikov, Mauro Villa, A. Bertin, F. Tosello, S. Tessaro, A Alberico, E. Lodi Rizzini, R. Bianconi, R. Garfagnini, A. Grasso, Felice Iazzi, Corrado Cicalo, F. Vigotti, G. L. Usai, F. Balestra, Adriano Fontana, A. Ferretti, Paolo Montagna, C. Guaraldo, Bruno Minetti, G. Bendiscioli, O.Yu. Denisov, M. Lombardi, M.G. Sapozhnikov, V.G. Ableev, and G. Maron

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, OZI rule, Branching fraction, Antiproton, Yield (chemistry), Mass spectrum, Dalitz plot, Quantum number
Abstract

The reaction p p→K + K − π 0 was analysed for antiproton annihilations at rest at three hydrogen target densities. A strong dependence of the p p→φπ 0 yield on the quantum numbers of the initial state is observed. The branching ratio of the φπ0 channel from the 3S1 initial state is more than 15 times larger than the one from the 1P1 state. A large apparent violation of the OZI rule for tensor meson production from p p -annihilations from the P-waves (1+++2++) is observed: Rexp(f′2π0/f2π0)=(149±20)·10−3, significantly exceeding the OZI-rule prediction R=16·10−3.

Published
1998
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11. Study of the isovector scalar mesons in the channel p̄p→K±K0Sπ∓ at rest with initial angular momentum state selection

Author

V. Filippini, N. Semprini Cesari, L. Santi, Antonietta Donzella, C. Scoglio, C. Cavion, Aldo Zenoni, A. Masoni, Felice Iazzi, Gianfranco Zosi, Tullio Bressani, U. Gastaldi, S. Mauro, Armando Lanaro, G. Bendiscioli, Adriano Fontana, Piergiorgio Cerello, G. Pauli, F. Vigotti, M. Poli, Corrado Cicalo, M. Capponi, A. Saino, S. Costa, Elena Botta, O. Y. Denisov, G. Vedovato, D. Calvo, Petar Temnikov, R. A. Ricci, Paola Gianotti, M. Corradini, Michelangelo Agnello, A. Bertin, S.N. Prakhov, F. Tosello, S. Tessaro, Paolo Montagna, A. Grasso, A. Feliciello, C. Guaraldo, Antonio Ferretti, L. Ferrero, A.M. Rozhdestvensky, F. Balestra, Benedetto Giacobbe, Roberto Spighi, G. Puddu, Paola Salvini, Massimo Piccinini, A. Benedettini, M. Lombardi, G. L. Usai, R. Garfagnini, Umberto Marini Bettolo Marconi, E. Lodi Rizzini, Alberto Rotondi, C. Petrascu, G. Maron, D. D'Isep, D. Galli, S. Marcello, V.I. Tretyak, R. Donà, Bruno Minetti, S. De Castro, A. Filippi, L. Busso, E. Rossetto, M.G. Sapozhnikov, M.P. Bussa, Stefania Vecchi, V. Lucherini, V.G. Ableev, D. Panzieri, Mauro Villa, L. Valacca, L. Venturelli, Sergio Serci, A. Vitale, A. Maggiora, O.E. Gorchakov, Marco Bruschi, A M Rosca, V. Vagnoni, F. Nichitiu, and Antonio Zoccoli

Subjects
Hydrogen density, Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Angular momentum, Isovector, Meson, Scalar (physics)
Abstract

The study of the I =1, J PC =0 ++ states with the OBELIX detector in the channel p p→K ± K 0 S π ∓ at three different target densities is reported. The data show the evidence for an extra scalar state with mass 1.29±0.01 GeV/ c 2 and width 0.080±0.005 GeV/ c 2 .

Published
1998
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12. Dynamical selection rules from p anti-p annihilation at rest in three meson final states

Author

G. Puddu, Paolo Montagna, R. Garfagnini, P. Cerello, Antonio Zoccoli, V. Filippini, M. Corradini, A. Bertin, F. Nichitiu, L. Venturelli, C. Guaraldo, E. Lodi Rizzini, Michelangelo Agnello, Armando Lanaro, Elena Botta, G. Pauli, Felice Iazzi, C. Cavion, S.N. Prakhov, Aldo Zenoni, M. Astrua, A. Saino, G. L. Usai, L. Ferrero, Andrea Fontana, G. Vedovato, L. Fava, S. Marcello, L. Vannucci, Alberto Andrighetto, A. Grasso, V.I. Tretyak, O. Y. Denisov, Alberto Rotondi, Mauro Villa, A. Maggiora, S. De Castro, Antonietta Donzella, Roberto Spighi, M. Lombardi, C. Petrascu, F. D'Isep, D. Parena, Benedetto Giacobbe, Antonio Ferretti, F. Tosello, A. Feliciello, A. Filippi, A. Vezzani, Bruno Minetti, L. Busso, D. Galli, M. Morando, S. Serci, A.M. Rozhdestvensky, E. Rossetto, M.G. Sapozhnikov, A. Vitale, N. Mirfakhraee, Umberto Marini Bettolo Marconi, S. Tessaro, P.P. Temnikov, Massimo Piccinini, Paola Salvini, I. D'Antone, Marco Bruschi, M.P. Bussa, R. A. Ricci, M. Capponi, Stefania Vecchi, V.G. Ableev, D. Panzieri, O.E. Gorchakov, A M Rosca, Alberto Masoni, D. Calvo, V. Lucherini, G. Bendiscioli, F. Balestra, C. Cicalo, N. Semprini Cesari, L. Santi, S. Costa, P. Gianotti, Tullio Bressani, U. Gastaldi, M. BARGIOTTI, A. BERTIN, M. BRUSCHI, M. CAPPONI, A. CARBONE, S. DE CASTRO, R. DONÀ, L. FABBRI, P. FACCIOLI, D. GALLI, B. GIACOBBE, F. GRIMALDI, U. MARCONI, I. MASSA, M. PICCININI, N. SEMPRINI CESARI, R. SPIGHI, S. VECCHI, M. VILLA, A. VITALE, A. ZOCCOLI, M. POLI, A. BIANCONI, M.P. BUSSA, M. CORRADINI, A. DONZELLA, E. LODI RIZZINI, L. VENTURELLI, C. CICALÒ, A. DE FALCO, A. MASONI, G. PUDDU, S. SERCI, G. USAI, O.E. GORCHAKOV, S.N. PRAKHOV, A.M. ROZHDESTVENSKY, M.G. SAPOZHNIKOV, V.I. TRETYAK, P. GIANOTTI, C. GUARALDO, A. LANARO, V. LUCHERINI, C. PETRASCU, R. A. RICCI, V. FILIPPINI, A. FONTANA, P. MONTAGNA, A. PANZARASA, A. ROTONDI, P. SALVINI, A. ZENONI, F. BALESTRA, L. BUSSO, P. CERELLO, O. DENISOV, L. FERRERO, R. GARFAGNINI, A. MAGGIORA, D. PANZIERI, F. TOSELLO, E. BOTTA, T. BRESSANI, D. CALVO, F. DE MORI, A. FELICIELLO, A. FILIPPI, N. MIRFAKHRAI, S. MARCELLO, M. AGNELLO, and F. IAZZI

Subjects
Physics, Annihilation, Physics and Astronomy (miscellaneous), Meson, Hydrogen, Hadron, chemistry.chemical_element, Coincidence, chemistry, Protonium, Isospin, Production (computer science), Atomic physics, Engineering (miscellaneous)
Abstract

The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from the observation of the reactions pbarp→π+π−π0, K+K−π0,KπK0 at rest in hydrogen targets at different densities. The enhancement or suppression of specific hadronic channels connected to dynamical selection rules is observed in the production of different resonances both in protonium S and P–waves, systematically investigated for the first time. Besides the well known ρ(770)π and a2(1320)π enhancement from 3S1 and 1S0 partial waves, the dominance of one isospin source in K*(892)Kbar production, well established from S–waves, is confirmed also in P–waves (1S0, I = 0; 3S1, I = 1; 1P1, I = 0; 3P1, I = 0; 3P2, I = 1). In addition, the experimental data clearly show a strong suppression of φ(1020)π and a0(980)π final states from P–wave which has a remarkable coincidence with K*(892)Kbar pattern production.

