1. LAr TPC: Status and progress in data analysis efforts
Y. Ramachers
(University of Warwick)
IDS-NF, RAL 22/09/2010
Y. Ramachers

2. IDS-NF, RAL 22/09/2010
Y. Ramachers

3. IDS-NF, RAL 22/09/2010
Y. Ramachers

4. Update: A. Rubbia@EuroNu2010
IDS-NF, RAL 22/09/2010
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5. The Data Analysis Challenge
Liquid argon TPC’s reconstruct events with bubble-chamber quality
But, automatic reconstruction in software is still not established
Why?
IDS-NF, RAL 22/09/2010
Y. Ramachers

6. 2. It’s not so easy!
Tracks and showers develop side-by-side in the same volume
 topologically complicated
No well defined start point for what initiated the event
Very high density of information: mm-scale energy deposits, delta- rays, vertices, kinks etc
Multiple scattering occurring continuously throughout volume
ICARUS, arxiv:0812:2373
IDS-NF, RAL 22/09/2010
Y. Ramachers

7. Past Developments: ICARUS
ICARUS Collab., Phys. Rev. D74, (2006)
Tools developed over the years by the ICARUS project: hit definition, clustering, 2D and 3D track fitting
Low multiplicity neutrino events reconstructed from a 50L module exposed to the CERN WANF beam
Some degree of visual scanning/selection involved before applying algorithms
IDS-NF, RAL 22/09/2010
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8. Warwick work in progress
Experimental programme:
Purity control
Measurements with SiPM arrays → spatial resolution
Alternative: CMOS/CCD camera and optics
Optical Fibre array readout
Solid Argon test
Cold electronics
Computational programme:
Monte-Carlo event generation
Novel high-granularity tracking analysis
Charge transport simulation – signal generation
D.Y.Stewart et al., acc. for publ. in JINST
Informal collaboration with
LArsoft: ArgoNeuT, MicroBooNE, data analysis code
A. Rubbia's group on data analysis (travel grant)
IDS-NF, RAL 22/09/2010
Y. Ramachers

9. What do we need to do?
J. Spitz
Classify energy deposit information into shower-like and track-like objects
Identify tracks (,p) and showers (e, ) from topology, kinematics and dE/dx in LAr
IDS-NF, RAL 22/09/2010
Y. Ramachers

10. Clustering
Aim to limit contamination of cluster with hits laid down by other particles
Develop a hierarchy of clusters/super- clusters
IDS-NF, RAL 22/09/2010
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11. Density-Based Clustering
Clusters: a density of points considerably higher than outside the cluster
DBSCAN* algorithm: the `density-neighbourhood’ (around each point in the cluster must contain at least Nmin other points
Kinga Partyka (Yale/ArgoNEUT)‏
Implemented in ArgoNeuT data
Issues with `over-clustering’ being addressed
Colours → Cluster found by DBSCAN
IDS-NF, RAL 22/09/2010
Y. Ramachers
* Sander et al., Data Mining and knowledge Discovery 2, pp (1998)

12. Cellular Automata clustering
Next 'Warwick Tool' to be quantified and published
Toy-MC data
Raw hits
GENIE
Simulated
CCQE
events
Reconstructed
IDS-NF, RAL 22/09/2010
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13. OPTICS Ordering Points To Identify the Clustering Structure*
Reachability Distance plot
Ordering Points To Identify the Clustering Structure*
Extended DBSCAN clustering
Reveals clusters on all scales
Getting the scale correct helps in associating disjoint clusters in E- Mag showers
Extend to cluster in more than spatial coordinates, e.g. dE/dx
3 clusters found
dE/dx used since
track density identical
N data points
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* M. Ankerst et al., ACM SIGMOD Int. Conf. on Management of Data pp49-60 (1999)

14. Track Finding: Hough Transform
Joshua Spitz ArgoNeuT/Yale
Reasonable job of reconstructing multiple tracks in ArgoNeuT events
Returns only gradient and intercept of line – definition of start/end-points of tracks continuing:
IDS-NF, RAL 22/09/2010
Y. Ramachers

15. Track Finding: KDTREE
KDTREE provides convenient data structure from which to launch a nearest-neighbour hit search
Fit straight-line segments through groups of nearest hits in 3D
Andrew Bennieston, Warwick
Currently testing on toy Monte Carlo – observe change in direction cosine of line segments to tag kink/vertex with high efficiency
IDS-NF, RAL 22/09/2010
Y. Ramachers

16. 3D Track fitting
Implemented a modified ICARUS Kalman filter: ICARUS, Eur. Phys. J. C48 (2006) 667
Momentum-measurement by multiple scattering!
Momentum reconstruction
ICARUS simulated tracks
Warwick simulated track,
Multiple scattering only
Track slope reconstruction
p=1.5 GeV/c
IDS-NF, RAL 22/09/2010
Y. Ramachers

17. Key Point Detection Vertex IP  corner in charge density
Delta-electron  corner in charge density
Prior knowledge of vertex points, kinks, track end-points etc is useful in aiding reconstruction algorithms e.g. blank-off hits around a vertex point from a cluster search
IDS-NF, RAL 22/09/2010
Y. Ramachers

18. Corner Finding GENIE generated CCQE events in 3T LAr TPC:
Ben Morgan, JINST 5 (2010) P07006
Vertex picked out
Proton Stop
Delta Electron ID!
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19. ArgoNeuT data update
Recently completed >5 months physics run in the NuMI beamline
ArgoNeuT, arXiv: , implementing B. Morgan's corner finding
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20. New toolbox target T. Dealtry, Warwick URSS- Project 2009
IDS-NF, RAL 22/09/2010
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21. Conclusion Great progress in expanding data analysis toolbox
Work in Quantify performance using GENIE simulated data for liquid argon
Next steps:
Model Analysis
Obtain Globes input parameters from Monte-Carlo data
Analyse the effect of (absence of) a magnetic field
Collaborate more closely with running experiments, testing analysis on real data
Provide input to IDS on liquid argon detector
IDS-NF, RAL 22/09/2010
Y. Ramachers