[en] Electromagnetic form factors are fundamental properties of the nucleon that describe the effect of its internal quark structure on the cross section and spin observables in elastic lepton-nucleon scattering. Double-polarization experiments have become the preferred technique to measure the proton and neutron electric form factors at high momentum transfers. The recently completed GEp-III experiment at the Thomas Jefferson National Accelerator Facility used the recoil polarization method to extend the knowledge of the proton electromagnetic form factor ratio GpE/GpM to Q2 = 8.5 GeV2. In this paper we present the preliminary results of the experiment.

[en] Electromagnetic form factors are fundamental properties of the nucleon that describe the effect of its internal quark structure on the cross section and spin observables in elastic lepton-nucleon scattering. Double-polarization experiments have become the preferred technique to measure the proton and neutron electric form factors at high momentum transfers. The recently completed GEp-III experiment at the Thomas Jefferson National Accelerator Facility used the recoil polarization method to extend the knowledge of the proton electromagnetic form factor ratio G^p_E/G^p_M to Q² = 8.5 GeV². In this paper we present the preliminary results of the experiment.

[en] The study of the transverse momentum dependent parton distributions (TMDs) of the nucleon in semi-inclusive deep-inelastic scattering (SIDIS) has emerged as one of the major physics motivations driving the experimental program using the upgraded 11 GeV electron beam at Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF). The accelerator construction phase of the CEBAF upgrade is essentially complete and commissioning of the accelerator has begun as of April, 2014. As the new era of CEBAF operations begins, it is appropriate to review the body of published and forthcoming results on TMDs from the 6 GeV era of CEBAF operations, discuss what has been learned, and discuss the key challenges and opportunities for the 11 GeV SIDIS program of CEBAF.

[en] In this paper, interest in the behavior of nucleon electromagnetic form factors at large momentum transfers has steadily increased since the discovery, using polarization observables, of the rapid decrease of the ratio G^p_E/G^p_M of the proton's electric and magnetic form factors for momentum transfers Q² ≳ 1 GeV², in strong disagreement with previous extractions of this ratio using the traditional Rosenbluth separation technique.

[en] We report the discovery of a minor planet (2006 SQ₃₇₂) on an orbit with a perihelion of 24 AU and a semimajor axis of 796 AU. Dynamical simulations show that this is a transient orbit and is unstable on a timescale of ∼200 Myr. Falling near the upper semimajor axis range of the scattered disk and the lower semimajor axis range of the Oort Cloud, previous membership in either class is possible. By modeling the production of similar orbits from the Oort Cloud as well as from the scattered disk, we find that the Oort Cloud produces 16 times as many objects on SQ₃₇₂-like orbits as the scattered disk. Given this result, we believe this to be the most distant long-period comet (LPC) ever discovered. Furthermore, our simulation results also indicate that 2000 OO₆₇ has had a similar dynamical history. Unaffected by the 'Jupiter-Saturn Barrier', these two objects are most likely LPCs from the inner Oort Cloud.

[en] The charge form factor of ⁴He has been extracted in the range 29 fm^-2 <= Q² <= 77 fm^-2 from elastic electron scattering, detecting ⁴He nuclei and electrons in coincidence with the High Resolution Spectrometers of the Hall A Facility of Jefferson Lab. The results are in qualitative agreement with realistic meson-nucleon theoretical calculations. The data have uncovered a second diffraction minimum, which was predicted in the Q² range of this experiment, and rule out conclusively long-standing predictions of dimensional scaling of high-energy amplitudes using quark counting