Semi-Inclusive Pion Electroproduction in Deep Inelastic Scattering

Measurements of pion electro-production in semi-inclusive deep inelastic scattering (SIDIS) have been performed. Data were taken with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target during the E1-f run period in 2003. All three pion channels ($\pi^+$, $\pi^0$ and $\pi^-$) were measured simultaneously over a large range of kinematics($Q^2\approx$ 1-4 $GeV^2$ and $x\approx$0.1-0.5). Preliminary results from our study of single-spin azimuthal asymmetries from all three pion channels as functions of x, z, and $P_{T}$, from which $A_{LU}^{sin\phi}$ is extracted, will be presented, as will preliminary measurements of $A_{UU}^{cos\phi}$ and $A_{UU}^{cos2\phi}$ in the charged pion channels. This new high statistical data could provide access to transverse-momentum dependent parton distribution functions (TMD's), which are thought to be important in understanding of the physics underlying the spin structure of the nucleon.