Published
2004

13. Antiproton stopping power in He in the energy range 1-KeV - 900-keV and the Barkas effect

Author

Maurizio Piccinini, S. De Castro, F. Tosello, S. Tessaro, C. Guaraldo, G.B. Pontecorvo, A. Grasso, L. Ferrero, Nicola Zurlo, Mauro Villa, M. Bargiotti, G. V. Margagliotti, M. Poli, A. Bertin, C. Petrascu, Gianfranco Zosi, Andrea Bianconi, I. Massa, M. Leali, A.M. Rozhdestvensky, E. Lodi Rizzini, F. Balestra, M.P. Bussa, Stefania Vecchi, Laura Fabbri, O. Y. Denisov, R. Donà, M. Capponi, L. Busso, N. Semprini Cesari, L. Santi, L. Venturelli, G. Piragino, Antonietta Donzella, B. Giacobbe, V.I. Tretyak, A. Vitale, Marco Bruschi, A. Maggiora, O.E. Gorchakov, R. Garfagnini, Antonio Zoccoli, Pietro Faccioli, F. Grimaldi, R. Spighi, M. Corradini, RUS, DIP. DI FISICA, DIPARTIMENTO DI FISICA E ASTRONOMIA 'AUGUSTO RIGHI', Facolta' di INGEGNERIA, SECONDA FACOLTA' DI INGEGNERIA DELL'UNIVERSITA' DI BOLOGNA CON SEDE CESENA, Da definire, AREA MIN. 02 - Scienze fisiche, E., Lodirizzini, A., Bianconi, M. P., Bussa, M., Corradini, A., Donzella, M., Leali, L., Venturelli, N., Zurlo, M., Bargiotti, A., Bertin, M., Bruschi, M., Capponi, S., DE CASTRO, R., Don, L., Fabbri, P., Faccioli, B., Giacobbe, F., Grimaldi, I., Massa, M., Piccinini, N., Semprinicesari, R., Spighi, S., Vecchi, M., Villa, A., Vitale, A., Zoccoli, O. E., Gorchakov, G. B., Pontecorvo, A. M., Rozhdestvensky, V. I., Tretyak, M., Poli, C., Guaraldo, C., Petrascu, F., Balestra, L., Busso, O. Y., Denisov, L., Ferrero, R., Garfagnini, A., Grasso, A., Maggiora, G., Piragino, F., Tosello, G., Zosi, Margagliotti, Giacomo, L., Santi, Tessaro, Susanna, E. Lodi Rizzini, A. Bianconi, M.P. Bussa, M. Corradini, A. Donzella, M. Leali, L. Venturelli, N. Zurlo, M. Bargiotti, A. Bertin, M. Bruschi, M. Capponi, S. De Castro, R. Dona, L. Fabbri, P. Faccioli, B. Giacobbe, F. Grimaldi, I. Massa, M. Piccinini, N. Semprini-Cesari, R. Spighi, S. Vecchi, M. Villa, A. Vitale, A. Zoccoli, O.E. Gorchakov, G.B. Pontecorvo, A.M. Rozhdestvensky, V. Tretyak, M. Poli, C. Guaraldo, C. Petrascu, F. Balestra, L. Busso, O.Yu. Denisov, L. Ferrero, R. Garfagnini, A. Grasso, A. Maggiora, G. Piragino, F. Tosello, G. Zosi, G. Margagliotti, L. Santi, and S. Tessaro

Subjects
Physics, Range (particle radiation), Nuclear and High Energy Physics, Proton, chemistry.chemical_element, Stopping power, Barkas, Kinetic energy, Nuclear physics, chemistry, Fundamental difference, Antiproton, Stopping power (particle radiation), Atomic physics, Helium, Energy (signal processing)
Abstract

none 46 The stopping power in helium from 1 keV kinetic energy is evaluated. Contrary to the effect observed around and below the maximum, Obelix data indicate a stopping power higher than that for proton, the difference being of the order of 15±5% at ≈700 keV. The result contributes to assert the fundamental difference between stoppings in the simplest gases (He, H2) and in solid targets below some MeV. none E. Lodi Rizzini; A. Bianconi; M.P. Bussa; M. Corradini; A. Donzella; M. Leali; L. Venturelli; N. Zurlo; M. Bargiotti; A. Bertin; M. Bruschi; M. Capponi; S. De Castro; R. Dona; L. Fabbri; P. Faccioli; B. Giacobbe; F. Grimaldi; I. Massa; M. Piccinini; N. Semprini-Cesari; R. Spighi; S. Vecchi; M. Villa; A. Vitale; A. Zoccoli; O.E. Gorchakov; G.B. Pontecorvo; A.M. Rozhdestvensky; V. Tretyak; M. Poli; C. Guaraldo; C. Petrascu; F. Balestra; L. Busso; O.Yu. Denisov; L. Ferrero; R. Garfagnini; A. Grasso; A. Maggiora; G. Piragino; F. Tosello; G. Zosi; G. Margagliotti; L. Santi; S. Tessaro E. Lodi Rizzini; A. Bianconi; M.P. Bussa; M. Corradini; A. Donzella; M. Leali; L. Venturelli; N. Zurlo; M. Bargiotti; A. Bertin; M. Bruschi; M. Capponi; S. De Castro; R. Dona; L. Fabbri; P. Faccioli; B. Giacobbe; F. Grimaldi; I. Massa; M. Piccinini; N. Semprini-Cesari; R. Spighi; S. Vecchi; M. Villa; A. Vitale; A. Zoccoli; O.E. Gorchakov; G.B. Pontecorvo; A.M. Rozhdestvensky; V. Tretyak; M. Poli; C. Guaraldo; C. Petrascu; F. Balestra; L. Busso; O.Yu. Denisov; L. Ferrero; R. Garfagnini; A. Grasso; A. Maggiora; G. Piragino; F. Tosello; G. Zosi; G. Margagliotti; L. Santi; S. Tessaro

Published
2004

14. Study of the annihilation from S states

Author

D. Galli, G. L. Usai, Paolo Montagna, Alberto Masoni, O.E. Gorchakov, I. Massa, A M Rosca, Michelangelo Agnello, Armando Lanaro, S. Marcello, M.P. Bussa, Stefania Vecchi, C. Scoglio, F. Tosello, A. Saino, S. Tessaro, V. Filippini, S. De Castro, M. Corradini, U. Marconi, Antonietta Donzella, A.M. Rozhdestvensky, C. Cavion, Aldo Zenoni, A. Feliciello, L. Perrero, A. Vitale, D. D'Isep, B. Giacobbe, Marco Bruschi, Bruno Minetti, Alberto Rotondi, L. Vannucci, S. Serci, F. Nichitiu, A. Bertin, C. Petrascu, M. Lombardi, S. Costa, M. Poli, Elena Botta, Maurizio Piccinini, G. Vedovato, G. Pauli, M.G. Sapozhnikov, V.I. Tretyak, P.P. Temnikov, Gianfranco Zosi, Paola Gianotti, A. Maggiora, V. Lucherini, V.G. Ableev, Adriano Fontana, L. Busso, A. Ferretti, A. Collamati, Mauro Villa, L. Valacca, S.N. Prakhov, L. Venturelli, N. Semprini Cesari, R. Garfagnini, Piergiorgio Cerello, A. Grasso, Felice Iazzi, Paola Salvini, R. Spighi, A. Filippi, L. Santi, G. Maron, Corrado Cicalo, R. Donà, F. Vigotti, M. Capponi, Tullio Bressani, U. Gastaldi, F. Balestra, C. Guaraldo, G. Bendiscioli, O.Yu. Denisov, E. Lodi Rizzini, Antonio Zoccoli, G. Puddu, E. Rossetto, D. Panzieri, and K. Calvo

Subjects
Momentum, Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Pion, Annihilation, Meson, State (functional analysis)
Abstract

The results of the spin-parity analysis of annihilations at very low momentum (≈ 50 MeV/c) are reported. To describe the data the production of the ϱ, f2, a2 and a1 mesons and the presence of the ππ interaction in S-wave (the σ term) in the final state are necessary. The best fit solution requires also the presence of a ϱ′ state of mass and width M = 1.282 ± 0.037, Γ = 0.236 ± 0.036 GeV/c2 and of a heavy pion π(1300) of mass and width M = 1.275 ± 0.015, Γ = 0.218 ± 0.100 GeV/c2. The measured fraction of the annihilation cross section into 2π+2π− is (7.61 ± 0.35) · 10−2.

Published
1997
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15. Study of annihilation in two mesons in the momentum range between 50 to 400 MeV/c with OBELIX

Author

P.P. Temnikov, Antonietta Donzella, Paolo Montagna, Stefania Vecchi, S. Costa, Elena Botta, L. Fava, Adriano Fontana, A.M. Rozhdestvensky, M.G. Sapozhnikov, I. Massa, R. Garfagnini, M. Corradini, S. Marcello, Marco Bruschi, Alberto Masoni, Paola Salvini, S.N. Prakhov, G. Pauli, L. Ferrero, Massimo Piccinini, F. Vigotti, D. Calvo, A. Vezzani, Bruno Minetti, Antonio Ferretti, L. Valacca, V.G. Ableev, S. Decastro, Alberto Rotondi, L. Venturelli, S. Serci, C. Petrascu, F. Nichitiu, L. Busso, O.E. Gorchakov, D. Parena, M. Poli, G. Vedovato, Tullio Bressani, F. Tosello, A. Saino, A M Rosca, Maria Pia Bussa, U. Gastaldi, S. Tessaro, V.I. Tretyak, G. L. Usai, G. Maron, O. Y. Denisov, A. Maggiora, Paola Gianotti, M. Lombardi, A. Collamati, Mauro Villa, V. Lucherini, M. Capponi, L. Vannucci, D. Galli, V. Filippini, G. Puddu, V. Vagnoni, L. Santi, Felice Iazzi, Armando Lanaro, C. Cavion, Roberto Spighi, Corrado Cicalo, Aldo Zenoni, Nicola Semprini-Cesari, D. Panzieri, C. Scoglio, A. Vitale, A. Grasso, Umberto Marini Bettolo Marconi, E. Rossetto, E. L. Rizzini, Alessandro Feliciello, Benedetto Giacobbe, G. Bendiscioli, A. Filippi, R. Donà, C. Guaraldo, A.E. Kudryavtsev, P. Cerello, A. Bertin, Michelangelo Agnello, F. Balestra, L. Filippi, and Antonio Zoccoli

Subjects
Momentum, Physics, Nuclear physics, Nuclear and High Energy Physics, Range (particle radiation), Annihilation, Deuterium, Meson, Atomic physics, Antineutron, Bar (unit)
Abstract

We measured the in flight annihilation frequencies and cross sections of reactions n p → π + π 0 ,π + η and K+KS in the antineutron momentum range between 50 and 400 MeV/c. The annihilation frequencies of these channels from the different allowed initial states were calculated and some information about the n p annihilation dynamics were obtained. The first determination of the D-wave contribution in this momentum range was also obtained.

