“ContainmentSize”: useful new cut parameters

1. “ContainmentSize”: useful new cut parameters Katherine Rawlins Olga Federova University of Alaska Anchorage

2. The old AMANDA “cylindersize” • The factor by which one would have to expand/contract the cylinder of AMANDA in order for the track to “just barely graze the edge” track which passes outside C > 1 track which passes inside C < 1

3. What’s nice about it • It tells you whether the track goes “inside” (C < 1) or “outside” (C > 1) • It also gives you a quantitative idea of “how far” inside or outside. • A track with C = 0.1 goes practically through the center. • A track with C = 0.95 is inside, but just barely. • A track with C = 1.05 is just barely outside. • A track with C = 4.2 is way out there. • Makes a good, very flexible, quality cut!

4. Wouldn’t it be nice… • … to have a similar variable for IceTop and IceCube? • Problem is, IceCube is no longer cylindrical. In fact, it is an irregular shape (which changes every year!) • It would be nice to have a general algorithm that could be applied to any shape detector, from any year.

5. The two-dimensional version (for IceTop) The three-dimensional version (for IceCube) Generalizing to IceTop/IceCube track landing outside track landing outside track landing inside track landing inside

6. Two-dimensional version (IceTop) • First, find the center of mass (Point where track hits the surface) CM

7. Two-dimensional version (IceTop) • Then, split the shape up into segments. • Find which segment is “pierced” by the track (Point where track hits the surface) CM

8. Two-dimensional version (IceTop) • Find the intersection of two lines: • C = D/d • (in this example, it’s greater than 1) (Point where track hits the surface) d D CM

9. Three-dimensional version (IceCube) • First, find the center of mass The track CM

10. Three-dimensional version (IceCube) • Then construct planes from pairs of corners, find where each is “pierced” by the track The track CM

11. Three-dimensional version (IceCube) • (Some intersection points will be very far away) The track CM

12. Three-dimensional version (IceCube) • Do all the lower planes too… The track CM

13. Three-dimensional version (IceCube) • …and also the vertical planes (for tracks which may graze the side edges) The track CM

14. Three-dimensional version (IceCube) • Again, find intertersection of two lines • C = D/d • (The smallest one found from all planes) • In this example, again, C happens to be >1 d The track D CM

15. Using it? • The algorithm as been programmed into “phys-services” • I3Cuts::ContainmentAreaSize • I3Cuts::ContainmentVolumeSize • (and also helper functions, such as I3Cuts::CMPolygon, etc.) • The variables have been programmed into “flat-ntuple” • CylSiz (the old AMANDA cylindersize) • IcetopSiz (IceTop area factor) • IniceSiz (IceCube volume factor) • SpaseSiz (area factor for hexagonal SPASE array)

16. Using it? • “flat-ntuple” will* compute these variables for every track • It takes the array shape from the geometry (if it sees 9 strings in the geometry, for instance, it uses IC-9) • * when the next release of icerec (which uses the next release of offline) comes out… in the meantime, try out the trunk of “flat-ntuple” and the trunk of “phys-services” • Please try this out and give me feedback!