Use of the Beam Cal to Constrain ILC

Use of the Beam. Cal to Constrain ILC IP Beam Parameter ECFA Linear Collider Workshop Palacio de la Magdalena Santander, Cantabria, Spain May 30 – June 5, 2016 Bruce Schumm UC Santa Cruz Institute for Particle Physics

Contributors • Luc D’Hauthuille, UCSC Undergraduate (thesis) • Anne Schuetz, DESY Graduate Student • Christopher Milke, UCSC Undergraduate With input from Glen White, Jan Strube, B. S. Goal Idea is to explore the sensitivity of various beamstrahlung observables, as reconstructed in the Beam. Cal, to variations in IP beam parameters. The sensitivity will be explored with various different Beam. Cal geometries. 2

IR Layout Low-Z Mask M 1 Mask Beam. Cal L* 3

Of these, we believe the following can be reconstructed in the Beam. Cal: • Total energy and its r, 1/r moment • Mean depth of shower • Thrust axis and value (relative to barycenter; could also use mode of distributions. What is wise choice though? Maybe just (0, 0)? ) • Mean x and y positions • Left-right, top-bottom, and diagonal asymmetries 4

Beam. Cal Face Geometry Options • “plugged” • Wedge cutout • Circle cutout “wedge” cutout Plug Insert plug here “circle” cutout 5

IP Parameter Scenarios Thanks to Anne Schuetz, Gunea. Pig expert Relative to nominal: • Increase beam envelop at origin (via -function), for electron and positron beam independently, by 10%, 20%, and 30% • Move waist of electron and positron beam (independently) back by 100 m, 200 m, 300 m. • Change targeting angle of electron and positron beam (independently) by 5 mrad and 20 mrad (in retrospect, isn’t this a bit much? ) Details at https: //wikis. bris. ac. uk/display/sid/Guinea. Pig+simulations+for+Beam. Cal+study 6

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The SCIPP Reconstruction Algorithm and Background Sensitivity Nomenclature: Tile: An individual Beam. Cal segment Palette: A collection of tiles within a layer, centered on a given tile and including some number of neighbors “P 0” = tile alone “P 1” = tile + nearest neighbors “P 2” = P 1+next-to-nearest neighbors New radial (vs. rectilinear) segmentation scheme 17 Cylinder: A palette extended through the depth of the Beam. Cal