Published
1997
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16. Spin-parity analysis of the final state π+π−π0 from annihilation at rest in hydrogen targets at three densities

Author

Nicola Semprini-Cesari, Alberto Masoni, Paola Salvini, S. Costa, D. Calvo, V. Vagnoni, M. Poli, G. Vedovato, A. Saino, C. Scoglio, Roberto Spighi, A. Grasso, Mauro Villa, Umberto Marini Bettolo Marconi, Paola Gianotti, M.P. Bussa, A. Vitale, A. Collamati, L. Filippi, Stefania Vecchi, O. Y. Denisov, C. Damiani, L. Ferrero, L. Fava, Michelangelo Agnello, Antonio Ferretti, V. Filippini, I. Massa, O.E. Gorchakov, G. Maron, V.I. Tretyak, C. Cavion, S. De Castro, Aldo Zenoni, A.M. Rozhdestvensky, A M Rosca, D. Galli, A. Maggiora, S. Marcello, M.G. Sapozhnikov, Antonietta Donzella, V. Lucherini, R. Garfagnini, L. Busso, Tullio Bressani, Bruno Minetti, F. Nichitiu, U. Gastaldi, S. Serci, P.P. Temnikov, Alberto Rotondi, L. Valacca, Massimo Piccinini, C. Petrascu, Adriano Fontana, D. Parena, A. Vezzani, L. Venturelli, V.G. Ableev, Paolo Montagna, G. Pauli, F. Vigotti, L. Vannucci, Armando Lanaro, G. Puddu, Elena Botta, E. Rossetto, Marco Bruschi, M. Capponi, R. A. Ricci, G. L. Usai, D. Panzieri, M. Corradini, S.N. Prakhov, F. Tosello, S. Tessaro, P. Cerello, Felice Iazzi, Corrado Cicalo, A. Bertin, A. Filippi, R. Donà, Antonio Zoccoli, F. Balestra, C. Guaraldo, G. Bendiscioli, L. Santi, Alessandro Feliciello, Benedetto Giacobbe, and E. Lodi Rizzini

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Annihilation, Amplitude, Hydrogen, chemistry, Partial wave analysis, Pi, chemistry.chemical_element, Parity (physics), Vector meson, Atomic physics
Abstract

The partial wave analysis of the reaction p p → π + π − π 0 at rest has been performed for the first time by using high-statistics data sets collected in hydrogen targets at three different densities. The different mixtures of partial waves corresponding to our samples allow a reliable determination of each contribution. This technique is crucial in the identification of the exotic candidate f2(1565) which can be produced by 1S0, 3P1 and 3P2 initial states. The amplitude analysis was performed in the frame of the K-Matrix and P-Vector approach. It requires presence of the exotic candidates f0(1500) and f2(1565) with the following masses and total widths: (1449 ± 20)MeV, (114 ± 30)MeV and (1507 ± 15)MeV, (130 ± 20)MeV respectively. In addition to f0(980), f0(1300) f2(1270) and ϱ(770), a clear evidence of I = 1, JP = 1− signal, which we identify with ϱ(1450), is obtained.

Published
1997
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17. A search for axial vectors in annihilations at rest in gaseous hydrogen at NTP

Author

L. Fava, R. Spighi, S.N. Prakhov, S. De Castro, D. Galli, A. Filippi, R. Donà, R. Garfagnini, F. Tosello, G. L. Usai, Marco Bruschi, S. Tessaro, S. Serci, A. Lai, Nicola Semprini-Cesari, Elena Botta, Michelangelo Agnello, Piergiorgio Cerello, V.I. Tretyak, A. Saino, L. Musa, S. Costa, A. Maggiora, Maurizio Piccinini, V. Lucherini, O.E. Gorchakov, A. Vezzani, A M Rosca, L. Valacca, F. Balestra, O. Y. Denisov, L. Venturelli, S. Marcello, M. Capponi, Petar Temnikov, Tullio Bressani, A. Grasso, A. Bertin, U. Gastaldi, C. Scoglio, Antonio Zoccoli, G. Bendiscioli, V. Filippini, F. Vigotti, Alberto Masoni, U. Marconi, D. Calvo, Mauro Villa, Paola Salvini, A. Vitale, L. Busso, C. Cavion, L. Santi, Adriano Fontana, Aldo Zenoni, C. Guaraldo, A. Ferretti, A. Collamati, Felice Iazzi, L. Vannucci, Corrado Cicalo, Paolo Montagna, M.P. Bussa, Stefania Vecchi, Antonietta Donzella, B. Giacobbe, M. Corradini, F. Nichitiu, G. Pauli, A. Feliciello, L. Ferrero, Alberto Rotondi, C. Petrascu, D. Parena, E. Lodi Rizzini, M.G. Sapozhnikov, V.G. Ableev, M. Lombardi, A.M. Rozhdestvensky, D. Panzieri, G. Puddu, E. Rossetto, Armando Lanaro, M. Poli, G. Vedovato, Paola Gianotti, Bruno Minetti, and G. Maron

Subjects
Pseudoscalar, Physics, Nuclear physics, Nuclear and High Energy Physics, Annihilation, Gaseous hydrogen, Pi
Abstract

The study of the K±Kmiss0π∓π+π− channel (7016 events), from p p annihilations in a gaseous hydrogen target at NTP, with the OBELIX spectrometer at LEAR (CERN), is presented. A spin-parity analysis provides evidence for two axial vectors, one in the low K K π mass region, the well established f1(1285), decaying to a0(980)π, the second, the 1++ component of the old puzzling E l , the f1(1420), decaying mainly to K ∗ K , seen for the first time in p p annihilation at rest. The analysis confirms the dominant production of the pseudoscalar η(1405), decaying mainly to (Kπ) S K , and the existence of a second pseudoscalar in the same mass region, the η(1460), decaying mainly to K ∗ K .

Published
1997
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18. Experimental estimation of the lifetime of atoms formed by π+ and π− mesons

Author

L. Afanasyev, A.V. Kuptsov, V.V. Kruglov, A.V. Kulikov, L.L. Nemenov, M.V. Nikitin, Zh.P. Pustylnik, A.V. Kolomyichenko, S.V. Trusov, V.I. Komarov, O.E. Gorchakov, V. Karpukhin, A.S. Chvyrov, and V. Yazkov

Subjects
Physics, Nuclear and High Energy Physics, Meson, State (functional analysis), Atomic physics, Pionium
Abstract

Based on observation [L.G. Afanasyev et al., Phys. Lett. B 308 (1993) 200] of 272±49 atoms formed by π + and π − an estimation of the atom lifetime in the ground (1S) state is obtained: τ 1 = (2.9 +∞ −2.1 ) · 10 −15 s or τ 1 > 0.6·10 −15 s at 90% confidence level. Atoms were produced in inclusive p Ta interactions at 70 GeV.

Published
1994
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19. Observations of atoms consisting of π+ and π− mesons

Author

Mikhail A. Ivanov, V. Yazkov, V. Karpukhin, A.V. Kolomyichenko, A.V. Kuptsov, Zh.P. Pustylnik, S.V. Trusov, A.V. Kulikov, V.V. Kruglov, M.V. Nikitin, O.E. Gorchakov, L.L. Nemenov, L. Afanasyev, V. Komarov, A.P. Kurov, G.G. Mkrtchyan, and A.S. Chvyrov

Subjects
Condensed Matter::Quantum Gases, Physics, Nuclear physics, Nuclear and High Energy Physics, Meson, Nuclear Theory, High Energy Physics::Experiment, Physics::Atomic Physics, Atomic physics, Nuclear Experiment, Pionium
Abstract

In the experiment 272±49 atoms consisting of π + and π + − mesons were observed. The atoms were produced in a Ta target by 70 GeV protons and π + and π − mesons were detected from the atom break-up in the same target.

Published
1993
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20. Measurement of the branching ratio for the π0-meson decay into a photon and a positronium atom

Author

A.V. Kuptsov, S.M. Frolikov, L.L. Nemenov, A.V. Kulikov, K.I. Gubrienko, M.V. Nikitin, M.N. Shumakov, V.I. Kotov, V.I. Komarov, V.V. Kruglov, L. Afanasyev, A.V. Kolomyichenko, A.S. Chvyrov, O.E. Gorchakov, S.V. Trusov, V. Karpukhin, and Zh.P. Pustylnik

Subjects
Momentum, Physics, Nuclear physics, Nuclear and High Energy Physics, Photon, Meson, Branching fraction, Atom, Radiative transfer, High Energy Physics::Experiment, Elementary particle, Atomic physics, Positronium
Abstract

The ratio of the number of ultrarelativistic positronium atoms ( A 2e ) to the photon number in the momentum interval 800–2000 MeV/ c has been measured in pC interactions at E p =70 GeV and at an angle of 8.4° in the laboratory frame. The branching ratio ϱ π =(1.84±0.29)×10 -9 for π 0 decay into a photon and A 2e has been obtained. The parameter ϱ π is determined by the conversion probability ϱ A of a time-like photon into A 2e in radiative decays of elementary particles.

