CC/NC SEPARATION STUDY

Andy BlakeCambridge University

Friday February 23rd 2007

Introduction

Andy Blake, Cambridge University CC/NC Separation, slide 2

• Have developed a PID for CC/NC separation

• PID is calculated using a likelihood technique, and extends the “standard” PID algorithm by incorporating some new PDFs and accounting for their change in shape as a function of energy.

• Code committed to “MadAbID” class in Mad package.

• Documentation also available in doc-db #2720.

• Will outline method and present some results in this talk.

PID Variables

Andy Blake, Cambridge University CC/NC Separation, slide 3

Variables for CC/NC separation

• Event Topology Variables.

– percentage pulse height in track.

– pulse height per track plane.

– number of track like planes.

– percentage error in track fit.

• Event Kinematics Variables.

– reconstructed y.

• Event Energy and Charge.

– number of track planes.

– reconstructed charge.

• Relative CC/NC Normalization.

Test consistency with muon track.

Test consistency with CC interaction.

Incorporate CC/NCspectral information.

PID Definition

Andy Blake, Cambridge University CC/NC Separation, slide 4

• PID calculated from the product of several 1D and 2D PDFs as follows:

PID Variables: (I) Track Topology

Andy Blake, Cambridge University CC/NC Separation, slide 5

TRACK-LIKE PLANES vs TRACK PLANES

PID Variables: (I) Track Topology

Andy Blake, Cambridge University CC/NC Separation, slide 6

TRACK PH / TRACK PLANES vs TRACK PLANES

PID Variables: (I) Track Topology

Andy Blake, Cambridge University CC/NC Separation, slide 7

TRACK PH / EVENT PH vs TRACK PLANES

PID Variables: (I) Track Topology

Andy Blake, Cambridge University CC/NC Separation, slide 8

TRACK FIT ERROR vs TRACK PLANES

PID Variables: (II) Event Kinematics

Andy Blake, Cambridge University CC/NC Separation, slide 9

RECO Y vs RECO E

PID Variables: (III) CC/NC Spectrum

Andy Blake, Cambridge University CC/NC Separation, slide 10

TRACK PLANES RECONSTRUCTED CHARGE

CC/NC NORMALIZATION

PID Study

Andy Blake, Cambridge University CC/NC Separation, slide 11

• Cedar MC Ntuples.

– Far Detector (generate PDFs using 8.7e22 PoTs calculate PIDs using 2.9e22 PoTs).

– Near Detector (generate PDFs using 8.5e18 PoTs calculate PIDs using 2.5e18 PoTs).

• Event Selection.

– reconstructed track.

– successful track fit.

– contained track vertex.

• Construction of PDFs.

– PDFs constructed assuming no oscillations.

– 2D PDFs normalized to remove any spectral information. (i.e. divide out the shape of the energy spectrum).

– as a final step, try pre-selecting events with PCC=1. (i.e. create second set of PDFs for events with PCC<1).

PID Results (Far Detector)

Andy Blake, Cambridge University CC/NC Separation, slide 12

Purity vs Efficiency (Far Detector)

Andy Blake, Cambridge University CC/NC Separation, slide 13

Standard PID:

track PH/ event PH.

track PH/ track planes.

track planes.

Incorporate:

track-like planes.

track fit error. track charge.

reconstructed Y. (replace trk.ph/evt.ph).

pre-selection.

N.B: maximum values of purity*efficiency indicated by stars

Purity vs Efficiency (Far Detector)

Andy Blake, Cambridge University CC/NC Separation, slide 14

Standard PID cutapproximately here!

PID Results (Near Detector)

Andy Blake, Cambridge University CC/NC Separation, slide 15

PID Results (Low Energies)

Andy Blake, Cambridge University CC/NC Separation, slide 16

E < 3 GeV

6 < E < 9 GeV

3 < E < 6 GeV

E > 9 GeV

Summary

Andy Blake, Cambridge University CC/NC Separation, slide 17

• Incorporation of new variables into PID calculation improves purity and efficiency of CC/NC separation in both detectors over all energies.

• This will hopefully improve the sensitivity of the oscillation analysis!

• Possible improvements to this method:

– Separate fully and partially contained events.

– Separate neutrinos and anti-neutrinos.

– Incorporate other topology variables (e.g. pulse height profile of event).

– Incorporate another kinematic variable (e.g. x distribution).