Detection of ${\pi }^{+}{\pi }^{-}$atoms with the DIRAC spectrometer at CERN

Abstract

The goal of the DIRAC experiment at CERN is to measure with high precision the lifetime of the ${\pi }^{+}{\pi }^{-}$ atom ($A_{2\pi }$), which is of order $3\times 10^{-15}$ s, and thus to determine the s-wave $\pi \pi$-scattering lengths difference $|a_0-a_2|$. $A_{2\pi }$ atoms are detected through the characteristic features of ${\pi }^{+}{\pi }^{-}$ 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.

19 pages, 12 figures, 1 table

References in corpus (1)

• A Monte Carlo Calculation of the Pionium Break-up Probability with Different Sets of Pionium Target Cross Sections

Cited by in corpus (12)

• First measurement of the ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Finite-size effect on two-particle production in continuous and discrete spectrum
• Radiative corrections in K --> 3 pi decays
• Isospin breaking in Kl4 decays
• Cross sections for low-energy ${\pi }^{-}\gamma$ reactions
• Chiral corrections to ${\pi }^{-}\gamma \to 3\pi$ processes at low energies
• Hadronic Atoms
• Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length
• Energy and decay width of the pi-K atom
• A Complete Version of the Glauber Theory for Elementary Atom - Target Atom Scattering and Its Approximations
• Formation of $\pi \mu$ atoms in $K_{μ4} decay
• Investigation of $K^{+}{K}^{-}$ pairs in the effective mass region near $2m_K$