Interferometric array assessment: Investigating UV coverage and imaging
Image quality assessment technology is introduced to assess interferometric array. Including existing assessments of Interferometric array, four categories of array assessment methods are concluded: assessing UV coverage directly, assessing UV coverage related to observing objects, assessing imaging quality related to observing objects and assessing imaging quality directly. A specific method in each category is proposed. All methods are used to design or optimize interferometric arrays, especially the early-stage study of Solar Low Frequency Array.
Interferometric array design: Optimizing the locations of the antenna pads
The design of an interferometric array should allow optimal instrumental response regarding all possible source positions, times of integration and scientic goals. It should also take into account constraints such as forbidden regions on the ground due to impracticable topography. The complexity of the problem requires one to proceed by steps. A possible approach is to rst consider a single observation and a single scientic purpose. A new algorithm is introduced to solve eciently this particular problem called the conguration problem. It is based on the computation of pressure forces related to the discrepancies between the model (as determined by the scientic purpose) and the actual distribution of Fourier samples. The flexibility and rapidity of the method are well adapted to the full array design. A software named APO that can be used for the design of new generation interferometers such as ALMA and ATA has been developed.
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.