arXiv subjects

The DIRAC collaboration

Publications and source records attributed to The DIRAC collaboration.

2 recordsLinked to original sources

arXiv2005

First measurement of the $π^+π^-$ atom lifetime

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 $|a_0-a_2|$. Based on part of the collected data we present a first result on the lifetime, $τ=[2.91 ^{+0.49}_{-0.62}]\times 10^{-15}$ s, and discuss the major systematic errors. This lifetime corresponds to $|a_0-a_2|=0.264 ^{+0.033}_{-0.020} m_π^{-1}$.

hep-ex↗

arXiv2004

Detection of $π^+π^-$atoms with the DIRAC spectrometer at CERN

The goal of the DIRAC experiment at CERN is to measure with high precision the lifetime of the $π^+π^-$ atom ($A_{2π}$), which is of order $3\times10^{-15}$ s, and thus to determine the s-wave $ππ$-scattering lengths difference $|a_{0}-a_{2}|$. $A_{2π}$ 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.

hep-ex↗