Published
1990
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21. Antiproton slowing down, capture, and decay in low-pressure helium gas

Author

F. Tosello, S. Tessaro, N. Semprini Cesari, L. Santi, M. Bargiotti, O.E. Gorchakov, M. Leali, Mauro Villa, A. Grasso, L. Ferrero, R. Garfagnini, Nicola Zurlo, I. Massa, G. Piragino, S. De Castro, Pietro Faccioli, Antonio Zoccoli, Antonietta Donzella, F. Grimaldi, A. Bertin, C. Petrascu, L. Venturelli, Roberto Spighi, M. Corradini, Marco Bruschi, Gianfranco Zosi, A. Vitale, M.P. Bussa, G.B. Pontecorvo, F. Balestra, G. V. Margagliotti, Stefania Vecchi, Andrea Bianconi, M. Poli, M. Capponi, C. Guaraldo, A.M. Rozhdestvensky, Benedetto Giacobbe, V.I. Tretyak, A. Maggiora, E. Lodi Rizzini, Massimo Piccinini, Laura Fabbri, O. Y. Denisov, L. Busso, A., Bianconi, M., Corradini, A., Donzella, M., Leali, E., Lodirizzini, L., Venturelli, N., Zurlo, M., Bargiotti, A., Bertin, M., Bruschi, M., Capponi, S., DE CASTRO, L., Fabbri, P., Faccioli, B., Giacobbe, F., Grimaldi, I., Massa, M., Piccinini, N., Semprinicesari, R., Spighi, S., Vecchi, M., Villa, A., Vitale, A., Zoccoli, O. E., Gorchakov, G. B., Pontecorvo, A. M., Rozhdestvensky, V. I., Tretyak, M., Poli, C., Guaraldo, C., Petrascu, F., Balestra, M. P., Bussa, L., Busso, O. Y., Denisov, L., Ferrero, R., Garfagnini, A., Grasso, A., Maggiora, G., Piragino, F., Tosello, G., Zosi, Margagliotti, Giacomo, L., Santi, S., Tessaro, A. Bianconi, M. Corradini, A. Donzella, M. Leali, E. Lodi Rizzini, L. Venturelli, N. Zurlo, M. Bargiotti, A. Bertin, M. Bruschi, M. Capponi, S. De Castro, L. Fabbri, P. Faccioli, B. Giacobbe, F. Grimaldi, I. Massa, M. Piccinini, N. Semprini Cesari, R. Spighi, S. Vecchi, M. Villa, A. Vitale, A. Zoccoli, O. E. Gorchakov, G. B. Pontecorvo, A. M. Rozhdestvensky, V. I. Tretyak, M. Poli, C. Guaraldo, C. Petrascu, F. Balestra, M. P. Bussa, 6 L. Busso, O. Y. Denisov, L. Ferrero, R. Garfagnini, A. Grasso, A. Maggiora, G. Piragino, F. Tosello, G. Zosi, G. Margagliotti, L. Santi, and S. Tessaro

Subjects
H-2, Physics, COLLISIONS, HE, Hydrogen, Monte Carlo method, Extrapolation, Antiproton, chemistry.chemical_element, HYDROGEN, Atomic and Molecular Physics, and Optics, ATOMS, Nuclear physics, NUCLEAR STOPPING POWER, Deuterium, chemistry, Ionization, IONIZATION, Stopping power (particle radiation), Atomic physics, Helium
Abstract

Data on p¯ slowing down and capture in helium at 1 and 0.2 mb at room temperature are presented and compared to the corresponding previously publicated data in molecular hydrogen and deuterium. A Monte Carlo simulation containing a low-energy extrapolation of measured p¯electronic stopping power in helium gas,screened Rutherford collisions, and simple cascade mechanisms is able to reproduce the gross features of the data, but cannot explain some nontrivial details of the measured distributions.

Published
2004
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22. Anti-pp annihilation into four charged pions at rest and in flight

Author

A. De Falco, Adriano Fontana, M. Poli, Paola Salvini, Paolo Montagna, N. Semprini Cesari, A. Feliciello, Paola Gianotti, M. Corradini, S.N. Prakhov, A. Panzarasa, F. De Mori, M.G. Sapozhnikov, Angelo Carbone, F. Balestra, Armando Lanaro, M. Capponi, G. Puddu, Pietro Faccioli, S. De Castro, Alberto Masoni, O.E. Gorchakov, L. Busso, Elena Botta, F. Grimaldi, Felice Iazzi, L. Ferrero, D. Calvo, C. Guaraldo, A.M. Rozhdestvensky, Corrado Cicalo, V.I. Tretyak, Mauro Villa, A. Maggiora, P. Cerello, V. Lucherini, Massimo Piccinini, Antonietta Donzella, Alberto Rotondi, C. Petrascu, A. Bertin, Laura Fabbri, S. Serci, Tullio Bressani, I. Massa, Michelangelo Agnello, F. Tosello, M. Bargiotti, Marco Bruschi, O. Y. Denisov, S. Marcello, Umberto Marini Bettolo Marconi, A. Filippi, Roberto Spighi, L. Venturelli, V. Filippini, Aldo Zenoni, A. Vitale, A. Grasso, D. Galli, Andrea Bianconi, G. L. Usai, M.P. Bussa, Stefania Vecchi, Benedetto Giacobbe, E. Lodi Rizzini, D. Panzieri, and Antonio Zoccoli

Subjects
Physics, Particle physics, Large Hadron Collider, Annihilation, Physics and Astronomy (miscellaneous), Spectrometer, Hydrogen, Gaseous hydrogen, chemistry.chemical_element, Nuclear physics, Pion, chemistry, High Energy Physics::Experiment, Exotic meson, Engineering (miscellaneous)
Abstract

The spin-parity analysis of the data on the ¯pp → 2π+ 2π − annihilation reaction at rest in liquid and in gaseous hydrogen at 3 bar pressure and in flight at p momentum of 50 MeV/c, collected by the Obelix spectrometer at the LEAR complex of CERN, is presented. The relative branching ratios (a1(1260) → σπ)/(a1(1260) → ρπ) = 0.06 ± 0.05 and (π(1300) → σπ)/(π(1300) → ρπ) = 2.2 ± 0.4 are obtained. It is also shown that the inclusion of the exotic meson π1(1400), JPC= 1−+, mass and width M = 1.384 ± 0.028, Γ = 0.378 ± 0.058 GeV/c2, in its decay to ρπ, improves the fit and some implications of these results are briefly discussed. The relative S and P-wave annihilation percentages in four charged pions at two target densities are obtained

Published
2004

23. Results of the coupled channel analysis of pi+ pi- pi0, K+ K- pi0 and K+- K0(S) pi-+ final states from anti-p p annihilation at rest in hydrogen targets at different densities

Author

Maurizio Piccinini, Paolo Montagna, Paola Salvini, Felice Iazzi, R. A. Ricci, I. Massa, L. Venturelli, Pietro Faccioli, F. Grimaldi, S. Marcello, M.G. Sapozhnikov, Adriano Fontana, L. Busso, L. Ferrero, D. Galli, S. De Castro, V.I. Tretyak, A. Maggiora, V. Lucherini, Piergiorgio Cerello, Stefania Vecchi, S. Serci, Alberto Rotondi, Laura Fabbri, Mauro Villa, Antonietta Donzella, Alberto Masoni, C. Petrascu, F. De Mori, A. Feliciello, M. Bargiotti, B. Giacobbe, D. Panzieri, Antonio Zoccoli, D. Calvo, Andrea Bianconi, O. Y. Denisov, G. Puddu, M.P. Bussa, G. L. Usai, M. Poli, N. Mirfakhrai, N. Semprini Cesari, Michelangelo Agnello, Paola Gianotti, S.N. Prakhov, M. Corradini, Armando Lanaro, F. Balestra, C. Guaraldo, R. Garfagnini, A. Panzarasa, A.M. Rozhdestvensky, M. Capponi, Tullio Bressani, R. Spighi, E. Lodi Rizzini, A. De Falco, Elena Botta, Marco Bruschi, V. Filippini, Aldo Zenoni, V. Vagnoni, Angelo Carbone, O.E. Gorchakov, Corrado Cicalo, F. Tosello, U. Marconi, A. Filippi, A. Vitale, R. Donà, and A. Bertin

Subjects
Physics, Nuclear and High Energy Physics, COLLISIONS, Annihilation, PI(0)ETA-ETA, Hydrogen, Scattering, Glueball, PI(0)PI(0)PI(0), F(0)(1500), chemistry.chemical_element, GLUEBALL, ANTIPROTON-PROTON ANNIHILATION, H-2 GAS, chemistry, MULTI-QUARK HADRONS, S-STATE, SEARCH, High mass, Channel analysis, Atomic physics
Abstract

The π+π−π0, K+K−π0 and K±K0π∓ final states produced by p p annihilation at rest at three different hydrogen target densities have been analyzed in the frame of a coupled channel analysis together with ππ and πK scattering data. Here we present the main results which concern masses, widths, ππ and K K partial widths of all the involved resonances (JP=0+,1−,2+), the direct determination of Γ K K /Γ ππ ratio for f0(1370) and f0(1500) ( Γ K K /Γ ππ =0.91±0.20 and Γ K K /Γ ππ =0.25±0.03 , respectively), the determination of a0(1300) parameters (M=1303±16 MeV; Γ=92±16 MeV) and the observation of two different high mass ρ signals associated to ρ(1450) and ρ(1700) (M=1182±30 MeV; Γ=389±20 MeV and M=1594±20 MeV; Γ=259±20 MeV, respectively).

