Jake Calcutt Sep. 12, 2019 Jake Calcutt 2 In addition to the total - PowerPoint PPT Presentation

Jake Calcutt Sep. 12, 2019

Jake Calcutt 2 In addition to the total (elastic + inelastic) cross section, exclusive (subsets of inelastic) pion-Ar cross sections provide useful information Have the added benefit of unique signals Exclusive channels:

Jake Calcutt 3 Absorption π + X X π + Charge Exchange π 0 X = Nucleons

Jake Calcutt 4 Last talk (July 11) I showed some studies on building up to an event selection for this selection Came across some issues with reconstruction and how I was defining some things between reco and truth Was looking at events/tracks too broadly -- i.e. at the track level ● But: need to consider things at the slice/vertex level ● Refining this is necessary to determine selection performance ●

Jake Calcutt 5

Jake Calcutt 6 Right: Example of an event with an elastic scatter splitting a track Previously: Looked at the process ending the track (i.e. ‘pi+Inelastic’) and the true particles leaving that interaction But within the Thin Slice Method, ● we only care about what happens at the end of the red track Becomes a question of “How do I ● define the event/elastic vertex?”

Jake Calcutt 7 Elastic Inelastic Reco Track Just look at the list of processes from the true particle? Pandora will miss low-angle elastic scatters, which is fine for my ● definition (to the point of a ‘small’ energy-loss systematic) Need to dig deeper into what’s happening along the true trajectory ● and determine what’s “causing” pandora to end the track

Jake Calcutt 8 Geant steps the particle through the Argon ( MCTrajectory points ) Some points have a process (‘hadElastic’, ‘pi+Inelastic’, etc.) ● associated Between each step, a set of ionization deposits occur ( IDE )

Jake Calcutt 9 Ionization drifts towards wires, creating signals on the wires (reconstructed as Hits ) ● Pandora collects Hits to form reconstructed Tracks/Showers Note: picture above is heavily simplified

Jake Calcutt 10 For a Thin-Slice analysis: split up the track/hits by wire-spacing

Jake Calcutt 11 Try to categorize the reco vertex by matching the Hits within the Slice to the IDEs that created them

Jake Calcutt 12 Collection of IDEs that created the hits True interaction points Once the hits from the vertex slice have been backtracked to their IDEs, try to determine their distance ( ΔR ) to any interaction points If any ΔR < (some value -- 5 cm for the following studies ): consider ● the reco vertex as matched to a true interaction Refine this? -- i.e. ΔR of center of IDEs, average ΔR, etc... ○ Use this to categorize what is happening at the reconstructed vertex ● I.e. Elastic scatter vs. Inelastic scatter, something else? ○

Jake Calcutt 13 Vertex ‘matched’ to elastic scatter Inelastic scatter (can further classify this by daughters) ‘Unmatched’ ( ΔR to any interaction is too large) Matched to both inelastic and elastic Some other process (i.e. decay)

Jake Calcutt 14 Of course, this is not the whole story and much more can happen I.e. the reco track extends past the inelastic vertex due to hits from ● daughters For now: just want to test event selection using daughter information, deal with subtleties like this at another point

Jake Calcutt 15 Also realized that I had to refine how to include daughter track info Idea: put some conditions on the daughter track positions relative to the vertex position Hits from the beam Should help with reco ● particle reconstructed Interaction point issues such as cosmics as daughter tagged as daughers

Jake Calcutt 16 Looking at the distance between vertex point and start* of daughter Inelastic track ( dR -- note this is different than Vertex the vertex-defining ΔR ) Legend notes: Nuc, Gamma, Pi, Proton, Mu are ● true daughters (i.e. pi → pi ) ○ GDaughter: Grand Daughter ● (i.e. pi → pi → pi) ○ * Start/end of daughter -- GGDaughter ● whichever is closer to the vertex Great Grand Daughter ○ (i.e. pi → pi → pi → pi) ○

Jake Calcutt 17 Looking at the distance between vertex point and start* of daughter Inelastic track Vertex * Start/end of daughter -- Cosmics are far away whichever is closer to the vertex

Jake Calcutt 18 Looking at the distance between vertex point and start* of daughter Inelastic track Vertex Pi0 (from primary * Start/end of daughter -- interaction) decay whichever is closer to the gammas tagged as vertex tracks

Jake Calcutt 19 Looking at the distance between vertex point and start* of daughter Inelastic track Vertex Mostly primary interaction daughters Some grand daughters from prompt reinteractions * Start/end of daughter -- Mix of muons, protons, ● whichever is closer to the pions, nuclear fragments, vertex etc.

Jake Calcutt 20 Looking at the distance between vertex point and start* of daughter Elastic track Vertex Need to understand why true daughters are associated close to vertex for elastic scatters Could be inaccuracies due to how I’ve defined the * Start/end of daughter -- whichever is closer to the vertex (i.e. matching IDEs vertex within 5cm of interactions)

Jake Calcutt 21 ‘Unmatched’ (no vertex-IDEs within 5cm of an interaction Unmatched point) is a bit more complicated Track could end in the middle of the true beam particle (itself reco’d as daughter) Or maybe some place on a downstream particle (true daughters and grand daughters reco’d)

Jake Calcutt 22 Refining how I treat reconstruction and truth should help with defining an event selection More granular/in-depth info is always better ● Need to ‘tune’ the IDE/interaction matching -- suggestions welcome ● Also need to look into shower daughter information ● Quantify how the event selection performs ●

Jake Calcutt Thanks for listening