Quark propagation and hadron formation observation at CLAS

In this paper are presented the perspectives of investigation in CLAS detector at Jefferson Lab (TJNAF) of the physics of the quark propagation in cold QCD matter and the resulting hadronization process. The determination of the "production time" and "formation time" are given as well as their interpretation as quark energy loss resulting in transverse momentum broadening of the produced hadron and hadronic attenuation in the nuclear medium. A novel target setup was used for these measurements in CLAS where two targets were placed in the beam simultaneously and a newly developed $\pi^+$ identification technique is presented from the $\mathrm{EG2}$ experiment [1].