Published
2003

24. Study of the K+.K-.pi+.pi-.pi0 final state in antiproton annihilation at rest in gaseous hydrogen at NTP with the OBELIX spectrometer

Author

A. Grasso, Alberto Masoni, A. Filippi, D. Calvo, C. Guaraldo, O. Y. Denisov, M. Poli, D. Galli, S. De Castro, Piergiorgio Cerello, Alberto Rotondi, Stefania Vecchi, Antonio Zoccoli, I. Massa, C. Petrascu, S. Marcello, S. Mauro, D. Panzieri, A. De Falco, L. Venturelli, Paolo Montagna, Paola Gianotti, R. Spighi, Michelangelo Agnello, Elena Botta, Mauro Villa, E. Lodi Rizzini, Paola Salvini, Armando Lanaro, Adriano Fontana, F. Balestra, G. Puddu, M.P. Bussa, L. Busso, Germano Bonomi, A. Feliciello, G. L. Usai, D. D'Isep, A.M. Rozhdestvensky, Antonietta Donzella, S.N. Prakhov, F. Nichitiu, R. Garfagnini, B. Giacobbe, A. Panzarasa, Marco Bruschi, N. Mirfakhrai, V.I. Tretyak, A. Maggiora, V. Lucherini, V. Filippini, Aldo Zenoni, A. Bertin, Nicola Semprini-Cesari, S. Costa, M. Capponi, Tullio Bressani, Felice Iazzi, Corrado Cicalo, F. Tosello, S. Tessaro, O.E. Gorchakov, A M Rosca, U. Marconi, A. Vitale, V. Vagnoni, Maurizio Piccinini, and Bruno Minetti

Subjects
Pseudoscalar, Physics, Nuclear and High Energy Physics, Annihilation, Antiproton, Isobar, Resonance, Invariant mass, Atomic physics, Pseudovector, P system
Abstract

A spin-parity analysis of a sample of p p→K + K − π + π − π 0 annihilation events taken at rest in gaseous H2 at NTP is reported. The invariant mass spectrum of the K+K−π0 system shows the presence of the E/ι resonance pattern at 1.42 GeV. The analysis of this signal confirms the results obtained by the OBELIX Collaboration in previous works, namely: the existence of two pseudoscalar states at 1.413 ± 0.002 and 1.460±0.012 GeV with widths 0.051 ± 0.004 and 0.120±0.015 GeV, respectively. The p p system in the 3 P 1 wave shows also a signal corresponding to the axial vector f1(1420) decaying to K ∗ K with mass 1.420±0.003 GeV and width 0.061±0.005 GeV. A study of the incoherent phase space background shows that its origin is mostly due to the reflection of a resonant state in the K+K−π+π− system. The isobar decomposition of this resonant state is mainly f0(1370)(ππ)S, its parameters are: JPC=0++, m=1.670±0.02 GeV and width 0.267±0.036 GeV. This signal can be probably identified with another decay mode of the f0(1710).

Published
2002

25. Antiprotons stopping in xenon

Author

M.P. Bussa, Germano Bonomi, A. Grasso, L. Venturelli, L. Santi, M. Corradini, M.L. Colantoni, F. Balestra, C. Guaraldo, G. Piragino, O.E. Gorchakov, F. Tosello, S. Tessaro, A.M. Rozhdestvensky, M. Maggiora, E. Lodi Rizzini, L. Ferrero, O. Y. Denisov, G. V. Margagliotti, R. Garfagnini, C. Petrascu, S.N. Prakhov, L. Busso, Antonietta Donzella, V.I. Tretyak, A. Maggiora, Andrea Bianconi, Gianfranco Zosi, E., Lodirizzini, A., Bianconi, G., Bonomi, M. P., Bussa, M., Corradini, A., Donzella, L., Venturelli, O. E., Gorchakov, S. N., Prakhov, A. M., Rozhdestvensky, V. I., Tretyak, F., Balestra, L., Busso, M. L., Colantoni, O. Y., Denisov, L., Ferrero, R., Garfagnini, A., Grasso, A., Maggiora, M., Maggiora, G., Piragino, F., Tosello, G., Zosi, Margagliotti, Giacomo, S., Tessaro, and L., Santi

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Cross section (physics), Xenon, Low energy, chemistry, Antiproton, Low density, chemistry.chemical_element, Atomic physics, Hyperfine structure
Abstract

Experimental data on p slowing down at very low energy in a low density (0.2 mbar pressure) Xe target evidence a very low capture cross section with respect to He, H 2 and D 2 in agreement with specific phenomenological previsions by Briggs et al. [Hyperfine Interact. 119 (1999) 235; J. Phys. B 32 (1999) 197].

Published
2001

26. An analysis of the contribution of isospin two ππ resonant states in the -np -> π+π+π- annihilation reaction

Author

A. Feliciello, S. Costa, B. Giacobbe, Bruno Minetti, Mauro Villa, M.P. Bussa, Germano Bonomi, D. Galli, R. Spighi, F. Cannata, Alberto Masoni, O. Y. Denisov, U. Marconi, N. Mirfakhraee, N. Semprini Cesari, V.I. Tretyak, D. Calvo, L. Ferrero, S. De Castro, A. Maggiora, F. Tosello, V. Lucherini, Paolo Montagna, Paola Salvini, S. Tessaro, A. Vitale, Alberto Rotondi, C. Petrascu, R. Garfagnini, C. Guaraldo, M. Capponi, S. Serci, Michelangelo Agnello, Tullio Bressani, Marco Bruschi, V. Vagnoni, A. Filippi, A. Grasso, Stefania Vecchi, L. Venturelli, R. Donà, Adriano Fontana, O.E. Gorchakov, Andrea Bianconi, L. Busso, F. Balestra, S.N. Prakhov, G. L. Usai, I. Massa, Antonio Zoccoli, Elena Botta, S. Marcello, A. De Falco, V. Filippini, Felice Iazzi, Corrado Cicalo, F. D'Isep, Aldo Zenoni, A. Bertin, Maurizio Piccinini, D. Panzieri, G. Puddu, M. Poli, A. Panzarasa, M. Astrua, E. Lodi Rizzini, Armando Lanaro, Paola Gianotti, and A.M. Rozhdestvensky

Subjects
Physics, Nuclear and High Energy Physics, Meson production, Annihilation, Isospin, Partial wave analysis, Scalar (mathematics), Isobar, State (functional analysis), Atomic physics, Resonance (chemistry)
Abstract

The results of a search for a possible evidence of a π + π + resonant state in the n p→π + π + π − annihilation reaction with data collected by the OBELIX Experiment are presented. The study has been performed by means of a partial wave analysis in the frame of the isobar model. Production fractions for a possible π + π + resonance have been evaluated. The observed effects at the π + π + threshold may be described reasonably well by the contributions of f 2 (1270), f 0 (1500), f 2 (1565) and ρ (1450) states and their interferences, but a meaningful statistical indication for a π + π + scalar state at about 1400 MeV emerges from the analysis.

Published
2000

27. Antineutron-proton total cross section from 50 to 400 MeV/c

Author

Felice Iazzi, Corrado Cicalo, M. Poli, Bruno Minetti, Alessandro Feliciello, A.M. Rozhdestvensky, M. Capponi, Tullio Bressani, N. Mirfakhraee, A. Masoni, F. Tosello, G. Puddu, C. Guaraldo, S. Tessaro, Germano Bonomi, G. Bendiscioli, D. Calvo, M. Lombardi, Paola Gianotti, P. Cerello, A. Panzarasa, E. Lodi Rizzini, M. Astrua, F. Balestra, Armando Lanaro, Paola Salvini, Sergio Serci, Antonio Zoccoli, D. Panzieri, Mauro Villa, S. Costa, V.I. Tretyak, A. Maggiora, S. Mauro, O.E. Gorchakov, A. Filippi, R. Donà, V. Lucherini, Vincenzo Vagnoni, N. Semprini Cesari, U. Marconi, L. Venturelli, A. Vitale, I. Massa, L. Vannucci, S. Marcello, M.P. Bussa, B. Giacobbe, M. Bruschi, R. A. Ricci, M. Piccinini, Stefania Vecchi, F. D'Isep, Aldo Zenoni, L. Ferrero, Alberto Rotondi, C. Petrascu, Andrea Bianconi, G. L. Usai, Paolo Montagna, L. Busso, A. Bertin, S. De Castro, O. Y. Denisov, R. Spighi, Michelangelo Agnello, S.N. Prakhov, D. Galli, R. Garfagnini, Elena Botta, and Adriano Fontana

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Range (particle radiation), Large Hadron Collider, Proton, Nuclear Theory, Antineutron, Nuclear physics, Momentum, Cross section (physics), Isospin, Physics::Accelerator Physics, Nuclear Experiment, Beam (structure)
Abstract

