RESUMO
The "standard" Hall A apparatus at Jefferson Lab (TOF and aerogel threshold Cherenkov detectors) does not provide complete identification for proton, kaon and pion. To this aim, a proximity focusing C(6)F(14)/CsI RICH (Ring Image CHerenkov) detector has been designed, built, tested and operated to separate kaons from pions with a pion contamination of a few percent up to 2.4GeV/c. Two quite different experimental investigations have benefitted of the RICH identification: on one side, the high-resolution hypernuclear spectroscopy series of experiments on carbon, beryllium and oxygen, devoted to the study of the lambda-nucleon potential. On the other side, the measurements of the single spin asymmetries of pion and kaon on a transversely polarized (3)He target are of utmost interest in understanding QCD dynamics in the nucleon. We present the technical features of such a RICH detector and comment on the presently achieved performance in hadron identification.
Assuntos
Elétrons , Partículas Elementares , Mésons , Prótons , Berílio/química , Carbono/química , Interações de Partículas Elementares , Desenho de Equipamento , Método de Monte Carlo , Física Nuclear , Oxigênio/química , Análise EspectralRESUMO
The ratio of the electromagnetic proton elastic form factors, G(p)(E)/G(p)(M), has been measured at Jefferson Lab up to Q(2) approximately 9(GeV/c)(2), by using the CEBAF 6GeV electron beam, and revealing an unexpected and challenging physical behaviour. The 2014 scheduled 12GeV upgrade will allow the measurement of G(p)(E)/G(p)(M) up to Q(2) approximately 15(GeV/c)(2), by taking advantage of the new large-acceptance forward spectrometer Super BigBite (SBS) in Hall A. Measurements of neutron form factors in the region around 10(GeV/c)(2), where quark confinement plays an important role, are expected to show the behaviour already observed in the proton case.
