(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.
Sivers function in constituent quark models
A formalism to evaluate the Sivers function, developed for calculations in constituent quark models, is applied to the Isgur-Karl model. A non-vanishing Sivers asymmetry, with opposite signs for the u and d flavor, is found; the Burkardt sum rule is fulfilled up to 2 %. Nuclear effects in the extraction of neutron single spin asymmetries in semi-inclusive deep inelastic scattering off 3He are also evaluated. In the kinematics of JLab, it is found that the nuclear effects described by an Impulse Approximation approach are under control.
Time behavior of gas pressure and PD activity in insulation cavities under AC voltage
In the framework of developing defect-based life models (i.e. the life model of partial discharge-induced damage growth from a micro-void in polymer matrix), ageing tests were performed on PE layered specimens with artificial cavities under constant gas pressure and constant gas volume conditions, respectively. Time behavior of the discharge repetition rate and amplitude were recorded and compared under these two conditions. Results show that pressure variation has little influence on PD activities at constant gas volume. Under constant gas pressure, the evolution of gas volume has similar characteristic to the product of discharge amplitude and repetition rate.