Z. Berka

Publications (5)4.18 Total impact

• Source

  Available from: Angeles Lopez Aguera

  Article: Determination of $\pi\pi$ scattering lengths from measurement of $\pi^+\pi^-$ atom lifetime

  B Adeva, L. Afanasyev, M Benayoun, A Benelli, Z. Berka, V. Brekhovskikh, G. Caragheorgheopol, T. Cechak, M Chiba, P V Chliapnikov, [......], V. Utkin, O. Vázquez Doce, S Vlachos, O. Voskresenskaya, T. Vrba, C Willmott, V. Yazkov, Y Yoshimura, M. Zhabitsky, P. Zrelov
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  ABSTRACT: The DIRAC experiment at CERN has achieved a sizeable production of $\pi^+\pi^-$ atoms and has significantly improved the precision on its lifetime determination. From a sample of 21227 atomic pairs, a 4% measurement of the S-wave $\pi\pi$ scattering length difference $|a_0-a_2| = (.0.2533^{+0.0080}_{-0.0078}|_\mathrm{stat}.{}^{+0.0078}_{-0.0073}|_\mathrm{syst})M_{\pi^+}^{-1}$ has been attained, providing an important test of Chiral Perturbation Theory.
  09/2011;
• Source

  Available from: Mircea Pentia

  Article: Detection of π+π− atoms with the DIRAC spectrometer at CERN

  B Adeva, L Afanasyev, M Benayoun, A Benelli, Z Berka, V Brekhovskikh, G Caragheorgheopol, T Cechak, M Chiba, S Constantinescu, [......], M J Tobar, S Trusov, V Utkin, O Vázquez Doce, P Vázquez, S Vlachos, V Yazkov, Y Yoshimura, M Zhabitsky, P Zrelov
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  ABSTRACT: The goal of the DIRAC experiment at CERN is to measure with high precision the lifetime of the π+π− atom (A2π), which is of order 3 × 10−15 s, and thus to determine the s-wave ππ-scattering lengths difference |a0 − a2|. A2π atoms are detected through the characteristic features of π+π− pairs from the atom break-up (ionization) in the target. We report on a first high statistics atomic data sample obtained from p–Ni interactions at 24 GeV/c proton momentum and present the methods to separate the signal from the background.
  Journal of Physics G Nuclear and Particle Physics 11/2004; 30(12):1929. · 4.18 Impact Factor
• Source

  Available from: Angeles Lopez Aguera

  Article: First measurement of the π+π− atom lifetime

  B. Adeva, L. Afanasyev, M. Benayoun, A. Benelli, Z. Berka, V. Brekhovskikh, G. Caragheorgheopol, T. Cechak, M. Chiba, S. Constantinescu, [......], M.J. Tobar, S. Trusov, V. Utkin, O. Vázquez Doce, P. Vázquez, S. Vlachos, V. Yazkov, Y. Yoshimura, M. Zhabitsky, P. Zrelov
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  ABSTRACT: The goal of the DIRAC experiment at CERN (PS212) is to measure the π+π− atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering lengths combination |a0−a2|. Based on part of the collected data we present a first result on the lifetime, s, and discuss the major systematic errors. This lifetime corresponds to .
  Physics Letters B.
• Article: Determination of $\pi\pi$ scattering lengths from measurement of $\pi^+\pi^-$ atom lifetime

  B Adeva, L. Afanasyev, M Benayoun, A Benelli, Z. Berka, V. Brekhovskikh, G. Caragheorgheopol, T. Cechak, M Chiba, P V Chliapnikov, [......], V. Utkin, O V\'azquez Doce, S Vlachos, O. Voskresenskaya, T. Vrba, C Willmott, V. Yazkov, Y Yoshimura, M. Zhabitsky, P. Zrelov
  [show abstract] [hide abstract]
  ABSTRACT: The DIRAC experiment at CERN has achieved a sizeable production of $\pi^+\pi^-$ atoms and has significantly improved the precision on their lifetime determination. From a sample of 21227 atoms, a $4\%$ measurement of the S-wave $\pi\pi$ scattering length difference $|a_0-a_2|$ has been attained, providing an important constraint for Chiral Perturbation Theory.
• Article: DIRAC: A high resolution spectrometer for pionium detection

  B. Adeva, L. Afanasyev, M. Benayoun, A. Benelli, Z. Berka, V. Brekhovskikh, G. Caragheorgheopol, T. Cechak, M. Chiba, E. Cima, [......], M.J. Tobar, F. Triantis, S. Trusov, V. Utkin, O. Vázquez Doce, P. Vázquez, S. Vlachos, V. Yazkov, Y. Yoshimura, P. Zrelov
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  ABSTRACT: The DIRAC spectrometer has been commissioned at CERN with the aim of detecting π+π− atoms produced by a high intensity proton beam in thin foil targets. A challenging apparatus is required to cope with the high interaction rates involved, the triggering of pion pairs with very low relative momentum and the measurement of the latter with resolution around . The general characteristics of the apparatus are explained and each part is described in some detail. The main features of the trigger system, data-acquisition, monitoring and set-up performances are also given.
  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.