Pion cloud system

The multiparticle Argo spectrometer system is a unique experimental apparatus which combines two good resolution, particle identifying, moveable spectrometer arms with a multiparticle-momentum detecting vertex spectrometer. With data obtained by this device, an analysis is carried out which allows one to obtain a system relatively free of final state leading particle influences. The resulting system, which is referred to as the Pion Cloud System or P.C.S., exhibits a strong tendency towards mass (particle) and energy distribution isotropy, two important qualifications for a statistically dominated system. Although statistical multiparticle production models were predicated on the existence of such a system for the past 20 years or so, this is the first reasonably straight forward experimental observation of it. Specific characteristics of the P.C.S. are also studied. An apparent lack of angular momentum in the cloud could be construed as consistent with its production resulting from point like quark/parton interactions. Its apparent statistical nature motivates one to fit various statistical distribution functions to cloud momentum distributions, obtaining a characteristic cloud temperature of kT approximately 130 MeV. The charge multiplicity of the cloud is observed to vary linearly with its mass, consistent with simple statistical fireball models. Relative topological cross sections show no significant low mass (less than 1 GeV/c2) resonances. In particular, a search for rho0 → π+π- using various cloud momentum cuts results in no distinct signal observation. Cloud multiplicity variation is seen to be roughly Poisson as in statistical independent particle production models and multiperipheral models. The cross section for the observed cloud data is estimated to be approximately 1 mb