(a New Proposal to Jefferson Lab 12 Gev -pac34) Measurement of the Semi-inclusive Π and K Electro-production in Dis Regime from Transversely Polarized He Target with the Sbs & Bb Spectrometers in Hall A
An experiment is proposed to measure the Single Spin Asymmetries of the Semi-Inclusive Deep Inelastic Scattering (SIDIS) process ~n(e, e′π±(K±)), using the large-solid-angle Super Bigbite Spectrometer (SBS), the BigBite Spectrometer, and a novel polarized He target that includes alkali-hybrid optical pumping and convection flow to achieve very high luminosity. Both spectrometer arms will utilize GEM-based tracking to accommodate the high rates. The abundant statistics will allow the determination of the Collins and Sivers functions for neutron roughly 10 times more accurate than obtained for proton at HERMES for a detailed grid of the kinematic variables x, p T , and z. Furthermore, by including data taking at two energies, an 8.8 and 11 GeV, we will have data at two values of Q for each bin in x. The azimuthal coverage of our experiment is excellent, and is facilitated by collecting data at a series of neutron polarization directions, always transverse to the beam direction. The SIDIS pions and kaons will be detected over a wide range of the hadron momenta above 2 GeV for the angle between the hadron production and the electron scattering planes up to ±60◦, and the angle between the hadron momenta and the virtual photon momenta up to 60◦. Between the large acceptances of the electron and hadron arms, an electron polarizednucleon luminosity on the level of 4 · 10 cm−2/s, and a target polarization of 65%, we will obtain in a two-month run about 100 times more statistics (after accounting for difference in polarization and dilutions) then was done by the HERMES experiment. The experiment has significant potential for the discovery of new effects in hadron physics.
Transverse spin effects in COMPASS
In the years 2002-2004 COMPASS has collected data with the LiD target polarization oriented transversely with respect to the muon beam direction for about 20% of the running time, to measure transverse spin effects in semi-inclusive deep inelastic scattering, one of the main objectives of the COMPASS spin program. In 2007, COMPASS has used for the first time a proton NH_3 target with the data taking time equally shared between longitudinal and transverse polarization of the target. After reviewing the results obtained with the deuteron, the new results for the Collins and Sivers asymmetries of the proton will be presented.
Observations of nearshore infragravity waves: Seaward and shoreward propagating components
[1] The variation of seaward and shoreward infragravity energy fluxes across the shoaling and surf zones of a gently sloping sandy beach is estimated from field observations and related to forcing by groups of sea and swell, dissipation, and shoreline reflection. Data from collocated pressure and velocity sensors deployed between 1 and 6 m water depth are combined, using the assumption of cross-shore propagation, to decompose the infragravity wave field into shoreward and seaward propagating components. Seaward of the surf zone, shoreward propagating infragravity waves are amplified by nonlinear interactions with groups of sea and swell, and the shoreward infragravity energy flux increases in the onshore direction. In the surf zone, nonlinear phase coupling between infragravity waves and groups of sea and swell decreases, as does the shoreward infragravity energy flux, consistent with the cessation of nonlinear forcing and the increased importance of infragravity wave dissipation. Seaward propagating infragravity waves are not phase coupled to incident wave groups, and their energy levels suggest strong infragravity wave reflection near the shoreline. The cross-shore variation of the seaward energy flux is weaker than that of the shoreward flux, resulting in cross-shore variation of the squared infragravity reflection coefficient (ratio of seaward to shoreward energy flux) between about 0.4 and 1.5.