The antineutron-proton total doss section has been measured in the low momentum range 50-400 MeV/c (below 100 MeV/c for the first time). The measurement was performed at LEAR (CERN) by the OBELIX experiment, thanks to its unique antineutron beam facility. A thick target transmission technique has been used. The measured total cross section shows an anomalous behaviour below 100 MeV/c. A dominance of the isospin I = 0 channel over the I = 1 one at low energy is clearly deduced. (C) 2000 Elsevier Science B.V. All lights reserved

Published
2000

28. Measurement of cascade times of antiprotons in molecular hydrogen and helium

Author

Paola Salvini, C. Guaraldo, Antonietta Donzella, B. Giacobbe, Vincenzo Vagnoni, S. Costa, A. Vitale, S. De Castro, A. Filippi, Sergio Serci, Elena Botta, Michelangelo Agnello, I. Massa, G. Gomez, Maurizio Piccinini, S. Marcello, R. Vilar, A. Masoni, R. A. Ricci, F. D'Isep, A. Maggiora, A. De Falco, M.P. Bussa, Germano Bonomi, O.E. Gorchakov, Stefania Vecchi, Antonio Zoccoli, Bruno Minetti, L. Ferrero, R. Spighi, L. Vannucci, Alberto Rotondi, A. Grasso, V.G. Ableev, A. Feliciello, Andrea Bianconi, G. L. Usai, C. Petrascu, V.I. Tretyak, N. Mirfakhraee, F. Tosello, S. Tessaro, V. Filippini, R. Garfagnini, A. Bertin, Aldo Zenoni, U. Marconi, Felice Iazzi, V. Lucherini, Corrado Cicalo, Mauro Villa, R. Donà, M. Corradini, D. Galli, S.N. Prakhov, D. Panzieri, G. Puddu, N. Semprini Cesari, L. Santi, A. Panzarasa, M. Capponi, Tullio Bressani, A.M. Rozhdestvensky, Piergiorgio Cerello, Adriano Fontana, E. Lodi Rizzini, Marco Bruschi, Armando Lanaro, D. Calvo, L. Venturelli, M. Poli, Paola Gianotti, O. Y. Denisov, L. Busso, and Paolo Montagna

Subjects
H-2, Physics, Nuclear and High Energy Physics, Large Hadron Collider, Hydrogen, Hydrogen molecule, chemistry.chemical_element, NUCLEAR STOPPING POWER, CAPTURE, ATOMS, Nuclear physics, Deuterium, chemistry, Cascade, Antiproton, Stopping power (particle radiation), High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Physics::Atomic Physics, Atomic physics, Nuclear Experiment, Helium
Abstract

The Obelix experiment at CERN collected samples of antiproton annihilations at rest in different gaseous targets, such as hydrogen, deuterium and helium. We analyze a set of the Obelix data using a new technique for measuring, for the first time, the cascade times independent of the capture energy and of the antiproton stopping power. We report on measurements of the cascade times for hydrogen at 3.4, 5.8, 9.8 and 150 mbar and for helium at 8.2, 50 and 150 mbar pressure. An estimate of the antiproton capture energy in hydrogen is also presented.

Published
2000

29. Observation of the Coulomb interaction effect in pion pairs from the reaction p + Ta → π+ + π− + X at 70 GeV

Author

S.V. Trusov, V.V. Kruglov, V.I. Komarov, M.N. Shumakov, A.V. Kulikov, Zh.P. Pustylnik, M.V. Nikitin, A.V. Kolomyichenko, A.P. Kurov, L.L. Nemenov, A.V. Kuptsov, L. Afanasyev, V. Karpukhin, A.S. Chvyrov, S.M. Frolikov, O.E. Gorchakov, Mikhail A. Ivanov, and V. Yazkov

Subjects
Scattering cross-section, Physics, Nuclear and High Energy Physics, Particle physics, Nuclear Theory, Function (mathematics), Proton energy, Momentum, Nuclear physics, Nuclear interaction, Pion, Pair production, Coulomb, High Energy Physics::Experiment, Nuclear Experiment
Abstract

Pion pair production from the proton-tantalum nuclear interaction at proton energy 70 GeV has been studied. Pion correlations as a function of the relative momentum in a pair CMS have been measured at the relative momentum region below 40 MeV/ c . The experimental data agree with the calculation that takes into account the Coulomb factor in the differential cross section of pion pairs production.

Published
1991
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30. New measurements of the p̄p annihilation cross section at very low energy

Author

Antonio Zoccoli, M.P. Bussa, A.M. Rozhdestvensky, Stefania Vecchi, Andrea Bianconi, G. L. Usai, Antonietta Donzella, Vincenzo Vagnoni, L. Venturelli, F. Tosello, S. Tessaro, A. Masoni, B. Giacobbe, E. Lodi Rizzini, U. Marconi, D. Galli, Aldo Zenoni, Germano Bonomi, M. Poli, F. Bocci, A. Feliciello, A. Vitale, Maurizio Piccinini, I. Massa, S. Marcello, Paola Gianotti, Paola Salvini, A. Maggiora, Marco Bruschi, Piergiorgio Cerello, G. Bendiscioli, G. Puddu, F. D'Isep, N. Mirfakhrai, O.E. Gorchakov, S. De Castro, A. Filippi, M. Capponi, Tullio Bressani, Armando Lanaro, D. Calvo, R. Garfagnini, Felice Iazzi, Corrado Cicalo, S. Costa, V.I. Tretyak, Elena Botta, L. Vannucci, S. Mauro, C. Guaraldo, U. Gastaldi, V. Lucherini, L. Ferrero, Adriano Fontana, A. Panzarasa, Alberto Rotondi, Mauro Villa, C. Petrascu, N. Semprini Cesari, F. Balestra, R. Spighi, A. Grasso, Sergio Serci, Michelangelo Agnello, R. Donà, M. Corradini, A. Bertin, S.N. Prakhov, V.G. Ableev, O. Y. Denisov, L. Busso, Bruno Minetti, and Paolo Montagna

Subjects
Momentum, Nuclear physics, Physics, Scattering amplitude, Nuclear and High Energy Physics, Cross section (physics), Low energy, Annihilation, Atomic physics
Abstract

The p p total annihilation cross section has been measured at four values of the p incident momentum, between 70 MeV/c and 38 MeV/c, with the Obelix apparatus at LEAR. The new measurements are in agreement with the trend of previous measurements of the p p total annihilation cross section at low energy, performed by the Obelix experiment [A. Bertin et al., Phys. Lett. B 369 (1996) 77; A. Benedettini et al., Nucl. Phys. B (Proc. Suppl.) 56A (1997) 58], as well as with a fit of the latter data based on a low energy expansion of the scattering amplitude [J. Carbonell, K.V. Protasov, A. Zenoni, Phys. Lett. B 397 (1997) 345]. The departure of the annihilation cross section from a smooth behaviour, suggested by a previous measurement of the cross section around 44 MeV/c [A. Bertin et al., Phys. Lett. B 369 (1996) 77], is not confirmed by the new data.

Published
1999

31. p̄p annihilation cross section at very low energy

Author

N. Mirfakhraee, F. Tosello, S. Tessaro, Felice Iazzi, Corrado Cicalo, V. Filippini, Maurizio Piccinini, A. Vezzani, C. Cavion, S. De Castro, A. Grasso, Aldo Zenoni, N. Semprini Cesari, M.G. Sapozhnikov, L. Venturelli, U. Marconi, L. Vannucci, L. Santi, Mauro Villa, G. Belli, Adriano Fontana, A. Vitale, B. Cereda, A. Masoni, G. Bendiscioli, A. Ferretti, A. Maggiora, E. Lodi Rizzini, A. Saino, Elena Botta, V.G. Ableev, Sergio Serci, Michelangelo Agnello, Piergiorgio Cerello, O.E. Gorchakov, L. Fava, A M Rosca, D. Calvo, Marco Bruschi, M. Capponi, Tullio Bressani, D. Galli, C. Guaraldo, U. Gastaldi, Alberto Andrighetto, G. Pauli, V.I. Tretyak, F. Nichitiu, R. Spighi, V. Lucherini, Salvatore Costa, M. Lombardi, Petar Temnikov, M. Morando, Bruno Minetti, A. Bertin, G. L. Usai, F. Balestra, D. Panzieri, G. Puddu, E. Rossetto, M. Corradini, A. Filippi, S.N. Prakhov, R. Garfagnini, S. Marcello, Armando Lanaro, G. Vedovato, Paola Gianotti, O.Yu. Denisov, A.M. Rozhdestvensky, F. D'Isep, Paola Salvini, Antonietta Donzella, B. Giacobbe, Antonio Zoccoli, R. A. Ricci, L. Ferrero, Alberto Rotondi, C. Petrascu, D. Parena, L. Busso, Paolo Montagna, A. Feliciello, M.P. Bussa, and Stefania Vecchi

Subjects
Physics, Nuclear physics, Coulomb's law, Momentum, Nuclear and High Energy Physics, Cross section (physics), Particle physics, symbols.namesake, Annihilation, Low energy, Antiproton, symbols
Abstract

The pp total annihilation cross section has been measured, with the Obelix apparatus at LEAR, at ten values of the antiproton incident momentum between 43 and 175 MeV/c. The values of the cross section show that the well known 1 p behaviour of the annihilation cross section is drastically modified at very low momenta, which demonstrates the important role of the Coulomb force in low energy pp interaction. Moreover, they do not present any explicit resonant behaviour. Finally, when compared to potential model calculations, the data suggest that the percentage of P-wave in pp interaction around 50 MeV/c antiproton incident momentum is less than 5%.

