The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.2

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New mapping (NTS 27 B, C, 37 A, D) has characterized the supracrustal rocks of the Archean Mary River Group and their relationship to the underlying Archean basement orthogneiss units of the Rae Craton. The primary depositional unconformity that separates the base of the Paleoproterozoic Piling Group from the Rae Craton basement has been documented across the project area. The basal, clastic Dewar Lakes formation has been subdivided into 3 informal members. Significant primary variations in thickness of the Dewar Lakes and carbonate Flint Lake formations have been identified throughout the project area. Mafic volcanic rocks and ultramafic to mafic sills interlayered with siliciclastic rocks (Bravo Lakes formation) overlie the basal clastic rocks. Sulphidic pelite (Astarte River formation) overlies the three lowest formations. Psammite-pelite turbidite units (Longstaff Bluff formation) blanket the entire area, and are interpreted as an orogenic molasse. Deformation and consequent metamorphism occurred during the 1.8 Ga Trans-Hudson Orogen.

The northern flank of the Trans-Hudson Orogen on central Baffin Island comprises, from north to south 1) reworked Archean basement (Rae Province); 2) the Paleoproterozoic Piling Group, which comprises a lower, pas- sive-margin sequence (Dewar Lakes and Flint Lake formations) and an upper, foredeep sequence (Astarte River and Longstaff Bluff formations); 3) a mafic volcanic thrust sheet (Bravo Lake formation); and 4) a metamor- phic-plutonic internal zone. Field relationships suggest that the contact between the Piling Group and the underly- ing Archean basement is a reworked unconformity. Locally, the contact is obscured by the presence of large biotite syeno- to monzogranite plutons that crosscut both the Piling Group and the Archean basement. Four distinct tectonometamorphic episodes are recorded, with an earlier, middle-amphibolite-facies Archean event (D 1A ), two compressional Paleoproterozoic events (D 1P and D 2P ), and a late cross-folding event (D 3P ) that produced a set of basement culminations in the southern portion of the map area.

New mapping has refined the stratigraphic relationships within the Paleoproterozoic PilingGroup (NTS 37 A, 27 B), as well as its relationship to underlying Archean basement orthogneiss of the Rae Craton. Across the project area, basal quartzite and rare psammite (Dewar Lakes Formation) are in tectonic contact with underlying orthogneiss, and are interpreted as a subsidence-related clastic sheet deposited on Rae basement. In the northern part of the area, carbonate units (Flint Lake Formation) overlie the quartzite, and are overlain by sulphidic pelite and iron-formation (Astarte River Formation), interpreted as a shelf that subsequently foundered. In the south, quartzite is overlain by mafic volcanic rocks and ultramafic to mafic sills interlayered with siliciclastic rocks (Bravo Lake Formation). Psammite/ pelite turbidites (Longstaff Bluff Formation) blanket the entire area, and are interpreted as an orogenic molasse that might have had a source area other than the Rae Craton. Deformation and consequent metamorphism occurred during the1.8 Ga Trans-Hudson Orogeny.