[en] We have measured the nuclear transparency of the A(e,e' pi⁺) process in ²H,¹²C, ²⁷Al, ⁶³Cu and ¹⁹⁷Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q² = 1.1 - 4.7 (GeV/c)². The nuclear transparency was extracted as the super-ratio of σ_Aσ_H from data to a model of pion-electroproduction from nuclei without pi-N final state interactions. The Q² and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations, and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency

[en] The quasielastic (e,e[prime]p) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer Q2 of 8.1 (GeV/c)2. A nuclear transparency was determined by comparing the data to calculations in the plane-wave impulse approximation. The dependence of the nuclear transparency on Q2 and the mass number A was investigated in a search for the onset of the color transparency phenomenon. We find no evidence for the onset of color transparency within our range of Q2. A fit to the world's nuclear transparency data reflects the energy dependence of the free-proton-nucleon cross section

[en] The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at theta_cm = 37^o are consistent with the constituent counting rules for E_gamma∼> 4 GeV, while those at 70^o are consistent with the constituent counting rules for E_gamma ∼> 1.5 GeV