Published
1996

32. Measurement of the η(1440) -> K±Kl0π± production rates from anti-p p annihilation at rest at three different hydrogen target densities

Author

A. Lai, L. Fava, M.G. Sapozhnikov, S. De Castro, L. Venturelli, A. Saino, S. Serci, V.G. Ableev, L. Musa, Roberto Spighi, A. Feliciello, Piergiorgio Cerello, F. Vigotti, Antonio Ferretti, Mauro Villa, M. Capponi, D. D'Isep, L. Ferrero, Paola Salvini, Nicola Semprini-Cesari, A. Adamo, A. Vezzani, Umberto Marini Bettolo Marconi, A. Vitale, Alberto Masoni, Marco Bruschi, L. Busso, M. Lombardi, Paola Gianotti, R. Garfagnini, V. Filippini, D. Galli, M.P. Bussa, Gianfranco Zosi, D. Calvo, S. Costa, C. Cavion, Paolo Montagna, Stefania Vecchi, V.I. Tretyak, Aldo Zenoni, Adriano Fontana, Antonietta Donzella, Alberto Rotondi, Bruno Minetti, Elena Botta, A. Maggiora, V. Lucherini, G. L. Usai, C. Petrascu, Armando Lanaro, D. Panzieri, M. Corradini, O.E. Gorchakov, D. Parena, L. Santi, Michelangelo Agnello, A M Rosca, O.Yu. Denisov, F. Nichitiu, A.M. Rozhdestvensky, Tullio Bressani, U. Gastaldi, S.N. Prakhov, Massimo Piccinini, G. Pauli, S. Marcello, G. Puddu, E. Rossetto, F. Tosello, S. Tessaro, Petar Temnikov, A. Bertin, A. Filippi, Antonio Zoccoli, M. Morando, A. Grasso, N. Mirfakhrai, Felice Iazzi, Corrado Cicalo, F. Balestra, G. Bendiscioli, C. Guaraldo, Benedetto Giacobbe, and E. Lodi Rizzini

Subjects
Physics, Nuclear and High Energy Physics, Annihilation, Hydrogen, chemistry, Protonium, Analytical chemistry, Pi, chemistry.chemical_element, Atomic physics, Bar (unit)
Abstract

From the study of the annihilation at rest p p → K ± K miss 0 π ∓ π + π − the production rates of the η (1440) → K ± K L 0 π ∓ were obtained for three different hydrogen target densities: liquid, gaseous at NTP and at low pressure (5 mbar). The rate values are: f η (1440) (LH) = (6.0±0.5) · 10 −4 , f η (1440) (NTP) = (2.9±0.4) · 10 −4 and f η (1440) (5mbar) = (1.0±0.2) · 10 −4 . From these results, the density dependence of the annihilation fraction from the 1 S 0 protonium level can be extracted directly.

Published
1996

33. Exotic trapping of antiprotons in 4He: dependence on pressure

Author

V. Filippini, E. Zavattini, C. Cavion, Aldo Zenoni, R. Spighi, M.G. Sapozhnikov, Alberto Andrighetto, M. Morando, V.I. Tretyak, Felice Iazzi, G. Puddu, A. Maggiora, O.E. Gorchakov, Bruno Minetti, V. Lucherini, A. Feliciello, E. Lodi Rizzini, Michelangelo Agnello, A. Saino, C. Guaraldo, Corrado Cicalo, S. Marcello, A M Rosca, S. De Castro, Maurizio Piccinini, V.G. Ableev, O.Yu. Denisov, Paolo Montagna, R. Garfagnini, Piergiorgio Cerello, Marco Bruschi, A. Vezzani, L. Venturelli, A. Grasso, S. Serci, G. Bendiscioli, Antonio Zoccoli, Alberto Masoni, L. Busso, A. Filippi, D. Calvo, N. Semprini Cesari, Paola Salvini, F. Tosello, S. N. Prakov, L. Santi, S. Tessaro, F. Vigotti, M. Lombardi, G. V. Margagliotti, Adriano Fontana, A. Ferretti, D. Galli, Elena Botta, E. Rossetto, Armando Lanaro, M. Capponi, M.P. Bussa, F. Balestra, Tullio Bressani, Antonietta Donzella, Stefania Vecchi, U. Marconi, Petar Temnikov, U. Gastaldi, A. Bertin, B. Giacobbe, M. Poli, G. Vedovato, A. Vitale, A. M. Rozhdestvenskii, Paola Gianotti, M. Corradini, F. Nichitiu, G. L. Usai, S. Costa, G. Pauli, Mauro Villa, G. Maron, R. A. Ricci, D. Panzieri, L. Ferrero, L. Vannucci, Alberto Rotondi, G. Belli, C. Petrascu, and D. Parena

Subjects
Physics, Range (particle radiation), Annihilation, Muon, Antiproton, Time distribution, Trapping, Atomic physics, Bar (unit)
Abstract

The behaviour of the «delayed» component of the time distribution of the annihilation of\(\bar p\) at rest in4He is experimentally studied at various pressures of the gas target, in the range 3000 to 5 mbar at room temperature.

Published
1996

34. New data on OZI rule violation in annihilation at rest

Author

Mauro Villa, A. Feliciello, Tullio Bressani, L. Fava, Felice Iazzi, A. Vezzani, O.Yu. Denisov, S. Marcello, D. D'Isep, A. Saino, U. Gastaldi, A.M. Rozhdestvensky, Maurizio Piccinini, S. De Castro, Corrado Cicalo, A. Grasso, Alberto Andrighetto, V.I. Tretyak, Michelangelo Agnello, A. Maggiora, Bruno Minetti, C. Guaraldo, V. Lucherini, R. Garfagnini, M.P. Bussa, S. Serci, A. Filippi, Paolo Montagna, Stefania Vecchi, D. Galli, L. Venturelli, Nicola Semprini-Cesari, F. Vigotti, E. Lodi Rizzini, Antonietta Donzella, Alberto Masoni, S. Costa, Gianfranco Zosi, Elena Botta, B. Giacobbe, D. Calvo, L. Busso, D. Panzieri, Adriano Fontana, G. Bendiscioli, G. Puddu, Paola Gianotti, A. Ferretti, Marco Bruschi, Paola Salvini, F. Tosello, G. L. Usai, V. Filippini, F. Balestra, S. Tessaro, G. V. Margagliotti, C. Cavion, E. Rossetto, L. Santi, Aldo Zenoni, Armando Lanaro, Petar Temnikov, A. Bertin, G. Belli, M. Morando, L. Ferrero, Alberto Rotondi, C. Petrascu, V.P. Nomokonov, D. Parena, U. Marconi, M. Lombardi, M.G. Sapozhnikov, V.G. Ableev, A. Vitale, R. Spighi, O.E. Gorchakov, A M Rosca, S.N. Prakhov, M. Corradini, F. Nichitiu, G. Pauli, Piergiorgio Cerello, M. Poli, Antonio Zoccoli, A., Bertin, M., Bruschi, S., De Castro, A., Ferretti, D., Galli, B., Giacobbe, U., Marconi, M., Poli, M., Piccinini, N., Semprini Cesari, R., Spighi, S., Vecchi, A., Vezzani, F., Vigotti, M., Villa, A., Vitale, A., Zoccoli, G., Belli, M., Corradini, A., Donzella, E., Lodi Rizzini, L., Venturelli, A., Zenoni, C., Cicaló, A., Masoni, G., Puddu, S., Serci, P. P., Temnikov, G., Usai, O., Yu Denisov, O. E., Gorchakov, V. P., Nomokonov, S. N., Prakhov, A. M., Rozhdestvensky, M. G., Sapozhnikov, V. I., Tretyak, P., Gianotti, C., Guaraldo, A., Lanaro, V., Lucherini, F., Nichitiu, C., Petrascu, A., Rosca, V. G., Ableev, C., Cavion, U., Gastaldi, M., Lombardi, A., Andrighetto, M., Morando, G., Bendiscioli, V., Filippini, A., Fontana, P., Montagna, A., Rotondi, A., Saino, P., Salvini, F., Balestra, E., Botta, T., Bressani, M. P., Bussa, L., Busso, D., Calvo, P., Cerello, S., Costa, L., Fava, A., Feliciello, L., Ferrero, A., Filippi, R., Garfagnini, A., Grasso, D., D'Isep, A., Maggiora, S., Marcello, D., Panzieri, D., Parena, E., Rossetto, F., Tosello, G., Zosi, M., Agnello, F., Iazzi, B., Minetti, Margagliotti, Giacomo, G., Pauli, Tessaro, Susanna, and L., Santi

Subjects
Physics, Rest (physics), Nuclear physics, Nuclear and High Energy Physics, Particle physics, PHI-MESON PRODUCTION, ANTIPROTON ANNIHILATION, Annihilation, OZI rule, Antiproton, Momentum transfer
Abstract

The results of measuring the ratio R = Y(φπ + π − ) Y(ωπ + π − ) for antiproton annihilation at rest in a gaseous and a liquid hydrogen target are presented. It was found that the value of this ratio increases with the decrease of the dipion mass, which demonstrates the difference between the φ and ω production mechanisms. An indication of the momentum transfer dependence of the apparent OZI rule violation for the φ production from the 3S1 initial state was found.

Published
1996

35. Study of the OZI-rule violation in antiproton annihilation in deuterium at rest

Author

S. De Castro, Bruno Minetti, Maurizio Piccinini, A. Maggiora, M.G. Sapozhnikov, O.E. Gorchakov, A. Masoni, I. Massa, Antonio Zoccoli, S. Marcello, L. Venturelli, Armando Lanaro, C. De Leo, V.G. Ableev, Sergio Serci, Michelangelo Agnello, G.C. Bonazzola, U. Marconi, Felice Iazzi, M. Poli, G. Vedovato, F. D'Isep, Nicola Semprini-Cesari, A. Saino, Corrado Cicalo, Elena Botta, P. Boccaccio, Paola Gianotti, G. Maron, G. Bendiscioli, Stefania Vecchi, Paola Salvini, M. Morando, A. Adamo, A.M. Rozhdestvensky, E. Lodi Rizzini, S. Costa, D. Panzieri, D. Yu. Denisov, B. Cereda, V.T. Tretyak, L. Vannucci, Gianfranco Zosi, C. Guaraldo, G. L. Usai, M. Lombardi, L. Ferrero, Adriano Fontana, M. Corradini, D. Calvo, G. Puddu, Alberto Rotondi, G. Pauli, Marco Bruschi, G. Piragino, Mauro Villa, D. Galli, A. Filippi, M. Capponi, Tullio Bressani, A. Vitale, Paolo Montagna, F. Balestra, F. Nichitiu, G. Belli, U. Gastaldi, R. A. Ricci, G. V. Margagliotti, Alessandro Feliciello, Antonietta Donzella, A. Grasso, E. Rossetto, R. Garfagnini, P. Cerello, B. Giacobbe, A. Bertin, F. Tosello, L. Santi, Maria Pia Bussa, S. Tessaro, L. Busso, V. Filippini, V. Lucherini, Aldo Zenoni, R. Spighi, S.N. Prakhov, L. Fava, V. G., Ableev, A., Adamo, M., Agnello, F., Balestra, G., Belli, G., Bendiscioli, A., Bertin, P., Boccaccio, G. C., Bonazzola, E., Botta, T., Bressani, M., Bruschi, M. P., Bussa, L., Busso, D., Calvo, M., Capponi, B., Cereda, P., Cerello, C., Cicalò, M., Corradini, S., Costa, S., Castro, C., Leo, Denisov, D. Y. u., F., D’Isep, A., Donzella, L., Fava, A., Feliciello, L., Ferrero, A., Filippi, V., Filippini, A., Fontana, D., Galli, R., Garfagnini, U., Gastaldi, B., Giacobbe, P., Gianotti, O. E., Gorchakov, A., Grasso, C., Guaraldo, F., Iazzi, A., Lanaro, E., Lodi Rizzini, M., Lombardi, V., Lucherini, A., Maggiora, S., Marcello, U., Marconi, Margagliotti, Giacomo, G., Maron, A., Masoni, I., Massa, B., Minetti, P., Montagna, M., Morando, F., Nichitiu, D., Panzieri, G., Pauli, M., Piccinini, G., Piragino, M., Poli, S. N., Prakhov, G., Puddu, R. A., Ricci, E., Rossetto, A., Rotondi, A. M., Rozhdestvensky, A., Saino, P., Salvini, L., Santi, M. G., Sapozhnikov, N., Semprini Cesari, S., Serci, R., Spighi, Tessaro, Susanna, F., Tosello, V. T., Tretyak, G., Usai, L., Vannucci, S., Vecchi, G., Vedovato, L., Venturelli, M., Villa, A., Vitale, A., Zenoni, A., Zoccoli, and G., Zosi

Subjects
Physics, Particle physics, Annihilation, OZI-RULE, High Energy Physics::Phenomenology, antiproton deuterium annihilation, OZI rule, Nuclear physics, Deuterium, ANTIPROTON ANNIHILATION, Antiproton, High Energy Physics::Experiment, Physics::Atomic Physics, Nuclear Experiment
Abstract

The branching ratios of Φπ− and ωπ− final states were measured for the antiproton annihilation in gaseous deuterium at rest. A significant violation of the OZI rule was found.

Published
1994

36. Measurement of the η(1440) → K±K0π± production rates from p annihilation at rest at three different hydrogen target densities [Phys. Lett. B 385 (1996) 493]

Author

A. Adamo, M. Morando, M. Capponi, Paolo Montagna, N. Mirfakhrai, Alberto Masoni, Antonio Zoccoli, V. Filippini, O.Yu. Denisov, Benedetto Giacobbe, D. Calvo, A.M. Rozhdestvensky, G. Puddu, L. Ferrero, A. Saino, Paola Salvini, M.G. Sapozhnikov, S. De Castro, E. Lodi Rizzini, P. Cerello, Massimo Piccinini, M.P. Bussa, Bruno Minetti, Antonietta Donzella, A. Grasso, Marco Bruschi, Stefania Vecchi, S. Serci, S.N. Prakhov, L. Santi, V. Lucherini, Andrea Fontana, Alberto Rotondi, E. Rossetto, A. Bertin, Michelangelo Agnello, V.I. Tretyak, L. Busso, C. Petrascu, G. Bendiscioli, F. Tosello, A. Maggiora, P.P. Temnikov, Gianfranco Zosi, P. Gianotti, S. Tessaro, L. Fava, D. Parena, A. Filippi, R. Garfagnini, Armando Lanaro, V.G. Ableev, D. D'Isep, Mauro Villa, A. Vezzani, L. Venturelli, C. Guaraldo, A. Lai, M. Corradini, Felice Iazzi, Corrado Cicalo, Antonio Ferretti, G. L. Usai, F. Nichitiu, A. Feliciello, S. Marcello, G. Pauli, F. Balestra, O.E. Gorchakov, Nicola Semprini-Cesari, L. Musa, F. Vigotti, M. Lombardi, A M Rosca, D. Galli, Elena Botta, Roberto Spighi, S. Costa, D. Panzieri, Tullio Bressani, U. Gastaldi, C. Cavion, Aldo Zenoni, A. Vitale, and Umberto Marini Bettolo Marconi

Subjects
Rest (physics), Nuclear and High Energy Physics, Annihilation, Hydrogen, Chemistry, chemistry.chemical_element, Production (computer science), Atomic physics
Abstract

Due to a most unfortunate technical mishap, half of the references in the list of references were not printed. Below the full list of references is being reprinted

Published
1997
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37. Barkas effect for antiproton stopping in H2

Author

G. V. Margagliotti, Roberto Spighi, N. Semprini Cesari, L. Santi, A. Vitale, Pietro Faccioli, Antonio Zoccoli, M. Bargiotti, V.I. Tretyak, A. Grasso, F. Balestra, Mauro Villa, O.E. Gorchakov, A. Maggiora, S. De Castro, M. Poli, G. Piragino, Antonietta Donzella, Marco Bruschi, M. Corradini, C. Guaraldo, A.M. Rozhdestvensky, L. Venturelli, V. Vagnoni, Massimo Piccinini, Benedetto Giacobbe, G.B. Pontecorvo, A. Bertin, E. Lodi Rizzini, D. Galli, Andrea Bianconi, I. Massa, F. Tosello, S. Tessaro, L. Ferrero, C. Petrascu, M.P. Bussa, Stefania Vecchi, Gianfranco Zosi, R. Garfagnini, M. Capponi, U. Marconi, L. Busso, Laura Fabbri, O. Y. Denisov, E., Lodirizzini, A., Bianconi, M. P., Bussa, M., Corradini, A., Donzella, L., Venturelli, M., Bargiotti, A., Bertin, M., Bruschi, M., Capponi, S., DE CASTRO, L., Fabbri, P., Faccioli, D., Galli, B., Giacobbe, U., Marconi, I., Massa, M., Piccinini, M., Poli, N., Semprinicesari, R., Spighi, V., Vagnoni, S., Vecchi, M., Villa, A., Vitale, A., Zoccoli, O. E., Gorchakov, G. B., Pontecorvo, A. M., Rozhdestvensky, V. I., Tretyak, C., Guaraldo, C., Petrascu, F., Balestra, L., Busso, O. Y., Denisov, L., Ferrero, R., Garfagnini, A., Grasso, A., Maggiora, G., Piragino, F., Tosello, G., Zosi, Margagliotti, Giacomo, L., Santi, and S., Tessaro

Subjects
Physics, Proton, Astrophysics::High Energy Astrophysical Phenomena, Hydrogen molecule, General Physics and Astronomy, Kinetic energy, Nuclear physics, Antiproton, 34.50.bW, Maximum difference, Physics::Accelerator Physics, Stopping power (particle radiation), Physics::Atomic Physics, Atomic physics, Nuclear Experiment
Abstract

We report the stopping power of molecular hydrogen for antiprotons of kinetic energy above the maximum (approximately 100 keV) with the purpose of comparing with the proton one. Our result is consistent with a positive difference in antiproton-proton stopping powers above approximately 250 keV and with a maximum difference between the stopping powers of 21%+/-3% at around 600 keV.

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